Api.Elm

module Api exposing
    ( Data
    , Error(..)
    , ErrorResponse
    , Origin
    , delete
    , deleteTask
    , errorToNotification
    , errorView
    , get
    , getTask
    , grid
    , handleResult
    , patch
    , patchTask
    , post
    , postTask
    , toResult
    , view
    )

import FontAwesome.Solid as Solid
import Html exposing (..)
import Html.Attributes as Attributes
import Http exposing (Metadata)
import Json.Decode as Decode exposing (Decoder)
import Json.Decode.Extra as Decode
import RemoteData exposing (RemoteData(..))
import Task exposing (Task)
import UI exposing (..)
import UI.Blocker as Blocker
import UI.Icon as Icon
import UI.Notifications as Notifications
import UI.Spinner as Spinner
import UrlBuilderPlus as UB exposing (QueryParameter)


class =
    namespace "Api"


type alias Data a =
    RemoteData Error a


type Error
    = BadUrl String
    | Timeout
    | NetworkError
    | BadStatus Metadata ErrorResponse
    | JsonError Metadata String


{-| Custom error response unique to FörsäkringsGirot
-}
type alias ErrorResponse =
    { error : String
    , exception : Maybe String
    , message : String
    , path : String
    , status : Int
    }


{-| Represents the address of a server, for example api-gateway
-}
type alias Origin =
    String


{-| Display HTML which depends on Remote Data
Displays a loading spinner while waiting, and an error message in case of failure.
-}
view : Data (Html msg) -> Html msg
view stuff =
    case stuff of
        NotAsked ->
            textSpan ""

        Loading ->
            Spinner.view

        Failure error ->
            errorView error

        Success content ->
            content


{-| Display a grid where rows can depend on Remote Data
Displays a loading spinner in the second column while waiting, and an error message in case of failure.
-}
grid : List (Data (List (List (Html msg)))) -> Html msg
grid =
    List.concatMap
        (\data ->
            case data of
                NotAsked ->
                    []

                Loading ->
                    [ [ none, Spinner.view ] ]

                Failure err ->
                    [ [ none, errorView err ] ]

                Success html ->
                    html
        )
        >> UI.grid


{-| Display info about an HTTP error
-}
errorView : Error -> Html msg
errorView error =
    let
        ( header, details ) =
            case error of
                BadUrl message ->
                    ( "Felaktig URL", Just message )

                Timeout ->
                    ( "Servern svarar inte", Nothing )

                NetworkError ->
                    ( "Nätverksfel", Nothing )

                BadStatus metadata errorResponse ->
                    ( String.fromInt metadata.statusCode ++ " " ++ metadata.statusText
                    , Just (metadata.url ++ "\n\n" ++ errorResponse.message)
                    )

                JsonError metadata message ->
                    ( "Servern svarade med oväntad JSON"
                    , Just (metadata.url ++ "\n\n" ++ message)
                    )
    in
    div [ class "error" ]
        [ heading [] [ text "Ett fel inträffade" ]
        , b [] [ text header ]
        , textSpan "Prova att ladda om sidan, eller kontakta kundservice om felet kvarstår."
        , row10
            [ a [ Attributes.href "tel:08-522 529 00" ] [ Icon.view [] Solid.phone, text "08-522 529 00" ]
            , a [ Attributes.href "mailto:[email protected]" ] [ Icon.view [] Solid.envelope, text "[email protected]" ]
            ]
        , case details of
            Just str ->
                div [ class "errorDetails", Attributes.tabindex 0 ]
                    [ div [ class "showDetailsButton" ] [ text "Teknisk info" ]
                    , div [ class "technical" ] [ text str ]
                    ]

            Nothing ->
                none
        ]


{-| Update a model based on a result. If the result is an Error, display an error notification.
-}
handleResult :
    { r | notifications : Notifications.Model, blocker : Blocker.Status }
    -> Result Error data
    -> (data -> ( { r | notifications : Notifications.Model, blocker : Blocker.Status }, Cmd msg ))
    -> ( { r | notifications : Notifications.Model, blocker : Blocker.Status }, Cmd msg )
handleResult model result onSuccess =
    case result of
        Ok data ->
            onSuccess data |> Tuple.mapFirst (\m -> { m | blocker = Blocker.decrement m.blocker })

