{-# OPTIONS_GHC -fglasgow-exts #-}
-----------------------------------------------------------------------------
--
-- Module      :  IDE.Core.State
-- Copyright   :  (c) Juergen Nicklisch-Franken (aka Jutaro)
-- License     :  GNU-GPL
--
-- Maintainer  :  Juergen Nicklisch-Franken <jnf at arcor.de>
-- Stability   :  experimental
-- Portability :  portable
--
-- | The core state of ide. This module is imported from every other module,
-- | and all data structures of the state are declared here, to avoid circular
-- | module dependencies.
--
-------------------------------------------------------------------------------

module IDE.Core.State (
    IDEObject(..)
,   IDEEditor
,   IDE(..)
,   IDERef
,   IDEM
,   IDEAction
,   IDEEvent(..)
,   EventSelector(..)

-- * Convenience methods for accesing the IDE State
,   readIDE
,   modifyIDE
,   modifyIDE_
,   withIDE
,   getIDE

,   ideMessage
,   logMessage
,   forceJust
,   module IDE.Core.Types
,   module IDE.Core.Panes
,   module IDE.Core.Exception

) where

import Graphics.UI.Gtk hiding (get)
import Data.Map (Map)
import qualified Data.Map as Map
import Data.IORef
import Control.Monad.Reader
import GHC (Session)
import Data.Unique

import IDE.Core.Types
import IDE.Core.Panes
import IDE.Core.Exception

ideMessage :: MessageLevel -> String -> IDEAction
ideMessage level str = do
    st <- ask
    triggerEvent st (LogMessage (str ++ "\n") LogTag)
    lift $ sysMessage level str

logMessage :: String -> LogTag -> IDEAction
logMessage str tag = do
    st <- ask
    triggerEvent st (LogMessage (str ++ "\n") tag)
    return ()

data IDEEvent  =
        CurrentInfo
    |   ActivePack
    |   SelectInfo String
    |   SelectIdent IdentifierDescr
    |   LogMessage String LogTag
    |   GetToolbar [Widget]

data EventSelector  =
        CurrentInfoS
    |   ActivePackS
    |   SelectInfoS
    |   SelectIdentS
    |   LogMessageS
    |   GetToolbarS
    deriving (Eq,Ord,Show)

eventAsSelector :: IDEEvent -> EventSelector
eventAsSelector CurrentInfo             =   CurrentInfoS
eventAsSelector ActivePack              =   ActivePackS
eventAsSelector (LogMessage _ _)        =   LogMessageS
eventAsSelector (GetToolbar _)          =   GetToolbarS
eventAsSelector (SelectInfo _)          =   SelectInfoS
eventAsSelector (SelectIdent _)         =   SelectIdentS

class IDEObject alpha  where

    canTriggerEvent :: alpha -> EventSelector -> Bool
    canTriggerEvent _ _             =   False

    triggerEvent :: alpha -> IDEEvent -> IDEM IDEEvent
    triggerEvent o e    =
        if canTriggerEvent o (eventAsSelector e)
            then do
                handlerMap      <-  readIDE handlers
                let selector    =   eventAsSelector e
                case selector `Map.lookup` handlerMap of
                    Nothing     ->  return e
                    Just l      ->  foldM (\e (_,ah) -> ah e) e l
            else throwIDE $ "Object can't trigger event " ++ show (eventAsSelector e)

    registerEvent   :: alpha -> EventSelector -> Either (IDEEvent -> IDEM IDEEvent) Unique -> IDEM Unique
    registerEvent o e (Left handler) =   do
        handlerMap      <-  readIDE handlers
        unique          <-  lift $ newUnique
        let newHandlers =   case e `Map.lookup` handlerMap of
                                Nothing -> Map.insert e [(unique,handler)] handlerMap
                                Just l  -> Map.insert e ((unique,handler):l) handlerMap
        modifyIDE_ (\ide -> return (ide{handlers = newHandlers}))
        return unique
    registerEvent o e (Right unique) =   do
        handlerMap      <-  readIDE handlers
        let newHandlers =   case e `Map.lookup` handlerMap of
                                Nothing -> handlerMap
                                Just l -> let newList = filter (\ (mu,_) -> mu /= unique) l
                                          in  Map.insert e newList handlerMap
        modifyIDE_ (\ide -> return (ide{handlers = newHandlers}))
        return unique


class IDEObject o => IDEEditor o


-- ---------------------------------------------------------------------
-- IDE State
--

