module Components.DataProcessors.PersistentDataProcessor where

import Data.Maybe
import Data.Either
import Data.Text (Text)
import Text.JSON (encodeStrict,toJSObject,JSValue,showJSONs,toJSObject,showJSON)
import qualified Control.Exception as E
import Model.ServerExceptions
import Model.ServerObjectTypes
import Components.ObjectHandlers.ObjectsHandler (getSubFields)


-- with root objects we want one json representation of separate graphql results...
processReturnedValues :: [RootObject] -> [[[[Text]]]] -> String
processReturnedValues robjs rlts = encodeStrict $ toJSObject [("data", toJSObject [processReturnedValue x y | x<-robjs, y<-groupSingleQueryResults rlts])]
-- with separated sql query results, we want a list of data rows that are separated by only graphql query...
groupSingleQueryResults :: [[[[Text]]]] -> [[[Text]]]
groupSingleQueryResults rlts = [foldr (\y z -> y++z) [] x | x<-rlts]
-- with qraphql query object and sql return data, we want json representation on graphql query results...
processReturnedValue :: RootObject -> [[Text]] -> (String, JSValue)
processReturnedValue (NestedObject alias name _ _ sfs) rlts = (if (alias==Nothing) then name else (fromJust alias), showJSONs $ processSubFields sfs rlts)
-- with SubFields and data rows, we want json representation on qraphql query data
processSubFields :: [Field] -> [[Text]] -> [JSValue]
processSubFields _ [] = []
processSubFields sfs rlts = ((showJSON $ toJSObject $ composeGraphQlRow sfs $ fetchGraphQlRow rlts):(processSubFields sfs $ removeDataRow rlts))
composeGraphQlRow :: [Field] -> [[Text]] -> [(String,JSValue)]
composeGraphQlRow [] [[]] = []  -- done
composeGraphQlRow [] _ = E.throw EOFDataProcessingException
composeGraphQlRow _ [[]] = E.throw EOFDataProcessingException
composeGraphQlRow (a:b) ((h:t):j)
    | (isLeft a)==True = (((getScalarFieldLabel $ fromLeft (E.throw InvalidScalarException) a), (showJSON h)):(composeGraphQlRow b (removeNDataColumns 1 ((h:t):j))))
    | otherwise = (((getNestedObjectFieldLabel $ fromRight (E.throw InvalidObjectException) a), showJSONs (processSubFields (getSubFields $ fromRight (E.throw InvalidObjectException) a) (pullNDataColumns nestedObjectFieldCount ((h:t):j)))):(composeGraphQlRow b (removeNDataColumns nestedObjectFieldCount ((h:t):j))))
  where
    nestedObjectFieldCount = (countNestedObjectQueriedFields $ fromRight (E.throw InvalidObjectException) a)
fetchGraphQlRow :: [[Text]] -> [[Text]]
fetchGraphQlRow rlts = [t | (h:t)<-rlts, (h)==(head $ head rlts)]
removeDataRow :: [[Text]] -> [[Text]]
removeDataRow rlts = [x | x<-rlts, (head x)/=(head $ head rlts)]
getScalarFieldLabel :: ScalarType -> String
getScalarFieldLabel (ScalarType alias name trans arg) = if (alias/=Nothing) then (fromJust alias) else name
getNestedObjectFieldLabel :: NestedObject -> String
getNestedObjectFieldLabel (NestedObject alias name sobj ss sfs) = if (alias/=Nothing) then (fromJust alias) else name
pullNDataColumns :: Int -> [[Text]] -> [[Text]]
pullNDataColumns _ [] = []
pullNDataColumns cnt rslt
    | (cnt<0) = E.throw InvalidArgumentException
    | otherwise = [if (length x)<cnt then (E.throw EOFDataProcessingException) else (take cnt x) | x<-rslt]
-- count how many columns are added to sql data result for this nested object including the nested object id
countNestedObjectQueriedFields :: NestedObject -> Int
countNestedObjectQueriedFields (NestedObject alias name sobj ss sfs) = 1+(countNestedObjectQueriedSubFields sfs)
countNestedObjectQueriedSubFields :: [Field] -> Int
countNestedObjectQueriedSubFields [] = 0
countNestedObjectQueriedSubFields (h:t)
 | (isLeft h)==True = 1+(countNestedObjectQueriedSubFields t)
 | otherwise = (countNestedObjectQueriedFields (fromRight (E.throw InvalidObjectException) h))+(countNestedObjectQueriedSubFields t) 
-- remove nested object columns from data row that is including nested object id
removeNDataColumns :: Int -> [[Text]] -> [[Text]]
removeNDataColumns 0 rslt = rslt
removeNDataColumns (-1) _ = E.throw EOFDataProcessingException
removeNDataColumns _ [[]] = [[]]
removeNDataColumns _ ([]:t) = E.throw EOFDataProcessingException
removeNDataColumns cnt rslt = removeNDataColumns (cnt-1) [t | (h:t)<-rslt]