module Chelleport.AppShell where

import Chelleport.Draw (colorBackground)
import Chelleport.Types
import Control.Monad (foldM)
import Control.Monad.IO.Class (MonadIO (liftIO))
import Control.Monad.RWS (MonadReader (ask))
import qualified Graphics.X11 as X11
import SDL (($=))
import qualified SDL
import System.Exit (exitSuccess)

class (Monad m) => MonadAppShell m where
  hideWindow :: m ()
  showWindow :: m ()
  shutdownApp :: m ()

instance (MonadIO m) => MonadAppShell (AppM m) where
  hideWindow = ask >>= SDL.hideWindow . ctxWindow
  showWindow = ask >>= SDL.showWindow . ctxWindow
  shutdownApp = do
    ctx <- ask
    SDL.destroyRenderer $ ctxRenderer ctx
    SDL.destroyWindow $ ctxWindow ctx
    liftIO $ do
      X11.closeDisplay $ ctxX11Display ctx
      exitSuccess

setupAppShell ::
  DrawContext ->
  Initializer state ->
  Update state appAction ->
  EventHandler state appAction ->
  View state ->
  IO ()
setupAppShell ctx initState update eventHandler draw = do
  state <- initState
  appLoop state
  where
    appLoop state = do
      SDL.rendererDrawColor (ctxRenderer ctx) $= colorBackground
      SDL.clear $ ctxRenderer ctx
      draw state
      SDL.present $ ctxRenderer ctx

      events <- SDL.pollEvents
      newState <- foldM evaluateEvent state events

      appLoop newState

    evaluateEvent state event =
      maybe (pure state) (updateState state) (eventHandler state event)

    updateState state action =
      update state action >>= evalUpdateResult

    evalUpdateResult (state, Nothing) = pure state
    evalUpdateResult (state, Just action) = updateState state action