{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE FlexibleInstances #-}


module YesodDsl.ParserState (ParserMonad, initParserState, getParserState,
    getPath, getParsed,
    setParserState, runParser, pushScope, popScope, declare, declareGlobal, SymType(..),
    ParserState, mkLoc, parseErrorCount, withSymbol, withGlobalSymbol, withSymbolNow,
    pError,
    hasReserved,
    fieldValueToType,
    fieldContentToType,
    getSymbolType,
    requireClass, 
    requireEntity,
    requireEntityOrClass,
    requireEntityId,
    requireEntityField,
    requireField,
    requireFieldType,
    requireEnum,
    requireEnumValue,
    requireParam,
    setCurrentHandlerType,
    getCurrentHandlerType,
    requireHandlerType,
    validateExtractField,
    validateInsert,
    beginHandler,
    statement,
    lastStatement,
    addCheck,
    postValidation) where
import qualified Data.Map as Map
import Control.Monad.State.Lazy
import Control.Monad.Trans.Class
import YesodDsl.AST 
import YesodDsl.Lexer 
import qualified Data.List as L
import Data.Maybe
data SymType = SEnum EnumType
             | SClass Class
             | SEntity EntityName
             | SEntityId EntityName
             | SDefine Define
             | SField Field
             | SFieldType FieldType
             | SUnique Unique
             | SRoute Route
             | SHandler Handler
             | SParam
             | SForParam InputFieldRef
             | SReserved

instance Show SymType where
    show st = case st of
        SEnum _  -> "enum"
        SClass _   -> "class"
        SEntity _  -> "entity"
        SEntityId _ -> "entity id"
        SDefine _  -> "define"
        SField _   -> "field"
        SFieldType _ -> "field type"
        SUnique _  -> "unique"
        SRoute _  -> "route"
        SHandler _ -> "handler"
        SParam   -> "param"
        SForParam _ -> "for-param"
        SReserved -> "reserved"

data Sym = Sym Int Location SymType deriving (Show)

type ParserMonad = StateT ParserState IO 

type Syms = Map.Map String [Sym]

type EntityValidation = (EntityName, Entity -> ParserMonad ())

type PendingValidation = Syms -> ParserMonad ()

data ParserState = ParserState {
    psSyms        :: Syms,
    psScopeId     :: Int,
    psPath        :: FilePath,
    psParsed      :: [FilePath],
    psErrors      :: Int,
    psHandlerType :: Maybe HandlerType,
    psPendingValidations :: [[PendingValidation]],
    psEntityValidations :: [EntityValidation],
    psLastStatement :: Maybe (Location, String),
    psChecks      :: [(Location,String,FieldType)]
} deriving (Show)

instance Show (Syms -> ParserMonad ()) where
    show _ = "<pendingvalidation>"

instance Show (Entity -> ParserMonad ()) where
    show _ = "<entityvalidation>"
initParserState :: ParserState
initParserState = ParserState {
    psSyms = Map.empty,
    psScopeId = 0,
    psPath = "",
    psParsed = [],
    psErrors = 0,
    psHandlerType = Nothing,
    psPendingValidations = [],
    psEntityValidations = [],
    psLastStatement = Nothing,
    psChecks = []
}
getParserState :: ParserMonad ParserState
getParserState = get

getPath :: ParserMonad FilePath
getPath = gets psPath

getParsed :: ParserMonad [FilePath]
getParsed = gets psParsed

setCurrentHandlerType :: HandlerType -> ParserMonad ()
setCurrentHandlerType ht = modify $ \ps -> ps {
        psHandlerType = Just ht
    }
    
