module Cart exposing (..)

import Browser
import Browser.Navigation as Nav
import Css exposing (..)
import Html
import Html.Styled exposing (..)
import Html.Styled.Attributes exposing (..)
import Html.Styled.Events exposing (..)
import Http
import Json.Decode as D
import Json.Encode as Encode
import Styles exposing (..)
import Utils exposing (..)


type alias Product =
    { id : Int
    , name : String
    , kind : Maybe String
    , price : Float
    , description : Maybe String
    }


type alias CartListing =
    { productItem : Product
    , quantity : Int
    }


type alias Model =
    { pageStatus : Status
    , products : List CartListing
    }


type Status
    = Loading
    | Loaded
    | NotLoaded


type Msg
    = CartLoaded (Result Http.Error (List CartListing))
    | FetchCartItems
    | RemoveFromCart Int
    | CartItemRemoved (Result Http.Error ())
    | AddToCartSuccess (Result Http.Error ())
    | AddToCartPressed Int


init : Model
init =
    Model NotLoaded []


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        CartLoaded res ->
            case res of
                Ok s ->
                    ( { model | products = s, pageStatus = Loaded }, Cmd.none )

                Err e ->
                    let
                        _ =
                            Debug.log "error" e
                    in
                    ( { model | pageStatus = NotLoaded }, Cmd.none )

        RemoveFromCart id ->
            ( model, removeProduct id )

        CartItemRemoved _ ->
            ( { model | pageStatus = Loading }, fetchCartItems )

        FetchCartItems ->
            ( { model | pageStatus = Loading }, fetchCartItems )

        AddToCartPressed id ->
            ( model, addToCart id )

        AddToCartSuccess _ ->
            ( { model | pageStatus = Loading }, fetchCartItems )


decodeProduct : D.Decoder Product
decodeProduct =
    D.map5 Product
        (D.field "id" D.int)
        (D.field "name" D.string)
        (D.field "kind" (D.nullable D.string))
        (D.field "price" D.float)
        (D.field "description" (D.nullable D.string))


decodeResponse : D.Decoder (List CartListing)
decodeResponse =
    D.list
        (D.map2 CartListing
            (D.field "product_item" decodeProduct)
            (D.field "quantity" D.int)
        )


removeProduct : Int -> Cmd Msg
removeProduct id =
    let
        _ =
            Debug.log "cart" "fetching cart items"
    in
    Http.riskyRequest
        { method = "POST"
        , headers = []
        , url = "http://127.0.0.1:7878/cart/remove"
        , body = Http.stringBody "application/json" <| String.fromInt id
        , expect = Http.expectWhatever CartItemRemoved
        , timeout = Nothing
        , tracker = Nothing
        }


fetchCartItems : Cmd Msg
fetchCartItems =
    let
        _ =
            Debug.log "cart" "fetching cart items"
    in
    Http.riskyRequest
        { method = "GET"
        , headers = []
        , url = "http://127.0.0.1:7878/cart/items"
        , body = Http.emptyBody
        , expect = Http.expectJson CartLoaded decodeResponse
        , timeout = Nothing
        , tracker = Nothing
        }


viewStatus : Status -> String
viewStatus s =
    case s of
        Loading ->
            "Loading"

        Loaded ->
            "Ready!"

        NotLoaded ->
            "Not loaded ..."


addToCart : Int -> Cmd Msg
addToCart id =
    let
        _ =
            Debug.log "err" <| "adding to cart: " ++ String.fromInt id
    in
    Http.riskyRequest
        { method = "POST"
        , headers = []
        , url = "http://127.0.0.1:7878/cart/add"
        , body = Http.stringBody "applcation/json" <| String.fromInt <| id
        , expect = Http.expectWhatever AddToCartSuccess
        , timeout = Nothing
        , tracker = Nothing
        }


calculateTotal : Model -> Float
calculateTotal model =
    let
        items =
            model.products
    in
    items
        |> List.map (\i -> toFloat i.quantity * i.productItem.price)
        |> List.foldl (+) 0


viewCartItemListing : CartListing -> Html Msg
viewCartItemListing listing =
    -- div []
    --     [ text listing.productItem.name
    --     , div [] [ text <| Maybe.withDefault "" listing.productItem.kind ]
    --     , div [] [ text <| Maybe.withDefault "" listing.productItem.description ]
    --     , div [] [ text <| String.fromFloat listing.productItem.price ]
    --     , div [] [ text <| String.fromInt listing.quantity ]
    --     , div [] [ button [ onClick (AddToCartPressed listing.productItem.id) ] [ text "Add" ] ]
    --     , div [] [ button [ onClick (RemoveFromCart listing.productItem.id) ] [ text "Remove" ] ]
    --     , div [] [ a [ href ("/product/" ++ String.fromInt listing.productItem.id) ] [ text "View Product" ] ]
    --     ]
    tr []
        [ td [] [ a [ href ("/product/" ++ String.fromInt listing.productItem.id) ] [ text listing.productItem.name ] ]
        , td [] [ text <| String.fromFloat listing.productItem.price ]
        , td []
            [ furbyButton [ onClick (RemoveFromCart listing.productItem.id) ] [ div [ style "font-family" "monospace" ] [ text "-" ] ]
            , text <| String.fromInt listing.quantity
            , furbyButton [ onClick (AddToCartPressed listing.productItem.id) ] [ div [ style "font-family" "monospace" ] [ text "+" ] ]
            ]
        ]


view : Model -> Html Msg
view model =
    case model.pageStatus of
        Loading ->
            div [] [ text <| viewStatus Loading ]

        _ ->
            let
                cart =
                    List.map viewCartItemListing model.products

                headings =
                    [ "Product Name", "Price (₹)", "Quantity" ]
                        |> List.map (th [] << List.singleton << text)
            in
            if List.isEmpty cart then
                text "No items in cart"

            else
                div
                    [ css
                        [ margin auto
                        , marginTop (pct 5)
                        , Css.width (pct 40)
                        ]
                    ]
                    [ div [ css [ bigHeading, marginBottom (px 20) ] ] [ text "Cart" ]
                    , Html.Styled.table
                        [ css
                            [ Css.width (pct 100)
                            , maxWidth (px 650)
                            , textAlign right
                            ]
                        ]
                        (tr [] headings
                            :: cart
                            ++ [ tr [ style "padding-top" "20px" ]
                                    [ td [ style "border-top" "1px solid black" ] []
                                    , td [ style "border-top" "1px solid black" ] [ div [] [ text "Cart total: " ] ]
                                    , td [ style "border-top" "1px solid black" ] [ calculateTotal model |> String.fromFloat |> text ]
                                    ]
                               ]
                        )
                    , a [ href "/checkout" ] [ text "Checkout" ]
                    ]