elm-review/tests/Simplify.elm

module Simplify exposing
    ( rule
    , Configuration, defaults, ignoreCaseOfForTypes
    )

{-| Reports when an expression can be simplified.

🔧 Running with `--fix` will automatically remove all the reported errors.

    config =
        [ Simplify.rule Simplify.defaults
        ]

@docs rule
@docs Configuration, defaults, ignoreCaseOfForTypes


## Try it out

You can try this rule out by running the following command:

```bash
elm-review --template jfmengels/elm-review-simplify/example --rules Simplify
```


## Simplifications

Below is the list of all kinds of simplifications this rule applies.


### Booleans

    x || True
    --> True

    x || False
    --> x

    x && True
    --> x

    x && False
    --> False

    not True
    --> False

    not (not x)
    --> x

    not >> not
    --> identity


### Comparisons

    x == True
    --> x

    x /= False
    --> x

    not x == not y
    --> x == y

    anything == anything
    --> True

    anything /= anything
    --> False

    { r | a = 1 } == { r | a = 2 }
    --> False


### If expressions

    if True then x else y
    --> x

    if False then x else y
    --> y

    if condition then x else x
    --> x

    if condition then True else False
    --> condition

    if condition then False else True
    --> not condition


    a =
        if condition then
            if not condition then
                1
            else
                2
        else
            3
    --> if condition then 2 else 3


### Case expressions

    case condition of
        True -> x
        False -> y
    --> if condition then x else y

    case condition of
        False -> y
        True -> x
    --> if not condition then x else y

    -- only when no variables are introduced in the pattern
    -- and no custom types defined in the project are referenced
    case value of
        Just _ -> x
        Nothing -> x
    --> x


### Record updates

    { a | b = a.b }
    --> a

    { a | b = a.b, c = 1 }
    --> { a | c = 1 }


### Field access

    { a = b }.a
    --> b

    { a | b = c }.b
    --> c

    { a | b = c }.d
    --> a.d

    (let a = b in c).d
    --> let a = b in c.d


### Basics functions

    identity x
    --> x

    f >> identity
    --> f

    always x y
    --> x

    f >> always x
    --> always x


### Lambdas

    (\\() -> x) data
    --> x

    (\\() y -> x) data
    --> (\y -> x)

    (\\_ y -> x) data
    --> (\y -> x)


### Operators

    (++) a b
    --> a ++ b


### Numbers

    n + 0
    --> n

    n - 0
    --> n

    0 - n
    --> -n

    n * 1
    --> n

    n * 0
    --> 0

    n / 1
    --> n

    -(-n)
    --> n

    negate >> negate
    --> identity

    negate (negate x)
    --> x


### Strings

    "a" ++ ""
    --> "a"

    String.isEmpty ""
    --> True

    String.isEmpty "a"
    --> False

    String.concat []
    --> ""

    String.join str []
    --> ""

    String.join "" list
    --> String.concat list

    String.length "abc"
    --> 3

    String.repeat n ""
    --> ""

    String.repeat 0 str
    --> ""

    String.repeat 1 str
    --> str

    String.replace x y ""
    --> ""

    String.replace x x z
    --> z

    String.replace "x" "y" "z"
    --> "z" -- only when resulting string is unchanged

    String.words ""
    --> []

    String.lines ""
    --> []

    String.reverse ""
    --> ""

    String.reverse <| String.reverse x
    --> x


### Maybe

    Maybe.map identity x
    --> x

    Maybe.map f Nothing
    --> Nothing

    Maybe.map f (Just x)
    --> Just (f x)

    MaybeThen f Nothing
    --> Nothing

    Maybe.andThen (always Nothing) x
    --> Nothing

    Maybe.andThen (\a -> Just b) x
    --> Maybe.map (\a -> b) x

    Maybe.andThen (\a -> if condition a then Just b else Just c) x
    --> Maybe.map (\a -> if condition a then b else c) x

    Maybe.andThen f (Just x)
    --> f x

    Maybe.withDefault x Nothing
    --> x

    Maybe.withDefault x (Just y)
    --> y


### Result

    Result.map identity x
    --> x.and

    Result.map f (Err x)
    --> Err x

    Result.map f (Ok x)
    --> Ok (f x)

    Result.andThen f (Err x)
    --> Err x

    Result.andThen f (Ok x)
    --> f x

    Result.andThen (\a -> Ok b) x
    --> Result.map (\a -> b) x

    Result.withDefault x (Err y)
    --> x

    Result.withDefault x (Ok y)
    --> y


### Lists

    a :: []
    --> [ a ]

    a :: [ b ]
    --> [ a, b ]

    [ a ] ++ list
    --> a :: list

    [] ++ list
    --> list

    [ a, b ] ++ [ c ]
    --> [ a, b, c ]

    [ a, b ] ++ [ c ]
    --> [ a, b, c ]

    List.map fn [] -- same for most List functions like List.filter, List.filterMap, ...
    --> []

    List.map identity list
    --> list

    List.map identity
    --> identity

    List.filter (always True) list
    --> list

    List.filter (\a -> True) list
    --> list

    List.filter (always False) list
    --> []

    List.filter (always True)
    --> identity

    List.filter (always False)
    --> always []

    List.filterMap Just list
    --> list

    List.filterMap (\a -> Just a) list
    --> list

    List.filterMap Just
    --> identity

    List.filterMap (\a -> if condition a then Just b else Just c) list
    --> List.map (\a -> if condition a then b else c) list

    List.filterMap (always Nothing) list
    --> []

    List.filterMap (always Nothing)
    --> (always [])

    List.filterMap identity (List.map f x)
    --> List.filterMap f x

    List.filterMap identity [ Just x, Just y ]
    --> [ x, y ]


    List.concat [ [ a, b ], [ c ] ]
    --> [ a, b, c ]

    List.concat [ a, [ 1 ], [ 2 ] ]
    --> List.concat [ a, [ 1, 2 ] ]

    List.concatMap identity x
    --> List.concat list

    List.concatMap identity
    --> List.concat

    List.concatMap (\a -> a) list
    --> List.concat list

    List.concatMap (\a -> [ b ]) list
    --> List.map (\a -> b) list

    List.concatMap fn [ x ]
    --> fn x

    List.concatMap (always []) list
    --> []

    List.concat (List.map f x)
    --> List.concatMap f x

    List.indexedMap (\_ value -> f value) list
    --> List.map (\value -> f value) list

    List.isEmpty []
    --> True

    List.isEmpty [ a ]
    --> False

    List.isEmpty (x :: xs)
    --> False

    List.all fn []
    --> True

    List.all (always True) list
    --> True

    List.any fn []
    --> True

    List.any (always False) list
    --> True

    List.range 6 3
    --> []

    List.length [ a ]
    --> 1

    List.repeat 0 list
    --> []

    List.partition fn []
    --> ( [], [] )

    List.partition (always True) list
    --> ( list, [] )


    List.take 0 x
    --> []


    List.drop 0 x
    --> x


    List.reverse <| List.reverse x
    --> x


### Set

    Set.map fn Set.empty -- same for Set.filter, Set.remove...
    --> Set.empty

    Set.map identity set
    --> set

    Set.map identity
    --> identity

    Set.isEmpty Set.empty
    --> True

    Set.member x Set.empty
    --> False

    Set.fromList []
    --> Set.empty

    Set.toList Set.empty
    --> []

    Set.length Set.empty
    --> 0

    Set.intersect Set.empty set
    --> Set.empty

    Set.diff Set.empty set
    --> Set.empty

    Set.diff set Set.empty
    --> set

    Set.union set Set.empty
    --> set

    Set.insert x Set.empty
    --> Set.singleton x

    Set.partition fn Set.empty
    --> ( Set.empty, Set.empty )

    Set.partition (always True) set
    --> ( set, Set.empty )


### Dict

    Dict.isEmpty Dict.empty
    --> True

    Dict.fromList []
    --> Dict.empty

    Dict.toList Dict.empty
    --> []

    Dict.size Dict.empty
    --> 0

    Dict.member x Dict.empty
    --> False


### Cmd / Sub

All of these also apply for `Sub`.

    Cmd.batch []
    --> Cmd.none

    Cmd.batch [ a ]
    --> a

    Cmd.batch [ a, Cmd.none, b ]
    --> Cmd.batch [ a, b ]

    Cmd.map identity cmd
    --> cmd

    Cmd.map fn Cmd.none
    --> Cmd.none


### Json.Decode

    Json.Decode.oneOf [a]
    --> a


### Parser

    Parser.oneOf [a]
    --> a

-}

import Dict exposing (Dict)
import Elm.Docs
import Elm.Syntax.Expression as Expression exposing (Expression, RecordSetter)
import Elm.Syntax.ModuleName exposing (ModuleName)
import Elm.Syntax.Node as Node exposing (Node(..))
import Elm.Syntax.Pattern as Pattern exposing (Pattern)
import Elm.Syntax.Range as Range exposing (Location, Range)
import Review.Fix as Fix exposing (Fix)
import Review.ModuleNameLookupTable as ModuleNameLookupTable exposing (ModuleNameLookupTable)
import Review.Project.Dependency as Dependency exposing (Dependency)
import Review.Rule as Rule exposing (Error, Rule)
import Set exposing (Set)
import Simplify.AstHelpers as AstHelpers
import Simplify.Evaluate as Evaluate
import Simplify.Infer as Infer
import Simplify.Match as Match exposing (Match(..))
import Simplify.Normalize as Normalize
import Simplify.RangeDict as RangeDict exposing (RangeDict)


{-| Rule to simplify Elm code.
-}
rule : Configuration -> Rule
rule (Configuration config) =
    Rule.newProjectRuleSchema "Simplify" initialContext
        |> Rule.withDirectDependenciesProjectVisitor (dependenciesVisitor (Set.fromList config.ignoreConstructors))
        |> Rule.withModuleVisitor moduleVisitor
        |> Rule.withModuleContextUsingContextCreator
            { fromProjectToModule = fromProjectToModule
            , fromModuleToProject = fromModuleToProject
            , foldProjectContexts = \_ previous -> previous
            }
        |> Rule.providesFixesForProjectRule
        |> Rule.fromProjectRuleSchema


moduleVisitor : Rule.ModuleRuleSchema schemaState ModuleContext -> Rule.ModuleRuleSchema { schemaState | hasAtLeastOneVisitor : () } ModuleContext
moduleVisitor schema =
    schema
        |> Rule.withDeclarationEnterVisitor (\node context -> ( [], declarationVisitor node context ))
        |> Rule.withExpressionEnterVisitor expressionVisitor
        |> Rule.withExpressionExitVisitor (\node context -> ( [], expressionExitVisitor node context ))



-- CONFIGURATION


{-| Configuration for this rule. Create a new one with [`defaults`](#defaults) and use [`ignoreCaseOfForTypes`](#ignoreCaseOfForTypes) to alter it.
-}
type Configuration
    = Configuration
        { ignoreConstructors : List String
        }


{-| Default configuration for this rule. Use [`ignoreCaseOfForTypes`](#ignoreCaseOfForTypes) if you want to change the configuration.

    config =
        [ Simplify.defaults
            |> Simplify.ignoreCaseOfForTypes [ "Module.Name.Type" ]
            |> Simplify.rule
        ]

-}
defaults : Configuration
defaults =
    Configuration { ignoreConstructors = [] }


{-| Ignore some reports about types from dependencies used in case expressions.

This rule simplifies the following construct:

    module Module.Name exposing (..)

    case value of
        Just _ -> x
        Nothing -> x
    --> x

(Since `v2.0.19`) it will not try to simplify the case expression when some of the patterns references custom types constructors
defined in the project. It will only do so for custom types that are defined in dependencies (including `elm/core`).

If you do happen to want to disable this simplification for a type `Module.Name.Type`, you can configure the rule like this:

    config =
        [ Simplify.defaults
            |> Simplify.ignoreCaseOfForTypes [ "Module.Name.Type" ]
            |> Simplify.rule
        ]

I personally don't recommend to use this function too much, because this could be a sign of premature abstraction, and because
I think that often [You Aren't Gonna Need this code](https://jfmengels.net/safe-dead-code-removal/#yagni-you-arent-gonna-need-it).

Please let me know by opening an issue if you do use this function, I am very curious to know;

-}
ignoreCaseOfForTypes : List String -> Configuration -> Configuration
ignoreCaseOfForTypes ignoreConstructors (Configuration config) =
    Configuration { config | ignoreConstructors = ignoreConstructors ++ config.ignoreConstructors }



-- CONTEXT


type alias ProjectContext =
    { customTypesToReportInCases : Set ( ModuleName, ConstructorName )
    }


type alias ModuleContext =
    { lookupTable : ModuleNameLookupTable
    , moduleName : ModuleName
    , rangesToIgnore : List Range
    , rightSidesOfPlusPlus : List Range
    , customTypesToReportInCases : Set ( ModuleName, ConstructorName )
    , localIgnoredCustomTypes : List Constructor
    , constructorsToIgnore : Set ( ModuleName, String )
    , inferredConstantsDict : RangeDict Infer.Inferred
    , inferredConstants : ( Infer.Inferred, List Infer.Inferred )
    }


type alias ConstructorName =
    String


type alias Constructor =
    { moduleName : ModuleName
    , name : String
    , constructors : List String
    }


initialContext : ProjectContext
initialContext =
    { customTypesToReportInCases = Set.empty
    }


fromModuleToProject : Rule.ContextCreator ModuleContext ProjectContext
fromModuleToProject =
    Rule.initContextCreator (\_ -> initialContext)


fromProjectToModule : Rule.ContextCreator ProjectContext ModuleContext
fromProjectToModule =
    Rule.initContextCreator
        (\lookupTable metadata projectContext ->
            { lookupTable = lookupTable
            , moduleName = Rule.moduleNameFromMetadata metadata
            , rangesToIgnore = []
            , rightSidesOfPlusPlus = []
            , localIgnoredCustomTypes = []
            , customTypesToReportInCases = projectContext.customTypesToReportInCases
            , constructorsToIgnore = Set.empty
            , inferredConstantsDict = RangeDict.empty
            , inferredConstants = ( Infer.empty, [] )
            }
        )
        |> Rule.withModuleNameLookupTable
        |> Rule.withMetadata



-- DEPENDENCIES VISITOR


dependenciesVisitor : Set String -> Dict String Dependency -> ProjectContext -> ( List (Error scope), ProjectContext )
dependenciesVisitor typeNamesAsStrings dict _ =
    let
        modules : List Elm.Docs.Module
        modules =
            dict
                |> Dict.values
                |> List.concatMap Dependency.modules

        unions : Set String
        unions =
            List.concatMap (\module_ -> List.map (\union -> module_.name ++ "." ++ union.name) module_.unions) modules
                |> Set.fromList

        unknownTypesToIgnore : List String
        unknownTypesToIgnore =
            Set.diff typeNamesAsStrings unions
                |> Set.toList

        customTypesToReportInCases : Set ( ModuleName, String )
        customTypesToReportInCases =
            modules
                |> List.concatMap
                    (\mod ->
                        let
                            moduleName : ModuleName
                            moduleName =
                                String.split "." mod.name
                        in
                        mod.unions
                            |> List.filter (\union -> not (Set.member (mod.name ++ "." ++ union.name) typeNamesAsStrings))
                            |> List.concatMap (\union -> union.tags)
                            |> List.map (\( tagName, _ ) -> ( moduleName, tagName ))
                    )
                |> Set.fromList
    in
    ( if List.isEmpty unknownTypesToIgnore then
        []

      else
        [ errorForUnknownIgnoredConstructor unknownTypesToIgnore ]
    , { customTypesToReportInCases = customTypesToReportInCases }
    )


errorForUnknownIgnoredConstructor : List String -> Error scope
errorForUnknownIgnoredConstructor list =
    Rule.globalError
        { message = "Could not find type names: " ++ (String.join ", " <| List.map wrapInBackticks list)
        , details =
            [ "I expected to find these custom types in the dependencies, but I could not find them."
            , "Please check whether these types and have not been removed, and if so, remove them from the configuration of this rule."
            , "If you find that these types have been moved or renamed, please update your configuration."
            , "Note that I may have provided fixes for things you didn't wish to be fixed, so you might want to undo the changes I have applied."
            , "Also note that the configuration for this rule changed in v2.0.19: types that are custom to your project are ignored by default, so this configuration setting can only be used to avoid simplifying case expressions that use custom types defined in dependencies."
            ]
        }


wrapInBackticks : String -> String
wrapInBackticks s =
    "`" ++ s ++ "`"



-- DECLARATION VISITOR


declarationVisitor : Node a -> ModuleContext -> ModuleContext
declarationVisitor _ context =
    { context
        | rangesToIgnore = []
        , rightSidesOfPlusPlus = []
        , inferredConstantsDict = RangeDict.empty
    }



-- EXPRESSION VISITOR


expressionVisitor : Node Expression -> ModuleContext -> ( List (Error {}), ModuleContext )
expressionVisitor node context =
    let
        newContext : ModuleContext
        newContext =
            case RangeDict.get (Node.range node) context.inferredConstantsDict of
                Just inferredConstants ->
                    let
                        ( previous, previousStack ) =
                            context.inferredConstants
                    in
                    { context | inferredConstants = ( inferredConstants, previous :: previousStack ) }

                Nothing ->
                    context
    in
    if List.member (Node.range node) newContext.rangesToIgnore then
        ( [], newContext )

    else
        let
            { errors, rangesToIgnore, rightSidesOfPlusPlus, inferredConstants } =
                expressionVisitorHelp node newContext
        in
        ( errors
        , { newContext
            | rangesToIgnore = rangesToIgnore ++ newContext.rangesToIgnore
            , rightSidesOfPlusPlus = rightSidesOfPlusPlus ++ newContext.rightSidesOfPlusPlus
            , inferredConstantsDict = List.foldl (\( range, constants ) acc -> RangeDict.insert range constants acc) newContext.inferredConstantsDict inferredConstants
          }
        )


expressionExitVisitor : Node Expression -> ModuleContext -> ModuleContext
expressionExitVisitor node context =
    if RangeDict.member (Node.range node) context.inferredConstantsDict then
        case Tuple.second context.inferredConstants of
            topOfStack :: restOfStack ->
                { context | inferredConstants = ( topOfStack, restOfStack ) }

            [] ->
                -- should never be empty
                context

    else
        context


errorsAndRangesToIgnore : List (Error {}) -> List Range -> { errors : List (Error {}), rangesToIgnore : List Range, rightSidesOfPlusPlus : List Range, inferredConstants : List ( Range, Infer.Inferred ) }
errorsAndRangesToIgnore errors rangesToIgnore =
    { errors = errors
    , rangesToIgnore = rangesToIgnore
    , rightSidesOfPlusPlus = []
    , inferredConstants = []
    }


onlyErrors : List (Error {}) -> { errors : List (Error {}), rangesToIgnore : List Range, rightSidesOfPlusPlus : List Range, inferredConstants : List ( Range, Infer.Inferred ) }
onlyErrors errors =
    { errors = errors
    , rangesToIgnore = []
    , rightSidesOfPlusPlus = []
    , inferredConstants = []
    }


expressionVisitorHelp : Node Expression -> ModuleContext -> { errors : List (Error {}), rangesToIgnore : List Range, rightSidesOfPlusPlus : List Range, inferredConstants : List ( Range, Infer.Inferred ) }
expressionVisitorHelp node context =
    case Node.value node of
        --------------------
        -- FUNCTION CALLS --
        --------------------
        Expression.Application ((Node fnRange (Expression.FunctionOrValue _ fnName)) :: firstArg :: restOfArguments) ->
            case
                ModuleNameLookupTable.moduleNameAt context.lookupTable fnRange
                    |> Maybe.andThen (\moduleName -> Dict.get ( moduleName, fnName ) functionCallChecks)
            of
                Just checkFn ->
                    onlyErrors
                        (checkFn
                            { lookupTable = context.lookupTable
                            , inferredConstants = context.inferredConstants
                            , parentRange = Node.range node
                            , fnRange = fnRange
                            , firstArg = firstArg
                            , secondArg = List.head restOfArguments
                            , thirdArg = List.head (List.drop 1 restOfArguments)
                            , usingRightPizza = False
                            }
                        )

                _ ->
                    onlyErrors []

        -------------------
        -- IF EXPRESSION --
        -------------------
        Expression.IfBlock condition trueBranch falseBranch ->
            ifChecks
                context
                (Node.range node)
                { condition = condition
                , trueBranch = trueBranch
                , falseBranch = falseBranch
                }

