Birthday.elm

{- Can be tested at: http://elm-lang.org/try 
-}

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (onClick)

import Signal exposing (Signal, Address)
import Random exposing (generate, int, Seed) 
import String exposing (concat)

rotate : List a -> List a
rotate xs =
    let first =
        case List.head xs of
          Just a -> [a]
          Nothing -> []
    in
      (Maybe.withDefault [] (List.tail xs)) ++ first
      

wuensche = 
    [ "Herzlichen Glückwunsch und alles, alles Gute zum Geburtstag!!"
    , "Happy Birthday too youuu, happy birthday to youu, happy birthday Timo, happy birthday too you!!"
    , "Alles Gute zum Geburtstag und einen schönen Tag wünsche ich dir!"
    ]

type alias Model = 
    { wuensche : List String
    , text : String
    }

type Action
    = NoOp
    | Next

update : Action -> Model -> Model
update action model =
    case action of
        NoOp -> model
        Next -> 
          let next = Maybe.withDefault "Happy Birthday!" (List.head model.wuensche)
          in 
            { model | text <- next, wuensche <- rotate model.wuensche }  

alignCenter = 
    [ ("display","flex")
    , ("align-items", "center")
    , ("justify-content", "center")
    ]
    
itemStyle =
    [ ("max-width", "50%")
    , ("font", "Georgia 16/24px")
    ]

buttonStyle =
    [ ("position", "absolute")
    , ("top", "0")
    , ("right", "0")
    , ("width", "100%")
    , ("height", "30px")
    , ("background", "lightgray")
    , ("border", "none")
    , ("cursor", "pointer")
    ]
    
view : Address Action -> Model -> Html
view address model =
    div 
      [ style alignCenter ] 
      [ h1 
          [ style itemStyle ]
          [ text model.text ]
      , button 
          [ style buttonStyle, onClick address Next ]
          [ text "Next" ]
      ]

actions : Signal.Mailbox Action
actions = 
    Signal.mailbox NoOp

initialModel : Model
initialModel = 
    let text = (Maybe.withDefault "" (List.head wuensche))
    in 
      { text = text
      , wuensche = rotate wuensche
      }

model : Signal Model
model = 
    Signal.foldp update initialModel actions.signal

main : Signal Html
main = 
    Signal.map (view actions.address) model