Point.elm

module Main exposing (main)

import Browser
import Html exposing (Html, input, li, text, ul)
import Html.Attributes exposing (value)
import Html.Events exposing (onInput)



-- MAIN


main : Program () Model Msg
main =
    Browser.element
        { init = init
        , update = update
        , view = view
        , subscriptions = subscriptions
        }



-- MODEL


type alias Model =
    { p1 : Point, p2 : Point }


init : () -> ( Model, Cmd Msg )
init _ =
    ( { p1 = { x = 1, y = 1 }, p2 = { x = 2, y = 3 } }, Cmd.none )



-- UPDATE


type Msg
    = UpdateP1X String
    | UpdateP1Y String
    | UpdateP2X String
    | UpdateP2Y String


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    let
        { p1, p2 } =
            model
    in
    case msg of
        UpdateP1X xStr ->
            let
                newP1 =
                    case String.toInt xStr of
                        Just x ->
                            { p1 | x = x }

                        Nothing ->
                            p1
            in
            ( { model | p1 = newP1 }, Cmd.none )

        UpdateP1Y yStr ->
            let
                newP1 =
                    case String.toInt yStr of
                        Just y ->
                            { p1 | y = y }

                        Nothing ->
                            p1
            in
            ( { model | p1 = newP1 }, Cmd.none )

        UpdateP2X xStr ->
            let
                newP2 =
                    case String.toInt xStr of
                        Just x ->
                            { p2 | x = x }

                        Nothing ->
                            p2
            in
            ( { model | p2 = newP2 }, Cmd.none )

        UpdateP2Y yStr ->
            let
                newP2 =
                    case String.toInt yStr of
                        Just y ->
                            { p2 | y = y }

                        Nothing ->
                            p2
            in
            ( { model | p2 = newP2 }, Cmd.none )



-- VIEW


boolToString : Bool -> String
boolToString bool =
    if bool then
        "true"

    else
        "false"


type alias Point =
    { x : Int, y : Int }


pointToString : Point -> String
pointToString { x, y } =
    "(" ++ String.fromInt x ++ ", " ++ String.fromInt y ++ ")"


plus : Point -> Point -> Point
plus p1 p2 =
    { x = p1.x + p2.x, y = p1.y + p2.y }


distance : Point -> Point -> Float
distance p1 p2 =
    sqrt <| toFloat <| (p1.x - p2.x) ^ 2 + (p1.y - p2.y) ^ 2


view : Model -> Html Msg
view model =
    let
        { p1, p2 } =
            model
    in
    ul []
        [ li [] [ text <| "p1 = (x = ", input [ value <| String.fromInt p1.x, onInput UpdateP1X ] [], text ",y = ", input [ value <| String.fromInt p1.y, onInput UpdateP1Y ] [], text ")" ]
        , li [] [ text <| "p2 = (x = ", input [ value <| String.fromInt p2.x, onInput UpdateP2X ] [], text ",y = ", input [ value <| String.fromInt p2.y, onInput UpdateP2Y ] [], text ")" ]
        , li [] [ text <| "(p1 == p2) == " ++ boolToString (p1 == p2) ]
        , li [] [ text <| "p1 + p2 = " ++ pointToString (plus p1 p2) ]
        , li [] [ text <| "distance p1, p2 = " ++ (String.fromFloat <| distance p1 p2) ]
        ]


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