module Components.ObjectHandlers.ObjectsHandler where


import Control.Exception (throw)
import Model.ServerExceptions (
        ReferenceException(
            UnrecognisedObjectException,
            DisagreeingObjectFieldsException,
            UnrecognisedScalarException,
            UnrecognisedArgumentException,
            UnrecognisedRelationshipException
        )
    )
import Model.ServerObjectTypes (
        NestedObject(..),
        ServerObject,
        ScalarType(..),
        Alias,
        SubSelection,
        SubFields,
        Field,
        InlinefragmentObject(..),
        Argument,
        Transformation
    )
import Components.Util (fst3,fst4)


-- SCALAR FIELDS
getScalarFieldLabel :: ScalarType -> String
getScalarFieldLabel (ScalarType Nothing name _ _) = name
getScalarFieldLabel (ScalarType (Just alias) _ _ _) = alias

-- NESTED OBJECTS
getServerObject :: NestedObject -> ServerObject
getServerObject (NestedObject _ _ sobj _ _) = sobj
withSubSelection :: NestedObject -> Bool
withSubSelection (NestedObject _ _ _ ss _) = (ss/=Nothing)
getSubSelectionField :: NestedObject -> String
getSubSelectionField (NestedObject _ _ _ (Just (ScalarType _ name _ _)) _) = name
getSubSelectionField _ = error "Subselection request value is not found (source error)."
getSubSelectionArgument :: NestedObject -> String
getSubSelectionArgument (NestedObject _ _ _ (Just (ScalarType _ _ _ (Just arg))) _) = arg
getSubSelectionArgument _ = error "Subselection request value is not found (source error)."
getSubFields :: NestedObject -> SubFields
getSubFields (NestedObject _ _ _ _ sf) = sf
isSameNObjectReference :: NestedObject -> NestedObject -> Bool
isSameNObjectReference (NestedObject alias1 name1 sobj1 _ _) (NestedObject alias2 name2 sobj2 _ _) = alias1==alias2&&name1==name2&&sobj1==sobj2
isSameObjectSubSelection :: NestedObject -> NestedObject -> Bool
isSameObjectSubSelection (NestedObject _ _ _ ss1 _) (NestedObject _ _ _ ss2 _) = ss1==ss2
getNestedObjectFieldLabel :: NestedObject -> String
getNestedObjectFieldLabel (NestedObject Nothing name _ _ _) = name
getNestedObjectFieldLabel (NestedObject (Just alias) _ _ _ _) = alias

-- BASIC
getIntersection :: Eq a => [[a]] -> [a]
getIntersection [] = []
getIntersection ([]:t) = []
getIntersection ((h:t1):t2) = if all (elem h) t2 then h:getIntersection (t1:t2) else getIntersection (t1:t2)