--
-- | The IDE state
--
data IDE            =  IDE {
    window          ::  Window                  -- ^ the gtk window
,   uiManager       ::  UIManager               -- ^ the gtk uiManager
,   panes           ::  Map PaneName IDEPane    -- ^ a map with all panes (subwindows)
,   activePane      ::  Maybe (PaneName,Connections)
,   paneMap         ::  Map PaneName (PanePath, Connections)
                    -- ^ a map from the pane name to its gui path and signal connections
,   layout          ::  PaneLayout              -- ^ a description of the general gui layout
,   specialKeys     ::  SpecialKeyTable IDERef  -- ^ a structure for emacs like keystrokes
,   specialKey      ::  SpecialKeyCons IDERef   -- ^ the first of a double keystroke
,   candy           ::  CandyTable              -- ^ table for source candy
,   prefs           ::  Prefs                   -- ^ configuration preferences
,   activePack      ::  Maybe IDEPackage
,   errors          ::  [ErrorSpec]
,   currentErr      ::  Maybe Int
,   accessibleInfo  ::  (Maybe (PackageScope))     -- ^  the world scope
,   currentInfo     ::  (Maybe (PackageScope,PackageScope))
                                                -- ^ the first is for the current package,
                                                --the second is the scope in the current package
,   session         ::  Session                  -- ^ a ghc session object, side effects
                                                -- reusing with sessions?
,   handlers        ::  Map EventSelector [(Unique, IDEEvent -> IDEM IDEEvent)]
                                                -- ^ event handling table
} --deriving Show

instance IDEObject IDERef where
    canTriggerEvent o LogMessageS       =   True
    canTriggerEvent o GetToolbarS       =   True
    canTriggerEvent o SelectInfoS       =   True
    canTriggerEvent o SelectIdentS      =   True
    canTriggerEvent o CurrentInfoS      =   True
    canTriggerEvent o ActivePackS       =   True
--    canTriggerEvent o _                 =   False

--
-- | A mutable reference to the IDE state
--
type IDERef = IORef IDE

--
-- | A reader monad for a mutable reference to the IDE state
--
type IDEM = ReaderT (IDERef) IO

--
-- | A shorthand for a reader monad for a mutable reference to the IDE state
--   which does not return a value
--
type IDEAction = IDEM ()

-- ---------------------------------------------------------------------
-- Convenience methods for accesing the IDE State
--

-- | Read an attribute of the contents
readIDE :: (IDE -> beta) -> IDEM beta
readIDE f = do
    e <- ask
    lift $ liftM f (readIORef e)

-- | Modify the contents, using an IO action.
modifyIDE_ :: (IDE -> IO IDE) -> IDEM ()
modifyIDE_ f = do
    e <- ask
    e' <- lift $ (f =<< readIORef e)
    lift $ writeIORef e e'

-- | Variation on modifyIDE_ that lets you return a value
modifyIDE :: (IDE -> IO (IDE,beta)) -> IDEM beta
modifyIDE f = do
    e <- ask
    (e',result) <- lift (f =<< readIORef e)
    lift $ writeIORef e e'
    return result

withIDE :: (IDE -> IO alpha) -> IDEM alpha
withIDE f = do
    e <- ask
    lift $ f =<< readIORef e

getIDE :: IDEM(IDE)
getIDE = do
    e <- ask
    st <- lift $ readIORef e
    return st

-- ---------------------------------------------------------------------
-- Convenience methods for accesing the IDE State
--
forceJust :: Maybe alpha -> String -> alpha
forceJust mb str = case mb of
			Nothing -> throwIDE str
			Just it -> it