        -------------------------------
        --  APPLIED LAMBDA FUNCTIONS --
        -------------------------------
        Expression.Application ((Node _ (Expression.ParenthesizedExpression (Node lambdaRange (Expression.LambdaExpression lambda)))) :: firstArgument :: _) ->
            case lambda.args of
                (Node unitRange Pattern.UnitPattern) :: otherPatterns ->
                    onlyErrors
                        [ Rule.errorWithFix
                            { message = "Unnecessary unit argument"
                            , details =
                                [ "This function is expecting a unit, but also passing it directly."
                                , "Maybe this was made in attempt to make the computation lazy, but in practice the function will be evaluated eagerly."
                                ]
                            }
                            unitRange
                            (case otherPatterns of
                                [] ->
                                    [ Fix.removeRange { start = lambdaRange.start, end = (Node.range lambda.expression).start }
                                    , Fix.removeRange (Node.range firstArgument)
                                    ]

                                secondPattern :: _ ->
                                    [ Fix.removeRange { start = unitRange.start, end = (Node.range secondPattern).start }
                                    , Fix.removeRange (Node.range firstArgument)
                                    ]
                            )
                        ]

                (Node allRange Pattern.AllPattern) :: otherPatterns ->
                    onlyErrors
                        [ Rule.errorWithFix
                            { message = "Unnecessary wildcard argument argument"
                            , details =
                                [ "This function is being passed an argument that is directly ignored."
                                , "Maybe this was made in attempt to make the computation lazy, but in practice the function will be evaluated eagerly."
                                ]
                            }
                            allRange
                            (case otherPatterns of
                                [] ->
                                    [ Fix.removeRange { start = lambdaRange.start, end = (Node.range lambda.expression).start }
                                    , Fix.removeRange (Node.range firstArgument)
                                    ]

                                secondPattern :: _ ->
                                    [ Fix.removeRange { start = allRange.start, end = (Node.range secondPattern).start }
                                    , Fix.removeRange (Node.range firstArgument)
                                    ]
                            )
                        ]

                _ ->
                    onlyErrors []

        -----------------------------------
        -- FULLY APPLIED PREFIX OPERATOR --
        -----------------------------------
        Expression.Application [ Node.Node operatorRange (Expression.PrefixOperator operator), left, right ] ->
            onlyErrors
                [ Rule.errorWithFix
                    { message = "Use the infix form (a + b) over the prefix form ((+) a b)"
                    , details = [ "The prefix form is generally more unfamiliar to Elm developers, and therefore it is nicer when the infix form is used." ]
                    }
                    operatorRange
                    [ Fix.removeRange { start = operatorRange.start, end = (Node.range left).start }
                    , Fix.insertAt (Node.range right).start (operator ++ " ")
                    ]
                ]

        -------------------
        -- RECORD UPDATE --
        -------------------
        Expression.RecordUpdateExpression variable fields ->
            onlyErrors (removeRecordFields (Node.range node) variable fields)

        -------------
        -- CASE OF --
        -------------
        Expression.CaseExpression caseBlock ->
            onlyErrors (caseOfChecks context (Node.range node) caseBlock)

        ----------
        -- (<|) --
        ----------
        Expression.OperatorApplication "<|" _ (Node fnRange (Expression.FunctionOrValue _ fnName)) firstArg ->
            case
                ModuleNameLookupTable.moduleNameAt context.lookupTable fnRange
                    |> Maybe.andThen (\moduleName -> Dict.get ( moduleName, fnName ) functionCallChecks)
            of
                Just checkFn ->
                    onlyErrors
                        (checkFn
                            { lookupTable = context.lookupTable
                            , inferredConstants = context.inferredConstants
                            , parentRange = Node.range node
                            , fnRange = fnRange
                            , firstArg = firstArg
                            , secondArg = Nothing
                            , thirdArg = Nothing
                            , usingRightPizza = False
                            }
                        )

                _ ->
                    onlyErrors []

        Expression.OperatorApplication "<|" _ (Node applicationRange (Expression.Application ((Node fnRange (Expression.FunctionOrValue _ fnName)) :: firstArg :: []))) secondArgument ->
            case
                ModuleNameLookupTable.moduleNameAt context.lookupTable fnRange
                    |> Maybe.andThen (\moduleName -> Dict.get ( moduleName, fnName ) functionCallChecks)
            of
                Just checkFn ->
                    errorsAndRangesToIgnore
                        (checkFn
                            { lookupTable = context.lookupTable
                            , inferredConstants = context.inferredConstants
                            , parentRange = Node.range node
                            , fnRange = fnRange
                            , firstArg = firstArg
                            , secondArg = Just secondArgument
                            , thirdArg = Nothing
                            , usingRightPizza = False
                            }
                        )
                        [ applicationRange ]

                _ ->
                    onlyErrors []

        ----------
        -- (|>) --
        ----------
        Expression.OperatorApplication "|>" _ firstArg (Node fnRange (Expression.FunctionOrValue _ fnName)) ->
            case
                ModuleNameLookupTable.moduleNameAt context.lookupTable fnRange
                    |> Maybe.andThen (\moduleName -> Dict.get ( moduleName, fnName ) functionCallChecks)
            of
                Just checkFn ->
                    onlyErrors
                        (checkFn
                            { lookupTable = context.lookupTable
                            , inferredConstants = context.inferredConstants
                            , parentRange = Node.range node
                            , fnRange = fnRange
                            , firstArg = firstArg
                            , secondArg = Nothing
                            , thirdArg = Nothing
                            , usingRightPizza = True
                            }
                        )

                _ ->
                    onlyErrors []

        Expression.OperatorApplication "|>" _ secondArgument (Node applicationRange (Expression.Application ((Node fnRange (Expression.FunctionOrValue _ fnName)) :: firstArg :: []))) ->
            case
                ModuleNameLookupTable.moduleNameAt context.lookupTable fnRange
                    |> Maybe.andThen (\moduleName -> Dict.get ( moduleName, fnName ) functionCallChecks)
            of
                Just checkFn ->
                    errorsAndRangesToIgnore
                        (checkFn
                            { lookupTable = context.lookupTable
                            , inferredConstants = context.inferredConstants
                            , parentRange = Node.range node
                            , fnRange = fnRange
                            , firstArg = firstArg
                            , secondArg = Just secondArgument
                            , thirdArg = Nothing
                            , usingRightPizza = True
                            }
                        )
                        [ applicationRange ]

                _ ->
                    onlyErrors []

        Expression.OperatorApplication ">>" _ left (Node _ (Expression.OperatorApplication ">>" _ right _)) ->
            onlyErrors
                (firstThatReportsError compositionChecks
                    { lookupTable = context.lookupTable
                    , fromLeftToRight = True
                    , parentRange = { start = (Node.range left).start, end = (Node.range right).end }
                    , left = left
                    , leftRange = Node.range left
                    , right = right
                    , rightRange = Node.range right
                    }
                )

        Expression.OperatorApplication ">>" _ left right ->
            onlyErrors
                (firstThatReportsError compositionChecks
                    { lookupTable = context.lookupTable
                    , fromLeftToRight = True
                    , parentRange = Node.range node
                    , left = left
                    , leftRange = Node.range left
                    , right = right
                    , rightRange = Node.range right
                    }
                )

        Expression.OperatorApplication "<<" _ (Node _ (Expression.OperatorApplication "<<" _ _ left)) right ->
            onlyErrors
                (firstThatReportsError compositionChecks
                    { lookupTable = context.lookupTable
                    , fromLeftToRight = False
                    , parentRange = { start = (Node.range left).start, end = (Node.range right).end }
                    , left = left
                    , leftRange = Node.range left
                    , right = right
                    , rightRange = Node.range right
                    }
                )

        Expression.OperatorApplication "<<" _ left right ->
            onlyErrors
                (firstThatReportsError compositionChecks
                    { lookupTable = context.lookupTable
                    , fromLeftToRight = False
                    , parentRange = Node.range node
                    , left = left
                    , leftRange = Node.range left
                    , right = right
                    , rightRange = Node.range right
                    }
                )

        Expression.OperatorApplication operator _ left right ->
            case Dict.get operator operatorChecks of
                Just checkFn ->
                    { errors =
                        checkFn
                            { lookupTable = context.lookupTable
                            , inferredConstants = context.inferredConstants
                            , parentRange = Node.range node
                            , operator = operator
                            , left = left
                            , leftRange = Node.range left
                            , right = right
                            , rightRange = Node.range right
                            , isOnTheRightSideOfPlusPlus = List.member (Node.range node) context.rightSidesOfPlusPlus
                            }
                    , rangesToIgnore = []
                    , rightSidesOfPlusPlus =
                        if operator == "++" then
                            [ Node.range <| AstHelpers.removeParens right ]

                        else
                            []
                    , inferredConstants = []
                    }

                Nothing ->
                    onlyErrors []

        Expression.Negation baseExpr ->
            case AstHelpers.removeParens baseExpr of
                Node range (Expression.Negation negatedValue) ->
                    let
                        doubleNegationRange : Range
                        doubleNegationRange =
                            { start = (Node.range node).start
                            , end = { row = range.start.row, column = range.start.column + 1 }
                            }
                    in
                    onlyErrors
                        [ Rule.errorWithFix
                            { message = "Unnecessary double number negation"
                            , details = [ "Negating a number twice is the same as the number itself." ]
                            }
                            doubleNegationRange
                            (replaceBySubExpressionFix (Node.range node) negatedValue)
                        ]

                _ ->
                    onlyErrors []

        Expression.RecordAccess record field ->
            case Node.value (AstHelpers.removeParens record) of
                Expression.RecordExpr setters ->
                    onlyErrors (recordAccessChecks (Node.range node) Nothing (Node.value field) setters)

                Expression.RecordUpdateExpression (Node recordNameRange _) setters ->
                    onlyErrors (recordAccessChecks (Node.range node) (Just recordNameRange) (Node.value field) setters)

                Expression.LetExpression { expression } ->
                    onlyErrors (recordAccessLetInChecks (Node.range node) field expression)

                _ ->
                    onlyErrors []

        _ ->
            onlyErrors []


recordAccessChecks : Range -> Maybe Range -> String -> List (Node RecordSetter) -> List (Error {})
recordAccessChecks nodeRange recordNameRange fieldName setters =
    case
        findMap
            (\(Node _ ( setterField, setterValue )) ->
                if Node.value setterField == fieldName then
                    Just setterValue

                else
                    Nothing
            )
            setters
    of
        Just setter ->
            [ Rule.errorWithFix
                { message = "Field access can be simplified"
                , details = [ "Accessing the field of a record or record update can be simplified to just that field's value" ]
                }
                nodeRange
                (replaceBySubExpressionFix nodeRange setter)
            ]

        Nothing ->
            case recordNameRange of
                Just rnr ->
                    [ Rule.errorWithFix
                        { message = "Field access can be simplified"
                        , details = [ "Accessing the field of an unrelated record update can be simplified to just the original field's value" ]
                        }
                        nodeRange
                        [ Fix.replaceRangeBy { start = nodeRange.start, end = rnr.start } ""
                        , Fix.replaceRangeBy { start = rnr.end, end = nodeRange.end } ("." ++ fieldName)
                        ]
                    ]

                Nothing ->
                    []


replaceBySubExpressionFix : Range -> Node Expression -> List Fix
replaceBySubExpressionFix outerRange (Node exprRange exprValue) =
    if needsParens exprValue then
        [ Fix.replaceRangeBy { start = outerRange.start, end = exprRange.start } "("
        , Fix.replaceRangeBy { start = exprRange.end, end = outerRange.end } ")"
        ]

    else
        [ Fix.removeRange { start = outerRange.start, end = exprRange.start }
        , Fix.removeRange { start = exprRange.end, end = outerRange.end }
        ]


needsParens : Expression -> Bool
needsParens expr =
    case expr of
        Expression.Application _ ->
            True

        Expression.OperatorApplication _ _ _ _ ->
            True

        Expression.IfBlock _ _ _ ->
            True

        Expression.Negation _ ->
            True

        Expression.LetExpression _ ->
            True

        Expression.CaseExpression _ ->
            True

        Expression.LambdaExpression _ ->
            True

        _ ->
            False


recordAccessLetInChecks : Range -> Node String -> Node Expression -> List (Error {})
recordAccessLetInChecks nodeRange (Node fieldRange fieldName) expr =
    let
        fieldRangeStart : Location
        fieldRangeStart =
            fieldRange.start

        fieldRemovalFix : Fix
        fieldRemovalFix =
            Fix.removeRange
                { start = { row = fieldRangeStart.row, column = fieldRangeStart.column - 1 }
                , end = fieldRange.end
                }
    in
    [ Rule.errorWithFix
        { message = "Field access can be simplified"
        , details = [ "Accessing the field outside a let expression can be simplified to access the field inside it" ]
        }
        nodeRange
        (if needsParens (Node.value expr) then
            [ Fix.insertAt (Node.range expr).start "("
            , Fix.insertAt (Node.range expr).end (")." ++ fieldName)
            , fieldRemovalFix
            ]

         else
            [ Fix.insertAt (Node.range expr).end ("." ++ fieldName)
            , fieldRemovalFix
            ]
        )
    ]


type alias CheckInfo =
    { lookupTable : ModuleNameLookupTable
    , inferredConstants : ( Infer.Inferred, List Infer.Inferred )
    , parentRange : Range
    , fnRange : Range
    , firstArg : Node Expression
    , secondArg : Maybe (Node Expression)
    , thirdArg : Maybe (Node Expression)
    , usingRightPizza : Bool
    }


functionCallChecks : Dict ( ModuleName, String ) (CheckInfo -> List (Error {}))
functionCallChecks =
    Dict.fromList
        [ ( ( [ "Basics" ], "identity" ), basicsIdentityChecks )
        , ( ( [ "Basics" ], "always" ), basicsAlwaysChecks )
        , ( ( [ "Basics" ], "not" ), basicsNotChecks )
        , ( ( [ "Basics" ], "negate" ), basicsNegateChecks )
        , ( ( [ "Maybe" ], "map" ), maybeMapChecks )
        , ( ( [ "Maybe" ], "andThen" ), maybeAndThenChecks )
        , ( ( [ "Maybe" ], "withDefault" ), maybeWithDefaultChecks )
        , ( ( [ "Result" ], "map" ), resultMapChecks )
        , ( ( [ "Result" ], "andThen" ), resultAndThenChecks )
        , ( ( [ "Result" ], "withDefault" ), resultWithDefaultChecks )
        , ( ( [ "List" ], "map" ), collectionMapChecks listCollection )
        , ( ( [ "List" ], "filter" ), collectionFilterChecks listCollection )
        , reportEmptyListSecondArgument ( ( [ "List" ], "filterMap" ), listFilterMapChecks )
        , reportEmptyListFirstArgument ( ( [ "List" ], "concat" ), listConcatChecks )
        , reportEmptyListSecondArgument ( ( [ "List" ], "concatMap" ), listConcatMapChecks )
        , reportEmptyListSecondArgument ( ( [ "List" ], "indexedMap" ), listIndexedMapChecks )
        , reportEmptyListSecondArgument ( ( [ "List" ], "intersperse" ), listIndexedMapChecks )
        , ( ( [ "List" ], "all" ), listAllChecks )
        , ( ( [ "List" ], "any" ), listAnyChecks )
        , ( ( [ "List" ], "range" ), listRangeChecks )
        , ( ( [ "List" ], "length" ), collectionSizeChecks listCollection )
        , ( ( [ "List" ], "repeat" ), listRepeatChecks )
        , ( ( [ "List" ], "isEmpty" ), collectionIsEmptyChecks listCollection )
        , ( ( [ "List" ], "partition" ), collectionPartitionChecks listCollection )
        , ( ( [ "List" ], "reverse" ), listReverseChecks )
        , ( ( [ "List" ], "take" ), listTakeChecks )
        , ( ( [ "List" ], "drop" ), listDropChecks )
        , ( ( [ "List" ], "member" ), collectionMemberChecks listCollection )
        , ( ( [ "Set" ], "map" ), collectionMapChecks setCollection )
        , ( ( [ "Set" ], "filter" ), collectionFilterChecks setCollection )
        , ( ( [ "Set" ], "remove" ), collectionRemoveChecks setCollection )
        , ( ( [ "Set" ], "isEmpty" ), collectionIsEmptyChecks setCollection )
        , ( ( [ "Set" ], "size" ), collectionSizeChecks setCollection )
        , ( ( [ "Set" ], "member" ), collectionMemberChecks setCollection )
        , ( ( [ "Set" ], "fromList" ), collectionFromListChecks setCollection )
        , ( ( [ "Set" ], "toList" ), collectionToListChecks setCollection )
        , ( ( [ "Set" ], "partition" ), collectionPartitionChecks setCollection )
        , ( ( [ "Set" ], "intersect" ), collectionIntersectChecks setCollection )
        , ( ( [ "Set" ], "diff" ), collectionDiffChecks setCollection )
        , ( ( [ "Set" ], "union" ), collectionUnionChecks setCollection )
        , ( ( [ "Set" ], "insert" ), collectionInsertChecks setCollection )
        , ( ( [ "Dict" ], "isEmpty" ), collectionIsEmptyChecks dictCollection )
        , ( ( [ "Dict" ], "fromList" ), collectionFromListChecks dictCollection )
        , ( ( [ "Dict" ], "toList" ), collectionToListChecks dictCollection )
        , ( ( [ "Dict" ], "size" ), collectionSizeChecks dictCollection )
        , ( ( [ "Dict" ], "member" ), collectionMemberChecks dictCollection )
        , ( ( [ "String" ], "isEmpty" ), stringIsEmptyChecks )
        , ( ( [ "String" ], "concat" ), stringConcatChecks )
        , ( ( [ "String" ], "join" ), stringJoinChecks )
        , ( ( [ "String" ], "length" ), stringLengthChecks )
        , ( ( [ "String" ], "repeat" ), stringRepeatChecks )
        , ( ( [ "String" ], "replace" ), stringReplaceChecks )
        , ( ( [ "String" ], "words" ), stringWordsChecks )
        , ( ( [ "String" ], "lines" ), stringLinesChecks )
        , ( ( [ "String" ], "reverse" ), stringReverseChecks )
        , ( ( [ "Platform", "Cmd" ], "batch" ), subAndCmdBatchChecks "Cmd" )
        , ( ( [ "Platform", "Cmd" ], "map" ), collectionMapChecks cmdCollection )
        , ( ( [ "Platform", "Sub" ], "batch" ), subAndCmdBatchChecks "Sub" )
        , ( ( [ "Platform", "Sub" ], "map" ), collectionMapChecks subCollection )
        , ( ( [ "Json", "Decode" ], "oneOf" ), oneOfChecks )
        , ( ( [ "Parser" ], "oneOf" ), oneOfChecks )
        , ( ( [ "Parser", "Advanced" ], "oneOf" ), oneOfChecks )
        ]


type alias OperatorCheckInfo =
    { lookupTable : ModuleNameLookupTable
    , inferredConstants : ( Infer.Inferred, List Infer.Inferred )
    , parentRange : Range
    , operator : String
    , left : Node Expression
    , leftRange : Range
    , right : Node Expression
    , rightRange : Range
    , isOnTheRightSideOfPlusPlus : Bool
    }


operatorChecks : Dict String (OperatorCheckInfo -> List (Error {}))
operatorChecks =
    Dict.fromList
        [ ( "+", plusChecks )
        , ( "-", minusChecks )
        , ( "*", multiplyChecks )
        , ( "/", divisionChecks )
        , ( "++", plusplusChecks )
        , ( "::", consChecks )
        , ( "||", orChecks )
        , ( "&&", andChecks )
        , ( "==", equalityChecks True )
        , ( "/=", equalityChecks False )
        , ( "<", comparisonChecks (<) )
        , ( ">", comparisonChecks (>) )
        , ( "<=", comparisonChecks (<=) )
        , ( ">=", comparisonChecks (>=) )
        ]


type alias CompositionCheckInfo =
    { lookupTable : ModuleNameLookupTable
    , fromLeftToRight : Bool
    , parentRange : Range
    , left : Node Expression
    , leftRange : Range
    , right : Node Expression
    , rightRange : Range
    }


firstThatReportsError : List (a -> List (Error {})) -> a -> List (Error {})
firstThatReportsError remainingChecks data =
    case remainingChecks of
        [] ->
            []

        checkFn :: restOfFns ->
            case checkFn data of
                [] ->
                    firstThatReportsError restOfFns data

                errors ->
                    errors


compositionChecks : List (CompositionCheckInfo -> List (Error {}))
compositionChecks =
    [ identityCompositionCheck
    , notNotCompositionCheck
    , negateCompositionCheck
    , alwaysCompositionCheck
    , maybeMapCompositionChecks
    , resultMapCompositionChecks
    , filterAndMapCompositionCheck
    , concatAndMapCompositionCheck
    ]


removeAlongWithOtherFunctionCheck :
    { message : String, details : List String }
    -> (ModuleNameLookupTable -> Node Expression -> Maybe Range)
    -> CheckInfo
    -> List (Error {})
removeAlongWithOtherFunctionCheck errorMessage secondFunctionCheck checkInfo =
    case Node.value (AstHelpers.removeParens checkInfo.firstArg) of
        Expression.Application (secondFn :: firstArgOfSecondCall :: _) ->
            case secondFunctionCheck checkInfo.lookupTable secondFn of
                Just secondRange ->
                    [ Rule.errorWithFix
                        errorMessage
                        (Range.combine [ checkInfo.fnRange, secondRange ])
                        [ removeFunctionFromFunctionCall checkInfo
                        , removeFunctionFromFunctionCall
                            { fnRange = Node.range secondFn
                            , firstArg = firstArgOfSecondCall
                            , usingRightPizza = False
                            }
                        ]
                    ]

