module Main exposing (Model, Msg(..), init, main, subscriptions, update, view, viewLink)

import Browser
import Browser.Navigation as Nav
import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (..)
import Url
import Url.Builder exposing (..)



-- MAIN


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



-- MODEL


type alias Model =
    { key : Nav.Key
    , url : Url.Url
    , n : Int
    }


init : () -> Url.Url -> Nav.Key -> ( Model, Cmd Msg )
init flags url key =
    ( Model key url 0, Cmd.none )



-- UPDATE


type Msg
    = LinkClicked Browser.UrlRequest
    | UrlChanged Url.Url
    | Goto Url.Url


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 ->
            ( { model | url = url, n = model.n + 1 }
            , Cmd.none
            )

        Goto url ->
            ( { model | url = url, n = model.n + 1 }
            , Nav.pushUrl model.key <| Url.toString url
            )



-- SUBSCRIPTIONS


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



-- VIEW


view : Model -> Browser.Document Msg
view model =
    let
        oldUrl =
            model.url

        newUrl =
            { oldUrl | path = "/foo" }
    in
    { title = "URL Interceptor"
    , body =
        [ text <| "N = " ++ String.fromInt model.n ++ "; The current URL is: "
        , b [] [ text (Url.toString model.url) ]
        , ul []
            [ viewLink "/home"
            , viewLink "/profile"
            , viewLink "/reviews/the-century-of-the-self"
            , viewLink "/reviews/public-opinion"
            , viewLink "/reviews/shah-of-shahs"
            ]
        , div [ onClick <| Goto newUrl ] [ text "/foo" ]
        ]
    }


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