{-# OPTIONS_HADDOCK hide #-}

-- This source file is part of HGamer3D
-- (A project to enable 3D game development in Haskell)
-- For the latest info, see http://www.althainz.de/HGamer3D.html
--
-- (c) 2014 Peter Althainz
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
--     http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.

-- HGamer3D/Internal/GameLoop Module
--

-- | HGamer3D - A game engine for the Haskell Programmer, this module includes the implementation of the gameloop and initialization routines. This is an internal module, the public API is in HGamer3D.BaseAPI.
module HGamer3D.Graphics3D.GameLoop

(
  HG3DEvent (..),
  
  initHGamer3D,
  freeHGamer3D,
  stepHGamer3D,
  
  ) where

  import HGamer3D.Data
  import HGamer3D.Common

  import HGamer3D.Graphics3D.Graphics3DBase
  import HGamer3D.Graphics3D.WinEvent
  import HGamer3D.Graphics3D.GUIBase
  import HGamer3D.Graphics3D.Event

  import qualified System.Info as SI

  freeHGamer3D :: Graphics3DSystem -> GUISystem -> IO ()
  freeHGamer3D g3ds guis = do 
     freeGraphics3D g3ds


  -- | Game Loop
  -- The game loop works in a way, that window events are much faster processed then 
  -- update of rendering -> all events needs to be cleared, then next renderOneFrame is processed
  -- after that the call returns.
  stepHGamer3D :: Graphics3DSystem -- ^ the Graphics System
                  -> GUISystem     -- ^ the GUI System
                  -> GameTime      -- ^ last time called
                  -> IO ([HG3DEvent], GameTime, Bool) -- ^ list of Events received, quit flag (True if quit received)
                  
  stepHGamer3D g3ds guis lastTime = do

    now <- getTime
    let tdiff = now - lastTime
    injectGUITimeDelta guis tdiff
    let getEvents evts = do
        mWinEvt <- pollWinEvent
        case mWinEvt of
           Just winEvt -> do
             injectWinEventToGUI guis winEvt  -- inject event into gui
             getEvents (evts ++ [WindowEvt winEvt])
           Nothing -> do
             mGuiEvt <- pollGUIEvent guis
             case mGuiEvt of
               Just guiEvt -> getEvents (evts ++ [GUIEvt guiEvt])
               Nothing -> return evts

    qFlag <- stepGraphics3D g3ds
    events <- getEvents []
    
    return (events, now, qFlag)
     
  initHGamer3D :: String -- ^ Window Title
                  -> Bool -- ^ Flag show config dialogue
                  -> Bool -- ^ Flag logging enabled
                  -> Bool -- ^ show Graphics Cursor
                  -> IO (Graphics3DSystem, GUISystem, GameTime)
  initHGamer3D windowTitle fConfigDialogue fLog fGraphicsCursor = do
        success <- initWinEvent [WEV_INIT_EVENTS, WEV_INIT_TIMER, WEV_INIT_VIDEO]
        (g3ds, window) <- initGraphics3D windowTitle "DefaultSceneManager" fConfigDialogue fLog
        win <- attachToWindow window
        guis <- initGUI fLog fGraphicsCursor
        now <- getTime
        return (g3ds, guis, now)