        Err error ->
            ( { model
                | notifications = model.notifications |> Notifications.insert (errorToNotification error)
                , blocker = Blocker.decrement model.blocker
              }
            , Cmd.none
            )


{-| Convert an Error to a Notification
-}
errorToNotification : Error -> Notifications.Notification
errorToNotification error =
    Notifications.Error <|
        case error of
            BadUrl message ->
                [ message ]

            Timeout ->
                [ "Servern svarar inte" ]

            NetworkError ->
                [ "Nätverksfel" ]

            BadStatus metadata errorResponse ->
                [ metadata.statusText
                , errorResponse.message
                , metadata.url
                ]

            JsonError metadata message ->
                [ message
                , metadata.url
                ]


toResult : Data a -> Result Error a
toResult data =
    case data of
        NotAsked ->
            Err NetworkError

        Loading ->
            Err NetworkError

        Failure e ->
            Err e

        Success a ->
            Ok a



-- MAKE REQUESTS


get : { path : List String, query : List QueryParameter, decoder : Decoder a } -> (Data a -> msg) -> Origin -> Cmd msg
get args msg origin =
    getTask args origin |> Task.attempt (RemoteData.fromResult >> msg)


post : { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> (Result Error a -> msg) -> Origin -> Cmd msg
post args msg origin =
    postTask args origin |> Task.attempt msg


patch : { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> (Result Error a -> msg) -> Origin -> Cmd msg
patch args msg origin =
    patchTask args origin |> Task.attempt msg


delete : { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> (Result Error a -> msg) -> Origin -> Cmd msg
delete args msg origin =
    deleteTask args origin |> Task.attempt msg


getTask : { path : List String, query : List QueryParameter, decoder : Decoder a } -> Origin -> Task Error a
getTask { path, query, decoder } =
    task "GET" { path = path, query = query, decoder = decoder, body = Http.emptyBody }


postTask : { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> Origin -> Task Error a
postTask =
    task "POST"


patchTask : { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> Origin -> Task Error a
patchTask =
    task "PATCH"


deleteTask : { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> Origin -> Task Error a
deleteTask =
    task "DELETE"



-- INTERNAL STUFF


task : String -> { path : List String, query : List QueryParameter, body : Http.Body, decoder : Decoder a } -> Origin -> Task Error a
task method { path, query, body, decoder } origin =
    Http.riskyTask
        { method = method
        , url = UB.crossOrigin origin ("app" :: path) query
        , body = body
        , headers = []
        , resolver = Http.stringResolver (toJsonResult decoder)
        , timeout = Nothing
        }


toJsonResult : Decoder a -> Http.Response String -> Result Error a
toJsonResult decoder response =
    case response of
        Http.BadUrl_ badUrl ->
            Err (BadUrl badUrl)

        Http.Timeout_ ->
            Err Timeout

        Http.NetworkError_ ->
            Err NetworkError

        Http.BadStatus_ metadata body ->
            Err
                (case Decode.decodeString errorResponseDecoder body of
                    Ok error ->
                        BadStatus metadata error

                    Err decodingError ->
                        JsonError metadata (Decode.errorToString decodingError)
                )

        Http.GoodStatus_ metadata body ->
            let
                -- replace empty body with "{}" so that Decode.succeed () doesn't fail
                body_ =
                    if body == "" then
                        "{}"

                    else
                        body
            in
            case Decode.decodeString decoder body_ of
                Ok value ->
                    Ok value

                Err err ->
                    Err (JsonError metadata (Decode.errorToString err))


errorResponseDecoder : Decoder ErrorResponse
errorResponseDecoder =
    Decode.map5 ErrorResponse
        (Decode.field "error" Decode.string)
        (Decode.maybe (Decode.field "exception" Decode.string))
        (Decode.field "message"
            (Decode.oneOf
                [ Decode.doubleEncoded (Decode.field "error" Decode.string)
                , Decode.string
                ]
            )
        )
        (Decode.field "path" Decode.string)
        (Decode.field "status" Decode.int)