requireHandlerType :: Location -> String -> (HandlerType -> Bool) -> ParserMonad ()
requireHandlerType l n f = do
    mht <- gets psHandlerType
    when (fmap f mht /= Just True) $ 
        pError l $ n ++ " not allowed " 
            ++ (fromMaybe "outside handler" $ 
                mht >>= \ht' -> return $ "in " ++ show ht' ++ " handler")
getCurrentHandlerType :: ParserMonad (Maybe HandlerType)
getCurrentHandlerType = gets psHandlerType    
setParserState :: ParserState -> ParserMonad ()
setParserState = put

runEntityValidation :: Module -> EntityValidation -> ParserMonad ()
runEntityValidation m (en,f) = do
    case L.find (\e -> entityName e == en) $ modEntities m of
        Just e -> f e
        Nothing -> return ()

validateExtractField :: Location -> String -> ParserMonad ()
validateExtractField l s = if s `elem` validFields
    then return ()
    else pError l $ "Unknown subfield '" ++ s ++ "' to extract"
    where 
        validFields = [
                "century", "day", "decade", "dow", "doy", "epoch", "hour",
                "isodow", "microseconds", "millennium", "milliseconds",
                "minute", "month", "quarter", "second", "timezone",
                "timezone_hour", "timezone_minute", "week", "year" 
            ]

validateInsert :: Location -> Entity -> Maybe [InputField] -> ParserMonad ()
validateInsert  l e (Just ifs) = do
    case [ fieldName f | f <- entityFields e, 
                         (not . fieldOptional) f, 
                         isNothing (fieldDefault f) ] 
                         L.\\ [ fn | (fn,_) <- ifs ] of
        fs@(_:_) -> pError l $ "Missing required fields without default value: " ++ (show fs)
        _ -> return ()
validateInsert _ _ _ = return ()

beginHandler :: ParserMonad ()
beginHandler = modify $ \ps -> ps {
        psLastStatement = Nothing
    }

statement :: Location -> String -> ParserMonad ()
statement l s= do
    mlast <- gets psLastStatement
    fromMaybe (return ()) (mlast >>= \(l',s') -> do
        return $ pError l $ "'" ++ s ++ "' not allowed after '" ++ s' ++ "' in "
            ++ show l')
lastStatement :: Location -> String -> ParserMonad ()
lastStatement l s = do
    statement l s
    modify $ \ps -> ps {
       psLastStatement = listToMaybe $ catMaybes [ 
           psLastStatement ps, Just (l,s) 
       ]
    }

addCheck :: Location -> String -> FieldType -> ParserMonad ()
addCheck l n ft = do
    checks <- gets psChecks
    forM_ [ c | c@(l',n',ft') <- checks, ft' /= ft, n' == n ] $ \(l',n',ft') ->
        pError l $ "'" ++ n ++ "' is for " ++ show ft ++ " but '" 
            ++ n' ++ "' in " ++ show l' ++ " is for " ++ show ft' 
    modify $ \ps -> ps { psChecks = psChecks ps ++ [(l,n,ft)] }

postValidation :: Module -> ParserState -> IO Int
postValidation m ps = do
    ps' <- execStateT f ps
    return $ psErrors ps'  
    where
        f = do
            forM_ (psEntityValidations ps) (runEntityValidation m)
            when (isNothing $ modName m) $ globalError "Missing top-level module name"

runParser :: FilePath -> ParserState -> ParserMonad a -> IO (a,ParserState)
runParser path ps m = do
    (r,ps') <- runStateT m $ ps { psPath = path, psParsed = path:psParsed ps }
    return (r, ps' { psPath = psPath ps} )

pushScope :: ParserMonad ()
pushScope = do
    syms <- gets psSyms
    modify $ \ps -> ps {
        psScopeId = psScopeId ps + 1,
        psPendingValidations = []:psPendingValidations ps 
    }

popScope :: ParserMonad ()
popScope = do
    (vs:_) <- gets psPendingValidations 
    syms <- gets psSyms

    forM_ vs $ \v -> v syms
    modify $ \ps -> ps {
        psSyms = Map.filter (not . null) $ 
            Map.map (filter (\(Sym s _ _) -> s < psScopeId ps)) $ psSyms ps,
        psScopeId = psScopeId ps - 1,
        psPendingValidations = tail $ psPendingValidations ps
    }

