module Page.NewPost exposing (Model, Msg, init, update, view)

import Browser.Navigation as Nav
import Post exposing (Post, PostId, postDecoder,postEncoder,emptyPost,newPostEncoder)
import Http exposing (..)

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (onClick, onInput)
import Route exposing (..)
import Error exposing (buildErrorMessage)
type alias Model =
    {navKey : Nav.Key
    ,post : Post
    , createError : Maybe String}

init : Nav.Key -> ( Model, Cmd Msg )
init navKey =
    ( initialModel navKey, Cmd.none )


initialModel : Nav.Key -> Model
initialModel navKey =
    { navKey = navKey
    , post = emptyPost
    , createError = Nothing
    }

type Msg
    = StoreTitle String
    | StoreAuthorName String
    | StoreAuthorUrl String
    | CreatePost
    | PostCreated (Result Http.Error Post)

update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        StoreTitle title ->
            let
                oldPost=model.post
                updateTitle={oldPost|title=title}
            in
            ( { model | post = updateTitle }, Cmd.none )
        StoreAuthorName name ->
            let
                oldPost=model.post
                updateAuthorName={oldPost|authorName=name}
            in
            ( { model | post = updateAuthorName }, Cmd.none )

        StoreAuthorUrl url ->
            let
                oldPost=model.post
                updateAuthorUrl={oldPost|authorUrl=url}
            in
            ( { model | post = updateAuthorUrl }, Cmd.none )

        
        CreatePost ->
            ( model, createPost model.post )
        
        PostCreated (Ok post) ->
            ( { model | post = post, createError = Nothing }
            , Route.pushUrl Route.Posts model.navKey
            )

        PostCreated (Err error) ->
            ( { model | createError = Just (buildErrorMessage error) }
            , Cmd.none
            )
createPost : Post -> Cmd Msg
createPost post =
    Http.post
        { url = "http://localhost:5019/posts"
        , body = Http.jsonBody (newPostEncoder post)
        , expect = Http.expectJson PostCreated postDecoder
        }

view : Model -> Html Msg
view model =
    div []
        [ h3 [] [ text "Create New Post" ]
        , newPostForm
        , viewError model.createError
        ]



newPostForm : Html Msg
newPostForm =
    Html.form []
        [ div []
            [ text "Title"
            , br [] []
            , input
                [ type_ "text"
                , onInput StoreTitle
                ]
                []
            ]
        , br [] []
        , div []
            [ text "Author Name"
            , br [] []
            , input
                [ type_ "text"
                , onInput StoreAuthorName
                ]
                []
            ]
        , br [] []
        , div []
            [ text "Author URL"
            , br [] []
            , input
                [ type_ "text"
                , onInput StoreAuthorUrl
                ]
                []
            ]
        , br [] []
        , div []
            [ button [ type_ "button", onClick CreatePost ]
                [ text "Submit" ]
            ]
        ]
viewError : Maybe String -> Html msg
viewError maybeError =
    case maybeError of
        Just error ->
            div []
                [ h3 [] [ text "Couldn't create a post at this time." ]
                , text ("Error: " ++ error)
                ]

        Nothing ->
            text ""