{-# 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 Data.Tree
import Exception
import Language.Haskell.GhcMod
import Language.Haskell.GhcMod.Internal
-- import Language.Haskell.Refact.Utils.GhcVersionSpecific
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)

                     -- liftIO $ warningM "HaRe" $ "initGhcSession:loadModuleGraphGhc done"

      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
   setCurrentDirectory $ gfromJust "getCabalAllTargets" (cradleCabalDir cradle)

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

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

       addCurrentDir ts = map (\t -> combine currentDir 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

      settings <- get
      put $ settings { rsGraph = (rsGraph settings) ++ [(targetFiles,cgraph)]
                     , rsModuleGraph = (rsModuleGraph settings) ++ [(targetFiles,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
      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
      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

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