{-# LANGUAGE DerivingVia #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE FlexibleContexts #-}
#ifdef PM36_HASKELL_SCRIPTING
{-# LANGUAGE TypeApplications #-}
#endif
module ProjectM36.Transaction.Persist where
import ProjectM36.Base
import ProjectM36.Error
import ProjectM36.Transaction
import ProjectM36.DatabaseContextFunction
import ProjectM36.AtomFunction
import ProjectM36.Persist (writeBSFileSync, DiskSync, renameSync)
import ProjectM36.Function
import qualified Data.Map as M
import qualified Data.HashSet as HS
import System.FilePath
import System.Directory
import qualified Data.Text as T
import Data.Foldable (toList)
import Control.Monad
import ProjectM36.ScriptSession
import ProjectM36.AtomFunctions.Basic (precompiledAtomFunctions)
import Codec.Winery

#ifdef PM36_HASKELL_SCRIPTING
import GHC
import Control.Exception
import GHC.Paths
#endif

getDirectoryNames :: FilePath -> IO [FilePath]
getDirectoryNames path =
  filter (\ n -> n `notElem` ["..", "."]) <$> getDirectoryContents path


tempTransactionDir :: FilePath -> TransactionId -> FilePath
tempTransactionDir dbdir transId = dbdir </> "." ++ show transId

transactionDir :: FilePath -> TransactionId -> FilePath
transactionDir dbdir transId = dbdir </> show transId

transactionInfoPath :: FilePath -> FilePath
transactionInfoPath transdir = transdir </> "info"

relvarsPath :: FilePath -> FilePath        
relvarsPath transdir = transdir </> "relvars"

incDepsDir :: FilePath -> FilePath
incDepsDir transdir = transdir </> "incdeps"

atomFuncsPath :: FilePath -> FilePath
atomFuncsPath transdir = transdir </> "atomfuncs"

dbcFuncsPath :: FilePath -> FilePath
dbcFuncsPath transdir = transdir </> "dbcfuncs"

typeConsPath :: FilePath -> FilePath
typeConsPath transdir = transdir </> "typecons"

subschemasPath :: FilePath -> FilePath
subschemasPath transdir = transdir </> "schemas"

-- | where compiled modules are stored within the database directory
objectFilesPath :: FilePath -> FilePath
objectFilesPath transdir = transdir </> ".." </> "compiled_modules"

readTransaction :: FilePath -> TransactionId -> Maybe ScriptSession -> IO (Either PersistenceError Transaction)
readTransaction dbdir transId mScriptSession = do
  let transDir = transactionDir dbdir transId
  transDirExists <- doesDirectoryExist transDir
  if not transDirExists then    
    return $ Left $ MissingTransactionError transId
    else do
    relvars <- readRelVars transDir
    transInfo <- readFileDeserialise (transactionInfoPath transDir)
    incDeps <- readIncDeps transDir
    typeCons <- readTypeConstructorMapping transDir
    sschemas <- readSubschemas transDir
    dbcFuncs <- readFuncs transDir (dbcFuncsPath transDir) basicDatabaseContextFunctions mScriptSession
    atomFuncs <- readFuncs transDir (atomFuncsPath transDir) precompiledAtomFunctions mScriptSession
    let newContext = DatabaseContext { inclusionDependencies = incDeps,
                                       relationVariables = relvars,
                                       typeConstructorMapping = typeCons,
                                       notifications = M.empty,
                                       atomFunctions = atomFuncs, 
                                       dbcFunctions = dbcFuncs }
        newSchemas = Schemas newContext sschemas
    return $ Right $ Transaction transId transInfo newSchemas
        
writeTransaction :: DiskSync -> FilePath -> Transaction -> IO ()
writeTransaction sync dbdir trans = do
  let tempTransDir = tempTransactionDir dbdir (transactionId trans)
      finalTransDir = transactionDir dbdir (transactionId trans)
      context = concreteDatabaseContext trans
  transDirExists <- doesDirectoryExist finalTransDir
  unless transDirExists $ do
    --create sub directories
    mapM_ createDirectory [tempTransDir, incDepsDir tempTransDir]
    writeRelVars sync tempTransDir (relationVariables context)
    writeIncDeps sync tempTransDir (inclusionDependencies context)
    writeFuncs sync (atomFuncsPath tempTransDir) (HS.toList (atomFunctions context))
    writeFuncs sync (dbcFuncsPath tempTransDir) (HS.toList (dbcFunctions context))
    writeTypeConstructorMapping sync tempTransDir (typeConstructorMapping context)
    writeSubschemas sync tempTransDir (subschemas trans)
    writeFileSerialise (transactionInfoPath tempTransDir) (transactionInfo trans)    --move the temp directory to final location
    renameSync sync tempTransDir finalTransDir

