collapse.elm

module Collapse exposing (..)

import Html exposing (Html, text, div, button)
import Html.Attributes exposing (class, style)
import Html.Events exposing (onClick)
import Maybe exposing (withDefault)


-- MODEL

type alias Model =
    { collapsed : Bool }


init : Bool -> Model
init collapsed =
    { collapsed = collapsed }


-- UPDATE

type Msg
    = Toggle


update : Msg -> Model -> Model
update msg model =
    case msg of
        Toggle ->
            { model | collapsed = not model.collapsed }


-- VIEW

view : Model -> Html Msg
view model =
    div
        []
        [ toggleButton
        , withDefault (div [] []) (element model.collapsed)
        ]


toggleButton : Html Msg
toggleButton =
    button
        [ class "toggling-button"
        , onClick Toggle
        ]
        [ text "Toggle" ]


element : Bool -> Maybe (Html Msg)
element v =
    case v of
        True ->
            Just (div [] [ text "I exist!" ])
        
        False ->
            Nothing