{-# LANGUAGE FlexibleContexts, FlexibleInstances, TypeSynonymInstances, ExistentialQuantification, MultiParamTypeClasses, FunctionalDependencies #-}

-- Copyright (c) Jean-Philippe Bernardy 2007.

module Yi.Keymap where

import Prelude hiding (error)
import Yi.UI.Common
import qualified Yi.Editor as Editor
import Yi.Editor (EditorM, Editor, runEditor)
import qualified Data.Map as M
import Yi.Kernel
import Control.Monad.Reader
import Data.Typeable
import Data.IORef
import Control.Exception
import Control.Concurrent
import Yi.Buffer
import qualified Yi.Interact as I
import Yi.Monad
import Control.Monad.State
import Yi.Event

data Action = forall a. Show a => YiA (YiM a)
            | forall a. Show a => EditorA (EditorM a)
            | forall a. Show a => BufferA (BufferM a)
--            | InsertA String
--             | TextA Direction Unit Operation

instance I.PEq Action where
    equiv _ _ = False

instance Show Action where
    show (YiA _) = "@Y"
    show (EditorA _) = "@E"
    show (BufferA _) = "@B"

type Interact ev a = I.I ev Action a

type KeymapM a = Interact Event a

type Keymap = KeymapM ()

type KeymapEndo = Keymap -> Keymap

type KeymapProcess = I.P Event Action


data BufferKeymap = BufferKeymap
    { bufferKeymap :: KeymapEndo -- ^ Buffer's local keymap modification
    , bufferKeymapProcess :: KeymapProcess -- ^ Current state of the keymap automaton
    }

data Yi = Yi {yiEditor :: IORef Editor,
              yiUi          :: UI,
              threads       :: IORef [ThreadId],           -- ^ all our threads
              input         :: Chan Event,                 -- ^ input stream
              output        :: Chan Action,                -- ^ output stream
              defaultKeymap :: IORef Keymap,
              bufferKeymaps :: IORef (M.Map BufferRef BufferKeymap),
              yiKernel  :: Kernel,
              editorModules :: IORef [String] -- ^ modules requested by user: (e.g. ["YiConfig", "Yi.Dired"])
             }

-- | The type of user-bindable functions
type YiM = ReaderT Yi IO

-----------------------
-- Keymap basics

write :: (I.MonadInteract m Action ev, YiAction a x, Show x) => a -> m ()
write x = I.write (makeAction x)


-----------------------
-- Keymap thread handling

setBufferKeymap :: BufferRef -> KeymapEndo -> YiM ()
setBufferKeymap b km = do
  bkm <- getBufferKeymap b
  modifiesRef bufferKeymaps (M.insert b bkm {bufferKeymap = km, bufferKeymapProcess = I.Fail})

restartBufferThread :: BufferRef -> YiM ()
restartBufferThread b = do
  bkm <- getBufferKeymap b
  modifiesRef bufferKeymaps (M.insert b bkm {bufferKeymapProcess = I.Fail})

deleteBufferKeymap :: BufferRef -> YiM ()
deleteBufferKeymap b = modifiesRef bufferKeymaps (M.delete b)

getBufferKeymap :: BufferRef -> YiM BufferKeymap
getBufferKeymap b = do
  kms <- readsRef bufferKeymaps
  return $ case M.lookup b kms of
    Just bkm -> bkm
    Nothing -> BufferKeymap {bufferKeymap = id, bufferKeymapProcess = I.Fail}

--------------------------------
-- Uninteresting glue code

withKernel :: (Kernel -> IO a) -> YiM a
withKernel = with yiKernel

withUI :: (UI -> IO a) -> YiM a
withUI = with yiUi

withUI2 :: (UI -> x -> EditorM a) -> (x -> YiM a)
withUI2 f x = do
  e <- ask
  withEditor $ f (yiUi e) x

withEditor :: EditorM a -> YiM a
withEditor f = do
  r <- asks yiEditor
  e <- readRef r
  let (a,e') = runEditor f e
  -- Make sure that the result of runEditor is evaluated before
  -- replacing the editor state. Otherwise, we might replace e
  -- with an exception-producing thunk, which makes it impossible
  -- to look at or update the editor state.
  e' `seq` a `seq` writeRef r e'
  return a

withGivenBuffer :: BufferRef -> BufferM a -> YiM a
withGivenBuffer b f = withEditor (Editor.withGivenBuffer0 b f)

withBuffer :: BufferM a -> YiM a
withBuffer f = withEditor (Editor.withBuffer0 f)

readEditor :: (Editor -> a) -> YiM a
readEditor f = withEditor (gets f)

catchDynE :: Typeable exception => YiM a -> (exception -> YiM a) -> YiM a
catchDynE inner handler = ReaderT (\r -> catchDyn (runReaderT inner r) (\e -> runReaderT (handler e) r))

catchJustE :: (Exception -> Maybe b) -- ^ Predicate to select exceptions
           -> YiM a      -- ^ Computation to run
           -> (b -> YiM a) -- ^   Handler
           -> YiM a
catchJustE p c h = ReaderT (\r -> catchJust p (runReaderT c r) (\b -> runReaderT (h b) r))

handleJustE :: (Exception -> Maybe b) -> (b -> YiM a) -> YiM a -> YiM a
handleJustE p h c = catchJustE p c h

-- | Shut down all of our threads. Should free buffers etc.
shutdown :: YiM ()
shutdown = do ts <- readsRef threads
              lift $ mapM_ killThread ts

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

class YiAction a x | a -> x where
    makeAction :: Show x => a -> Action

instance YiAction (YiM x) x where
    makeAction = YiA


instance YiAction (EditorM x) x where
    makeAction = EditorA

instance YiAction (BufferM x) x where
    makeAction = BufferA