pError :: Location -> String -> ParserMonad ()
pError l e = do
    lift $ putStrLn $ show l ++ ": " ++ e
    modify $ \ps -> ps { psErrors = psErrors ps + 1 }
globalError :: String -> ParserMonad ()
globalError e = do
    lift $ putStrLn e
    modify $ \ps -> ps { psErrors = psErrors ps + 1 }

declare :: Location -> String -> SymType -> ParserMonad ()
declare l n t = declare' False l n t

declareGlobal :: Location -> String -> SymType -> ParserMonad ()
declareGlobal l n t = declare' True l n t

declare' :: Bool -> Location -> String -> SymType -> ParserMonad ()
declare' global l n t = do
    ps <- get
    let sym = [Sym (if global then 0 else psScopeId ps) l t] 
    case Map.lookup n (psSyms ps) of
        Just ((Sym s l' _):_) -> if s == psScopeId ps
            then do
                pError l $ "'" ++ n 
                    ++ "' already declared in " ++ show l'
                return ()
            else put $ ps { 
                psSyms = Map.adjust (sym++) n (psSyms ps)
            }
        _ -> put $ ps {
                psSyms = Map.insert n sym $ psSyms ps
            }


mkLoc :: Token -> ParserMonad Location
mkLoc t = do
    path <- gets psPath
    return $ Loc path (tokenLineNum t) (tokenColNum t) 
 
parseErrorCount :: ParserState -> Int
parseErrorCount = psErrors
  
addEntityValidation :: EntityValidation -> ParserMonad ()
addEntityValidation ev = modify $ \ps -> ps {
        psEntityValidations = psEntityValidations ps ++ [ev]
    }

addPendingValidation :: (Syms -> ParserMonad ()) -> ParserMonad ()
addPendingValidation v = modify $ \ps -> let vs = psPendingValidations ps in ps {
        psPendingValidations = (v:(head vs)):tail vs
    }
addGlobalPendingValidation :: (Syms -> ParserMonad ()) -> ParserMonad ()
addGlobalPendingValidation v = modify $ \ps -> let vs = psPendingValidations ps in ps {
        psPendingValidations = init vs ++ [v : last vs]
    }


hasReserved :: String -> ParserMonad Bool
hasReserved n = do
    syms <- gets psSyms
    return $ fromMaybe False $ 
        Map.lookup n syms >>= return . (not . null . (filter match))
    where
        match (Sym _ _ SReserved) = True
        match _ = False 


withSymbol' :: Syms -> a -> Location -> String -> (Location -> Location -> SymType -> ParserMonad a) -> ParserMonad a
withSymbol' syms d l n f = do
    case Map.lookup n syms >>= return . (filter notReserved) of
        Just ((Sym _ l' st):_) -> f l l' st
        _ -> pError l ("Reference to an undeclared identifier '"
                ++ n ++ "'") >> return d
    where
        notReserved (Sym _ _ SReserved) = False
        notReserved _ = True        

withSymbolNow :: a -> Location -> String -> (Location -> Location -> SymType -> ParserMonad a) -> ParserMonad a
withSymbolNow d l n f = do
    syms <- gets psSyms
    withSymbol' syms d l n f

withSymbol :: Location -> String -> (Location -> Location -> SymType -> ParserMonad ()) -> ParserMonad ()
withSymbol l n f = addPendingValidation $ \syms -> void $ withSymbol' syms () l n f    

withGlobalSymbol :: Location -> String -> (Location -> Location -> SymType -> ParserMonad ()) -> ParserMonad ()
withGlobalSymbol l n f = addGlobalPendingValidation $ \syms -> void $ withSymbol' syms () l n f    


