module Main exposing (..)

import Browser
import Browser.Navigation as Nav
import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (onInput)
import Http
import Json.Decode as D
import SwitchData
import Url
import Url.Builder


main : Program () Model Msg
main =
    Browser.application
        { init = init
        , view = view
        , update = update
        , subscriptions = subscriptions
        , onUrlChange = UrlChanged
        , onUrlRequest = LinkClicked
        }


type alias Model =
    { key : Nav.Key
    , url : Url.Url
    , token : Maybe String
    , token_data : Maybe TokenData
    , switch_cursor : ( Int, Int )
    , switch_data : Maybe (List SwitchData.Switch)
    }


init : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
init flags url key =
    ( Model
        key
        url
        Nothing
        Nothing
        ( 40, 0 )
        Nothing
    , Cmd.none
    )


type Msg
    = LinkClicked Browser.UrlRequest
    | UrlChanged Url.Url
    | TokenInput String
    | TokenValidate (Result Http.Error TokenData)
    | Logout
    | GetSwitchData ( Int, Int )
    | GotSwitchData (Result Http.Error (List SwitchData.Switch))


type alias TokenData =
    { sub : String
    , jti : String
    }


tokenDecoder : D.Decoder TokenData
tokenDecoder =
    D.map2 TokenData
        (D.field "sub" D.string)
        (D.field "jti" D.string)


request method token path body expect =
    Http.request
        { method = method
        , body = body
        , headers =
            [ Http.header "Authorization" token
            ]
        , url = path
        , expect = expect
        , timeout = Nothing
        , tracker = Nothing
        }


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        LinkClicked urlRequest ->
            case urlRequest of
                Browser.Internal url ->
                    ( model, Nav.pushUrl model.key (Url.toString url) )

                Browser.External href ->
                    ( model, Nav.load href )

        UrlChanged url ->
            case url.path of
                "/logout" ->
                    ( model, Nav.load "/" )

                default ->
                    ( { model | url = url }
                    , Cmd.none
                    )

        TokenInput token ->
            ( { model | token = Just token }
            , request "GET" token "/.within/tokeninfo" Http.emptyBody (expectJson TokenValidate tokenDecoder)
            )

        TokenValidate result ->
            case result of
                Ok data ->
                    ( { model | token_data = Just data }
                    , Cmd.none
                    )

                Err _ ->
                    ( { model | token = Nothing }
                    , Cmd.none
                    )

        Logout ->
            ( { model | token = Nothing, token_data = Nothing }
            , Nav.load "/"
            )

        GetSwitchData ( limit, page ) ->
            case model.token of
                Just token ->
                    ( model
                    , request "GET"
                        token
                        (SwitchData.dataURL limit page)
                        Http.emptyBody
                        (expectJson GotSwitchData (D.list SwitchData.decoder))
                    )

                Nothing ->
                    ( model, Cmd.none )

        _ ->
            ( model, Cmd.none )


subscriptions : Model -> Sub Msg
subscriptions _ =
    Sub.none


view : Model -> Browser.Document Msg
view model =
    case model.token_data of
        Nothing ->
            { title = "Login"
            , body =
                [ node "main"
                    [ style "align" "center" ]
                    [ h1 [] [ text "Login" ]
                    , viewInput "password" "API Token" "" TokenInput
                    ]
                ]
            }

        Just token_data ->
            case model.url.path of
                "/" ->
                    template "Mi"
                        [ h1 [] [ text "Mi" ]
                        , h2 [] [ text "TODO" ]
                        , ul []
                            [ li [] [ text "Switch CRUD" ]
                            , li [] [ text "POSSE manual announcement" ]
                            ]
                        , h2 [] [ text "Token data" ]
                        , p []
                            [ text "Token sub: "
                            , text token_data.sub
                            , Html.br [] []
                            , text "ID: "
                            , text token_data.jti
                            ]
                        ]

                "/switch" ->
                    case model.switch_data of
                        Nothing ->
                            template "Switch counter"
                                [ h1 [] [ text "Switch counter" ]
                                , p [] [ text "loading..." ]
                                ]

                        Just switches ->
                            template "Switch counter"
                                [ h1 [] [ text "TODO: table" ]
                                ]

                other ->
                    template "Not found"
                        [ h1 [] [ text "Not found" ]
                        , p []
                            [ text "The requested URL "
                            , b [] [ text other ]
                            , text " was not found."
                            ]
                        ]


viewInput : String -> String -> String -> (String -> msg) -> Html msg
viewInput t p v toMsg =
    input [ type_ t, placeholder p, value v, onInput toMsg ] []


viewLink : String -> String -> Html msg
viewLink path title =
    a [ href path ] [ text title ]


template : String -> List (Html msg) -> Browser.Document msg
template title body =
    { title = title
    , body =
        [ node "main"
            []
            [ navBar
            , div [] body
            , footer
            ]
        ]
    }


navBar : Html msg
navBar =
    node "nav"
        []
        [ p []
            [ viewLink "/" "Mi"
            , text " - "
            , viewLink "/switch" "Switch tracker"
            , text " - "
            , viewLink "/logout" "Logout"
            ]
        ]


footer : Html msg
footer =
    node "footer"
        []
        [ p []
            [ a [ href "https://within.website" ] [ text "From Within" ]
            , text " - "
            , a [ href "https://tulpa.dev/cadey/mi" ] [ text "Source code" ]
            ]
        ]


expectJson : (Result Http.Error a -> msg) -> D.Decoder a -> Http.Expect msg
expectJson toMsg decoder =
    Http.expectStringResponse toMsg <|
        \response ->
            case response of
                Http.BadUrl_ url ->
                    Err (Http.BadUrl url)

                Http.Timeout_ ->
                    Err Http.Timeout

                Http.NetworkError_ ->
                    Err Http.NetworkError

                Http.BadStatus_ metadata body ->
                    Err (Http.BadStatus metadata.statusCode)

                Http.GoodStatus_ metadata body ->
                    case D.decodeString decoder body of
                        Ok value ->
                            Ok value

                        Err err ->
                            Err (Http.BadBody (D.errorToString err))