writeRelVars :: DiskSync -> FilePath -> RelationVariables -> IO ()
writeRelVars sync transDir relvars = do
  let path = relvarsPath transDir
  writeBSFileSync sync path (serialise relvars)

readRelVars :: FilePath -> IO RelationVariables
readRelVars transDir = 
  readFileDeserialise (relvarsPath transDir)

writeFuncs :: Traversable t => DiskSync -> FilePath -> t (Function a) -> IO ()
writeFuncs sync funcWritePath funcs = do
  funcs' <- forM funcs $ \fun -> do
    case funcBody fun of
      FunctionScriptBody{} -> pure fun
      FunctionBuiltInBody{} -> pure fun
      FunctionObjectLoadedBody objPath a b c -> do
         let newFuncBody = FunctionObjectLoadedBody objPath a b c
         pure (fun { funcBody = newFuncBody })
  --write additional data for object-loaded functions (which are not built-in or scripted)
  let functionData f =
          (funcType f, funcName f, functionScript f, objInfo f)
      objInfo :: Function a -> Maybe ObjectFileInfo
      objInfo f =
        case funcBody f of
          FunctionObjectLoadedBody objPath modName entryFunc _ ->
            Just (ObjectFileInfo (objPath, modName, entryFunc))
          FunctionScriptBody{} -> Nothing
          FunctionBuiltInBody{} -> Nothing
  writeBSFileSync sync funcWritePath (serialise $ fmap functionData (toList funcs'))

readFuncs :: FilePath -> FilePath -> HS.HashSet (Function a) -> Maybe ScriptSession -> IO (HS.HashSet (Function a))
readFuncs transDir funcPath precompiledFunctions mScriptSession = do
  funcsList <- readFileDeserialise funcPath
  --we always return the pre-compiled functions
  --load object files and functions in objects (shared libraries or flat object files)
  let objFilesDir = objectFilesPath transDir
  funcs <- mapM (\(funcType', funcName', mFuncScript, mObjInfo) -> 
                    loadFunc objFilesDir precompiledFunctions mScriptSession funcName' funcType' mFuncScript mObjInfo) funcsList
  pure (HS.union precompiledFunctions (HS.fromList funcs))

newtype ObjectFileInfo = ObjectFileInfo { _unFileInfo :: (FilePath, String, String) }
 deriving (Show, Serialise)
-- deriving Serialise via WineryVariant ObjectFileInfo

loadFunc :: FilePath -> HS.HashSet (Function a) -> Maybe ScriptSession -> FunctionName -> [AtomType] -> Maybe FunctionBodyScript -> Maybe ObjectFileInfo -> IO (Function a)
loadFunc objFilesDir precompiledFuncs _mScriptSession funcName' _funcType mFuncScript mObjInfo = do
  case mObjInfo of
    --load from shared or static object library
    Just (ObjectFileInfo (path, modName, entryFunc)) -> do
      eFuncs <- loadFunctions modName entryFunc (Just objFilesDir) path
      case eFuncs of
        Left _ -> error $ "Failed to load " <> path
        Right funcs -> 
          case filter (\f -> funcName f == funcName'
                      ) funcs of
            [f] -> pure f
            [] -> error $ "Failed to find function \"" <> T.unpack funcName' <> "\" in " <> path
            _ -> error $ "impossible error in loading \"" <> T.unpack funcName' <> "\""
    Nothing -> 
      case mFuncScript of
        --handle pre-compiled case- pull it from the precompiled list
        Nothing -> case functionForName funcName' precompiledFuncs of
          --WARNING: possible landmine here if we remove a precompiled atom function in the future, then the transaction cannot be restored
          Left _ -> error ("expected precompiled atom function: " ++ T.unpack funcName')
          Right realFunc -> pure realFunc
        --handle a real Haskell scripted function- compile and load
        Just _funcScript ->
#ifdef PM36_HASKELL_SCRIPTING
          case _mScriptSession of
            Nothing -> error "attempted to read serialized AtomFunction without scripting enabled"
            Just scriptSession -> do
              --risk of GHC exception during compilation here
              eCompiledScript <- runGhc (Just libdir) $ do
                setSession (hscEnv scriptSession)
                compileScript (atomFunctionBodyType scriptSession) _funcScript
              case eCompiledScript of
                Left err -> throwIO err
                Right compiledScript -> pure Function { funcName = funcName',
                                                        funcType = _funcType,
                                                        funcBody = FunctionScriptBody _funcScript compiledScript }
#else
         error "Haskell scripting is disabled"
#endif                                    

