-- |
-- Module      :  $Header$
-- Copyright   :  (c) 2013-2015 Galois, Inc.
-- License     :  BSD3
-- Maintainer  :  cryptol@galois.com
-- Stability   :  provisional
-- Portability :  portable

{-# LANGUAGE FlexibleContexts #-}

module Cryptol.ModuleSystem.Monad where

import           Cryptol.Eval.Env (EvalEnv)
import           Cryptol.ModuleSystem.Env
import           Cryptol.ModuleSystem.Interface
import           Cryptol.ModuleSystem.Renamer (RenamerError(),RenamerWarning())
import qualified Cryptol.Parser     as Parser
import qualified Cryptol.Parser.AST as P
import           Cryptol.Parser.Position (Located)
import           Cryptol.Utils.Panic (panic)
import qualified Cryptol.Parser.NoPat as NoPat
import qualified Cryptol.Parser.NoInclude as NoInc
import qualified Cryptol.TypeCheck as T
import qualified Cryptol.TypeCheck.AST as T
import           Cryptol.Parser.Position (Range)
import           Cryptol.Utils.PP

import Control.Exception (IOException)
import Data.Function (on)
import Data.Maybe (isJust)
import MonadLib

#if __GLASGOW_HASKELL__ < 710
import Control.Applicative (Applicative(..))
#endif

-- Errors ----------------------------------------------------------------------

data ImportSource
  = FromModule P.ModName
  | FromImport (Located P.Import)
    deriving (Show)

instance Eq ImportSource where
  (==) = (==) `on` importedModule

instance PP ImportSource where
  ppPrec _ is = case is of
    FromModule n  -> text "module name" <+> pp n
    FromImport li -> text "import of module" <+> pp (P.iModule (P.thing li))

importedModule :: ImportSource -> P.ModName
importedModule is = case is of
  FromModule n  -> n
  FromImport li -> P.iModule (P.thing li)


data ModuleError
  = ModuleNotFound P.ModName [FilePath]
    -- ^ Unable to find the module given, tried looking in these paths
  | CantFindFile FilePath
    -- ^ Unable to open a file
  | OtherIOError FilePath IOException
    -- ^ Some other IO error occurred while reading this file
  | ModuleParseError FilePath Parser.ParseError
    -- ^ Generated this parse error when parsing the file for module m
  | RecursiveModules [ImportSource]
    -- ^ Recursive module group discovered
  | RenamerErrors ImportSource [RenamerError]
    -- ^ Problems during the renaming phase
  | NoPatErrors ImportSource [NoPat.Error]
    -- ^ Problems during the NoPat phase
  | NoIncludeErrors ImportSource [NoInc.IncludeError]
    -- ^ Problems during the NoInclude phase
  | TypeCheckingFailed ImportSource [(Range,T.Error)]
    -- ^ Problems during type checking
  | OtherFailure String
    -- ^ Problems after type checking, eg. specialization
  | ModuleNameMismatch P.ModName (Located P.ModName)
    -- ^ Module loaded by 'import' statement has the wrong module name
  | DuplicateModuleName P.ModName FilePath FilePath
    -- ^ Two modules loaded from different files have the same module name
    deriving (Show)

instance PP ModuleError where
  ppPrec _ e = case e of

    ModuleNotFound src path ->
      text "[error]" <+>
      text "Could not find module" <+> pp src
      $$
      hang (text "Searched paths:")
         4 (vcat (map text path))
      $$
      text "Set the CRYPTOLPATH environment variable to search more directories"

    CantFindFile path ->
      text "[error]" <+>
      text "can't find file:" <+> text path

    OtherIOError path exn ->
      hang (text "[error]" <+>
            text "IO error while loading file:" <+> text path <> colon)
         4 (text (show exn))

    ModuleParseError _source err -> Parser.ppError err

    RecursiveModules mods ->
      hang (text "[error] module imports form a cycle:")
         4 (vcat (map pp (reverse mods)))

    RenamerErrors _src errs -> vcat (map pp errs)

    NoPatErrors _src errs -> vcat (map pp errs)

    NoIncludeErrors _src errs -> vcat (map NoInc.ppIncludeError errs)

    TypeCheckingFailed _src errs -> vcat (map T.ppError errs)

    ModuleNameMismatch expected found ->
      hang (text "[error]" <+> pp (P.srcRange found) <> char ':')
         4 (vcat [ text "File name does not match module name:"
                 , text "Saw:"      <+> pp (P.thing found)
                 , text "Expected:" <+> pp expected
                 ])

    DuplicateModuleName name path1 path2 ->
      hang (text "[error] module" <+> pp name <+>
            text "is defined in multiple files:")
         4 (vcat [text path1, text path2])

