{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

module Language.Haskell.Refact.Utils.Monad
       ( ParseResult
       , VerboseLevel(..)
       , RefactSettings(..)
       , RefactState(..)
       , RefactModule(..)
       , TargetModule
       , RefactStashId(..)
       , RefactFlags(..)
       , StateStorage(..)

       -- GHC monad stuff
       , RefactGhc
       , runRefactGhc
       , getRefacSettings
       , defaultSettings
       , logSettings
       , initGhcSession

       , loadModuleGraphGhc
       , ensureTargetLoaded
       , canonicalizeGraph

       , logm
       ) where


import qualified GHC           as GHC
import qualified GHC.Paths     as GHC
import qualified GhcMonad      as GHC
import qualified MonadUtils    as GHC

import Control.Monad.State
import Data.List
import Data.Time.Clock
import Exception
import Language.Haskell.GhcMod
import Language.Haskell.GhcMod.Internal
import Language.Haskell.Refact.Utils.TokenUtilsTypes
import Language.Haskell.Refact.Utils.TypeSyn
import System.Directory
import System.FilePath.Posix
import System.Log.Logger
import qualified Control.Monad.IO.Class as MU

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

data VerboseLevel = Debug | Normal | Off
            deriving (Eq,Show)

data RefactSettings = RefSet
        { rsetGhcOpts      :: ![String]
        , rsetImportPaths :: ![FilePath]
        , rsetExpandSplice :: Bool
        , rsetLineSeparator :: LineSeparator
        , rsetMainFile     :: Maybe [FilePath]
        , rsetCheckTokenUtilsInvariant :: !Bool
        , rsetVerboseLevel :: !VerboseLevel
        , rsetEnabledTargets :: (Bool,Bool,Bool,Bool)
        } deriving (Show)

deriving instance Show LineSeparator

defaultSettings :: RefactSettings
defaultSettings = RefSet
    { rsetGhcOpts = []
    , rsetImportPaths = []
    , rsetExpandSplice = False
    , rsetLineSeparator = LineSeparator "\0"
    , rsetMainFile = Nothing
    , rsetCheckTokenUtilsInvariant = False
    , rsetVerboseLevel = Normal
    -- , rsetEnabledTargets = (True,False,True,False)
    , rsetEnabledTargets = (True,True,True,True)
    }

logSettings :: RefactSettings
logSettings = defaultSettings { rsetVerboseLevel = Debug }

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

data RefactStashId = Stash !String deriving (Show,Eq,Ord)

data RefactModule = RefMod
        { rsTypecheckedMod  :: !GHC.TypecheckedModule
        , rsOrigTokenStream :: ![PosToken]  -- ^Original Token stream for the current module
        , rsTokenCache      :: !TokenCache  -- ^Token stream for the current module, maybe modified, in SrcSpan tree form
        , rsStreamModified  :: !Bool        -- ^current module has updated the token stream
        }

data RefactFlags = RefFlags
       { rsDone :: !Bool -- ^Current traversal has already made a change
       }

-- | State for refactoring a single file. Holds/hides the token
-- stream, which gets updated transparently at key points.
data RefactState = RefSt
        { rsSettings  :: !RefactSettings -- ^Session level settings
        , rsUniqState :: !Int -- ^ Current Unique creator value, incremented every time it is used
        , rsFlags     :: !RefactFlags -- ^ Flags for controlling generic traversals
        , rsStorage   :: !StateStorage -- ^Temporary storage of values
                                      -- while refactoring takes place
        , rsGraph     :: [TargetGraph]
        , rsModuleGraph :: [([FilePath],GHC.ModuleGraph)]
        , rsCurrentTarget :: Maybe [FilePath]
        , rsModule    :: !(Maybe RefactModule) -- ^The current module being refactored
        }

type TargetModule = ([FilePath], GHC.ModSummary)

type TargetGraph = ([FilePath],[(Maybe FilePath, GHC.ModSummary)])

-- |Result of parsing a Haskell source file. It is simply the
-- TypeCheckedModule produced by GHC.
type ParseResult = GHC.TypecheckedModule

-- |Provide some temporary storage while the refactoring is taking
-- place
data StateStorage = StorageNone
                  | StorageBind (GHC.LHsBind GHC.Name)
                  | StorageSig (GHC.LSig GHC.Name)

instance Show StateStorage where
  show StorageNone        = "StorageNone"
  show (StorageBind _bind) = "(StorageBind " {- ++ (showGhc bind) -} ++ ")"
  show (StorageSig _sig)   = "(StorageSig " {- ++ (showGhc sig) -} ++ ")"