-- REFERENCE SCHEMA
{-
parsing frontend query to server query
- A valid argument is any string that is provided to reference database objects
-}
readServerObject :: String -> [(String,[String])] -> [(String,[String],[String])] -> ServerObject
readServerObject str ptv ((a,b,_):t) = if (elem str b)==True then (a :: ServerObject) else readServerObject str ptv t
readServerObject str ((a,b):t) [] = if (elem str b)==True then (a :: ServerObject) else readServerObject str t []
readServerObject _ [] [] = throw UnrecognisedObjectException
readFieldObject :: String -> [(String,[(String,[String])])] -> [(String,[String],[String])] -> ServerObject -> ServerObject
readFieldObject str ((ptv,objs):rst) [] hld = if hld==ptv then
    readServerObject str objs []
  else readFieldObject str rst [] hld
readFieldObject str ptvs ((pObj,_,pCldn):rst) hld = if hld==pObj then 
    findSingularObject $ map (\cld->readFieldObject str ptvs [] cld) pCldn
  else readFieldObject str ptvs rst hld
readFieldObject _ [] [] _ = throw UnrecognisedObjectException
findSingularObject :: [String] -> String
findSingularObject (fst:rst) = if all ((==) fst) rst then fst else throw DisagreeingObjectFieldsException
findSingularObject [] = throw UnrecognisedObjectException
-- INLINE-FRAGMENTS
isSameIFObjectReference :: InlinefragmentObject -> InlinefragmentObject -> Bool
isSameIFObjectReference (InlinefragmentObject obj1 _) (InlinefragmentObject obj2 _) = obj1==obj2
-- SERVER OBJECTS
isValidServerObjectChild :: ServerObject -> ServerObject -> [(String,[String],[String])] -> Bool
isValidServerObjectChild pnt cld ((so,_,cdn):t) = if pnt==so then elem cld cdn else isValidServerObjectChild pnt cld t
isValidServerObjectChild _ _ [] = False
-- SCHEMA HEIRARCHY
isServerObjectTable :: String -> ServerObject -> [(String,[String],String)] -> [(String,[String],[String])] -> Bool
isServerObjectTable tbl soj sodn soa = any ((==) tbl . snd) $ translateServerObjectToDBName soj sodn soa 
translateTableToObject :: String -> [(String,[String],String)] -> String
translateTableToObject tbl ((pObj,_,pTbl):rst) = if tbl==pTbl then pObj else translateTableToObject tbl rst
translateTableToObject _ [] = error "Table not found in schema (source error)."
countTableIds :: String -> [(String,[String],String)] -> Int
countTableIds tbl ((_,ids,ntbl):t) = if tbl==ntbl then length ids else countTableIds tbl t
countTableIds " " _ = 0
countTableIds _ [] = error "Table not found in schema (source error)."
fetchTableIds :: String -> [(String,[String],String)] -> [String]
fetchTableIds tbl ((_,ids,ntbl):t) = if tbl==ntbl then ids else fetchTableIds tbl t
{-
checking server type attributes
-}
-- returns exclusive list of valid fields that are found in the database table for each Server object 
-- this is used to check queries against valid subfields
isValidServerObjectScalarField :: ServerObject -> String -> [(String,[(String,String,[(String,[(String,String,String,String)])])])] -> [(String,[String],[String])] -> Bool
isValidServerObjectScalarField sobj name ((ptv,fds):t) []
 | sobj==ptv = any ((==) name . fst3) fds
 | otherwise = isValidServerObjectScalarField sobj name t []
isValidServerObjectScalarField sobj name pvs ((pnt,_,cdn):t) = if sobj==pnt then all (\x->isValidServerObjectScalarField x name pvs []) cdn else isValidServerObjectScalarField sobj name pvs t
isValidServerObjectScalarField _ _ [] _ = throw UnrecognisedObjectException
isValidScalarTransformation :: ServerObject -> String -> Transformation -> Argument -> [(String,[(String,String,[(String,[(String,String,String,String)])])])] -> [(String,[String],[String])] -> Bool
isValidScalarTransformation _ _ Nothing _ _ _ = True
isValidScalarTransformation sobj name (Just trans) arg ((ptv,fds):t) [] = if sobj==ptv then findAndCheckScalarTransformation name trans arg fds else isValidScalarTransformation sobj name (Just trans) arg t []
isValidScalarTransformation sobj name trans arg pvs ((pnt,_,cdn):t) = if sobj==pnt then all (\x->isValidScalarTransformation x name trans arg pvs []) cdn else isValidScalarTransformation sobj name trans arg pvs t
isValidScalarTransformation _ _ _ _ [] _ = throw UnrecognisedObjectException
findAndCheckScalarTransformation :: String -> String -> Argument -> [(String,String,[(String,[(String,String,String,String)])])] -> Bool
findAndCheckScalarTransformation name trans arg ((n,_,args):t) = if name==n then findAndCheckTransformationOption trans arg args else findAndCheckScalarTransformation name trans arg t
findAndCheckScalarTransformation name trans arg [] = throw UnrecognisedScalarException
findAndCheckTransformationOption :: String -> Argument -> [(String,[(String,String,String,String)])] -> Bool
findAndCheckTransformationOption _ Nothing _ = True
findAndCheckTransformationOption trans (Just arg) ((name,opts):t) = if trans==name then any ((==) arg . fst4) opts else findAndCheckTransformationOption trans (Just arg) t
findAndCheckTransformationOption _ _ [] = throw UnrecognisedArgumentException
-- INTERFACES
-- split server object to sql query
-- EFFECTS: returns the database table references for the server object.
translateServerObjectToDBName :: ServerObject -> [(String,[String],String)] -> [(String,[String],[String])] -> [([String],String)]
translateServerObjectToDBName sobj ((a,b,c):t) [] = if sobj==a then [(b,c)] else translateServerObjectToDBName sobj t []
translateServerObjectToDBName sobj pdn ((so,_,cdn):t) = if sobj==so then concat $ map (\x->translateServerObjectToDBName x pdn []) cdn else translateServerObjectToDBName sobj pdn t
translateServerObjectToDBName _ [] _ = throw UnrecognisedObjectException
getDBObjectRelationships :: String -> String -> [(String,String,[String])] -> [String]
getDBObjectRelationships from to ((a,b,c):t) = if from==a&&to==b then c else getDBObjectRelationships from to t
getDBObjectRelationships _ _ [] = throw UnrecognisedRelationshipException
isInterface :: [(String,[String],[String])] -> ServerObject -> Bool
isInterface ((so,_,_):t) sobj = if sobj==so then True else isInterface t so
isInterface [] _ = False
translateInterfaceToServerObjects :: [(String,[String],[String])] -> ServerObject -> [String]
translateInterfaceToServerObjects ((so,_,cdn):t) sobj = if sobj==so then cdn else translateInterfaceToServerObjects t sobj
translateInterfaceToServerObjects _ _ = throw UnrecognisedObjectException