                Nothing ->
                    []

        Expression.OperatorApplication "|>" _ firstArgOfSecondCall secondFn ->
            case secondFunctionCheck checkInfo.lookupTable secondFn of
                Just secondRange ->
                    [ Rule.errorWithFix
                        errorMessage
                        (Range.combine [ checkInfo.fnRange, secondRange ])
                        [ removeFunctionFromFunctionCall checkInfo
                        , removeFunctionFromFunctionCall
                            { fnRange = Node.range secondFn
                            , firstArg = firstArgOfSecondCall
                            , usingRightPizza = True
                            }
                        ]
                    ]

                Nothing ->
                    []

        Expression.OperatorApplication "<|" _ secondFn firstArgOfSecondCall ->
            case secondFunctionCheck checkInfo.lookupTable secondFn of
                Just secondRange ->
                    [ Rule.errorWithFix
                        errorMessage
                        (Range.combine [ checkInfo.fnRange, secondRange ])
                        [ removeFunctionFromFunctionCall checkInfo
                        , removeFunctionFromFunctionCall
                            { fnRange = Node.range secondFn
                            , firstArg = firstArgOfSecondCall
                            , usingRightPizza = False
                            }
                        ]
                    ]

                Nothing ->
                    []

        _ ->
            []


plusChecks : OperatorCheckInfo -> List (Error {})
plusChecks { leftRange, rightRange, left, right } =
    findMap
        (\( node, getRange ) ->
            if getUncomputedNumberValue node == Just 0 then
                Just
                    [ Rule.errorWithFix
                        { message = "Unnecessary addition with 0"
                        , details = [ "Adding 0 does not change the value of the number." ]
                        }
                        (getRange ())
                        [ Fix.removeRange (getRange ()) ]
                    ]

            else
                Nothing
        )
        [ ( right, \() -> { start = leftRange.end, end = rightRange.end } )
        , ( left, \() -> { start = leftRange.start, end = rightRange.start } )
        ]
        |> Maybe.withDefault []


minusChecks : OperatorCheckInfo -> List (Error {})
minusChecks { leftRange, rightRange, left, right } =
    if getUncomputedNumberValue right == Just 0 then
        let
            range : Range
            range =
                { start = leftRange.end, end = rightRange.end }
        in
        [ Rule.errorWithFix
            { message = "Unnecessary subtraction with 0"
            , details = [ "Subtracting 0 does not change the value of the number." ]
            }
            range
            [ Fix.removeRange range ]
        ]

    else if getUncomputedNumberValue left == Just 0 then
        let
            range : Range
            range =
                { start = leftRange.start, end = rightRange.start }
        in
        [ Rule.errorWithFix
            { message = "Unnecessary subtracting from 0"
            , details = [ "You can negate the expression on the right like `-n`." ]
            }
            range
            [ Fix.replaceRangeBy range "-" ]
        ]

    else
        []


multiplyChecks : OperatorCheckInfo -> List (Error {})
multiplyChecks { parentRange, leftRange, rightRange, left, right } =
    findMap
        (\( node, getRange ) ->
            case getUncomputedNumberValue node of
                Just value ->
                    if value == 1 then
                        Just
                            [ Rule.errorWithFix
                                { message = "Unnecessary multiplication by 1"
                                , details = [ "Multiplying by 1 does not change the value of the number." ]
                                }
                                (getRange ())
                                [ Fix.removeRange (getRange ()) ]
                            ]

                    else if value == 0 then
                        Just
                            [ Rule.errorWithFix
                                { message = "Multiplying by 0 equals 0"
                                , details = [ "You can replace this value by 0." ]
                                }
                                (getRange ())
                                [ Fix.replaceRangeBy parentRange "0" ]
                            ]

                    else
                        Nothing

                _ ->
                    Nothing
        )
        [ ( right, \() -> { start = leftRange.end, end = rightRange.end } )
        , ( left, \() -> { start = leftRange.start, end = rightRange.start } )
        ]
        |> Maybe.withDefault []


divisionChecks : OperatorCheckInfo -> List (Error {})
divisionChecks { leftRange, rightRange, right } =
    if getUncomputedNumberValue right == Just 1 then
        let
            range : Range
            range =
                { start = leftRange.end, end = rightRange.end }
        in
        [ Rule.errorWithFix
            { message = "Unnecessary division by 1"
            , details = [ "Dividing by 1 does not change the value of the number." ]
            }
            range
            [ Fix.removeRange range ]
        ]

    else
        []


findMap : (a -> Maybe b) -> List a -> Maybe b
findMap mapper nodes =
    case nodes of
        [] ->
            Nothing

        node :: rest ->
            case mapper node of
                Just value ->
                    Just value

                Nothing ->
                    findMap mapper rest


plusplusChecks : OperatorCheckInfo -> List (Error {})
plusplusChecks { parentRange, leftRange, rightRange, left, right, isOnTheRightSideOfPlusPlus } =
    case ( Node.value left, Node.value right ) of
        ( Expression.Literal "", Expression.Literal _ ) ->
            [ errorForAddingEmptyStrings leftRange
                { start = leftRange.start
                , end = rightRange.start
                }
            ]

        ( Expression.Literal _, Expression.Literal "" ) ->
            [ errorForAddingEmptyStrings rightRange
                { start = leftRange.end
                , end = rightRange.end
                }
            ]

        ( Expression.ListExpr [], _ ) ->
            [ errorForAddingEmptyLists leftRange
                { start = leftRange.start
                , end = rightRange.start
                }
            ]

        ( _, Expression.ListExpr [] ) ->
            [ errorForAddingEmptyLists rightRange
                { start = leftRange.end
                , end = rightRange.end
                }
            ]

        ( Expression.ListExpr _, Expression.ListExpr _ ) ->
            [ Rule.errorWithFix
                { message = "Expression could be simplified to be a single List"
                , details = [ "Try moving all the elements into a single list." ]
                }
                parentRange
                [ Fix.replaceRangeBy
                    { start = { row = leftRange.end.row, column = leftRange.end.column - 1 }
                    , end = { row = rightRange.start.row, column = rightRange.start.column + 1 }
                    }
                    ","
                ]
            ]

        ( Expression.ListExpr [ listElement ], _ ) ->
            if isOnTheRightSideOfPlusPlus then
                []

            else
                [ Rule.errorWithFix
                    { message = "Should use (::) instead of (++)"
                    , details = [ "Concatenating a list with a single value is the same as using (::) on the list with the value." ]
                    }
                    parentRange
                    (Fix.replaceRangeBy
                        { start = leftRange.end
                        , end = rightRange.start
                        }
                        " :: "
                        :: replaceBySubExpressionFix leftRange listElement
                    )
                ]

        _ ->
            []


errorForAddingEmptyStrings : Range -> Range -> Error {}
errorForAddingEmptyStrings range rangeToRemove =
    Rule.errorWithFix
        { message = "Unnecessary concatenation with an empty string"
        , details = [ "You should remove the concatenation with the empty string." ]
        }
        range
        [ Fix.removeRange rangeToRemove ]


errorForAddingEmptyLists : Range -> Range -> Error {}
errorForAddingEmptyLists range rangeToRemove =
    Rule.errorWithFix
        { message = "Concatenating with a single list doesn't have any effect"
        , details = [ "You should remove the concatenation with the empty list." ]
        }
        range
        [ Fix.removeRange rangeToRemove ]


consChecks : OperatorCheckInfo -> List (Error {})
consChecks { right, leftRange, rightRange } =
    case Node.value right of
        Expression.ListExpr [] ->
            [ Rule.errorWithFix
                { message = "Element added to the beginning of the list could be included in the list"
                , details = [ "Try moving the element inside the list it is being added to." ]
                }
                leftRange
                [ Fix.insertAt leftRange.start "[ "
                , Fix.replaceRangeBy
                    { start = leftRange.end
                    , end = rightRange.end
                    }
                    " ]"
                ]
            ]

        Expression.ListExpr _ ->
            [ Rule.errorWithFix
                { message = "Element added to the beginning of the list could be included in the list"
                , details = [ "Try moving the element inside the list it is being added to." ]
                }
                leftRange
                [ Fix.insertAt leftRange.start "[ "
                , Fix.replaceRangeBy
                    { start = leftRange.end
                    , end = { row = rightRange.start.row, column = rightRange.start.column + 1 }
                    }
                    ","
                ]
            ]

        _ ->
            []



-- NUMBERS


negateNegateCompositionErrorMessage : { message : String, details : List String }
negateNegateCompositionErrorMessage =
    { message = "Unnecessary double negation"
    , details = [ "Composing `negate` with `negate` cancel each other out." ]
    }


negateCompositionCheck : CompositionCheckInfo -> List (Error {})
negateCompositionCheck { lookupTable, fromLeftToRight, parentRange, left, right, leftRange, rightRange } =
    case Maybe.map2 Tuple.pair (getNegateFunction lookupTable left) (getNegateFunction lookupTable right) of
        Just _ ->
            [ Rule.errorWithFix
                negateNegateCompositionErrorMessage
                parentRange
                [ Fix.replaceRangeBy parentRange "identity" ]
            ]

        _ ->
            case getNegateFunction lookupTable left of
                Just leftNotRange ->
                    case getNegateComposition lookupTable fromLeftToRight right of
                        Just rightNotRange ->
                            [ Rule.errorWithFix
                                negateNegateCompositionErrorMessage
                                { start = leftNotRange.start, end = rightNotRange.end }
                                [ Fix.removeRange { start = leftNotRange.start, end = rightRange.start }
                                , Fix.removeRange rightNotRange
                                ]
                            ]

                        Nothing ->
                            []

                Nothing ->
                    case getNegateFunction lookupTable right of
                        Just rightNotRange ->
                            case getNegateComposition lookupTable (not fromLeftToRight) left of
                                Just leftNotRange ->
                                    [ Rule.errorWithFix
                                        negateNegateCompositionErrorMessage
                                        { start = leftNotRange.start, end = rightNotRange.end }
                                        [ Fix.removeRange leftNotRange
                                        , Fix.removeRange { start = leftRange.end, end = rightNotRange.end }
                                        ]
                                    ]

                                Nothing ->
                                    []

                        Nothing ->
                            []


getNegateComposition : ModuleNameLookupTable -> Bool -> Node Expression -> Maybe Range
getNegateComposition lookupTable takeFirstFunction node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.OperatorApplication "<<" _ left right ->
            if takeFirstFunction then
                getNegateFunction lookupTable right
                    |> Maybe.map (\_ -> { start = (Node.range left).end, end = (Node.range right).end })

            else
                getNegateFunction lookupTable left
                    |> Maybe.map (\_ -> { start = (Node.range left).start, end = (Node.range right).start })

        Expression.OperatorApplication ">>" _ left right ->
            if takeFirstFunction then
                getNegateFunction lookupTable left
                    |> Maybe.map (\_ -> { start = (Node.range left).start, end = (Node.range right).start })

            else
                getNegateFunction lookupTable right
                    |> Maybe.map (\_ -> { start = (Node.range left).end, end = (Node.range right).end })

        _ ->
            Nothing


basicsNegateChecks : CheckInfo -> List (Error {})
basicsNegateChecks checkInfo =
    removeAlongWithOtherFunctionCheck negateNegateCompositionErrorMessage getNegateFunction checkInfo


getNegateFunction : ModuleNameLookupTable -> Node Expression -> Maybe Range
getNegateFunction lookupTable baseNode =
    case AstHelpers.removeParens baseNode of
        Node range (Expression.FunctionOrValue _ "negate") ->
            case ModuleNameLookupTable.moduleNameAt lookupTable range of
                Just [ "Basics" ] ->
                    Just range

                _ ->
                    Nothing

        _ ->
            Nothing



-- BOOLEAN


basicsNotChecks : CheckInfo -> List (Error {})
basicsNotChecks checkInfo =
    case Evaluate.getBoolean checkInfo checkInfo.firstArg of
        Determined bool ->
            [ Rule.errorWithFix
                { message = "Expression is equal to " ++ boolToString (not bool)
                , details = [ "You can replace the call to `not` by the boolean value directly." ]
                }
                checkInfo.parentRange
                [ Fix.replaceRangeBy checkInfo.parentRange (boolToString (not bool)) ]
            ]

        Undetermined ->
            removeAlongWithOtherFunctionCheck notNotCompositionErrorMessage getNotFunction checkInfo


notNotCompositionCheck : CompositionCheckInfo -> List (Error {})
notNotCompositionCheck { lookupTable, fromLeftToRight, parentRange, left, right, leftRange, rightRange } =
    let
        notOnLeft : Maybe Range
        notOnLeft =
            getNotFunction lookupTable left

        notOnRight : Maybe Range
        notOnRight =
            getNotFunction lookupTable right
    in
    case ( notOnLeft, notOnRight ) of
        ( Just _, Just _ ) ->
            [ Rule.errorWithFix
                notNotCompositionErrorMessage
                parentRange
                [ Fix.replaceRangeBy parentRange "identity" ]
            ]

        ( Just leftNotRange, _ ) ->
            case getNotComposition lookupTable fromLeftToRight right of
                Just rightNotRange ->
                    [ Rule.errorWithFix
                        notNotCompositionErrorMessage
                        { start = leftNotRange.start, end = rightNotRange.end }
                        [ Fix.removeRange { start = leftNotRange.start, end = rightRange.start }
                        , Fix.removeRange rightNotRange
                        ]
                    ]

                Nothing ->
                    []

        ( _, Just rightNotRange ) ->
            case getNotComposition lookupTable (not fromLeftToRight) left of
                Just leftNotRange ->
                    [ Rule.errorWithFix
                        notNotCompositionErrorMessage
                        { start = leftNotRange.start, end = rightNotRange.end }
                        [ Fix.removeRange leftNotRange
                        , Fix.removeRange { start = leftRange.end, end = rightNotRange.end }
                        ]
                    ]

                Nothing ->
                    []

        _ ->
            []


notNotCompositionErrorMessage : { message : String, details : List String }
notNotCompositionErrorMessage =
    { message = "Unnecessary double negation"
    , details = [ "Composing `not` with `not` cancel each other out." ]
    }


getNotComposition : ModuleNameLookupTable -> Bool -> Node Expression -> Maybe Range
getNotComposition lookupTable takeFirstFunction node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.OperatorApplication "<<" _ left right ->
            if takeFirstFunction then
                getNotFunction lookupTable right
                    |> Maybe.map (\_ -> { start = (Node.range left).end, end = (Node.range right).end })

            else
                getNotFunction lookupTable left
                    |> Maybe.map (\_ -> { start = (Node.range left).start, end = (Node.range right).start })

        Expression.OperatorApplication ">>" _ left right ->
            if takeFirstFunction then
                getNotFunction lookupTable left
                    |> Maybe.map (\_ -> { start = (Node.range left).start, end = (Node.range right).start })

            else
                getNotFunction lookupTable right
                    |> Maybe.map (\_ -> { start = (Node.range left).end, end = (Node.range right).end })

        _ ->
            Nothing


orChecks : OperatorCheckInfo -> List (Error {})
orChecks operatorCheckInfo =
    firstThatReportsError
        [ \() ->
            List.concat
                [ or_isLeftSimplifiableError operatorCheckInfo
                , or_isRightSimplifiableError operatorCheckInfo
                ]
        , \() -> findSimilarConditionsError operatorCheckInfo
        ]
        ()


type RedundantConditionResolution
    = RemoveFrom Location
    | ReplaceByNoop Bool


findSimilarConditionsError : OperatorCheckInfo -> List (Error {})
findSimilarConditionsError operatorCheckInfo =
    let
        conditionsOnTheRight : List ( RedundantConditionResolution, Node Expression )
        conditionsOnTheRight =
            listConditions
                operatorCheckInfo.operator
                (RemoveFrom operatorCheckInfo.leftRange.end)
                operatorCheckInfo.right

        errorsForNode : Node Expression -> List (Error {})
        errorsForNode nodeToCompareTo =
            List.concatMap
                (areSimilarConditionsError
                    operatorCheckInfo
                    operatorCheckInfo.operator
                    nodeToCompareTo
                )
                conditionsOnTheRight
    in
    operatorCheckInfo.left
        |> listConditions operatorCheckInfo.operator (RemoveFrom operatorCheckInfo.leftRange.end)
        |> List.concatMap (Tuple.second >> errorsForNode)


areSimilarConditionsError : Infer.Resources a -> String -> Node Expression -> ( RedundantConditionResolution, Node Expression ) -> List (Error {})
areSimilarConditionsError resources operator nodeToCompareTo ( redundantConditionResolution, nodeToLookAt ) =
    case Normalize.compare resources nodeToCompareTo nodeToLookAt of
        Normalize.ConfirmedEquality ->
            errorForRedundantCondition operator redundantConditionResolution nodeToLookAt

        Normalize.ConfirmedInequality ->
            []

        Normalize.Unconfirmed ->
            []


errorForRedundantCondition : String -> RedundantConditionResolution -> Node a -> List (Error {})
errorForRedundantCondition operator redundantConditionResolution node =
    let
        ( range, fix ) =
            rangeAndFixForRedundantCondition redundantConditionResolution node
    in
    [ Rule.errorWithFix
        { message = "Condition is redundant"
        , details =
            [ "This condition is the same as another one found on the left side of the (" ++ operator ++ ") operator, therefore one of them can be removed."
            ]
        }
        range
        fix
    ]


rangeAndFixForRedundantCondition : RedundantConditionResolution -> Node a -> ( Range, List Fix )
rangeAndFixForRedundantCondition redundantConditionResolution node =
    case redundantConditionResolution of
        RemoveFrom locationOfPrevElement ->
            let
                range : Range
                range =
                    { start = locationOfPrevElement
                    , end = (Node.range node).end
                    }
            in
            ( range
            , [ Fix.removeRange range ]
            )

        ReplaceByNoop noopValue ->
            let
                range : Range
                range =
                    Node.range node
            in
            ( range
            , [ Fix.replaceRangeBy range (boolToString noopValue) ]
            )


listConditions : String -> RedundantConditionResolution -> Node Expression -> List ( RedundantConditionResolution, Node Expression )
listConditions operatorToLookFor redundantConditionResolution node =
    case Node.value node of
        Expression.ParenthesizedExpression expr ->
            let
                noopValue : Bool
                noopValue =
                    operatorToLookFor == "&&"
            in
            listConditions operatorToLookFor (ReplaceByNoop noopValue) expr

        Expression.OperatorApplication operator _ left right ->
            if operator == operatorToLookFor then
                listConditions operatorToLookFor redundantConditionResolution left
                    ++ listConditions operatorToLookFor (RemoveFrom (Node.range left).end) right

            else
                [ ( redundantConditionResolution, node ) ]

        _ ->
            [ ( redundantConditionResolution, node ) ]


or_isLeftSimplifiableError : OperatorCheckInfo -> List (Error {})
or_isLeftSimplifiableError ({ parentRange, left, leftRange, rightRange } as checkInfo) =
    case Evaluate.getBoolean checkInfo left of
        Determined True ->
            [ Rule.errorWithFix
                { message = "Comparison is always True"
                , details = alwaysSameDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.end
                    , end = rightRange.end
                    }
                ]
            ]

        Determined False ->
            [ Rule.errorWithFix
                { message = unnecessaryMessage
                , details = unnecessaryDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.start
                    , end = rightRange.start
                    }
                ]
            ]