    OtherFailure x -> text x




moduleNotFound :: P.ModName -> [FilePath] -> ModuleM a
moduleNotFound name paths = ModuleT (raise (ModuleNotFound name paths))

cantFindFile :: FilePath -> ModuleM a
cantFindFile path = ModuleT (raise (CantFindFile path))

otherIOError :: FilePath -> IOException -> ModuleM a
otherIOError path exn = ModuleT (raise (OtherIOError path exn))

moduleParseError :: FilePath -> Parser.ParseError -> ModuleM a
moduleParseError path err =
  ModuleT (raise (ModuleParseError path err))

recursiveModules :: [ImportSource] -> ModuleM a
recursiveModules loaded = ModuleT (raise (RecursiveModules loaded))

renamerErrors :: [RenamerError] -> ModuleM a
renamerErrors errs = do
  src <- getImportSource
  ModuleT (raise (RenamerErrors src errs))

noPatErrors :: [NoPat.Error] -> ModuleM a
noPatErrors errs = do
  src <- getImportSource
  ModuleT (raise (NoPatErrors src errs))

noIncludeErrors :: [NoInc.IncludeError] -> ModuleM a
noIncludeErrors errs = do
  src <- getImportSource
  ModuleT (raise (NoIncludeErrors src errs))

typeCheckingFailed :: [(Range,T.Error)] -> ModuleM a
typeCheckingFailed errs = do
  src <- getImportSource
  ModuleT (raise (TypeCheckingFailed src errs))

moduleNameMismatch :: P.ModName -> Located P.ModName -> ModuleM a
moduleNameMismatch expected found =
  ModuleT (raise (ModuleNameMismatch expected found))

duplicateModuleName :: P.ModName -> FilePath -> FilePath -> ModuleM a
duplicateModuleName name path1 path2 =
  ModuleT (raise (DuplicateModuleName name path1 path2))


-- Warnings --------------------------------------------------------------------

data ModuleWarning
  = TypeCheckWarnings [(Range,T.Warning)]
  | RenamerWarnings [RenamerWarning]
    deriving (Show)

instance PP ModuleWarning where
  ppPrec _ w = case w of
    TypeCheckWarnings ws -> vcat (map T.ppWarning ws)
    RenamerWarnings ws   -> vcat (map pp ws)

warn :: [ModuleWarning] -> ModuleM ()
warn  = ModuleT . put

typeCheckWarnings :: [(Range,T.Warning)] -> ModuleM ()
typeCheckWarnings ws
  | null ws   = return ()
  | otherwise = warn [TypeCheckWarnings ws]

renamerWarnings :: [RenamerWarning] -> ModuleM ()
renamerWarnings ws
  | null ws   = return ()
  | otherwise = warn [RenamerWarnings ws]


-- Module System Monad ---------------------------------------------------------

data RO = RO
  { roLoading :: [ImportSource]
  }

emptyRO :: RO
emptyRO  = RO { roLoading = [] }

newtype ModuleT m a = ModuleT
  { unModuleT :: ReaderT RO (StateT ModuleEnv
                    (ExceptionT ModuleError (WriterT [ModuleWarning] m))) a
  }

instance Monad m => Functor (ModuleT m) where
  {-# INLINE fmap #-}
  fmap f m      = ModuleT (fmap f (unModuleT m))

instance Monad m => Applicative (ModuleT m) where
  {-# INLINE pure #-}
  pure x = ModuleT (pure x)

  {-# INLINE (<*>) #-}
  l <*> r = ModuleT (unModuleT l <*> unModuleT r)

instance Monad m => Monad (ModuleT m) where
  {-# INLINE return #-}
  return x      = ModuleT (return x)

  {-# INLINE (>>=) #-}
  m >>= f       = ModuleT (unModuleT m >>= unModuleT . f)
  {-# INLINE fail #-}
  fail          = ModuleT . raise . OtherFailure

instance MonadT ModuleT where
  {-# INLINE lift #-}
  lift = ModuleT . lift . lift . lift . lift

runModuleT :: Monad m
           => ModuleEnv
           -> ModuleT m a
           -> m (Either ModuleError (a, ModuleEnv), [ModuleWarning])
runModuleT env m = 
    runWriterT
  $ runExceptionT
  $ runStateT env
  $ runReaderT emptyRO
  $ unModuleT m

