elm-review/tests/Documentation/ReadmeLinksPointToCurrentVersion.elm

module Documentation.ReadmeLinksPointToCurrentVersion exposing (rule)

{-| Reports links to this project's package documentation on <https://package.elm-lang.org/>,
where the version is set to `latest` or a different version than the current version of the package.

**NOTE**: Just make sure to run tests between bumping the Elm version and publishing the package,
otherwise the link for a given version could link to a previous one.

-}

import Elm.Package
import Elm.Project
import Elm.Syntax.Range exposing (Range)
import Elm.Version
import Regex exposing (Regex)
import Review.Rule as Rule exposing (Error, Rule)


rule : Rule
rule =
    Rule.newProjectRuleSchema "ReadmeLinksPointToCurrentVersion" initialProjectContext
        |> Rule.withElmJsonProjectVisitor elmJsonVisitor
        |> Rule.withReadmeProjectVisitor readmeVisitor
        |> Rule.fromProjectRuleSchema


type alias ProjectContext =
    Maybe
        { projectName : String
        , version : String
        }


initialProjectContext : ProjectContext
initialProjectContext =
    Nothing



-- elm.json VISITOR


elmJsonVisitor : Maybe { a | project : Elm.Project.Project } -> ProjectContext -> ( List nothing, ProjectContext )
elmJsonVisitor maybeProject _ =
    case maybeProject |> Maybe.map .project of
        Just (Elm.Project.Package pkg) ->
            ( []
            , Just
                { projectName = Elm.Package.toString pkg.name
                , version = Elm.Version.toString pkg.version
                }
            )

        _ ->
            ( [], Nothing )



-- README VISITOR


readmeVisitor : Maybe { readmeKey : Rule.ReadmeKey, content : String } -> ProjectContext -> ( List (Error scope), ProjectContext )
readmeVisitor maybeReadme maybeContext =
    case ( maybeReadme, maybeContext ) of
        ( Just { readmeKey, content }, Just context ) ->
            ( findRangeForSubstring context readmeKey content, maybeContext )

        _ ->
            ( [], maybeContext )


linkRegex : Regex
linkRegex =
    Regex.fromString "]\\(https://package\\.elm-lang\\.org/packages/([\\w-]+/[\\w-]+)/(\\w+(\\.\\w+\\.\\w+)?)(.*)\\)"
        |> Maybe.withDefault Regex.never


findRangeForSubstring : { projectName : String, version : String } -> Rule.ReadmeKey -> String -> List (Error scope)
findRangeForSubstring context readmeKey content =
    content
        |> String.lines
        |> List.indexedMap Tuple.pair
        |> List.concatMap
            (\( row, line ) ->
                Regex.find linkRegex line
                    |> List.filterMap (notAMatch context readmeKey row)
            )


notAMatch : { projectName : String, version : String } -> Rule.ReadmeKey -> Int -> Regex.Match -> Maybe (Error scope)
notAMatch { projectName, version } readmeKey row match =
    case match.submatches of
        (Just authorAndPackage) :: (Just linkVersion) :: _ ->
            if authorAndPackage == projectName && linkVersion /= version then
                Rule.errorForReadme readmeKey
                    { message = "Link does not point to the current version of the package"
                    , details = [ "I suggest to run elm-review in fix mode" ]
                    }
                    { start =
                        { row = row + 1
                        , column = match.index + 3
                        }
                    , end =
                        { row = row + 1
                        , column = match.index + String.length match.match
                        }
                    }
                    |> Just

            else
                Nothing

        _ ->
            Nothing