        Undetermined ->
            []


or_isRightSimplifiableError : OperatorCheckInfo -> List (Error {})
or_isRightSimplifiableError ({ parentRange, right, leftRange, rightRange } as checkInfo) =
    case Evaluate.getBoolean checkInfo right of
        Determined True ->
            [ Rule.errorWithFix
                { message = unnecessaryMessage
                , details = unnecessaryDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.start
                    , end = rightRange.start
                    }
                ]
            ]

        Determined False ->
            [ Rule.errorWithFix
                { message = unnecessaryMessage
                , details = unnecessaryDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.end
                    , end = rightRange.end
                    }
                ]
            ]

        Undetermined ->
            []


andChecks : OperatorCheckInfo -> List (Error {})
andChecks operatorCheckInfo =
    firstThatReportsError
        [ \() ->
            List.concat
                [ and_isLeftSimplifiableError operatorCheckInfo
                , and_isRightSimplifiableError operatorCheckInfo
                ]
        , \() -> findSimilarConditionsError operatorCheckInfo
        ]
        ()


and_isLeftSimplifiableError : OperatorCheckInfo -> List (Rule.Error {})
and_isLeftSimplifiableError ({ parentRange, left, leftRange, rightRange } as checkInfo) =
    case Evaluate.getBoolean checkInfo left of
        Determined True ->
            [ Rule.errorWithFix
                { message = unnecessaryMessage
                , details = unnecessaryDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.start
                    , end = rightRange.start
                    }
                ]
            ]

        Determined False ->
            [ Rule.errorWithFix
                { message = "Comparison is always False"
                , details = alwaysSameDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.end
                    , end = rightRange.end
                    }
                ]
            ]

        Undetermined ->
            []


and_isRightSimplifiableError : OperatorCheckInfo -> List (Rule.Error {})
and_isRightSimplifiableError ({ parentRange, leftRange, right, rightRange } as checkInfo) =
    case Evaluate.getBoolean checkInfo right of
        Determined True ->
            [ Rule.errorWithFix
                { message = unnecessaryMessage
                , details = unnecessaryDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.end
                    , end = rightRange.end
                    }
                ]
            ]

        Determined False ->
            [ Rule.errorWithFix
                { message = "Comparison is always False"
                , details = alwaysSameDetails
                }
                parentRange
                [ Fix.removeRange
                    { start = leftRange.start
                    , end = rightRange.start
                    }
                ]
            ]

        Undetermined ->
            []



-- EQUALITY


equalityChecks : Bool -> OperatorCheckInfo -> List (Error {})
equalityChecks isEqual ({ lookupTable, parentRange, left, right, leftRange, rightRange } as checkInfo) =
    if Evaluate.getBoolean checkInfo right == Determined isEqual then
        [ Rule.errorWithFix
            { message = "Unnecessary comparison with boolean"
            , details = [ "The result of the expression will be the same with or without the comparison." ]
            }
            parentRange
            [ Fix.removeRange { start = leftRange.end, end = rightRange.end } ]
        ]

    else if Evaluate.getBoolean checkInfo left == Determined isEqual then
        [ Rule.errorWithFix
            { message = "Unnecessary comparison with boolean"
            , details = [ "The result of the expression will be the same with or without the comparison." ]
            }
            parentRange
            [ Fix.removeRange { start = leftRange.start, end = rightRange.start } ]
        ]

    else
        case Maybe.map2 Tuple.pair (getNotCall lookupTable left) (getNotCall lookupTable right) of
            Just ( notRangeLeft, notRangeRight ) ->
                [ Rule.errorWithFix
                    { message = "Unnecessary negation on both sides"
                    , details = [ "Since both sides are negated using `not`, they are redundant and can be removed." ]
                    }
                    parentRange
                    [ Fix.removeRange notRangeLeft, Fix.removeRange notRangeRight ]
                ]

            _ ->
                let
                    inferred : Infer.Inferred
                    inferred =
                        Tuple.first checkInfo.inferredConstants

                    normalizeAndInfer : Node Expression -> Node Expression
                    normalizeAndInfer node =
                        let
                            newNode : Node Expression
                            newNode =
                                Normalize.normalize checkInfo node
                        in
                        case Infer.get (Node.value newNode) inferred of
                            Just expr ->
                                Node Range.emptyRange expr

                            Nothing ->
                                newNode

                    normalizedLeft : Node Expression
                    normalizedLeft =
                        normalizeAndInfer left

                    normalizedRight : Node Expression
                    normalizedRight =
                        normalizeAndInfer right
                in
                case Normalize.compareWithoutNormalization normalizedLeft normalizedRight of
                    Normalize.ConfirmedEquality ->
                        [ comparisonError isEqual parentRange ]

                    Normalize.ConfirmedInequality ->
                        [ comparisonError (not isEqual) parentRange ]

                    Normalize.Unconfirmed ->
                        []


getNotCall : ModuleNameLookupTable -> Node Expression -> Maybe Range
getNotCall lookupTable baseNode =
    case Node.value (AstHelpers.removeParens baseNode) of
        Expression.Application ((Node notRange (Expression.FunctionOrValue _ "not")) :: _) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable notRange of
                Just [ "Basics" ] ->
                    Just notRange

                _ ->
                    Nothing

        _ ->
            Nothing


getNotFunction : ModuleNameLookupTable -> Node Expression -> Maybe Range
getNotFunction lookupTable baseNode =
    case AstHelpers.removeParens baseNode of
        Node notRange (Expression.FunctionOrValue _ "not") ->
            case ModuleNameLookupTable.moduleNameAt lookupTable notRange of
                Just [ "Basics" ] ->
                    Just notRange

                _ ->
                    Nothing

        _ ->
            Nothing


getSpecificFunction : ( ModuleName, String ) -> ModuleNameLookupTable -> Node Expression -> Maybe Range
getSpecificFunction ( moduleName, name ) lookupTable baseNode =
    case AstHelpers.removeParens baseNode of
        Node fnRange (Expression.FunctionOrValue _ foundName) ->
            if
                (foundName == name)
                    && (ModuleNameLookupTable.moduleNameAt lookupTable fnRange == Just moduleName)
            then
                Just fnRange

            else
                Nothing

        _ ->
            Nothing


getSpecificFunctionCall : ( ModuleName, String ) -> ModuleNameLookupTable -> Node Expression -> Maybe { nodeRange : Range, fnRange : Range }
getSpecificFunctionCall ( moduleName, name ) lookupTable baseNode =
    let
        match : Maybe ( Range, String )
        match =
            case Node.value (AstHelpers.removeParens baseNode) of
                Expression.Application ((Node fnRange (Expression.FunctionOrValue _ foundName)) :: _ :: _) ->
                    Just ( fnRange, foundName )

                Expression.OperatorApplication "|>" _ _ (Node _ (Expression.Application ((Node fnRange (Expression.FunctionOrValue _ foundName)) :: _))) ->
                    Just ( fnRange, foundName )

                Expression.OperatorApplication "<|" _ (Node _ (Expression.Application ((Node fnRange (Expression.FunctionOrValue _ foundName)) :: _))) _ ->
                    Just ( fnRange, foundName )

                _ ->
                    Nothing
    in
    case match of
        Just ( fnRange, foundName ) ->
            if
                (foundName == name)
                    && (ModuleNameLookupTable.moduleNameAt lookupTable fnRange == Just moduleName)
            then
                Just { nodeRange = Node.range baseNode, fnRange = fnRange }

            else
                Nothing

        Nothing ->
            Nothing


alwaysSameDetails : List String
alwaysSameDetails =
    [ "This condition will always result in the same value. You may have hardcoded a value or mistyped a condition."
    ]


unnecessaryMessage : String
unnecessaryMessage =
    "Part of the expression is unnecessary"


unnecessaryDetails : List String
unnecessaryDetails =
    [ "A part of this condition is unnecessary. You can remove it and it would not impact the behavior of the program."
    ]



-- COMPARISONS


comparisonChecks : (Float -> Float -> Bool) -> OperatorCheckInfo -> List (Error {})
comparisonChecks operatorFunction operatorCheckInfo =
    case
        Maybe.map2 operatorFunction
            (Normalize.getNumberValue operatorCheckInfo.left)
            (Normalize.getNumberValue operatorCheckInfo.right)
    of
        Just bool ->
            [ comparisonError bool operatorCheckInfo.parentRange ]

        Nothing ->
            []


comparisonError : Bool -> Range -> Error {}
comparisonError bool range =
    let
        boolAsString : String
        boolAsString =
            boolToString bool
    in
    Rule.errorWithFix
        { message = "Comparison is always " ++ boolAsString
        , details =
            [ "Based on the values and/or the context, we can determine that the value of this operation will always be " ++ boolAsString ++ "."
            ]
        }
        range
        [ Fix.replaceRangeBy range boolAsString ]



-- IF EXPRESSIONS


targetIfKeyword : Range -> Range
targetIfKeyword { start } =
    { start = start
    , end = { start | column = start.column + 2 }
    }



-- BASICS


basicsIdentityChecks : CheckInfo -> List (Error {})
basicsIdentityChecks checkInfo =
    [ Rule.errorWithFix
        { message = "`identity` should be removed"
        , details = [ "`identity` can be a useful function to be passed as arguments to other functions, but calling it manually with an argument is the same thing as writing the argument on its own." ]
        }
        checkInfo.fnRange
        [ removeFunctionFromFunctionCall checkInfo
        ]
    ]


identityCompositionCheck : CompositionCheckInfo -> List (Error {})
identityCompositionCheck { lookupTable, left, right } =
    if isIdentity lookupTable right then
        [ Rule.errorWithFix
            { message = "`identity` should be removed"
            , details = [ "Composing a function with `identity` is the same as simplify referencing the function." ]
            }
            (Node.range right)
            [ Fix.removeRange { start = (Node.range left).end, end = (Node.range right).end }
            ]
        ]

    else if isIdentity lookupTable left then
        [ Rule.errorWithFix
            { message = "`identity` should be removed"
            , details = [ "Composing a function with `identity` is the same as simplify referencing the function." ]
            }
            (Node.range left)
            [ Fix.removeRange { start = (Node.range left).start, end = (Node.range right).start }
            ]
        ]

    else
        []


basicsAlwaysChecks : CheckInfo -> List (Error {})
basicsAlwaysChecks ({ fnRange, firstArg, secondArg, usingRightPizza } as checkInfo) =
    case secondArg of
        Just (Node secondArgRange _) ->
            [ Rule.errorWithFix
                { message = "Expression can be replaced by the first argument given to `always`"
                , details = [ "The second argument will be ignored because of the `always` call." ]
                }
                fnRange
                (if usingRightPizza then
                    [ Fix.removeRange { start = secondArgRange.start, end = (Node.range firstArg).start }
                    ]

                 else
                    [ removeFunctionFromFunctionCall checkInfo
                    , Fix.removeRange { start = (Node.range firstArg).end, end = secondArgRange.end }
                    ]
                )
            ]

        Nothing ->
            []


alwaysCompositionCheck : CompositionCheckInfo -> List (Error {})
alwaysCompositionCheck { lookupTable, fromLeftToRight, left, right, leftRange, rightRange } =
    if fromLeftToRight then
        if isAlwaysCall lookupTable right then
            [ Rule.errorWithFix
                { message = "Function composed with always will be ignored"
                , details = [ "`always` will swallow the function composed into it." ]
                }
                rightRange
                [ Fix.removeRange { start = leftRange.start, end = rightRange.start } ]
            ]

        else
            []

    else if isAlwaysCall lookupTable left then
        [ Rule.errorWithFix
            { message = "Function composed with always will be ignored"
            , details = [ "`always` will swallow the function composed into it." ]
            }
            leftRange
            [ Fix.removeRange { start = leftRange.end, end = rightRange.end } ]
        ]

    else
        []


isAlwaysCall : ModuleNameLookupTable -> Node Expression -> Bool
isAlwaysCall lookupTable node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.Application ((Node alwaysRange (Expression.FunctionOrValue _ "always")) :: _ :: []) ->
            ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange == Just [ "Basics" ]

        _ ->
            False


getAlwaysArgument : ModuleNameLookupTable -> Node Expression -> Maybe { alwaysRange : Range, rangeToRemove : Range }
getAlwaysArgument lookupTable node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.Application ((Node alwaysRange (Expression.FunctionOrValue _ "always")) :: arg :: []) ->
            if ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange == Just [ "Basics" ] then
                Just
                    { alwaysRange = alwaysRange
                    , rangeToRemove = { start = alwaysRange.start, end = (Node.range arg).start }
                    }

            else
                Nothing

        Expression.OperatorApplication "<|" _ (Node alwaysRange (Expression.FunctionOrValue _ "always")) arg ->
            if ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange == Just [ "Basics" ] then
                Just
                    { alwaysRange = alwaysRange
                    , rangeToRemove = { start = alwaysRange.start, end = (Node.range arg).start }
                    }

            else
                Nothing

        Expression.OperatorApplication "|>" _ arg (Node alwaysRange (Expression.FunctionOrValue _ "always")) ->
            if ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange == Just [ "Basics" ] then
                Just
                    { alwaysRange = alwaysRange
                    , rangeToRemove = { start = (Node.range arg).end, end = alwaysRange.end }
                    }

            else
                Nothing

        _ ->
            Nothing


reportEmptyListSecondArgument : ( ( ModuleName, String ), CheckInfo -> List (Error {}) ) -> ( ( ModuleName, String ), CheckInfo -> List (Error {}) )
reportEmptyListSecondArgument ( ( moduleName, name ), function ) =
    ( ( moduleName, name )
    , \checkInfo ->
        case checkInfo.secondArg of
            Just (Node _ (Expression.ListExpr [])) ->
                [ Rule.errorWithFix
                    { message = "Using " ++ String.join "." moduleName ++ "." ++ name ++ " on an empty list will result in an empty list"
                    , details = [ "You can replace this call by an empty list." ]
                    }
                    checkInfo.fnRange
                    [ Fix.replaceRangeBy checkInfo.parentRange "[]" ]
                ]

            _ ->
                function checkInfo
    )


reportEmptyListFirstArgument : ( ( ModuleName, String ), CheckInfo -> List (Error {}) ) -> ( ( ModuleName, String ), CheckInfo -> List (Error {}) )
reportEmptyListFirstArgument ( ( moduleName, name ), function ) =
    ( ( moduleName, name )
    , \checkInfo ->
        case checkInfo.firstArg of
            Node _ (Expression.ListExpr []) ->
                [ Rule.errorWithFix
                    { message = "Using " ++ String.join "." moduleName ++ "." ++ name ++ " on an empty list will result in an empty list"
                    , details = [ "You can replace this call by an empty list." ]
                    }
                    checkInfo.fnRange
                    [ Fix.replaceRangeBy checkInfo.parentRange "[]" ]
                ]

            _ ->
                function checkInfo
    )



-- STRING


stringIsEmptyChecks : CheckInfo -> List (Error {})
stringIsEmptyChecks { parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.Literal str ->
            let
                replacementValue : String
                replacementValue =
                    boolToString (str == "")
            in
            [ Rule.errorWithFix
                { message = "The call to String.isEmpty will result in " ++ replacementValue
                , details = [ "You can replace this call by " ++ replacementValue ++ "." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange replacementValue ]
            ]

        _ ->
            []


stringConcatChecks : CheckInfo -> List (Error {})
stringConcatChecks { parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.ListExpr [] ->
            [ Rule.errorWithFix
                { message = "Using String.concat on an empty list will result in a empty string"
                , details = [ "You can replace this call by an empty string." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "\"\"" ]
            ]

        _ ->
            []


stringWordsChecks : CheckInfo -> List (Error {})
stringWordsChecks { parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.Literal "" ->
            [ Rule.errorWithFix
                { message = "Using String.words on an empty string will result in an empty list"
                , details = [ "You can replace this call by an empty list." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "[]" ]
            ]

        _ ->
            []


stringLinesChecks : CheckInfo -> List (Error {})
stringLinesChecks { parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.Literal "" ->
            [ Rule.errorWithFix
                { message = "Using String.lines on an empty string will result in an empty list"
                , details = [ "You can replace this call by an empty list." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "[]" ]
            ]

        _ ->
            []


stringReverseChecks : CheckInfo -> List (Error {})
stringReverseChecks ({ parentRange, fnRange, firstArg } as checkInfo) =
    case Node.value firstArg of
        Expression.Literal "" ->
            [ Rule.errorWithFix
                { message = "Using String.reverse on an empty string will result in a empty string"
                , details = [ "You can replace this call by an empty string." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "\"\"" ]
            ]

        _ ->
            removeAlongWithOtherFunctionCheck
                reverseReverseCompositionErrorMessage
                (getSpecificFunction ( [ "String" ], "reverse" ))
                checkInfo


reverseReverseCompositionErrorMessage : { message : String, details : List String }
reverseReverseCompositionErrorMessage =
    { message = "Unnecessary double reversal"
    , details = [ "Composing `reverse` with `reverse` cancel each other out." ]
    }


stringJoinChecks : CheckInfo -> List (Error {})
stringJoinChecks { parentRange, fnRange, firstArg, secondArg } =
    case secondArg of
        Just (Node _ (Expression.ListExpr [])) ->
            [ Rule.errorWithFix
                { message = "Using String.join on an empty list will result in a empty string"
                , details = [ "You can replace this call by an empty string." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "\"\"" ]
            ]

        _ ->
            case Node.value firstArg of
                Expression.Literal "" ->
                    [ Rule.errorWithFix
                        { message = "Use String.concat instead"
                        , details = [ "Using String.join with an empty separator is the same as using String.concat." ]
                        }
                        fnRange
                        [ Fix.replaceRangeBy { start = fnRange.start, end = (Node.range firstArg).end } "String.concat" ]
                    ]

                _ ->
                    []


stringLengthChecks : CheckInfo -> List (Error {})
stringLengthChecks { parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.Literal str ->
            [ Rule.errorWithFix
                { message = "The length of the string is " ++ String.fromInt (String.length str)
                , details = [ "The length of the string can be determined by looking at the code." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange (String.fromInt (String.length str)) ]
            ]

        _ ->
            []


stringRepeatChecks : CheckInfo -> List (Error {})
stringRepeatChecks ({ parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    case secondArg of
        Just (Node _ (Expression.Literal "")) ->
            [ Rule.errorWithFix
                { message = "Using String.repeat with an empty string will result in a empty string"
                , details = [ "You can replace this call by an empty string." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "\"\"" ]
            ]

        _ ->
            case Evaluate.getInt checkInfo firstArg of
                Just intValue ->
                    if intValue == 1 then
                        [ Rule.errorWithFix
                            { message = "String.repeat 1 won't do anything"
                            , details = [ "Using String.repeat with 1 will result in the second argument." ]
                            }
                            fnRange
                            [ Fix.removeRange { start = fnRange.start, end = (Node.range firstArg).end } ]
                        ]

                    else if intValue < 1 then
                        [ Rule.errorWithFix
                            { message = "String.repeat will result in an empty string"
                            , details = [ "Using String.repeat with a number less than 1 will result in an empty string. You can replace this call by an empty string." ]
                            }
                            fnRange
                            (replaceByEmptyFix "\"\"" parentRange secondArg)
                        ]

                    else
                        []

                _ ->
                    []


stringReplaceChecks : CheckInfo -> List (Error {})
stringReplaceChecks ({ fnRange, firstArg, secondArg, thirdArg } as checkInfo) =
    case secondArg of
        Just secondArg_ ->
            case Normalize.compare checkInfo firstArg secondArg_ of
                Normalize.ConfirmedEquality ->
                    [ Rule.errorWithFix
                        { message = "The result of String.replace will be the original string"
                        , details = [ "The pattern to replace and the replacement are equal, therefore the result of the String.replace call will be the original string." ]
                        }
                        fnRange
                        (case thirdArg of
                            Just thirdArg_ ->
                                [ Fix.removeRange
                                    { start = fnRange.start
                                    , end = (Node.range thirdArg_).start
                                    }
                                ]

                            Nothing ->
                                [ Fix.replaceRangeBy
                                    { start = fnRange.start
                                    , end = (Node.range secondArg_).end
                                    }
                                    "identity"
                                ]
                        )
                    ]

                _ ->
                    case ( Node.value firstArg, Node.value secondArg_, thirdArg ) of
                        ( _, _, Just (Node thirdRange (Expression.Literal "")) ) ->
                            [ Rule.errorWithFix
                                { message = "The result of String.replace will be the empty string"
                                , details = [ "Replacing anything on an empty string results in an empty string." ]
                                }
                                fnRange
                                [ Fix.removeRange
                                    { start = fnRange.start
                                    , end = thirdRange.start
                                    }
                                ]
                            ]

