import Html exposing (..)
import Html.Attributes exposing (..)
import Html.App as App
import Html.Events exposing (..)
import Random
import Color exposing (..)
import Time exposing (Time, second)


main =
  App.program
    { init = (init size)
    , view = view
    , update = update
    , subscriptions = subscriptions
    }

size = 36

-- MODEL

type alias State = Maybe Int
type alias Automaton = List (Int, Int)

type alias Model =
  { states : List State
  , system : Automaton
  }


init : Int -> (Model, Cmd Msg)
init n = (Model (List.map Just [1 .. size]) [], Random.generate Update (genAut n))



-- UPDATE

type Msg
  = Step
  | Regen
  | Update Automaton
  | Sort

zip = List.map2 (,)

genAut : Int -> Random.Generator Automaton
genAut n = Random.map (zip [1 .. n]) (Random.list n <| Random.int 1 n)

step : Automaton -> State -> State
step ls s0 = case s0 of
  Nothing -> Nothing
  Just s -> List.filter (\(a,b) -> a == s) ls |> List.head |> Maybe.map snd

cmp l r = case (l, r) of
  (Nothing, Nothing) -> EQ
  (Nothing, Just n) -> LT
  (Just n, Nothing) -> GT
  (Just n, Just m) -> compare n m

update : Msg -> Model -> (Model, Cmd Msg)
update msg model =
  case msg of
    Step -> (Model (List.map (step model.system) model.states) model.system, Cmd.none)

    Regen ->
      init size

    Update newAut ->
      (Model model.states newAut, Cmd.none)

    Sort ->
      (Model (List.sortWith cmp model.states) model.system, Cmd.none)


-- SUBSCRIPTIONS

subscriptions : Model -> Sub Msg
subscriptions model =
  Time.every (0.1 * second) (\a -> Step)



-- VIEW

(=>) = (,)

state2Color : State -> Color
state2Color s = case s of
  Nothing -> Color.black
  Just n -> hsl (degrees (toFloat n)*77) 1.0 (0.8 - 0.6 * (toFloat n)/size)

color2String : Color -> String
color2String c = let rgb = toRgb c in "rgb(" ++ toString rgb.red ++ ", " ++ toString rgb.green ++ ", " ++ toString rgb.blue ++ ")"

block : Color -> Html msg
block c = div [style ["background-color" => color2String c, "width" => "100px", "height" => "100px", "display" => "inline-block"]] []

view : Model -> Html Msg
view model =
  div []
    (  button [ onClick Regen ] [ text "Regenerate" ]
    :: button [ onClick Sort ] [ text "Sort" ]
    :: br [] []
    :: List.map (block << state2Color) model.states
    )