-- ---------------------------------------------------------------------
-- StateT and GhcT stack

type RefactGhc a = GHC.GhcT (StateT RefactState IO) a

instance (MU.MonadIO (GHC.GhcT (StateT RefactState IO))) where
         liftIO = GHC.liftIO

instance GHC.MonadIO (StateT RefactState IO) where
         liftIO f = MU.liftIO f

instance ExceptionMonad m => ExceptionMonad (StateT s m) where
    gcatch f h = StateT $ \s -> gcatch (runStateT f s) (\e -> runStateT (h e) s)
    gblock = mapStateT gblock
    gunblock = mapStateT gunblock


instance (MonadState RefactState (GHC.GhcT (StateT RefactState IO))) where
    get = lift get
    put = lift . put
    -- state = lift . state

instance (MonadTrans GHC.GhcT) where
   lift = GHC.liftGhcT

instance (MonadPlus m,Functor m,GHC.MonadIO m,ExceptionMonad m) => MonadPlus (GHC.GhcT m) where
  mzero = GHC.GhcT $ \_s -> mzero
  x `mplus` y = GHC.GhcT $ \_s -> (GHC.runGhcT (Just GHC.libdir) x) `mplus` (GHC.runGhcT (Just GHC.libdir) y)

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

-- | Initialise the GHC session, when starting a refactoring.
--   This should never be called directly.
initGhcSession :: Cradle -> [FilePath] -> RefactGhc ()
initGhcSession cradle importDirs = do
    settings <- getRefacSettings
    let ghcOptsDirs =
         case importDirs of
           [] -> (rsetGhcOpts settings)
           _  -> ("-i" ++ (intercalate ":" importDirs)):(rsetGhcOpts settings)
    let opt = Options {
                 outputStyle = PlainStyle
                 , hlintOpts = []
                 , ghcOpts = ghcOptsDirs
                 , operators = False
                 , detailed = False
                 , qualified = False
                 , expandSplice = False
                 , lineSeparator = rsetLineSeparator settings
                 , packageId = Nothing -- TODO: work this through if needed
                 }
    (_readLog,mcabal) <- initializeFlagsWithCradle opt cradle (options settings) True

    case mcabal of
      Just cabal -> do
        -- targets <- liftIO $ cabalAllTargets cabal
        targets <- liftIO $ getCabalAllTargets cradle cabal
        -- liftIO $ warningM "HaRe" $ "initGhcSession:targets=" ++ show targets
        logm $ "initGhcSession:targets=" ++ show targets

        -- TODO: Cannot load multiple main modules, must try to load
        -- each main module and retrieve its module graph, and then
        -- set the targets to this superset.

        let targets' = getEnabledTargets settings targets

        case targets' of
          ([],[]) -> return ()
          (libTgts,exeTgts) -> do
                     -- liftIO $ warningM "HaRe" $ "initGhcSession:tgts=" ++ (show (libTgts,exeTgts))
                     logm $ "initGhcSession:(libTgts,exeTgts)=" ++ (show (libTgts,exeTgts))
                     -- setTargetFiles tgts
                     -- void $ GHC.load GHC.LoadAllTargets

                     mapM_ loadModuleGraphGhc $ map (\t -> Just [t]) exeTgts

                     -- Load the library last, most likely in context
                     case libTgts of
                       [] -> return ()
                       _ -> loadModuleGraphGhc (Just libTgts)

                     -- moduleGraph <- gets rsModuleGraph
                     -- logm $ "initGhcSession:rsModuleGraph=" ++ (show moduleGraph)

      Nothing -> do
          let maybeMainFile = rsetMainFile settings
          loadModuleGraphGhc maybeMainFile
          return()

    -- graph <- gets rsGraph
    -- liftIO $ warningM "HaRe" $ "initGhcSession:graph=" ++ show graph
    return ()
    where
      options opt
        | rsetExpandSplice opt = "-w:"   : rsetGhcOpts opt
        | otherwise            = "-Wall" : rsetGhcOpts opt

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


-- getCabalAllTargets :: Cradle -> PackageDescription -> IO ([FilePath],[FilePath],[FilePath],[FilePath])
getCabalAllTargets cradle cabal = do
   currentDir <- getCurrentDirectory
   let cabalDir = gfromJust "getCabalAllTargets" (cradleCabalDir cradle)
   setCurrentDirectory cabalDir

   (libs,exes,tests,benches) <- liftIO $ cabalAllTargets cabal
   setCurrentDirectory currentDir

   let -- libs'    = addCurrentDir libs
       exes'    = addCabalDir exes
       tests'   = addCabalDir tests
       benches' = addCabalDir benches

       addCabalDir ts = map (\t -> combine cabalDir t) ts

   return (libs,exes',tests',benches')