                        ( Expression.Literal first, Expression.Literal second, Just (Node thirdRange (Expression.Literal third)) ) ->
                            if String.replace first second third == third then
                                [ Rule.errorWithFix
                                    { message = "The result of String.replace will be the original string"
                                    , details = [ "The replacement doesn't haven't any noticeable impact. You can remove the call to String.replace." ]
                                    }
                                    fnRange
                                    [ Fix.removeRange
                                        { start = fnRange.start
                                        , end = thirdRange.start
                                        }
                                    ]
                                ]

                            else
                                []

                        _ ->
                            []

        Nothing ->
            []



-- MAYBE FUNCTIONS


maybeMapChecks : CheckInfo -> List (Error {})
maybeMapChecks checkInfo =
    firstThatReportsError
        [ \() -> collectionMapChecks maybeCollection checkInfo
        , \() ->
            case Match.maybeAndThen (getMaybeValues checkInfo.lookupTable) checkInfo.secondArg of
                Determined (Just justRanges) ->
                    [ Rule.errorWithFix
                        { message = "Calling Maybe.map on a value that is Just"
                        , details = [ "The function can be called without Maybe.map." ]
                        }
                        checkInfo.fnRange
                        (if checkInfo.usingRightPizza then
                            [ Fix.removeRange { start = checkInfo.fnRange.start, end = (Node.range checkInfo.firstArg).start }
                            , Fix.insertAt (Node.range checkInfo.firstArg).end " |> Just"
                            ]
                                ++ List.map Fix.removeRange justRanges

                         else
                            [ Fix.replaceRangeBy { start = checkInfo.parentRange.start, end = (Node.range checkInfo.firstArg).start } "Just ("
                            , Fix.insertAt checkInfo.parentRange.end ")"
                            ]
                                ++ List.map Fix.removeRange justRanges
                        )
                    ]

                _ ->
                    []
        ]
        ()


maybeMapCompositionChecks : CompositionCheckInfo -> List (Error {})
maybeMapCompositionChecks { lookupTable, fromLeftToRight, parentRange, left, right } =
    if fromLeftToRight then
        case ( AstHelpers.removeParens left, Node.value (AstHelpers.removeParens right) ) of
            ( Node justRange (Expression.FunctionOrValue _ "Just"), Expression.Application ((Node maybeMapRange (Expression.FunctionOrValue _ "map")) :: mapperFunction :: []) ) ->
                if
                    (ModuleNameLookupTable.moduleNameAt lookupTable justRange == Just [ "Maybe" ])
                        && (ModuleNameLookupTable.moduleNameAt lookupTable maybeMapRange == Just [ "Maybe" ])
                then
                    [ Rule.errorWithFix
                        { message = "Calling Maybe.map on a value that is Just"
                        , details = [ "The function can be called without Maybe.map." ]
                        }
                        maybeMapRange
                        [ Fix.removeRange { start = parentRange.start, end = (Node.range mapperFunction).start }
                        , Fix.insertAt (Node.range mapperFunction).end " >> Just"
                        ]
                    ]

                else
                    []

            _ ->
                []

    else
        case ( Node.value (AstHelpers.removeParens left), AstHelpers.removeParens right ) of
            ( Expression.Application ((Node maybeMapRange (Expression.FunctionOrValue _ "map")) :: mapperFunction :: []), Node justRange (Expression.FunctionOrValue _ "Just") ) ->
                if ModuleNameLookupTable.moduleNameAt lookupTable justRange == Just [ "Maybe" ] && ModuleNameLookupTable.moduleNameAt lookupTable maybeMapRange == Just [ "Maybe" ] then
                    [ Rule.errorWithFix
                        { message = "Calling Maybe.map on a value that is Just"
                        , details = [ "The function can be called without Maybe.map." ]
                        }
                        maybeMapRange
                        [ Fix.replaceRangeBy { start = parentRange.start, end = (Node.range mapperFunction).start } "Just << "
                        , Fix.removeRange { start = (Node.range mapperFunction).end, end = parentRange.end }
                        ]
                    ]

                else
                    []

            _ ->
                []


resultMapCompositionChecks : CompositionCheckInfo -> List (Error {})
resultMapCompositionChecks { lookupTable, fromLeftToRight, parentRange, left, right } =
    if fromLeftToRight then
        case ( AstHelpers.removeParens left, Node.value (AstHelpers.removeParens right) ) of
            ( Node justRange (Expression.FunctionOrValue _ "Ok"), Expression.Application ((Node resultMapRange (Expression.FunctionOrValue _ "map")) :: mapperFunction :: []) ) ->
                if
                    (ModuleNameLookupTable.moduleNameAt lookupTable justRange == Just [ "Result" ])
                        && (ModuleNameLookupTable.moduleNameAt lookupTable resultMapRange == Just [ "Result" ])
                then
                    [ Rule.errorWithFix
                        { message = "Calling Result.map on a value that is Ok"
                        , details = [ "The function can be called without Result.map." ]
                        }
                        resultMapRange
                        [ Fix.removeRange { start = parentRange.start, end = (Node.range mapperFunction).start }
                        , Fix.insertAt (Node.range mapperFunction).end " >> Ok"
                        ]
                    ]

                else
                    []

            _ ->
                []

    else
        case ( Node.value (AstHelpers.removeParens left), AstHelpers.removeParens right ) of
            ( Expression.Application ((Node resultMapRange (Expression.FunctionOrValue _ "map")) :: mapperFunction :: []), Node justRange (Expression.FunctionOrValue _ "Ok") ) ->
                if ModuleNameLookupTable.moduleNameAt lookupTable justRange == Just [ "Result" ] && ModuleNameLookupTable.moduleNameAt lookupTable resultMapRange == Just [ "Result" ] then
                    [ Rule.errorWithFix
                        { message = "Calling Result.map on a value that is Ok"
                        , details = [ "The function can be called without Result.map." ]
                        }
                        resultMapRange
                        [ Fix.replaceRangeBy { start = parentRange.start, end = (Node.range mapperFunction).start } "Ok << "
                        , Fix.removeRange { start = (Node.range mapperFunction).end, end = parentRange.end }
                        ]
                    ]

                else
                    []

            _ ->
                []



-- RESULT FUNCTIONS


resultMapChecks : CheckInfo -> List (Error {})
resultMapChecks checkInfo =
    firstThatReportsError
        [ \() -> collectionMapChecks resultCollection checkInfo
        , \() ->
            case Maybe.andThen (getResultValues checkInfo.lookupTable) checkInfo.secondArg of
                Just (Ok okRanges) ->
                    [ Rule.errorWithFix
                        { message = "Calling Result.map on a value that is Ok"
                        , details = [ "The function can be called without Result.map." ]
                        }
                        checkInfo.fnRange
                        (if checkInfo.usingRightPizza then
                            [ Fix.removeRange { start = checkInfo.fnRange.start, end = (Node.range checkInfo.firstArg).start }
                            , Fix.insertAt (Node.range checkInfo.firstArg).end " |> Ok"
                            ]
                                ++ List.map Fix.removeRange okRanges

                         else
                            [ Fix.replaceRangeBy { start = checkInfo.parentRange.start, end = (Node.range checkInfo.firstArg).start } "Ok ("
                            , Fix.insertAt checkInfo.parentRange.end ")"
                            ]
                                ++ List.map Fix.removeRange okRanges
                        )
                    ]

                _ ->
                    []
        ]
        ()



-- LIST FUNCTIONS


listConcatChecks : CheckInfo -> List (Error {})
listConcatChecks ({ lookupTable, parentRange, fnRange, firstArg } as checkInfo) =
    case Node.value firstArg of
        Expression.ListExpr list ->
            case list of
                [ Node elementRange _ ] ->
                    [ Rule.errorWithFix
                        { message = "Unnecessary use of List.concat on a list with 1 element"
                        , details = [ "The value of the operation will be the element itself. You should replace this expression by that." ]
                        }
                        parentRange
                        [ Fix.removeRange { start = parentRange.start, end = elementRange.start }
                        , Fix.removeRange { start = elementRange.end, end = parentRange.end }
                        ]
                    ]

                (firstListElement :: restOfListElements) as args ->
                    if List.all isListLiteral list then
                        [ Rule.errorWithFix
                            { message = "Expression could be simplified to be a single List"
                            , details = [ "Try moving all the elements into a single list." ]
                            }
                            parentRange
                            (Fix.removeRange fnRange
                                :: List.concatMap removeBoundariesFix args
                            )
                        ]

                    else
                        case findConsecutiveListLiterals firstListElement restOfListElements of
                            [] ->
                                []

                            fixes ->
                                [ Rule.errorWithFix
                                    { message = "Consecutive literal lists should be merged"
                                    , details = [ "Try moving all the elements from consecutive list literals so that they form a single list." ]
                                    }
                                    fnRange
                                    fixes
                                ]

                _ ->
                    []

        _ ->
            case getSpecificFunctionCall ( [ "List" ], "map" ) lookupTable firstArg of
                Just match ->
                    [ Rule.errorWithFix
                        { message = "List.map and List.concat can be combined using List.concatMap"
                        , details = [ "List.concatMap is meant for this exact purpose and will also be faster." ]
                        }
                        fnRange
                        [ removeFunctionFromFunctionCall checkInfo
                        , Fix.replaceRangeBy match.fnRange "List.concatMap"
                        ]
                    ]

                Nothing ->
                    []


findConsecutiveListLiterals : Node Expression -> List (Node Expression) -> List Fix
findConsecutiveListLiterals firstListElement restOfListElements =
    case ( firstListElement, restOfListElements ) of
        ( Node firstRange (Expression.ListExpr _), ((Node secondRange (Expression.ListExpr _)) as second) :: rest ) ->
            Fix.replaceRangeBy
                { start = { row = firstRange.end.row, column = firstRange.end.column - 1 }
                , end = { row = secondRange.start.row, column = secondRange.start.column + 1 }
                }
                ", "
                :: findConsecutiveListLiterals second rest

        ( _, x :: xs ) ->
            findConsecutiveListLiterals x xs

        _ ->
            []


listConcatMapChecks : CheckInfo -> List (Error {})
listConcatMapChecks { lookupTable, parentRange, fnRange, firstArg, secondArg } =
    if isIdentity lookupTable firstArg then
        [ Rule.errorWithFix
            { message = "Using List.concatMap with an identity function is the same as using List.concat"
            , details = [ "You can replace this call by List.concat." ]
            }
            fnRange
            [ Fix.replaceRangeBy { start = fnRange.start, end = (Node.range firstArg).end } "List.concat" ]
        ]

    else if isAlwaysEmptyList lookupTable firstArg then
        [ Rule.errorWithFix
            { message = "List.concatMap will result in on an empty list"
            , details = [ "You can replace this call by an empty list." ]
            }
            fnRange
            (replaceByEmptyFix "[]" parentRange secondArg)
        ]

    else
        case replaceSingleElementListBySingleValue_RENAME lookupTable fnRange firstArg of
            Just errors ->
                errors

            Nothing ->
                case secondArg of
                    Just (Node listRange (Expression.ListExpr [ listElement ])) ->
                        [ Rule.errorWithFix
                            { message = "Using List.concatMap on an element with a single item is the same as calling the function directly on that lone element."
                            , details = [ "You can replace this call by a call to the function directly." ]
                            }
                            fnRange
                            (Fix.removeRange fnRange
                                :: replaceBySubExpressionFix listRange listElement
                            )
                        ]

                    _ ->
                        []


concatAndMapCompositionCheck : CompositionCheckInfo -> List (Error {})
concatAndMapCompositionCheck { lookupTable, fromLeftToRight, left, right } =
    if fromLeftToRight then
        if isSpecificFunction [ "List" ] "concat" lookupTable right then
            case Node.value (AstHelpers.removeParens left) of
                Expression.Application [ leftFunction, _ ] ->
                    if isSpecificFunction [ "List" ] "map" lookupTable leftFunction then
                        [ Rule.errorWithFix
                            { message = "List.map and List.concat can be combined using List.concatMap"
                            , details = [ "List.concatMap is meant for this exact purpose and will also be faster." ]
                            }
                            (Node.range right)
                            [ Fix.removeRange { start = (Node.range left).end, end = (Node.range right).end }
                            , Fix.replaceRangeBy (Node.range leftFunction) "List.concatMap"
                            ]
                        ]

                    else
                        []

                _ ->
                    []

        else
            []

    else if isSpecificFunction [ "List" ] "concat" lookupTable left then
        case Node.value (AstHelpers.removeParens right) of
            Expression.Application [ rightFunction, _ ] ->
                if isSpecificFunction [ "List" ] "map" lookupTable rightFunction then
                    [ Rule.errorWithFix
                        { message = "List.map and List.concat can be combined using List.concatMap"
                        , details = [ "List.concatMap is meant for this exact purpose and will also be faster." ]
                        }
                        (Node.range left)
                        [ Fix.removeRange { start = (Node.range left).start, end = (Node.range right).start }
                        , Fix.replaceRangeBy (Node.range rightFunction) "List.concatMap"
                        ]
                    ]

                else
                    []

            _ ->
                []

    else
        []


listIndexedMapChecks : CheckInfo -> List (Error {})
listIndexedMapChecks { lookupTable, fnRange, firstArg } =
    case AstHelpers.removeParens firstArg of
        Node lambdaRange (Expression.LambdaExpression { args, expression }) ->
            case Maybe.map AstHelpers.removeParensFromPattern (List.head args) of
                Just (Node patternRange Pattern.AllPattern) ->
                    let
                        rangeToRemove : Range
                        rangeToRemove =
                            case args of
                                [] ->
                                    Range.emptyRange

                                [ _ ] ->
                                    -- Only one argument, remove the entire lambda except the expression
                                    { start = lambdaRange.start, end = (Node.range expression).start }

                                first :: second :: _ ->
                                    { start = (Node.range first).start, end = (Node.range second).start }
                    in
                    [ Rule.errorWithFix
                        { message = "Use List.map instead"
                        , details = [ "Using List.indexedMap while ignoring the first argument is the same thing as calling List.map." ]
                        }
                        patternRange
                        [ Fix.replaceRangeBy fnRange "List.map"
                        , Fix.removeRange rangeToRemove
                        ]
                    ]

                _ ->
                    []

        _ ->
            case getAlwaysArgument lookupTable firstArg of
                Just { alwaysRange, rangeToRemove } ->
                    [ Rule.errorWithFix
                        { message = "Use List.map instead"
                        , details = [ "Using List.indexedMap while ignoring the first argument is the same thing as calling List.map." ]
                        }
                        alwaysRange
                        [ Fix.replaceRangeBy fnRange "List.map"
                        , Fix.removeRange rangeToRemove
                        ]
                    ]

                Nothing ->
                    []


listAllChecks : CheckInfo -> List (Error {})
listAllChecks ({ parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    case Maybe.map (AstHelpers.removeParens >> Node.value) secondArg of
        Just (Expression.ListExpr []) ->
            [ Rule.errorWithFix
                { message = "The call to List.all will result in True"
                , details = [ "You can replace this call by True." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "True" ]
            ]

        _ ->
            case Evaluate.isAlwaysBoolean checkInfo firstArg of
                Determined True ->
                    [ Rule.errorWithFix
                        { message = "The call to List.all will result in True"
                        , details = [ "You can replace this call by True." ]
                        }
                        fnRange
                        (replaceByBoolFix parentRange secondArg True)
                    ]

                _ ->
                    []


listAnyChecks : CheckInfo -> List (Error {})
listAnyChecks ({ parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    case Maybe.map (AstHelpers.removeParens >> Node.value) secondArg of
        Just (Expression.ListExpr []) ->
            [ Rule.errorWithFix
                { message = "The call to List.any will result in False"
                , details = [ "You can replace this call by False." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "False" ]
            ]

        _ ->
            case Evaluate.isAlwaysBoolean checkInfo firstArg of
                Determined False ->
                    [ Rule.errorWithFix
                        { message = "The call to List.any will result in False"
                        , details = [ "You can replace this call by False." ]
                        }
                        fnRange
                        (replaceByBoolFix parentRange secondArg False)
                    ]

                _ ->
                    []


listFilterMapChecks : CheckInfo -> List (Error {})
listFilterMapChecks ({ lookupTable, parentRange, fnRange, firstArg } as checkInfo) =
    case isAlwaysMaybe lookupTable firstArg of
        Determined (Just { ranges, throughLambdaFunction }) ->
            if throughLambdaFunction then
                [ Rule.errorWithFix
                    { message = "Using List.filterMap with a function that will always return Just is the same as using List.map"
                    , details = [ "You can remove the `Just`s and replace the call by List.map." ]
                    }
                    fnRange
                    (Fix.replaceRangeBy fnRange "List.map"
                        :: List.map Fix.removeRange ranges
                    )
                ]

            else
                [ Rule.errorWithFix
                    { message = "Using List.filterMap with a function that will always return Just is the same as not using List.filterMap"
                    , details = [ "You can remove this call and replace it by the list itself." ]
                    }
                    fnRange
                    (noopFix checkInfo)
                ]

        Determined Nothing ->
            [ Rule.errorWithFix
                { message = "Using List.filterMap with a function that will always return Nothing will result in an empty list"
                , details = [ "You can remove this call and replace it by an empty list." ]
                }
                fnRange
                (replaceByEmptyFix "[]" parentRange checkInfo.secondArg)
            ]

        Undetermined ->
            if isIdentity lookupTable firstArg then
                case Maybe.andThen (getSpecificFunctionCall ( [ "List" ], "map" ) lookupTable) checkInfo.secondArg of
                    Just secondArg ->
                        [ Rule.errorWithFix
                            { message = "List.map and List.filterMap identity can be combined using List.filterMap"
                            , details = [ "List.filterMap is meant for this exact purpose and will also be faster." ]
                            }
                            { start = fnRange.start, end = (Node.range firstArg).end }
                            [ removeFunctionAndFirstArg checkInfo secondArg.nodeRange
                            , Fix.replaceRangeBy secondArg.fnRange "List.filterMap"
                            ]
                        ]

                    Nothing ->
                        case checkInfo.secondArg of
                            Just (Node listRange (Expression.ListExpr list)) ->
                                case collectJusts lookupTable list [] of
                                    Just justRanges ->
                                        [ Rule.errorWithFix
                                            { message = "Unnecessary use of List.filterMap identity"
                                            , details = [ "All of the elements in the list are `Just`s, which can be simplified by removing all of the `Just`s." ]
                                            }
                                            { start = fnRange.start, end = (Node.range firstArg).end }
                                            ((if checkInfo.usingRightPizza then
                                                Fix.removeRange { start = listRange.end, end = (Node.range firstArg).end }

                                              else
                                                Fix.removeRange { start = fnRange.start, end = listRange.start }
                                             )
                                                :: List.map Fix.removeRange justRanges
                                            )
                                        ]

                                    Nothing ->
                                        []

                            _ ->
                                []

            else
                []


collectJusts : ModuleNameLookupTable -> List (Node Expression) -> List Range -> Maybe (List Range)
collectJusts lookupTable list acc =
    case list of
        [] ->
            Just acc

        element :: restOfList ->
            case Node.value element of
                Expression.Application ((Node justRange (Expression.FunctionOrValue _ "Just")) :: justArg :: []) ->
                    case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                        Just [ "Maybe" ] ->
                            collectJusts lookupTable restOfList ({ start = justRange.start, end = (Node.range justArg).start } :: acc)

                        _ ->
                            Nothing

                _ ->
                    Nothing


filterAndMapCompositionCheck : CompositionCheckInfo -> List (Error {})
filterAndMapCompositionCheck { lookupTable, fromLeftToRight, left, right } =
    if fromLeftToRight then
        case Node.value (AstHelpers.removeParens right) of
            Expression.Application [ rightFunction, arg ] ->
                if isSpecificFunction [ "List" ] "filterMap" lookupTable rightFunction && isIdentity lookupTable arg then
                    case Node.value (AstHelpers.removeParens left) of
                        Expression.Application [ leftFunction, _ ] ->
                            if isSpecificFunction [ "List" ] "map" lookupTable leftFunction then
                                [ Rule.errorWithFix
                                    { message = "List.map and List.filterMap identity can be combined using List.filterMap"
                                    , details = [ "List.filterMap is meant for this exact purpose and will also be faster." ]
                                    }
                                    (Node.range right)
                                    [ Fix.removeRange { start = (Node.range left).end, end = (Node.range right).end }
                                    , Fix.replaceRangeBy (Node.range leftFunction) "List.filterMap"
                                    ]
                                ]

