module Web06RandomFloat exposing (..)

-- import GrammarABequallyOften as ConcreteGrammar
--import PrefixArithmeticGrammar as Grammar

import Browser
import Html exposing (Attribute, Html, button, div, input, text)
import Html.Attributes as Att
import Html.Events exposing (onClick, onInput)
import Random


type alias Model =
    { randomFloat : Maybe Float
    }


type Msg
    = GenerateRandomFloat -- when the button has been clicked
    | RandomFloatReceived Float -- when the random number has arrived


randomFloatGenerator : Random.Generator Float
randomFloatGenerator =
    Random.float 0 1


randomFloatCmd : Cmd Msg
randomFloatCmd =
    Random.generate RandomFloatReceived randomFloatGenerator


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        GenerateRandomFloat ->
            ( model, randomFloatCmd )

        RandomFloatReceived number ->
            ( { model | randomFloat = Just number }, Cmd.none )


css path =
    Html.node "link" [ Att.rel "stylesheet", Att.href path ] []


view : Model -> Html Msg
view model =
    div
        [ Att.class "container" ]
        [ css "https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css"
        , Html.p [] [ Html.text "source can be found under ", Html.code [] [ Html.text "/elm-codebase/random/DemoRandom.elm" ] ]
        , Html.h2 []
            [ Html.text "Demo for random numbers" ]
        , div []
            [ Html.button [ Html.Events.onClick GenerateRandomFloat ] [ Html.text "Number!" ]
            , Html.text
                (case model.randomFloat of
                    Nothing ->
                        "No random float received yet"

                    Just r ->
                        "Number is " ++ String.fromFloat r
                )
            ]
        ]


init : () -> ( Model, Cmd Msg )
init _ =
    ( { randomFloat = Nothing
      }
    , Cmd.none
    )


main =
    Browser.element
        { init = init
        , view = view
        , update = update
        , subscriptions = \_ -> Sub.none

        -- subscriptions is stuff we want to listen to, beyond the input elements of our web app
        -- this could, for example, be web sockets ...
        }