module Common exposing
    ( classes
    , decodeJsonMessage
    , decodeResponse
    , expectJsonMessage
    , expectStringResponse
    , maybe
    , resultEither
    )

import Dict
import Html.Styled exposing (Attribute)
import Html.Styled.Attributes exposing (class)
import Http exposing (Response)
import Json.Decode as D


classes : List String -> Attribute msg
classes xs =
    class (String.join " " xs)


maybe : b -> (a -> b) -> Maybe a -> b
maybe b f =
    Maybe.map f >> Maybe.withDefault b


resultEither : (a -> c) -> (b -> c) -> Result a b -> c
resultEither mapErr mapOk result =
    case result of
        Err a ->
            mapErr a

        Ok b ->
            mapOk b


type alias ToMsg a msg =
    Result String a -> msg


type alias ReadError =
    String -> String


decodeResponse : ReadError -> D.Decoder a -> Response String -> Result String a
decodeResponse readErr decoder resp =
    let
        badStatus code body =
            "BadStatus "
                ++ String.fromInt code
                ++ " : "
                ++ readErr body
    in
    case resp of
        Http.BadUrl_ x ->
            Err <| "BadUrl : " ++ x

        Http.Timeout_ ->
            Err "Timeout"

        Http.NetworkError_ ->
            Err "NetworkError"

        Http.BadStatus_ metadata body ->
            Err <| badStatus metadata.statusCode body

        Http.GoodStatus_ _ body ->
            D.decodeString decoder body
                |> Result.mapError D.errorToString


readErrorMessage : ReadError
readErrorMessage =
    let
        dictToStr =
            Dict.toList
                >> List.map (\( k, v ) -> "(" ++ k ++ ", " ++ v ++ ")")
                >> String.join " "

        getMessage x =
            Dict.get "message" x
                |> Maybe.withDefault (dictToStr x)
    in
    D.decodeString (D.dict D.string)
        >> Result.map getMessage
        >> resultEither D.errorToString identity


decodeJsonMessage : D.Decoder a -> Response String -> Result String a
decodeJsonMessage =
    decodeResponse readErrorMessage


expectStringResponse : ToMsg a msg -> ReadError -> D.Decoder a -> Http.Expect msg
expectStringResponse toMsg readErr decoder =
    Http.expectStringResponse toMsg (decodeResponse readErr decoder)


expectJsonMessage : ToMsg a msg -> D.Decoder a -> Http.Expect msg
expectJsonMessage toMsg =
    expectStringResponse toMsg readErrorMessage