                            else
                                []

                        _ ->
                            []

                else
                    []

            _ ->
                []

    else
        case Node.value (AstHelpers.removeParens left) of
            Expression.Application [ leftFunction, arg ] ->
                if isSpecificFunction [ "List" ] "filterMap" lookupTable leftFunction && isIdentity lookupTable arg then
                    case Node.value (AstHelpers.removeParens right) of
                        Expression.Application [ rightFunction, _ ] ->
                            if isSpecificFunction [ "List" ] "map" lookupTable rightFunction then
                                [ Rule.errorWithFix
                                    { message = "List.map and List.filterMap identity can be combined using List.filterMap"
                                    , details = [ "List.filterMap is meant for this exact purpose and will also be faster." ]
                                    }
                                    (Node.range left)
                                    [ Fix.removeRange { start = (Node.range left).start, end = (Node.range right).start }
                                    , Fix.replaceRangeBy (Node.range rightFunction) "List.filterMap"
                                    ]
                                ]

                            else
                                []

                        _ ->
                            []

                else
                    []

            _ ->
                []


listRangeChecks : CheckInfo -> List (Error {})
listRangeChecks ({ parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    case Maybe.andThen (Evaluate.getInt checkInfo) secondArg of
        Just second ->
            case Evaluate.getInt checkInfo firstArg of
                Just first ->
                    if first > second then
                        [ Rule.errorWithFix
                            { message = "The call to List.range will result in []"
                            , details = [ "The second argument to List.range is bigger than the first one, therefore you can replace this list by an empty list." ]
                            }
                            fnRange
                            (replaceByEmptyFix "[]" parentRange secondArg)
                        ]

                    else
                        []

                Nothing ->
                    []

        Nothing ->
            []


listRepeatChecks : CheckInfo -> List (Error {})
listRepeatChecks ({ parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    case Evaluate.getInt checkInfo firstArg of
        Just intValue ->
            if intValue < 1 then
                [ Rule.errorWithFix
                    { message = "List.repeat will result in an empty list"
                    , details = [ "Using List.repeat with a number less than 1 will result in an empty list. You can replace this call by an empty list." ]
                    }
                    fnRange
                    (replaceByEmptyFix "[]" parentRange secondArg)
                ]

            else
                []

        _ ->
            []


listReverseChecks : CheckInfo -> List (Error {})
listReverseChecks ({ parentRange, fnRange, firstArg } as checkInfo) =
    case Node.value (AstHelpers.removeParens firstArg) of
        Expression.ListExpr [] ->
            [ Rule.errorWithFix
                { message = "Using List.reverse on [] will result in []"
                , details = [ "You can replace this call by []." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "[]" ]
            ]

        _ ->
            removeAlongWithOtherFunctionCheck
                reverseReverseCompositionErrorMessage
                (getSpecificFunction ( [ "List" ], "reverse" ))
                checkInfo


listTakeChecks : CheckInfo -> List (Error {})
listTakeChecks { lookupTable, parentRange, fnRange, firstArg, secondArg } =
    if getUncomputedNumberValue firstArg == Just 0 then
        [ Rule.errorWithFix
            { message = "Taking 0 items from a list will result in []"
            , details = [ "You can replace this call by []." ]
            }
            fnRange
            (case secondArg of
                Just _ ->
                    [ Fix.replaceRangeBy parentRange "[]" ]

                Nothing ->
                    [ Fix.replaceRangeBy parentRange "(always [])" ]
            )
        ]

    else
        case Maybe.andThen (determineListLength lookupTable) secondArg of
            Just (Exactly 0) ->
                [ Rule.errorWithFix
                    { message = "Using List.take on [] will result in []"
                    , details = [ "You can replace this call by []." ]
                    }
                    fnRange
                    [ Fix.replaceRangeBy parentRange "[]" ]
                ]

            _ ->
                []


listDropChecks : CheckInfo -> List (Error {})
listDropChecks { lookupTable, parentRange, fnRange, firstArg, secondArg, usingRightPizza } =
    if getUncomputedNumberValue firstArg == Just 0 then
        case secondArg of
            Just (Node secondArgRange _) ->
                [ Rule.errorWithFix
                    { message = "Dropping 0 items from a list will result in the list itself"
                    , details = [ "You can replace this call by the list itself." ]
                    }
                    fnRange
                    [ if usingRightPizza then
                        Fix.removeRange { start = secondArgRange.end, end = parentRange.end }

                      else
                        Fix.removeRange { start = parentRange.start, end = secondArgRange.start }
                    ]
                ]

            Nothing ->
                [ Rule.errorWithFix
                    { message = "Dropping 0 items from a list will result in the list itself"
                    , details = [ "You can replace this function by identity." ]
                    }
                    fnRange
                    [ Fix.replaceRangeBy parentRange "identity" ]
                ]

    else
        case Maybe.andThen (determineListLength lookupTable) secondArg of
            Just (Exactly 0) ->
                [ Rule.errorWithFix
                    { message = "Using List.drop on [] will result in []"
                    , details = [ "You can replace this call by []." ]
                    }
                    fnRange
                    [ Fix.replaceRangeBy parentRange "[]" ]
                ]

            _ ->
                []


subAndCmdBatchChecks : String -> CheckInfo -> List (Error {})
subAndCmdBatchChecks moduleName { lookupTable, parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.ListExpr [] ->
            [ Rule.errorWithFix
                { message = "Replace by " ++ moduleName ++ ".batch"
                , details = [ moduleName ++ ".batch [] and " ++ moduleName ++ ".none are equivalent but the latter is more idiomatic in Elm code" ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange (moduleName ++ ".none") ]
            ]

        Expression.ListExpr [ listElement ] ->
            [ Rule.errorWithFix
                { message = "Unnecessary " ++ moduleName ++ ".batch"
                , details = [ moduleName ++ ".batch with a single element is equal to that element." ]
                }
                fnRange
                (replaceBySubExpressionFix parentRange listElement)
            ]

        Expression.ListExpr args ->
            List.map3 (\a b c -> ( a, b, c ))
                (Nothing :: List.map (Node.range >> Just) args)
                args
                (List.map (Node.range >> Just) (List.drop 1 args) ++ [ Nothing ])
                |> List.filterMap
                    (\( prev, arg, next ) ->
                        case AstHelpers.removeParens arg of
                            Node batchRange (Expression.FunctionOrValue _ "none") ->
                                if ModuleNameLookupTable.moduleNameAt lookupTable batchRange == Just [ "Platform", moduleName ] then
                                    Just
                                        (Rule.errorWithFix
                                            { message = "Unnecessary " ++ moduleName ++ ".none"
                                            , details = [ moduleName ++ ".none will be ignored by " ++ moduleName ++ ".batch." ]
                                            }
                                            (Node.range arg)
                                            (case prev of
                                                Just prevRange ->
                                                    [ Fix.removeRange { start = prevRange.end, end = (Node.range arg).end } ]

                                                Nothing ->
                                                    case next of
                                                        Just nextRange ->
                                                            [ Fix.removeRange { start = (Node.range arg).start, end = nextRange.start } ]

                                                        Nothing ->
                                                            [ Fix.replaceRangeBy parentRange (moduleName ++ ".none") ]
                                            )
                                        )

                                else
                                    Nothing

                            _ ->
                                Nothing
                    )

        _ ->
            []



-- PARSER


oneOfChecks : CheckInfo -> List (Error {})
oneOfChecks { parentRange, fnRange, firstArg } =
    case AstHelpers.removeParens firstArg of
        Node _ (Expression.ListExpr [ listElement ]) ->
            [ Rule.errorWithFix
                { message = "Unnecessary oneOf"
                , details = [ "There is only a single element in the list of elements to try out." ]
                }
                fnRange
                (replaceBySubExpressionFix parentRange listElement)
            ]

        _ ->
            []


type alias Collection =
    { moduleName : String
    , represents : String
    , emptyAsString : String
    , emptyDescription : String
    , isEmpty : ModuleNameLookupTable -> Node Expression -> Bool
    , nameForSize : String
    , determineSize : ModuleNameLookupTable -> Node Expression -> Maybe CollectionSize
    }


listCollection : Collection
listCollection =
    { moduleName = "List"
    , represents = "list"
    , emptyAsString = "[]"
    , emptyDescription = "[]"
    , isEmpty = \_ -> isEmptyList
    , nameForSize = "length"
    , determineSize = determineListLength
    }


setCollection : Collection
setCollection =
    { moduleName = "Set"
    , represents = "set"
    , emptyAsString = "Set.empty"
    , emptyDescription = "Set.empty"
    , isEmpty = isSpecificFunction [ "Set" ] "empty"
    , nameForSize = "size"
    , determineSize = determineIfCollectionIsEmpty [ "Set" ] 1
    }


dictCollection : Collection
dictCollection =
    { moduleName = "Dict"
    , represents = "Dict"
    , emptyAsString = "Dict.empty"
    , emptyDescription = "Dict.empty"
    , isEmpty = isSpecificFunction [ "Dict" ] "empty"
    , nameForSize = "size"
    , determineSize = determineIfCollectionIsEmpty [ "Dict" ] 2
    }


type alias Mappable =
    { moduleName : String
    , represents : String
    , emptyAsString : String
    , emptyDescription : String
    , isEmpty : ModuleNameLookupTable -> Node Expression -> Bool
    }


type alias Defaultable =
    { moduleName : String
    , represents : String
    , emptyAsString : String
    , emptyDescription : String
    , isEmpty : ModuleNameLookupTable -> Node Expression -> Bool
    , isSomethingConstructor : String
    }


maybeCollection : Defaultable
maybeCollection =
    { moduleName = "Maybe"
    , represents = "maybe"
    , emptyAsString = "Nothing"
    , emptyDescription = "Nothing"
    , isEmpty = isSpecificFunction [ "Maybe" ] "Nothing"
    , isSomethingConstructor = "Just"
    }


resultCollection : Defaultable
resultCollection =
    { moduleName = "Result"
    , represents = "result"
    , emptyAsString = "Nothing"
    , emptyDescription = "an error"
    , isEmpty = isSpecificCall [ "Result" ] "Err"
    , isSomethingConstructor = "Ok"
    }


cmdCollection : Mappable
cmdCollection =
    { moduleName = "Cmd"
    , represents = "command"
    , emptyAsString = "Cmd.none"
    , emptyDescription = "Cmd.none"
    , isEmpty = isSpecificFunction [ "Platform", "Cmd" ] "none"
    }


subCollection : Mappable
subCollection =
    { moduleName = "Sub"
    , represents = "subscription"
    , emptyAsString = "Sub.none"
    , emptyDescription = "Sub.none"
    , isEmpty = isSpecificFunction [ "Platform", "Sub" ] "none"
    }


collectionMapChecks :
    { a
        | moduleName : String
        , represents : String
        , emptyDescription : String
        , emptyAsString : String
        , isEmpty : ModuleNameLookupTable -> Node Expression -> Bool
    }
    -> CheckInfo
    -> List (Error {})
collectionMapChecks collection checkInfo =
    case Maybe.map (collection.isEmpty checkInfo.lookupTable) checkInfo.secondArg of
        Just True ->
            [ Rule.errorWithFix
                { message = "Using " ++ collection.moduleName ++ ".map on " ++ collection.emptyDescription ++ " will result in " ++ collection.emptyDescription
                , details = [ "You can replace this call by " ++ collection.emptyDescription ++ "." ]
                }
                checkInfo.fnRange
                (noopFix checkInfo)
            ]

        _ ->
            if isIdentity checkInfo.lookupTable checkInfo.firstArg then
                [ Rule.errorWithFix
                    { message = "Using " ++ collection.moduleName ++ ".map with an identity function is the same as not using " ++ collection.moduleName ++ ".map"
                    , details = [ "You can remove this call and replace it by the " ++ collection.represents ++ " itself." ]
                    }
                    checkInfo.fnRange
                    (noopFix checkInfo)
                ]

            else
                []


maybeAndThenChecks : CheckInfo -> List (Error {})
maybeAndThenChecks checkInfo =
    firstThatReportsError
        [ \() ->
            case Match.maybeAndThen (getMaybeValues checkInfo.lookupTable) checkInfo.secondArg of
                Determined (Just justRanges) ->
                    [ Rule.errorWithFix
                        { message = "Calling " ++ maybeCollection.moduleName ++ ".andThen on a value that is known to be Just"
                        , details = [ "You can remove the Just and just call the function directly." ]
                        }
                        checkInfo.fnRange
                        (Fix.removeRange { start = checkInfo.fnRange.start, end = (Node.range checkInfo.firstArg).start }
                            :: List.map Fix.removeRange justRanges
                        )
                    ]

                Determined Nothing ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ maybeCollection.moduleName ++ ".andThen on " ++ maybeCollection.emptyAsString ++ " will result in " ++ maybeCollection.emptyAsString
                        , details = [ "You can replace this call by " ++ maybeCollection.emptyAsString ++ "." ]
                        }
                        checkInfo.fnRange
                        (noopFix checkInfo)
                    ]

                _ ->
                    []
        , \() ->
            case isAlwaysMaybe checkInfo.lookupTable checkInfo.firstArg of
                Determined (Just { ranges, throughLambdaFunction }) ->
                    if throughLambdaFunction then
                        [ Rule.errorWithFix
                            { message = "Use " ++ maybeCollection.moduleName ++ ".map instead"
                            , details = [ "Using " ++ maybeCollection.moduleName ++ ".andThen with a function that always returns Just is the same thing as using Maybe.map." ]
                            }
                            checkInfo.fnRange
                            (Fix.replaceRangeBy checkInfo.fnRange (maybeCollection.moduleName ++ ".map")
                                :: List.map Fix.removeRange ranges
                            )
                        ]

                    else
                        [ Rule.errorWithFix
                            { message = "Using Maybe.andThen with a function that will always return Just is the same as not using Maybe.andThen"
                            , details = [ "You can remove this call and replace it by the value itself." ]
                            }
                            checkInfo.fnRange
                            (noopFix checkInfo)
                        ]

                Determined Nothing ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ maybeCollection.moduleName ++ ".andThen with a function that will always return Nothing will result in Nothing"
                        , details = [ "You can remove this call and replace it by Nothing." ]
                        }
                        checkInfo.fnRange
                        (replaceByEmptyFix maybeCollection.emptyAsString checkInfo.parentRange checkInfo.secondArg)
                    ]

                Undetermined ->
                    []
        ]
        ()


resultAndThenChecks : CheckInfo -> List (Error {})
resultAndThenChecks checkInfo =
    firstThatReportsError
        [ \() ->
            case Maybe.andThen (getResultValues checkInfo.lookupTable) checkInfo.secondArg of
                Just (Ok okRanges) ->
                    [ Rule.errorWithFix
                        { message = "Calling " ++ resultCollection.moduleName ++ ".andThen on a value that is known to be Ok"
                        , details = [ "You can remove the Ok and just call the function directly." ]
                        }
                        checkInfo.fnRange
                        (Fix.removeRange { start = checkInfo.fnRange.start, end = (Node.range checkInfo.firstArg).start }
                            :: List.map Fix.removeRange okRanges
                        )
                    ]

                Just (Err _) ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ resultCollection.moduleName ++ ".andThen on an error will result in the error"
                        , details = [ "You can replace this call by the error itself." ]
                        }
                        checkInfo.fnRange
                        (noopFix checkInfo)
                    ]

                _ ->
                    []
        , \() ->
            case isAlwaysResult checkInfo.lookupTable checkInfo.firstArg of
                Just (Ok { ranges, throughLambdaFunction }) ->
                    if throughLambdaFunction then
                        [ Rule.errorWithFix
                            { message = "Use Result.map instead"
                            , details = [ "Using Result.andThen with a function that always returns Ok is the same thing as using Result.map." ]
                            }
                            checkInfo.fnRange
                            (Fix.replaceRangeBy checkInfo.fnRange (resultCollection.moduleName ++ ".map")
                                :: List.map Fix.removeRange ranges
                            )
                        ]

                    else
                        [ Rule.errorWithFix
                            { message = "Using Result.andThen with a function that will always return Just is the same as not using Result.andThen"
                            , details = [ "You can remove this call and replace it by the value itself." ]
                            }
                            checkInfo.fnRange
                            (noopFix checkInfo)
                        ]

                _ ->
                    []
        ]
        ()


resultWithDefaultChecks : CheckInfo -> List (Error {})
resultWithDefaultChecks checkInfo =
    case Maybe.andThen (getResultValues checkInfo.lookupTable) checkInfo.secondArg of
        Just (Ok okRanges) ->
            [ Rule.errorWithFix
                { message = "Using Result.withDefault on a value that is Ok will result in that value"
                , details = [ "You can replace this call by the value wrapped in Ok." ]
                }
                checkInfo.fnRange
                (List.map Fix.removeRange okRanges ++ noopFix checkInfo)
            ]

        Just (Err _) ->
            [ Rule.errorWithFix
                { message = "Using Result.withDefault on an error will result in the default value"
                , details = [ "You can replace this call by the default value." ]
                }
                checkInfo.fnRange
                [ Fix.removeRange { start = checkInfo.parentRange.start, end = (Node.range checkInfo.firstArg).start }
                , Fix.removeRange { start = (Node.range checkInfo.firstArg).end, end = checkInfo.parentRange.end }
                ]
            ]

        Nothing ->
            []


collectionFilterChecks : Collection -> CheckInfo -> List (Error {})
collectionFilterChecks collection ({ parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    case Maybe.andThen (collection.determineSize checkInfo.lookupTable) checkInfo.secondArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "Using " ++ collection.moduleName ++ ".filter on " ++ collection.emptyAsString ++ " will result in " ++ collection.emptyAsString
                , details = [ "You can replace this call by " ++ collection.emptyAsString ++ "." ]
                }
                checkInfo.fnRange
                (noopFix checkInfo)
            ]

        _ ->
            case Evaluate.isAlwaysBoolean checkInfo firstArg of
                Determined True ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ collection.moduleName ++ ".filter with a function that will always return True is the same as not using " ++ collection.moduleName ++ ".filter"
                        , details = [ "You can remove this call and replace it by the " ++ collection.represents ++ " itself." ]
                        }
                        fnRange
                        (noopFix checkInfo)
                    ]

                Determined False ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ collection.moduleName ++ ".filter with a function that will always return False will result in " ++ collection.emptyAsString
                        , details = [ "You can remove this call and replace it by " ++ collection.emptyAsString ++ "." ]
                        }
                        fnRange
                        (replaceByEmptyFix collection.emptyAsString parentRange secondArg)
                    ]

                Undetermined ->
                    []


collectionRemoveChecks : Collection -> CheckInfo -> List (Error {})
collectionRemoveChecks collection ({ lookupTable, fnRange, secondArg } as checkInfo) =
    case Maybe.andThen (collection.determineSize lookupTable) secondArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "Using " ++ collection.moduleName ++ ".remove on " ++ collection.emptyAsString ++ " will result in " ++ collection.emptyAsString
                , details = [ "You can replace this call by " ++ collection.emptyAsString ++ "." ]
                }
                fnRange
                (noopFix checkInfo)
            ]

        _ ->
            []


collectionIntersectChecks : Collection -> CheckInfo -> List (Error {})
collectionIntersectChecks collection { lookupTable, parentRange, fnRange, firstArg, secondArg } =
    firstThatReportsError
        [ \() ->
            case collection.determineSize lookupTable firstArg of
                Just (Exactly 0) ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ collection.moduleName ++ ".intersect on " ++ collection.emptyAsString ++ " will result in " ++ collection.emptyAsString
                        , details = [ "You can replace this call by " ++ collection.emptyAsString ++ "." ]
                        }
                        fnRange
                        (replaceByEmptyFix collection.emptyAsString parentRange secondArg)
                    ]

                _ ->
                    []
        , \() ->
            case Maybe.andThen (collection.determineSize lookupTable) secondArg of
                Just (Exactly 0) ->
                    [ Rule.errorWithFix
                        { message = "Using " ++ collection.moduleName ++ ".intersect on " ++ collection.emptyAsString ++ " will result in " ++ collection.emptyAsString
                        , details = [ "You can replace this call by " ++ collection.emptyAsString ++ "." ]
                        }
                        fnRange
                        (replaceByEmptyFix collection.emptyAsString parentRange secondArg)
                    ]

