module AltsIn where
import "TripleData"
import "Utils"
import "Observe"

-- Author: G.Naudts. Mail: naudts_vannoten@yahoo.com.

functionListI = []

-- first tripleset is goal; second is from db
altsIn :: (TripleSet,TripleSet) -> (TripleSet, TripleSet)
altsIn (ts1, ts2) = (ts3, ts4)
    where (ts3, ts4, _) = fLoop (ts1, ts2, functionListI)

fLoop (ts1, ts2, []) = (ts1, ts2, [])
fLoop (ts1, ts2, functionList@(x:xs))
   = fLoop (ts3, ts4, xs)
   where (ts3, ts4) = x (ts1, ts2)    

noLoop :: (TripleSet, TripleSet) -> (TripleSet, TripleSet)
-- if no rule take :norec triple away.
-- if 'the' rule make goal []
noLoop ([], []) = ([], [])
noLoop ([], ts2) = ([], ts2)
noLoop (ts1, []) = (ts1, [])
noLoop (ts1, ts2)
   = (checkNoRec ts1 ts2, ts2)
   where  checkNoRec [] _  = []
          checkNoRec (x:xs) ts2
             | bv3 && bv1 && bv2 = [] -- x:checkNoRec xs ts2
             | bv1 = checkNoRec xs ts2
             | otherwise = x:checkNoRec xs ts2
             where Triple (s, p, v) = x
                   URI s2 = p
                   (bool, s1, r) = parseUntil ' ' s2
                   bv1 = s1 == ":norec"
                   Literal s3 = s
                   nr1 = stringToInt s3
                   bv2 = nr == nr1
                   testRule (Rule r) = True
                   testRule t = False

                   bv3 = testRule (head ts2)
                   Rule (_, _, nr) = head ts2

-- this checks whether a predicate has a certain value
checkPredicate :: Triple -> String -> Bool
checkPredicate x sIn
             | bv3 = False
             | bv1 = True
             | otherwise = False
             where Triple (s, p, v) = x
                   URI s2 = p
                   (bool, s1, r) = parseUntil ' ' s2
                   bv1 = s1 == sIn

                   testRule (Rule r) = True
                   testRule t = False

                   bv3 = testRule x