fieldValueToType :: FieldValue -> Maybe Type
fieldValueToType fv = case fv of
    StringValue _ -> Just $ TypeField FTText
    IntValue _ -> Just $ TypeField FTInt32
    FloatValue _ -> Just $ TypeField FTDouble
    BoolValue _ -> Just $ TypeField FTBool
    NothingValue -> Nothing
    
fieldContentToType :: FieldContent -> Type
fieldContentToType fc = case fc of
    NormalField ft _ -> TypeField ft
    EntityField en -> TypeEntityId en
    EnumField en -> TypeEnum en

getSymbolType :: Location -> Location -> SymType -> ParserMonad (Maybe Type)
getSymbolType l1 l2 st = return $ case st of
    SEnum et -> Just $ TypeEnum $ enumName et
    SEntityId en -> Just $ TypeEntityId en
    SField f -> Just $ fieldContentToType $ fieldContent f
    _ -> Nothing

requireClass :: (Class -> ParserMonad ()) -> (Location -> Location -> SymType -> ParserMonad ())
requireClass f = f'
    where f' _ _ (SClass c) = f c
          f' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected class)"

requireEntity :: (Entity -> ParserMonad ()) -> (Location -> Location -> SymType -> ParserMonad ())
requireEntity f = f'
    where f' _ _ (SEntity en) = addEntityValidation (en, f)
          f' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected entity)"

requireEntityOrClass :: (Location -> Location -> SymType -> ParserMonad ())
requireEntityOrClass = f'
    where f' _ _ (SEntity en) = return ()
          f' _ _ (SClass cn) = return ()
          f' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected entity or class)"


requireEntityId :: (EntityName -> ParserMonad (Maybe a)) -> (Location -> Location -> SymType -> ParserMonad (Maybe a))
requireEntityId f = f'
    where f' _ _ (SEntityId en) = f en
          f' l1 l2 st = pError l1 ("Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected entity id)") >> return Nothing

requireEntityField :: Location -> FieldName -> ((Entity,Field) -> ParserMonad ()) -> (Location -> Location -> SymType -> ParserMonad ())
requireEntityField l fn fun = fun'
    where fun' _ _ (SEntity en) = addEntityValidation (en, \e -> 
            case L.find (\f -> fieldName f == fn) $ entityFields e of
              Just f -> fun (e,f)
              Nothing -> pError l ("Reference to undeclared field '" 
                            ++ fn ++ "' of entity '" ++ entityName e ++ "'"))
          fun' l1 l2 st = pError l1 ( "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected entity)") 
requireFieldType :: (FieldType -> ParserMonad()) -> (Location -> Location -> SymType -> ParserMonad ())
requireFieldType f = fun'
    where 
        fun' _ _ (SFieldType ft) = f ft
        fun' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected field type)"  
        
requireEnum :: Location -> Location -> SymType -> ParserMonad ()
requireEnum = fun'
    where 
        fun' _ _ (SEnum e) = return ()
        fun' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected enum)"
 
requireEnumValue :: Location -> FieldName -> (Location -> Location -> SymType -> ParserMonad ())
requireEnumValue l fn = fun'
    where 
        fun' _ _ (SEnum e) = 
            case L.find (\ev' -> ev' == fn) $ enumValues e of
                Just ev -> return ()
                Nothing -> pError l $ "Reference to undeclared enum value '"
                    ++ fn ++ "' of enum '" ++ enumName e ++ "'"
        fun' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected enum)"
          
requireParam :: (Location -> Location -> SymType -> ParserMonad ())
requireParam = fun'
    where
        fun' _ _ SParam = return ()
        fun' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected param)"
        


requireField:: (Field -> ParserMonad ()) -> (Location -> Location -> SymType -> ParserMonad ())
requireField f = f'
    where f' _ _ (SField sf) = f sf
          f' l1 l2 st = pError l1 $ "Reference to " ++ show st ++ " declared in " ++ show l2 ++ " (expected field)"