                _ ->
                    []
        ]
        ()


collectionDiffChecks : Collection -> CheckInfo -> List (Error {})
collectionDiffChecks collection { lookupTable, parentRange, fnRange, firstArg, secondArg } =
    firstThatReportsError
        [ \() ->
            case collection.determineSize lookupTable firstArg of
                Just (Exactly 0) ->
                    [ Rule.errorWithFix
                        { message = "Diffing " ++ collection.emptyAsString ++ " will result in " ++ collection.emptyAsString
                        , details = [ "You can replace this call by " ++ collection.emptyAsString ++ "." ]
                        }
                        fnRange
                        (replaceByEmptyFix collection.emptyAsString parentRange secondArg)
                    ]

                _ ->
                    []
        , \() ->
            case Maybe.andThen (collection.determineSize lookupTable) secondArg of
                Just (Exactly 0) ->
                    [ Rule.errorWithFix
                        { message = "Diffing a " ++ collection.represents ++ " with " ++ collection.emptyAsString ++ " will result in the " ++ collection.represents ++ " itself"
                        , details = [ "You can replace this call by the " ++ collection.represents ++ " itself." ]
                        }
                        fnRange
                        [ Fix.removeRange { start = parentRange.start, end = (Node.range firstArg).start }
                        , Fix.removeRange { start = (Node.range firstArg).end, end = parentRange.end }
                        ]
                    ]

                _ ->
                    []
        ]
        ()


collectionUnionChecks : Collection -> CheckInfo -> List (Error {})
collectionUnionChecks collection ({ lookupTable, parentRange, fnRange, firstArg, secondArg } as checkInfo) =
    firstThatReportsError
        [ \() ->
            case collection.determineSize lookupTable firstArg of
                Just (Exactly 0) ->
                    [ Rule.errorWithFix
                        { message = "Unnecessary union with Set.empty"
                        , details = [ "You can replace this call by the set itself." ]
                        }
                        fnRange
                        (noopFix checkInfo)
                    ]

                _ ->
                    []
        , \() ->
            case Maybe.andThen (collection.determineSize lookupTable) secondArg of
                Just (Exactly 0) ->
                    [ Rule.errorWithFix
                        { message = "Unnecessary union with Set.empty"
                        , details = [ "You can replace this call by the set itself." ]
                        }
                        fnRange
                        [ Fix.removeRange { start = parentRange.start, end = (Node.range firstArg).start }
                        , Fix.removeRange { start = (Node.range firstArg).end, end = parentRange.end }
                        ]
                    ]

                _ ->
                    []
        ]
        ()


collectionInsertChecks : Collection -> CheckInfo -> List (Error {})
collectionInsertChecks collection { lookupTable, usingRightPizza, parentRange, fnRange, firstArg, secondArg } =
    case Maybe.andThen (collection.determineSize lookupTable) secondArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "Use " ++ collection.moduleName ++ ".singleton instead of inserting in " ++ collection.emptyAsString
                , details = [ "You can replace this call by " ++ collection.moduleName ++ ".singleton." ]
                }
                fnRange
                [ Fix.replaceRangeBy fnRange (collection.moduleName ++ ".singleton")
                , if usingRightPizza then
                    Fix.removeRange { start = parentRange.start, end = fnRange.start }

                  else
                    Fix.removeRange { start = (Node.range firstArg).end, end = parentRange.end }
                ]
            ]

        _ ->
            []


collectionMemberChecks : Collection -> CheckInfo -> List (Error {})
collectionMemberChecks collection { lookupTable, parentRange, fnRange, secondArg } =
    case Maybe.andThen (collection.determineSize lookupTable) secondArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "Using " ++ collection.moduleName ++ ".member on " ++ collection.emptyAsString ++ " will result in False"
                , details = [ "You can replace this call by False." ]
                }
                fnRange
                (replaceByBoolFix parentRange secondArg False)
            ]

        _ ->
            []


collectionIsEmptyChecks : Collection -> CheckInfo -> List (Error {})
collectionIsEmptyChecks collection { lookupTable, parentRange, fnRange, firstArg } =
    case collection.determineSize lookupTable firstArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "The call to " ++ collection.moduleName ++ ".isEmpty will result in True"
                , details = [ "You can replace this call by True." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "True" ]
            ]

        Just _ ->
            [ Rule.errorWithFix
                { message = "The call to " ++ collection.moduleName ++ ".isEmpty will result in False"
                , details = [ "You can replace this call by False." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "False" ]
            ]

        Nothing ->
            []


collectionSizeChecks : Collection -> CheckInfo -> List (Error {})
collectionSizeChecks collection { lookupTable, parentRange, fnRange, firstArg } =
    case collection.determineSize lookupTable firstArg of
        Just (Exactly size) ->
            [ Rule.errorWithFix
                { message = "The " ++ collection.nameForSize ++ " of the " ++ collection.represents ++ " is " ++ String.fromInt size
                , details = [ "The " ++ collection.nameForSize ++ " of the " ++ collection.represents ++ " can be determined by looking at the code." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange (String.fromInt size) ]
            ]

        _ ->
            []


collectionFromListChecks : Collection -> CheckInfo -> List (Error {})
collectionFromListChecks collection { parentRange, fnRange, firstArg } =
    case Node.value firstArg of
        Expression.ListExpr [] ->
            [ Rule.errorWithFix
                { message = "The call to " ++ collection.moduleName ++ ".fromList will result in " ++ collection.emptyAsString
                , details = [ "You can replace this call by " ++ collection.emptyAsString ++ "." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange collection.emptyAsString ]
            ]

        _ ->
            []


collectionToListChecks : Collection -> CheckInfo -> List (Error {})
collectionToListChecks collection { lookupTable, parentRange, fnRange, firstArg } =
    case collection.determineSize lookupTable firstArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "The call to " ++ collection.moduleName ++ ".toList will result in []"
                , details = [ "You can replace this call by []." ]
                }
                fnRange
                [ Fix.replaceRangeBy parentRange "[]" ]
            ]

        _ ->
            []


collectionPartitionChecks : Collection -> CheckInfo -> List (Error {})
collectionPartitionChecks collection checkInfo =
    case Maybe.andThen (collection.determineSize checkInfo.lookupTable) checkInfo.secondArg of
        Just (Exactly 0) ->
            [ Rule.errorWithFix
                { message = "Using " ++ collection.moduleName ++ ".partition on " ++ collection.emptyAsString ++ " will result in ( " ++ collection.emptyAsString ++ ", " ++ collection.emptyAsString ++ " )"
                , details = [ "You can replace this call by ( " ++ collection.emptyAsString ++ ", " ++ collection.emptyAsString ++ " )." ]
                }
                checkInfo.fnRange
                [ Fix.replaceRangeBy checkInfo.parentRange ("( " ++ collection.emptyAsString ++ ", " ++ collection.emptyAsString ++ " )") ]
            ]

        _ ->
            case Evaluate.isAlwaysBoolean checkInfo checkInfo.firstArg of
                Determined True ->
                    case checkInfo.secondArg of
                        Just listArg ->
                            [ Rule.errorWithFix
                                { message = "All elements will go to the first " ++ collection.represents
                                , details = [ "Since the predicate function always returns True, the second " ++ collection.represents ++ " will always be " ++ collection.emptyAsString ++ "." ]
                                }
                                checkInfo.fnRange
                                [ Fix.replaceRangeBy { start = checkInfo.fnRange.start, end = (Node.range listArg).start } "( "
                                , Fix.insertAt (Node.range listArg).end (", " ++ collection.emptyAsString ++ " )")
                                ]
                            ]

                        Nothing ->
                            []

                Determined False ->
                    [ Rule.errorWithFix
                        { message = "All elements will go to the second " ++ collection.represents
                        , details = [ "Since the predicate function always returns False, the first " ++ collection.represents ++ " will always be " ++ collection.emptyAsString ++ "." ]
                        }
                        checkInfo.fnRange
                        (case checkInfo.secondArg of
                            Just listArg ->
                                [ Fix.replaceRangeBy { start = checkInfo.fnRange.start, end = (Node.range listArg).start } ("( " ++ collection.emptyAsString ++ ", ")
                                , Fix.insertAt (Node.range listArg).end " )"
                                ]

                            Nothing ->
                                [ Fix.replaceRangeBy checkInfo.parentRange ("(Tuple.pair " ++ collection.emptyAsString ++ ")") ]
                        )
                    ]

                Undetermined ->
                    []


maybeWithDefaultChecks : CheckInfo -> List (Error {})
maybeWithDefaultChecks checkInfo =
    case Match.maybeAndThen (getMaybeValues checkInfo.lookupTable) checkInfo.secondArg of
        Determined (Just justRanges) ->
            [ Rule.errorWithFix
                { message = "Using Maybe.withDefault on a value that is Just will result in that value"
                , details = [ "You can replace this call by the value wrapped in Just." ]
                }
                checkInfo.fnRange
                (List.map Fix.removeRange justRanges ++ noopFix checkInfo)
            ]

        Determined Nothing ->
            [ Rule.errorWithFix
                { message = "Using Maybe.withDefault on Nothing will result in the default value"
                , details = [ "You can replace this call by the default value." ]
                }
                checkInfo.fnRange
                [ Fix.removeRange { start = checkInfo.parentRange.start, end = (Node.range checkInfo.firstArg).start }
                , Fix.removeRange { start = (Node.range checkInfo.firstArg).end, end = checkInfo.parentRange.end }
                ]
            ]

        Undetermined ->
            []


type CollectionSize
    = Exactly Int
    | NotEmpty


determineListLength : ModuleNameLookupTable -> Node Expression -> Maybe CollectionSize
determineListLength lookupTable node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.ListExpr list ->
            Just (Exactly (List.length list))

        Expression.OperatorApplication "::" _ _ right ->
            case determineListLength lookupTable right of
                Just (Exactly n) ->
                    Just (Exactly (n + 1))

                _ ->
                    Just NotEmpty

        Expression.Application ((Node fnRange (Expression.FunctionOrValue _ "singleton")) :: _ :: []) ->
            if ModuleNameLookupTable.moduleNameAt lookupTable fnRange == Just [ "List" ] then
                Just (Exactly 1)

            else
                Nothing

        _ ->
            Nothing


replaceSingleElementListBySingleValue_RENAME : ModuleNameLookupTable -> Range -> Node Expression -> Maybe (List (Error {}))
replaceSingleElementListBySingleValue_RENAME lookupTable fnRange node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.LambdaExpression { expression } ->
            case replaceSingleElementListBySingleValue lookupTable expression of
                Just fixes ->
                    Just
                        [ Rule.errorWithFix
                            { message = "Use List.map instead"
                            , details = [ "The function passed to List.concatMap always returns a list with a single element." ]
                            }
                            fnRange
                            (Fix.replaceRangeBy fnRange "List.map" :: fixes)
                        ]

                Nothing ->
                    Nothing

        _ ->
            Nothing


replaceSingleElementListBySingleValue : ModuleNameLookupTable -> Node Expression -> Maybe (List Fix)
replaceSingleElementListBySingleValue lookupTable node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.ListExpr [ listElement ] ->
            Just (replaceBySubExpressionFix (Node.range node) listElement)

        Expression.Application ((Node fnRange (Expression.FunctionOrValue _ "singleton")) :: _ :: []) ->
            if ModuleNameLookupTable.moduleNameAt lookupTable fnRange == Just [ "List" ] then
                Just [ Fix.removeRange fnRange ]

            else
                Nothing

        Expression.IfBlock _ thenBranch elseBranch ->
            combineSingleElementFixes lookupTable [ thenBranch, elseBranch ] []

        Expression.CaseExpression { cases } ->
            combineSingleElementFixes lookupTable (List.map Tuple.second cases) []

        _ ->
            Nothing


combineSingleElementFixes : ModuleNameLookupTable -> List (Node Expression) -> List Fix -> Maybe (List Fix)
combineSingleElementFixes lookupTable nodes soFar =
    case nodes of
        [] ->
            Just soFar

        node :: restOfNodes ->
            case replaceSingleElementListBySingleValue lookupTable node of
                Nothing ->
                    Nothing

                Just fixes ->
                    combineSingleElementFixes lookupTable restOfNodes (fixes ++ soFar)


determineIfCollectionIsEmpty : ModuleName -> Int -> ModuleNameLookupTable -> Node Expression -> Maybe CollectionSize
determineIfCollectionIsEmpty moduleName singletonNumberOfArgs lookupTable node =
    if isSpecificFunction moduleName "empty" lookupTable node then
        Just (Exactly 0)

    else
        case Node.value (AstHelpers.removeParens node) of
            Expression.Application ((Node fnRange (Expression.FunctionOrValue _ "singleton")) :: args) ->
                if List.length args == singletonNumberOfArgs && ModuleNameLookupTable.moduleNameAt lookupTable fnRange == Just moduleName then
                    Just (Exactly 1)

                else
                    Nothing

            Expression.Application ((Node fnRange (Expression.FunctionOrValue _ "fromList")) :: (Node _ (Expression.ListExpr list)) :: []) ->
                if ModuleNameLookupTable.moduleNameAt lookupTable fnRange == Just moduleName then
                    if moduleName == [ "Set" ] then
                        case list of
                            [] ->
                                Just (Exactly 0)

                            [ _ ] ->
                                Just (Exactly 1)

                            _ ->
                                case traverse getComparableExpression list of
                                    Nothing ->
                                        Just NotEmpty

                                    Just comparableExpressions ->
                                        comparableExpressions |> unique |> List.length |> Exactly |> Just

                    else
                        Just (Exactly (List.length list))

                else
                    Nothing

            _ ->
                Nothing


getComparableExpression : Node Expression -> Maybe (List Expression)
getComparableExpression =
    getComparableExpressionHelper 1


getComparableExpressionHelper : Int -> Node Expression -> Maybe (List Expression)
getComparableExpressionHelper sign (Node _ expression) =
    case expression of
        Expression.Integer int ->
            Just [ Expression.Integer (sign * int) ]

        Expression.Hex hex ->
            Just [ Expression.Integer (sign * hex) ]

        Expression.Floatable float ->
            Just [ Expression.Floatable (toFloat sign * float) ]

        Expression.Negation expr ->
            getComparableExpressionHelper (-1 * sign) expr

        Expression.Literal string ->
            Just [ Expression.Literal string ]

        Expression.CharLiteral char ->
            Just [ Expression.CharLiteral char ]

        Expression.ParenthesizedExpression expr ->
            getComparableExpressionHelper 1 expr

        Expression.TupledExpression exprs ->
            exprs
                |> traverse (getComparableExpressionHelper 1)
                |> Maybe.map List.concat

        Expression.ListExpr exprs ->
            exprs
                |> traverse (getComparableExpressionHelper 1)
                |> Maybe.map List.concat

        _ ->
            Nothing


traverse : (a -> Maybe b) -> List a -> Maybe (List b)
traverse f list =
    traverseHelp f list []


traverseHelp : (a -> Maybe b) -> List a -> List b -> Maybe (List b)
traverseHelp f list acc =
    case list of
        head :: tail ->
            case f head of
                Just a ->
                    traverseHelp f tail (a :: acc)

                Nothing ->
                    Nothing

        [] ->
            Just (List.reverse acc)


unique : List a -> List a
unique list =
    uniqueHelp [] list []


uniqueHelp : List a -> List a -> List a -> List a
uniqueHelp existing remaining accumulator =
    case remaining of
        [] ->
            List.reverse accumulator

        first :: rest ->
            if List.member first existing then
                uniqueHelp existing rest accumulator

            else
                uniqueHelp (first :: existing) rest (first :: accumulator)



-- RECORD UPDATE


removeRecordFields : Range -> Node String -> List (Node Expression.RecordSetter) -> List (Error {})
removeRecordFields recordUpdateRange variable fields =
    case fields of
        [] ->
            -- Not possible
            []

        (Node _ ( field, valueWithParens )) :: [] ->
            let
                value : Node Expression
                value =
                    AstHelpers.removeParens valueWithParens
            in
            if isUnnecessaryRecordUpdateSetter variable field value then
                [ Rule.errorWithFix
                    { message = "Unnecessary field assignment"
                    , details = [ "The field is being set to its own value." ]
                    }
                    (Node.range value)
                    [ Fix.removeRange { start = recordUpdateRange.start, end = (Node.range variable).start }
                    , Fix.removeRange { start = (Node.range variable).end, end = recordUpdateRange.end }
                    ]
                ]

            else
                []

        (Node firstRange _) :: second :: _ ->
            List.filterMap
                (\( Node range ( field, valueWithParens ), previousRange ) ->
                    let
                        value : Node Expression
                        value =
                            AstHelpers.removeParens valueWithParens
                    in
                    if isUnnecessaryRecordUpdateSetter variable field value then
                        Just
                            (Rule.errorWithFix
                                { message = "Unnecessary field assignment"
                                , details = [ "The field is being set to its own value." ]
                                }
                                (Node.range value)
                                (case previousRange of
                                    Just prevRange ->
                                        [ Fix.removeRange { start = prevRange.end, end = range.end } ]

                                    Nothing ->
                                        -- It's the first element, so we can remove until the second element
                                        [ Fix.removeRange { start = firstRange.start, end = (Node.range second).start } ]
                                )
                            )

                    else
                        Nothing
                )
                (List.map2 Tuple.pair fields (Nothing :: List.map (Node.range >> Just) fields))


isUnnecessaryRecordUpdateSetter : Node String -> Node String -> Node Expression -> Bool
isUnnecessaryRecordUpdateSetter variable field value =
    case Node.value value of
        Expression.RecordAccess (Node _ (Expression.FunctionOrValue [] valueHolder)) fieldName ->
            Node.value field == Node.value fieldName && Node.value variable == valueHolder

        _ ->
            False



-- IF


ifChecks :
    ModuleContext
    -> Range
    ->
        { condition : Node Expression
        , trueBranch : Node Expression
        , falseBranch : Node Expression
        }
    -> { errors : List (Error {}), rangesToIgnore : List Range, rightSidesOfPlusPlus : List Range, inferredConstants : List ( Range, Infer.Inferred ) }
ifChecks context nodeRange { condition, trueBranch, falseBranch } =
    case Evaluate.getBoolean context condition of
        Determined True ->
            errorsAndRangesToIgnore
                [ Rule.errorWithFix
                    { message = "The condition will always evaluate to True"
                    , details = [ "The expression can be replaced by what is inside the 'then' branch." ]
                    }
                    (targetIfKeyword nodeRange)
                    [ Fix.removeRange
                        { start = nodeRange.start
                        , end = (Node.range trueBranch).start
                        }
                    , Fix.removeRange
                        { start = (Node.range trueBranch).end
                        , end = nodeRange.end
                        }
                    ]
                ]
                [ Node.range condition ]

        Determined False ->
            errorsAndRangesToIgnore
                [ Rule.errorWithFix
                    { message = "The condition will always evaluate to False"
                    , details = [ "The expression can be replaced by what is inside the 'else' branch." ]
                    }
                    (targetIfKeyword nodeRange)
                    [ Fix.removeRange
                        { start = nodeRange.start
                        , end = (Node.range falseBranch).start
                        }
                    ]
                ]
                [ Node.range condition ]

        Undetermined ->
            case ( Evaluate.getBoolean context trueBranch, Evaluate.getBoolean context falseBranch ) of
                ( Determined True, Determined False ) ->
                    onlyErrors
                        [ Rule.errorWithFix
                            { message = "The if expression's value is the same as the condition"
                            , details = [ "The expression can be replaced by the condition." ]
                            }
                            (targetIfKeyword nodeRange)
                            [ Fix.removeRange
                                { start = nodeRange.start
                                , end = (Node.range condition).start
                                }
                            , Fix.removeRange
                                { start = (Node.range condition).end
                                , end = nodeRange.end
                                }
                            ]
                        ]

                ( Determined False, Determined True ) ->
                    onlyErrors
                        [ Rule.errorWithFix
                            { message = "The if expression's value is the inverse of the condition"
                            , details = [ "The expression can be replaced by the condition wrapped by `not`." ]
                            }
                            (targetIfKeyword nodeRange)
                            [ Fix.replaceRangeBy
                                { start = nodeRange.start
                                , end = (Node.range condition).start
                                }
                                "not ("
                            , Fix.replaceRangeBy
                                { start = (Node.range condition).end
                                , end = nodeRange.end
                                }
                                ")"
                            ]
                        ]

                _ ->
                    case Normalize.compare context trueBranch falseBranch of
                        Normalize.ConfirmedEquality ->
                            onlyErrors
                                [ Rule.errorWithFix
                                    { message = "The values in both branches is the same."
                                    , details = [ "The expression can be replaced by the contents of either branch." ]
                                    }
                                    (targetIfKeyword nodeRange)
                                    [ Fix.removeRange
                                        { start = nodeRange.start
                                        , end = (Node.range trueBranch).start
                                        }
                                    , Fix.removeRange
                                        { start = (Node.range trueBranch).end
                                        , end = nodeRange.end
                                        }
                                    ]
                                ]

