module Main exposing (main)

import Browser
import Html exposing (..)
import Html.Attributes exposing (class, id, style)
import Html.Events exposing (onInput)
import Lint exposing (Rule, Severity(..), lintSource)
import Lint.Rule.DefaultPatternPosition
import Lint.Rule.NoDebug
import Lint.Rule.NoExtraBooleanComparison
import Lint.Rule.NoImportingEverything
import Lint.Rule.NoUnusedVariables
import Lint.RuleError exposing (RuleError)



-- LINT CONFIGURATION


config : List ( Severity, Rule )
config =
    [ ( Critical, Lint.Rule.NoDebug.rule )
    , ( Critical, Lint.Rule.NoUnusedVariables.rule )
    , ( Critical, Lint.Rule.NoImportingEverything.rule { exceptions = [ "Html" ] } )
    , ( Critical, Lint.Rule.DefaultPatternPosition.rule { position = Lint.Rule.DefaultPatternPosition.Last } )
    , ( Critical, Lint.Rule.NoExtraBooleanComparison.rule )

    -- , ( Critical, Lint.Rule.NoConstantCondition.rule )
    -- , ( Critical, Lint.Rule.NoDuplicateImports.rule )
    -- , ( Critical, Lint.Rule.NoExposingEverything.rule )
    -- , ( Critical, Lint.Rule.NoNestedLet.rule )
    -- , ( Critical, Lint.Rule.NoUnannotatedFunction.rule )
    -- , ( Critical, Lint.Rule.NoUselessIf.rule )
    -- , ( Critical, Lint.Rule.NoUselessPatternMatching.rule )
    -- , ( Warning, Lint.Rule.NoWarningComments.rule )
    -- , ( Critical, Lint.Rule.SimplifyPiping.rule )
    -- , ( Critical, Lint.Rule.SimplifyPropertyAccess.rule )
    -- , ( Critical, Lint.Rule.ElmTest.NoDuplicateTestBodies.rule )
    ]



-- MODEL


type alias Model =
    { sourceCode : String
    , lintResult : Result (List String) (List ( Severity, RuleError ))
    }


init : Model
init =
    let
        sourceCode : String
        sourceCode =
            """module Main exposing (f)

import Html.Events exposing (..)
import Html exposing (..)
import NotUsed
import SomeModule exposing (notUsed)

f : Int -> Int
f x = x Debug.log 1

g n = n + 1
"""
    in
    { sourceCode = sourceCode
    , lintResult = lintSource config sourceCode
    }



-- UPDATE


type Msg
    = UserEditedSourceCode String


update : Msg -> Model -> Model
update action model =
    case action of
        UserEditedSourceCode sourceCode ->
            { model
                | sourceCode = sourceCode
                , lintResult = lintSource config sourceCode
            }



-- VIEW


view : Model -> Html Msg
view model =
    div [ id "wrapper" ]
        [ div [ id "left" ]
            [ p [ class "title" ] [ text "Source code" ]
            , div
                [ style "display" "flex"
                , style "flex-direction" "row"
                ]
                [ textarea
                    [ id "input"
                    , onInput UserEditedSourceCode
                    , style "height" "500px"
                    , style "width" "60%"
                    ]
                    [ text model.sourceCode ]
                , div [ style "margin-left" "2rem" ]
                    [ p [ class "title" ] [ text "Linting errors" ]
                    , ul [ id "lint" ]
                        (lintErrors model)
                    ]
                ]
            ]
        ]


lintErrors : Model -> List (Html Msg)
lintErrors model =
    let
        messages : List String
        messages =
            case model.lintResult of
                Err errors ->
                    errors

                Ok errors ->
                    if List.isEmpty errors then
                        [ "No errors." ]

                    else
                        List.map (Tuple.second >> errorToString) errors
    in
    List.map
        (\message -> li [] [ text message ])
        messages


errorToString : RuleError -> String
errorToString { rule, message, range } =
    let
        location : String
        location =
            "(line " ++ String.fromInt range.start.row ++ ", column " ++ String.fromInt range.start.column ++ ")"
    in
    rule ++ ": " ++ message ++ " " ++ location


main : Program () Model Msg
main =
    Browser.sandbox
        { init = init
        , update = update
        , view = view
        }