{-# LANGUAGE DoAndIfThenElse #-}
{-# LANGUAGE ScopedTypeVariables #-}

-- | This module starts a Interpreter server that will read our strings representing rules to convert them to plain Rules.
module Nomyx.Core.Interpret where

import Language.Haskell.Interpreter
import Language.Haskell.Interpreter.Server
import Language.Nomyx
import System.Directory (createDirectoryIfMissing, copyFile, removeFile, doesFileExist)
import System.FilePath ((</>), joinPath, dropExtension, takeFileName)
import Control.Exception as CE
import Data.Either.Unwrap
import Nomyx.Core.Utils
import Data.List
import Control.Monad
import Language.Haskell.Interpreter.Unsafe (unsafeSetGhcOption)
import qualified Mueval.Resources as MR (limitResources)
import qualified Mueval.Context as MC
import qualified Mueval.Interpreter as MI
import System.IO.Error



unQualImports :: [String]
unQualImports = "Language.Nomyx" :
                "Language.Nomyx.Examples" :
                "Safe" :
                "Data.Typeable" :
                "Data.Lens" :
                MC.defaultModules

qualImports :: [(String, Maybe String)]
qualImports = ("Control.Category", Just "C") : MC.qualifiedModules

defaultPackages :: [String]
defaultPackages = "Nomyx-Language" : MC.defaultPackages


exts :: [String]
exts = ["Safe", "GADTs"] ++ map show namedExts

namedExts :: [Extension]
namedExts = [GADTs,
             ScopedTypeVariables,
             TypeFamilies,
             DeriveDataTypeable]
                                
-- | the server handle
startInterpreter :: FilePath -> IO ServerHandle
startInterpreter saveDir = do
   sh <- start
   liftIO $ createDirectoryIfMissing True $ saveDir </> uploadDir
   ir <- runIn sh $ initializeInterpreter saveDir
   case ir of
      Right r -> do
         putStrLn "Interpreter Loaded"
         return $ Just r
      Left e -> error $ "sHandle: initialization error:\n" ++ show e
   return sh

-- get all uploaded modules from the directory (may be empty)
getUploadModules :: FilePath -> IO [FilePath]
getUploadModules saveDir = do
    files <- getUploadedModules saveDir `catch` (\(_::SomeException) -> return [])
    return $ map (\f -> joinPath [saveDir, uploadDir, f]) files

   
-- | initializes the interpreter by loading some modules.
initializeInterpreter :: FilePath -> Interpreter ()
initializeInterpreter saveDir = do
   reset -- Make sure nothing is available
   set [installedModulesInScope := False,
        languageExtensions := map MI.readExt exts]
   unsafeSetGhcOption "-fpackage-trust"
   forM_ (defaultPackages >>= words) $ \pkg -> unsafeSetGhcOption ("-trust " ++ pkg)
   uploadedMods <- liftIO $ getUploadModules saveDir
   liftIO $ putStrLn $ "Loading modules: " ++ (intercalate ", " uploadedMods)
   loadModules uploadedMods
   setTopLevelModules $ map (dropExtension . takeFileName) uploadedMods
   liftIO $ MR.limitResources False
   let importMods = qualImports ++ zip (unQualImports) (repeat Nothing)
   setImportsQ importMods

--initializeInterpreter :: FilePath -> Interpreter ()
--initializeInterpreter saveDir = do
--   uploadedMods <- liftIO $ getUploadModules saveDir
--   liftIO $ putStrLn $ "Loading modules: " ++ (concat $ intersperse ", " uploadedMods)
--   let o = Options { extensions = True,
--                     namedExtensions = exts,
--                     typeOnly = True,
--                     rLimits = True,
--                     loadFile = "",
--                     packageTrust = True,
--                     modules = Just unQualImports}
--   MI.initializeInterpreter o
--   uploadedMods <- liftIO $ getUploadModules saveDir
--   liftIO $ putStrLn $ "Loading modules: " ++ (concat $ intersperse ", " uploadedMods)
--   loadModules uploadedMods

---- | reads maybe a Rule out of a string.
interpretRule :: String -> ServerHandle -> IO (Either InterpreterError Rule)
interpretRule s sh = (liftIO $ runIn sh $ interpret s (as :: Rule))
   `catchIOError` (\(e::IOException) -> return $ Left $ NotAllowed $ "Caught exception: " ++ (show e))

getRuleFunc :: ServerHandle -> RuleCode -> IO Rule
getRuleFunc sh rc = do
   res <- interpretRule rc sh
   case res of
      Right rf -> return rf
      Left e -> error $ show e

-- | check an uploaded file and reload
loadModule :: FilePath -> FilePath -> ServerHandle -> FilePath -> IO (Maybe InterpreterError)
loadModule tempModName name sh saveDir = do
   --copy the new module in the upload directory
   let dest = saveDir </> uploadDir </> name
   exist <- doesFileExist dest
   if exist then return $ Just $ NotAllowed "Module already uploaded"
   else do
      copyFile tempModName dest
      setMode dest
      inter <- runIn sh $ initializeInterpreter saveDir
      case inter of
         Right _ -> return Nothing
         Left e -> do
            --suppress the faulty module
            removeFile dest
            final <- runIn sh $ initializeInterpreter saveDir
            when (isLeft final) $ putStrLn "Error: reinitialize interpreter failed"
            return $ Just e


showInterpreterError :: InterpreterError -> String
showInterpreterError (UnknownError s)  = "Unknown Error\n" ++ s
showInterpreterError (WontCompile ers) = "Won't Compile\n" ++ concatMap (\(GhcError errMsg) -> errMsg ++ "\n") ers
showInterpreterError (NotAllowed s)    = "Not Allowed (Probable cause: bad module or file name)\n" ++ s
showInterpreterError (GhcException s)  = "Ghc Exception\n" ++ s