                        _ ->
                            { errors = []
                            , rangesToIgnore = []
                            , rightSidesOfPlusPlus = []
                            , inferredConstants =
                                Infer.inferForIfCondition
                                    (Node.value (Normalize.normalize context condition))
                                    { trueBranchRange = Node.range trueBranch
                                    , falseBranchRange = Node.range falseBranch
                                    }
                                    (Tuple.first context.inferredConstants)
                            }



-- CASE OF


caseOfChecks : ModuleContext -> Range -> Expression.CaseBlock -> List (Error {})
caseOfChecks context parentRange caseBlock =
    firstThatReportsError
        [ \() -> sameBodyForCaseOfChecks context parentRange caseBlock.cases
        , \() -> booleanCaseOfChecks context.lookupTable parentRange caseBlock
        ]
        ()


sameBodyForCaseOfChecks : ModuleContext -> Range -> List ( Node Pattern, Node Expression ) -> List (Error {})
sameBodyForCaseOfChecks context parentRange cases =
    case cases of
        [] ->
            []

        ( firstPattern, firstBody ) :: rest ->
            let
                restPatterns : List (Node Pattern)
                restPatterns =
                    List.map Tuple.first rest
            in
            if
                introducesVariableOrUsesTypeConstructor context (firstPattern :: restPatterns)
                    || not (Normalize.areAllTheSame context firstBody (List.map Tuple.second rest))
            then
                []

            else
                let
                    firstBodyRange : Range
                    firstBodyRange =
                        Node.range firstBody
                in
                [ Rule.errorWithFix
                    { message = "Unnecessary case expression"
                    , details = [ "All the branches of this case expression resolve to the same value. You can remove the case expression and replace it with the body of one of the branches." ]
                    }
                    (caseKeyWordRange parentRange)
                    [ Fix.removeRange { start = parentRange.start, end = firstBodyRange.start }
                    , Fix.removeRange { start = firstBodyRange.end, end = parentRange.end }
                    ]
                ]


caseKeyWordRange : Range -> Range
caseKeyWordRange range =
    { start = range.start
    , end = { row = range.start.row, column = range.start.column + 4 }
    }


introducesVariableOrUsesTypeConstructor : ModuleContext -> List (Node Pattern) -> Bool
introducesVariableOrUsesTypeConstructor context nodesToLookAt =
    case nodesToLookAt of
        [] ->
            False

        node :: remaining ->
            case Node.value node of
                Pattern.VarPattern _ ->
                    True

                Pattern.RecordPattern _ ->
                    True

                Pattern.AsPattern _ _ ->
                    True

                Pattern.ParenthesizedPattern pattern ->
                    introducesVariableOrUsesTypeConstructor context (pattern :: remaining)

                Pattern.TuplePattern nodes ->
                    introducesVariableOrUsesTypeConstructor context (nodes ++ remaining)

                Pattern.UnConsPattern first rest ->
                    introducesVariableOrUsesTypeConstructor context (first :: rest :: remaining)

                Pattern.ListPattern nodes ->
                    introducesVariableOrUsesTypeConstructor context (nodes ++ remaining)

                Pattern.NamedPattern { name } nodes ->
                    case ModuleNameLookupTable.fullModuleNameFor context.lookupTable node of
                        Just moduleName ->
                            if Set.member ( moduleName, name ) context.customTypesToReportInCases then
                                introducesVariableOrUsesTypeConstructor context (nodes ++ remaining)

                            else
                                True

                        Nothing ->
                            True

                _ ->
                    introducesVariableOrUsesTypeConstructor context remaining


booleanCaseOfChecks : ModuleNameLookupTable -> Range -> Expression.CaseBlock -> List (Error {})
booleanCaseOfChecks lookupTable parentRange { expression, cases } =
    case cases of
        [ ( firstPattern, Node firstRange _ ), ( Node secondPatternRange _, Node secondExprRange _ ) ] ->
            case getBooleanPattern lookupTable firstPattern of
                Just isTrueFirst ->
                    [ Rule.errorWithFix
                        { message = "Replace `case..of` by an `if` condition"
                        , details =
                            [ "The idiomatic way to check for a condition is to use an `if` expression."
                            , "Read more about it at: https://guide.elm-lang.org/core_language.html#if-expressions"
                            ]
                        }
                        (Node.range firstPattern)
                        (if isTrueFirst then
                            [ Fix.replaceRangeBy { start = parentRange.start, end = (Node.range expression).start } "if "
                            , Fix.replaceRangeBy { start = (Node.range expression).end, end = firstRange.start } " then "
                            , Fix.replaceRangeBy { start = secondPatternRange.start, end = secondExprRange.start } "else "
                            ]

                         else
                            [ Fix.replaceRangeBy { start = parentRange.start, end = (Node.range expression).start } "if not ("
                            , Fix.replaceRangeBy { start = (Node.range expression).end, end = firstRange.start } ") then "
                            , Fix.replaceRangeBy { start = secondPatternRange.start, end = secondExprRange.start } "else "
                            ]
                        )
                    ]

                _ ->
                    []

        _ ->
            []


isSpecificFunction : ModuleName -> String -> ModuleNameLookupTable -> Node Expression -> Bool
isSpecificFunction moduleName fnName lookupTable node =
    case AstHelpers.removeParens node of
        Node noneRange (Expression.FunctionOrValue _ foundFnName) ->
            (foundFnName == fnName)
                && (ModuleNameLookupTable.moduleNameAt lookupTable noneRange == Just moduleName)

        _ ->
            False


isSpecificCall : ModuleName -> String -> ModuleNameLookupTable -> Node Expression -> Bool
isSpecificCall moduleName fnName lookupTable node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.Application ((Node noneRange (Expression.FunctionOrValue _ foundFnName)) :: _ :: []) ->
            (foundFnName == fnName)
                && (ModuleNameLookupTable.moduleNameAt lookupTable noneRange == Just moduleName)

        _ ->
            False


getUncomputedNumberValue : Node Expression -> Maybe Float
getUncomputedNumberValue node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.Integer n ->
            Just (toFloat n)

        Expression.Hex n ->
            Just (toFloat n)

        Expression.Floatable n ->
            Just n

        Expression.Negation expr ->
            Maybe.map negate (getUncomputedNumberValue expr)

        _ ->
            Nothing



-- FIX HELPERS


removeFunctionFromFunctionCall : { a | fnRange : Range, firstArg : Node b, usingRightPizza : Bool } -> Fix
removeFunctionFromFunctionCall { fnRange, firstArg, usingRightPizza } =
    if usingRightPizza then
        Fix.removeRange { start = (Node.range firstArg).end, end = fnRange.end }

    else
        Fix.removeRange { start = fnRange.start, end = (Node.range firstArg).start }


removeFunctionAndFirstArg : { a | fnRange : Range, firstArg : Node b, usingRightPizza : Bool } -> Range -> Fix
removeFunctionAndFirstArg { fnRange, firstArg, usingRightPizza } secondArgRange =
    if usingRightPizza then
        Fix.removeRange { start = secondArgRange.end, end = (Node.range firstArg).end }

    else
        Fix.removeRange { start = fnRange.start, end = secondArgRange.start }


removeBoundariesFix : Node a -> List Fix
removeBoundariesFix node =
    let
        { start, end } =
            Node.range node
    in
    [ Fix.removeRange
        { start = { row = start.row, column = start.column }
        , end = { row = start.row, column = start.column + 1 }
        }
    , Fix.removeRange
        { start = { row = end.row, column = end.column - 1 }
        , end = { row = end.row, column = end.column }
        }
    ]


noopFix : CheckInfo -> List Fix
noopFix { fnRange, parentRange, secondArg, usingRightPizza } =
    [ case secondArg of
        Just listArg ->
            if usingRightPizza then
                Fix.removeRange { start = (Node.range listArg).end, end = parentRange.end }

            else
                Fix.removeRange { start = fnRange.start, end = (Node.range listArg).start }

        Nothing ->
            Fix.replaceRangeBy parentRange "identity"
    ]


replaceByEmptyFix : String -> Range -> Maybe a -> List Fix
replaceByEmptyFix empty parentRange secondArg =
    [ case secondArg of
        Just _ ->
            Fix.replaceRangeBy parentRange empty

        Nothing ->
            Fix.replaceRangeBy parentRange ("(always " ++ empty ++ ")")
    ]


replaceByBoolFix : Range -> Maybe a -> Bool -> List Fix
replaceByBoolFix parentRange secondArg replacementValue =
    [ case secondArg of
        Just _ ->
            Fix.replaceRangeBy parentRange (boolToString replacementValue)

        Nothing ->
            Fix.replaceRangeBy parentRange ("(always " ++ boolToString replacementValue ++ ")")
    ]


boolToString : Bool -> String
boolToString bool =
    if bool then
        "True"

    else
        "False"



-- MATCHERS


isIdentity : ModuleNameLookupTable -> Node Expression -> Bool
isIdentity lookupTable baseNode =
    let
        node : Node Expression
        node =
            AstHelpers.removeParens baseNode
    in
    case Node.value node of
        Expression.FunctionOrValue _ "identity" ->
            ModuleNameLookupTable.moduleNameFor lookupTable node == Just [ "Basics" ]

        Expression.LambdaExpression { args, expression } ->
            case args of
                arg :: [] ->
                    case getVarPattern arg of
                        Just patternName ->
                            case getExpressionName expression of
                                Just expressionName ->
                                    patternName == expressionName

                                _ ->
                                    False

                        _ ->
                            False

                _ ->
                    False

        _ ->
            False


getVarPattern : Node Pattern -> Maybe String
getVarPattern node =
    case Node.value node of
        Pattern.VarPattern name ->
            Just name

        Pattern.ParenthesizedPattern pattern ->
            getVarPattern pattern

        _ ->
            Nothing


getExpressionName : Node Expression -> Maybe String
getExpressionName node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.FunctionOrValue [] name ->
            Just name

        _ ->
            Nothing


isListLiteral : Node Expression -> Bool
isListLiteral node =
    case Node.value node of
        Expression.ListExpr _ ->
            True

        _ ->
            False


getBooleanPattern : ModuleNameLookupTable -> Node Pattern -> Maybe Bool
getBooleanPattern lookupTable node =
    case Node.value node of
        Pattern.NamedPattern { name } _ ->
            case name of
                "True" ->
                    if ModuleNameLookupTable.moduleNameFor lookupTable node == Just [ "Basics" ] then
                        Just True

                    else
                        Nothing

                "False" ->
                    if ModuleNameLookupTable.moduleNameFor lookupTable node == Just [ "Basics" ] then
                        Just False

                    else
                        Nothing

                _ ->
                    Nothing

        Pattern.ParenthesizedPattern pattern ->
            getBooleanPattern lookupTable pattern

        _ ->
            Nothing


isAlwaysMaybe : ModuleNameLookupTable -> Node Expression -> Match (Maybe { ranges : List Range, throughLambdaFunction : Bool })
isAlwaysMaybe lookupTable baseNode =
    let
        node : Node Expression
        node =
            AstHelpers.removeParens baseNode
    in
    case Node.value node of
        Expression.FunctionOrValue _ "Just" ->
            case ModuleNameLookupTable.moduleNameFor lookupTable node of
                Just [ "Maybe" ] ->
                    Determined (Just { ranges = [ Node.range node ], throughLambdaFunction = False })

                _ ->
                    Undetermined

        Expression.Application ((Node alwaysRange (Expression.FunctionOrValue _ "always")) :: value :: []) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange of
                Just [ "Basics" ] ->
                    getMaybeValues lookupTable value
                        |> Match.map (Maybe.map (\ranges -> { ranges = ranges, throughLambdaFunction = False }))

                _ ->
                    Undetermined

        Expression.LambdaExpression { expression } ->
            getMaybeValues lookupTable expression
                |> Match.map (Maybe.map (\ranges -> { ranges = ranges, throughLambdaFunction = True }))

        _ ->
            Undetermined


getMaybeValues : ModuleNameLookupTable -> Node Expression -> Match (Maybe (List Range))
getMaybeValues lookupTable baseNode =
    let
        node : Node Expression
        node =
            AstHelpers.removeParens baseNode
    in
    case Node.value node of
        Expression.Application ((Node justRange (Expression.FunctionOrValue _ "Just")) :: arg :: []) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Maybe" ] ->
                    Determined (Just [ { start = justRange.start, end = (Node.range arg).start } ])

                _ ->
                    Undetermined

        Expression.OperatorApplication "|>" _ arg (Node justRange (Expression.FunctionOrValue _ "Just")) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Maybe" ] ->
                    Determined (Just [ { start = (Node.range arg).end, end = justRange.end } ])

                _ ->
                    Undetermined

        Expression.OperatorApplication "<|" _ (Node justRange (Expression.FunctionOrValue _ "Just")) arg ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Maybe" ] ->
                    Determined (Just [ { start = justRange.start, end = (Node.range arg).start } ])

                _ ->
                    Undetermined

        Expression.FunctionOrValue _ "Nothing" ->
            case ModuleNameLookupTable.moduleNameFor lookupTable node of
                Just [ "Maybe" ] ->
                    Determined Nothing

                _ ->
                    Undetermined

        Expression.LetExpression { expression } ->
            getMaybeValues lookupTable expression

        Expression.ParenthesizedExpression expression ->
            getMaybeValues lookupTable expression

        Expression.IfBlock _ thenBranch elseBranch ->
            combineMaybeValues lookupTable [ thenBranch, elseBranch ]

        Expression.CaseExpression { cases } ->
            combineMaybeValues lookupTable (List.map Tuple.second cases)

        _ ->
            Undetermined


combineMaybeValues : ModuleNameLookupTable -> List (Node Expression) -> Match (Maybe (List Range))
combineMaybeValues lookupTable nodes =
    case nodes of
        node :: restOfNodes ->
            case getMaybeValues lookupTable node of
                Undetermined ->
                    Undetermined

                Determined nodeValue ->
                    combineMaybeValuesHelp lookupTable restOfNodes nodeValue

        [] ->
            Undetermined


combineMaybeValuesHelp : ModuleNameLookupTable -> List (Node Expression) -> Maybe (List Range) -> Match (Maybe (List Range))
combineMaybeValuesHelp lookupTable nodes soFar =
    case nodes of
        node :: restOfNodes ->
            case getMaybeValues lookupTable node of
                Undetermined ->
                    Undetermined

                Determined nodeValue ->
                    case ( nodeValue, soFar ) of
                        ( Just _, Nothing ) ->
                            Undetermined

                        ( Nothing, Just _ ) ->
                            Undetermined

                        ( Nothing, Nothing ) ->
                            combineMaybeValuesHelp lookupTable restOfNodes Nothing

                        ( Just a, Just b ) ->
                            combineMaybeValuesHelp lookupTable restOfNodes (Just (a ++ b))

        [] ->
            Determined soFar


isAlwaysResult : ModuleNameLookupTable -> Node Expression -> Maybe (Result Range { ranges : List Range, throughLambdaFunction : Bool })
isAlwaysResult lookupTable baseNode =
    let
        node : Node Expression
        node =
            AstHelpers.removeParens baseNode
    in
    case Node.value node of
        Expression.FunctionOrValue _ "Ok" ->
            case ModuleNameLookupTable.moduleNameFor lookupTable node of
                Just [ "Result" ] ->
                    Just (Ok { ranges = [ Node.range node ], throughLambdaFunction = False })

                _ ->
                    Nothing

        Expression.FunctionOrValue _ "Err" ->
            case ModuleNameLookupTable.moduleNameFor lookupTable node of
                Just [ "Result" ] ->
                    Just (Err (Node.range node))

                _ ->
                    Nothing

        Expression.Application ((Node alwaysRange (Expression.FunctionOrValue _ "always")) :: value :: []) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange of
                Just [ "Basics" ] ->
                    getResultValues lookupTable value
                        |> Maybe.map (Result.map (\ranges -> { ranges = ranges, throughLambdaFunction = False }))

                _ ->
                    Nothing

        Expression.LambdaExpression { expression } ->
            getResultValues lookupTable expression
                |> Maybe.map (Result.map (\ranges -> { ranges = ranges, throughLambdaFunction = True }))

        _ ->
            Nothing


getResultValues : ModuleNameLookupTable -> Node Expression -> Maybe (Result Range (List Range))
getResultValues lookupTable baseNode =
    let
        node : Node Expression
        node =
            AstHelpers.removeParens baseNode
    in
    case Node.value node of
        Expression.Application ((Node justRange (Expression.FunctionOrValue _ "Ok")) :: arg :: []) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Result" ] ->
                    Just (Ok [ { start = justRange.start, end = (Node.range arg).start } ])

                _ ->
                    Nothing

        Expression.OperatorApplication "|>" _ arg (Node justRange (Expression.FunctionOrValue _ "Ok")) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Result" ] ->
                    Just (Ok [ { start = (Node.range arg).end, end = justRange.end } ])

                _ ->
                    Nothing

        Expression.OperatorApplication "<|" _ (Node justRange (Expression.FunctionOrValue _ "Ok")) arg ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Result" ] ->
                    Just (Ok [ { start = justRange.start, end = (Node.range arg).start } ])

                _ ->
                    Nothing

        Expression.Application ((Node justRange (Expression.FunctionOrValue _ "Err")) :: arg :: []) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Result" ] ->
                    Just (Err { start = justRange.start, end = (Node.range arg).start })

                _ ->
                    Nothing

        Expression.OperatorApplication "|>" _ arg (Node justRange (Expression.FunctionOrValue _ "Err")) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Result" ] ->
                    Just (Err { start = (Node.range arg).end, end = justRange.end })

                _ ->
                    Nothing

        Expression.OperatorApplication "<|" _ (Node justRange (Expression.FunctionOrValue _ "Err")) arg ->
            case ModuleNameLookupTable.moduleNameAt lookupTable justRange of
                Just [ "Result" ] ->
                    Just (Err { start = justRange.start, end = (Node.range arg).start })

                _ ->
                    Nothing

        Expression.LetExpression { expression } ->
            getResultValues lookupTable expression

        Expression.ParenthesizedExpression expression ->
            getResultValues lookupTable expression

        Expression.IfBlock _ thenBranch elseBranch ->
            combineResultValues lookupTable [ thenBranch, elseBranch ]

        Expression.CaseExpression { cases } ->
            combineResultValues lookupTable (List.map Tuple.second cases)

        _ ->
            Nothing


combineResultValues : ModuleNameLookupTable -> List (Node Expression) -> Maybe (Result Range (List Range))
combineResultValues lookupTable nodes =
    case nodes of
        node :: restOfNodes ->
            case getResultValues lookupTable node of
                Nothing ->
                    Nothing

                Just nodeValue ->
                    combineResultValuesHelp lookupTable restOfNodes nodeValue

        [] ->
            Nothing


combineResultValuesHelp : ModuleNameLookupTable -> List (Node Expression) -> Result Range (List Range) -> Maybe (Result Range (List Range))
combineResultValuesHelp lookupTable nodes soFar =
    case nodes of
        node :: restOfNodes ->
            case getResultValues lookupTable node of
                Nothing ->
                    Nothing

                Just nodeValue ->
                    case ( nodeValue, soFar ) of
                        ( Ok _, Err _ ) ->
                            Nothing

                        ( Err _, Ok _ ) ->
                            Nothing

                        ( Err _, Err soFarRange ) ->
                            combineResultValuesHelp lookupTable restOfNodes (Err soFarRange)

                        ( Ok a, Ok b ) ->
                            combineResultValuesHelp lookupTable restOfNodes (Ok (a ++ b))

        [] ->
            Just soFar


isAlwaysEmptyList : ModuleNameLookupTable -> Node Expression -> Bool
isAlwaysEmptyList lookupTable node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.Application ((Node alwaysRange (Expression.FunctionOrValue _ "always")) :: alwaysValue :: []) ->
            case ModuleNameLookupTable.moduleNameAt lookupTable alwaysRange of
                Just [ "Basics" ] ->
                    isEmptyList alwaysValue

                _ ->
                    False

        Expression.LambdaExpression { expression } ->
            isEmptyList expression

        _ ->
            False


isEmptyList : Node Expression -> Bool
isEmptyList node =
    case Node.value (AstHelpers.removeParens node) of
        Expression.ListExpr [] ->
            True

        _ ->
            False