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

-- | Load a module graph into the GHC session, starting from main
loadModuleGraphGhc ::
  Maybe [FilePath] -> RefactGhc ()
loadModuleGraphGhc maybeTargetFiles = do
  -- currentDir <- liftIO getCurrentDirectory
  -- liftIO $ warningM "HaRe" $ "loadModuleGraphGhc:maybeTargetFiles=" ++ show (maybeTargetFiles,currentDir)
  case maybeTargetFiles of
    Just targetFiles -> do
      loadTarget targetFiles
      -- setTargetFiles [targetFile]
      -- void $ GHC.load GHC.LoadAllTargets

      graph <- GHC.getModuleGraph
      cgraph <- liftIO $ canonicalizeGraph graph

      let canonMaybe filepath = ghandle handler (canonicalizePath filepath)
            where
              handler :: SomeException -> IO FilePath
              handler _e = return filepath

      ctargetFiles <- liftIO $ mapM canonMaybe targetFiles

      settings <- get
      put $ settings { -- rsGraph = (rsGraph settings) ++ [(targetFiles,cgraph)]
                       rsGraph = (rsGraph settings) ++ [(ctargetFiles,cgraph)]
                     -- , rsModuleGraph = (rsModuleGraph settings) ++ [(targetFiles,graph)]
                     , rsModuleGraph = (rsModuleGraph settings) ++ [(ctargetFiles,graph)]
                     , rsCurrentTarget = maybeTargetFiles
                     }

      -- logm $ "loadModuleGraphGhc:cgraph=" ++ show (map fst cgraph)
      -- logm $ "loadModuleGraphGhc:cgraph=" ++ showGhc graph

      return ()
    Nothing -> return ()
  return ()

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

loadTarget :: [FilePath] -> RefactGhc ()
loadTarget targetFiles = do
      setTargetFiles targetFiles
      checkSlowAndSet
      void $ GHC.load GHC.LoadAllTargets

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

-- | Make sure the given file is the currently loaded target, and load
-- it if not. Assumes that all the module graphs had been generated
-- before, so these are not updated.
ensureTargetLoaded :: TargetModule -> RefactGhc GHC.ModSummary
ensureTargetLoaded (target,modSum) = do
  settings <- get
  let currentTarget = rsCurrentTarget settings
  if currentTarget == Just target
    then return modSum
    else do
      logm $ "ensureTargetLoaded: loading:" ++ show target
      loadTarget target
      put $ settings { rsCurrentTarget = Just target}
      graph <- GHC.getModuleGraph
      let newModSum = filter (\ms -> GHC.ms_mod modSum == GHC.ms_mod ms) graph
      return $ ghead "ensureTargetLoaded" newModSum

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

canonicalizeGraph ::
  [GHC.ModSummary] -> IO [(Maybe (FilePath), GHC.ModSummary)]
canonicalizeGraph graph = do
  let mm = map (\m -> (GHC.ml_hs_file $ GHC.ms_location m, m)) graph
      canon ((Just fp),m) = do
        fp' <- canonicalizePath fp
        return $ (Just fp',m)
      canon (Nothing,m)  = return (Nothing,m)

  mm' <- mapM canon mm

  return mm'

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

runRefactGhc ::
  RefactGhc a -> RefactState -> IO (a, RefactState)
runRefactGhc comp initState = do
    runStateT (GHC.runGhcT (Just GHC.libdir) comp) initState

getRefacSettings :: RefactGhc RefactSettings
getRefacSettings = do
  s <- get
  return (rsSettings s)

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

getEnabledTargets :: RefactSettings -> ([FilePath],[FilePath],[FilePath],[FilePath]) -> ([FilePath],[FilePath])
getEnabledTargets settings (libt,exet,testt,bencht) = (targetsLib,targetsExe)
  where
    (libEnabled, exeEnabled, testEnabled, benchEnabled) = rsetEnabledTargets settings
    targetsLib = on libEnabled libt
    targetsExe = on exeEnabled exet
              ++ on testEnabled testt
              ++ on benchEnabled bencht

    on flag xs = if flag then xs else []


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

logm :: String -> RefactGhc ()
logm string = do
  settings <- getRefacSettings
  let loggingOn = (rsetVerboseLevel settings == Debug)
             --     || (rsetVerboseLevel settings == Normal)
  when loggingOn $ do
     -- ts <- liftIO timeStamp
     -- liftIO $ warningM "HaRe" (ts ++ ":" ++ string)
     liftIO $ warningM "HaRe" (string)
  return ()

timeStamp :: IO String
timeStamp = do
  k <- getCurrentTime
  return (show k)

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

instance Show GHC.ModSummary where
  show m = show $ GHC.ms_mod m

instance Show GHC.Module where
  show m = GHC.moduleNameString $ GHC.moduleName m

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