    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.UI.GLUT.DeviceControl
    -- Copyright   :  (c) Sven Panne 2002-2018
    -- License     :  BSD3
    --
    -- Maintainer  :  Sven Panne <svenpanne@gmail.com>
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- GLUT offers some routines for controlling the key repeat and polling the
    -- joystick.
    --
    --------------------------------------------------------------------------------

    module Graphics.UI.GLUT.DeviceControl (
       GlobalKeyRepeat(..), globalKeyRepeat,
       PerWindowKeyRepeat(..), perWindowKeyRepeat,
       forceJoystickCallback
    ) where

    import Control.Monad.IO.Class ( MonadIO(..) )
    import Data.StateVar ( StateVar, makeStateVar )
    import Foreign.C.Types ( CInt )

    import Graphics.UI.GLUT.QueryUtils
    import Graphics.UI.GLUT.Raw

    --------------------------------------------------------------------------------

    -- | The state of the global key repeat

    data GlobalKeyRepeat
       = GlobalKeyRepeatOff
       | GlobalKeyRepeatOn
       | GlobalKeyRepeatDefault
       deriving ( Eq, Ord, Show )

    marshalGlobalKeyRepeat :: GlobalKeyRepeat -> CInt
    marshalGlobalKeyRepeat x = case x of
       GlobalKeyRepeatOff -> glut_KEY_REPEAT_OFF
       GlobalKeyRepeatOn -> glut_KEY_REPEAT_ON
       GlobalKeyRepeatDefault -> glut_KEY_REPEAT_DEFAULT

    unmarshalGlobalKeyRepeat :: CInt -> GlobalKeyRepeat
    unmarshalGlobalKeyRepeat x
       | x == glut_KEY_REPEAT_OFF = GlobalKeyRepeatOff
       | x == glut_KEY_REPEAT_ON = GlobalKeyRepeatOn
       | x == glut_KEY_REPEAT_DEFAULT = GlobalKeyRepeatDefault
       | otherwise = error ("unmarshalGlobalKeyRepeat: illegal value " ++ show x)

    --------------------------------------------------------------------------------

    -- | Controls the key repeat mode for the window system on a global basis if
    -- possible. If supported by the window system, the key repeat can either be
    -- disabled, enabled, or set to the window system\'s default key repeat state.
    --
    -- /X Implementation Notes:/ X11 sends @KeyPress@ events repeatedly when the
    -- window system\'s global auto repeat is enabled. 'perWindowKeyRepeat' can
    -- prevent these auto repeated keystrokes from being reported as keyboard or
    -- special callbacks, but there is still some minimal overhead by the X server
    -- to continually stream @KeyPress@ events to the GLUT application. The
    -- 'globalKeyRepeat' state variable can be used to actually disable the global
    -- sending of auto repeated @KeyPress@ events. Note that 'globalKeyRepeat'
    -- affects the global window system auto repeat state so other applications
    -- will not auto repeat if you disable auto repeat globally through
    -- 'globalKeyRepeat'. GLUT applications using the X11 GLUT implementation
    -- should disable key repeat with 'globalKeyRepeat' to disable key repeats most
    -- efficiently, but are responsible for explicitly restoring the default key
    -- repeat state on exit.
    --
    -- /Win32 Implementation Notes:/ The Win32 implementation of 'globalKeyRepeat'
    -- does nothing. The 'perWindowKeyRepeat' can be used in the Win32 GLUT
    -- implementation to ignore repeated keys on a per-window basis without changing
    -- the global window system key repeat.

    globalKeyRepeat :: StateVar GlobalKeyRepeat
    globalKeyRepeat =
       makeStateVar (deviceGet unmarshalGlobalKeyRepeat glut_DEVICE_KEY_REPEAT)
                    (glutSetKeyRepeat . marshalGlobalKeyRepeat)

    --------------------------------------------------------------------------------

    -- | The state of the per-window key repeat

    data PerWindowKeyRepeat
       = PerWindowKeyRepeatOff
       | PerWindowKeyRepeatOn
       deriving ( Eq, Ord, Show )

    marshalPerWindowKeyRepeat :: PerWindowKeyRepeat -> CInt
    marshalPerWindowKeyRepeat x = case x of
       PerWindowKeyRepeatOn -> 0
       PerWindowKeyRepeatOff -> 1

    unmarshalPerWindowKeyRepeat :: CInt -> PerWindowKeyRepeat
    unmarshalPerWindowKeyRepeat x
       | x == 0 = PerWindowKeyRepeatOn
       | otherwise = PerWindowKeyRepeatOff

    --------------------------------------------------------------------------------

    -- | Controls if auto repeat keystrokes are reported to the /current window./
    -- Ignoring auto repeated keystrokes is generally done in conjunction with using
    -- the 'Graphics.UI.GLUT.Callbacks.Window.keyboardMouseCallback'. If you do
    -- not ignore auto repeated keystrokes, your GLUT application will experience
    -- repeated release\/press callbacks. Games using the keyboard will typically
    -- want to ignore key repeat.

    perWindowKeyRepeat :: StateVar PerWindowKeyRepeat
    perWindowKeyRepeat =
       makeStateVar
          (deviceGet unmarshalPerWindowKeyRepeat glut_DEVICE_IGNORE_KEY_REPEAT)
          (glutIgnoreKeyRepeat . marshalPerWindowKeyRepeat)

    --------------------------------------------------------------------------------

    -- | Execute the joystick callback set by
    -- 'Graphics.UI.GLUT.Callbacks.Window.joystickCallback' once (if one exists).
    -- This is done in a synchronous fashion within the current context, i.e. when
    -- 'forceJoystickCallback' returns, the callback will have already happened.

    forceJoystickCallback :: MonadIO m => m ()
    forceJoystickCallback = glutForceJoystickFunc