--if the script session is enabled, compile the script, otherwise, hard error!  
  
readAtomFunc :: FilePath -> FunctionName -> Maybe ScriptSession -> AtomFunctions -> IO AtomFunction
#if !defined(PM36_HASKELL_SCRIPTING)
readAtomFunc _ _ _ _ = error "Haskell scripting is disabled"
#else
readAtomFunc transDir funcName' mScriptSession precompiledFuncs = do
  let atomFuncPath = atomFuncsPath transDir
  (funcType', mFuncScript) <- readFileDeserialise @([AtomType],Maybe T.Text) atomFuncPath
  case mFuncScript of
    --handle pre-compiled case- pull it from the precompiled list
    Nothing -> case atomFunctionForName funcName' precompiledFuncs of
      --WARNING: possible landmine here if we remove a precompiled atom function in the future, then the transaction cannot be restored
      Left _ -> error ("expected precompiled atom function: " ++ T.unpack funcName')
      Right realFunc -> pure realFunc
    --handle a real Haskell scripted function- compile and load
    Just funcScript ->

      case mScriptSession of
        Nothing -> error "attempted to read serialized AtomFunction without scripting enabled"
        Just scriptSession -> do
          --risk of GHC exception during compilation here
          eCompiledScript <- runGhc (Just libdir) $ do
            setSession (hscEnv scriptSession)
            compileScript (atomFunctionBodyType scriptSession) funcScript
          case eCompiledScript of
            Left err -> throwIO err
            Right compiledScript -> pure Function { funcName = funcName',
                                                    funcType = funcType',
                                                    funcBody = FunctionScriptBody funcScript compiledScript }
#endif

writeIncDep :: DiskSync -> FilePath -> (IncDepName, InclusionDependency) -> IO ()  
writeIncDep sync transDir (incDepName, incDep) = 
  writeBSFileSync sync (incDepsDir transDir </> T.unpack incDepName) $ serialise incDep
  
writeIncDeps :: DiskSync -> FilePath -> M.Map IncDepName InclusionDependency -> IO ()  
writeIncDeps sync transDir incdeps = mapM_ (writeIncDep sync transDir) $ M.toList incdeps 
  
readIncDep :: FilePath -> IncDepName -> IO (IncDepName, InclusionDependency)
readIncDep transDir incdepName = do
  let incDepPath = incDepsDir transDir </> T.unpack incdepName
  incDepData <- readFileDeserialise incDepPath
  pure (incdepName, incDepData)
  
readIncDeps :: FilePath -> IO (M.Map IncDepName InclusionDependency)  
readIncDeps transDir = do
  let incDepsPath = incDepsDir transDir
  incDepNames <- getDirectoryNames incDepsPath
  M.fromList <$> mapM (readIncDep transDir . T.pack) incDepNames
  
readSubschemas :: FilePath -> IO Subschemas  
readSubschemas transDir = do
  let sschemasPath = subschemasPath transDir
  readFileDeserialise sschemasPath
  
writeSubschemas :: DiskSync -> FilePath -> Subschemas -> IO ()  
writeSubschemas sync transDir sschemas = do
  let sschemasPath = subschemasPath transDir
  writeBSFileSync sync sschemasPath (serialise sschemas)
  
writeTypeConstructorMapping :: DiskSync -> FilePath -> TypeConstructorMapping -> IO ()  
writeTypeConstructorMapping sync path types = let atPath = typeConsPath path in
  writeBSFileSync sync atPath $ serialise types

readTypeConstructorMapping :: FilePath -> IO TypeConstructorMapping
readTypeConstructorMapping path = do
  let atPath = typeConsPath path
  readFileDeserialise atPath