-- runM (unModuleT m) emptyRO env

type ModuleM = ModuleT IO

runModuleM :: ModuleEnv -> ModuleM a
           -> IO (Either ModuleError (a,ModuleEnv),[ModuleWarning])
runModuleM = runModuleT



io :: BaseM m IO => IO a -> ModuleT m a
io m = ModuleT (inBase m)

getModuleEnv :: Monad m => ModuleT m ModuleEnv
getModuleEnv = ModuleT get

setModuleEnv :: Monad m => ModuleEnv -> ModuleT m ()
setModuleEnv = ModuleT . set

modifyModuleEnv :: Monad m => (ModuleEnv -> ModuleEnv) -> ModuleT m ()
modifyModuleEnv f = ModuleT $ do
  env <- get
  set $! f env

isLoaded :: P.ModName -> ModuleM Bool
isLoaded mn = ModuleT $ do
  env <- get
  return (isJust (lookupModule mn env))

loadingImport :: Located P.Import -> ModuleM a -> ModuleM a
loadingImport  = loading . FromImport

loadingModule :: P.ModName -> ModuleM a -> ModuleM a
loadingModule  = loading . FromModule

-- | Push an "interactive" context onto the loading stack.  A bit of a hack, as
-- it uses a faked module name
interactive :: ModuleM a -> ModuleM a
interactive  = loadingModule (P.ModName ["<interactive>"])

loading :: ImportSource -> ModuleM a -> ModuleM a
loading src m = ModuleT $ do
  ro <- ask
  let ro'  = ro { roLoading = src : roLoading ro }

  -- check for recursive modules
  when (src `elem` roLoading ro) (raise (RecursiveModules (roLoading ro')))

  local ro' (unModuleT m)

-- | Get the currently focused import source.
getImportSource :: ModuleM ImportSource
getImportSource  = ModuleT $ do
  ro <- ask
  case roLoading ro of
    is : _ -> return is
    _      -> panic "ModuleSystem: getImportSource" ["Import stack is empty"]


getIface :: P.ModName -> ModuleM Iface
getIface mn = ModuleT $ do
  env <- get
  case lookupModule mn env of
    Just lm -> return (lmInterface lm)
    Nothing -> panic "ModuleSystem" ["Interface not available "]

getNameSeeds :: ModuleM T.NameSeeds
getNameSeeds  = ModuleT (meNameSeeds `fmap` get)

getMonoBinds :: ModuleM Bool
getMonoBinds  = ModuleT (meMonoBinds `fmap` get)

setMonoBinds :: Bool -> ModuleM ()
setMonoBinds b = ModuleT $ do
  env <- get
  set $! env { meMonoBinds = b }

setNameSeeds :: T.NameSeeds -> ModuleM ()
setNameSeeds seeds = ModuleT $ do
  env <- get
  set $! env { meNameSeeds = seeds }

-- | Remove a module from the set of loaded module, by its path.
unloadModule :: FilePath -> ModuleM ()
unloadModule path = ModuleT $ do
  env <- get
  set $! env { meLoadedModules = removeLoadedModule path (meLoadedModules env) }

loadedModule :: FilePath -> T.Module -> ModuleM ()
loadedModule path m = ModuleT $ do
  env <- get
  set $! env { meLoadedModules = addLoadedModule path m (meLoadedModules env) }

modifyEvalEnv :: (EvalEnv -> EvalEnv) -> ModuleM ()
modifyEvalEnv f = ModuleT $ do
  env <- get
  set $! env { meEvalEnv = f (meEvalEnv env) }

getEvalEnv :: ModuleM EvalEnv
getEvalEnv  = ModuleT (meEvalEnv `fmap` get)

getFocusedModule :: ModuleM (Maybe P.ModName)
getFocusedModule  = ModuleT (meFocusedModule `fmap` get)

setFocusedModule :: P.ModName -> ModuleM ()
setFocusedModule n = ModuleT $ do
  me <- get
  set $! me { meFocusedModule = Just n }

getSearchPath :: ModuleM [FilePath]
getSearchPath  = ModuleT (meSearchPath `fmap` get)

-- | Run a 'ModuleM' action in a context with a prepended search
-- path. Useful for temporarily looking in other places while
-- resolving imports, for example.
withPrependedSearchPath :: [FilePath] -> ModuleM a -> ModuleM a
withPrependedSearchPath fps m = ModuleT $ do
  env0 <- get
  let fps0 = meSearchPath env0
  set $! env0 { meSearchPath = fps ++ fps0 }
  x <- unModuleT m
  env <- get
  set $! env { meSearchPath = fps0 }
  return x

-- XXX improve error handling here
getFocusedEnv :: ModuleM IfaceDecls
getFocusedEnv  = ModuleT (focusedEnv `fmap` get)

getQualifiedEnv :: ModuleM IfaceDecls
getQualifiedEnv  = ModuleT (qualifiedEnv `fmap` get)

getDynEnv :: ModuleM DynamicEnv
getDynEnv  = ModuleT (meDynEnv `fmap` get)

setDynEnv :: DynamicEnv -> ModuleM ()
setDynEnv denv = ModuleT $ do
  me <- get
  set $! me { meDynEnv = denv }