module Control.Concurrent.Futures.Example06 where
import Control.Concurrent.Futures.Buffer
import Control.Concurrent
import IO
import Data.List

-- | a binary tree data structure
data BTree a = BLeaf a 
			 | BNode a
				(BTree a)
				(BTree a)

-- | sum of all nodevalues of a binary tree
concSumB :: (Num a) => BTree a -> IO a
concSumB t = do 
  putStrLn $ "Sum of nodes and leafs of a binary tree example using buffers"
  result <- newBuf
  case t of
    BLeaf a -> putBuf result a; -- own value
    BNode a t1 t2 -> sumB result t -- calculate recursivly
  out <- getBuf result
  return out

sumB :: (Num a) => Buffer a -> BTree a -> IO ()
sumB mvar tree = do 
 case tree of 
   BLeaf a -> putBuf mvar a --  own value
   BNode a t1 t2 -> do
			sem <- newBuf
			forkIO (sumB sem t1) -- compute left section beam
			forkIO (sumB sem t2) -- compute right section beam
			erg1 <-getBuf sem -- get result of left computation
			erg2 <-getBuf sem -- get result of right computation
			putBuf mvar (erg1 + erg2 + a) --return left + right + own value

--test data
treeb = BNode 1 (BNode 24 (BLeaf 2) (BNode 6 (BLeaf 24) (BLeaf 3)))(BNode 33 (BLeaf 7) (BLeaf 8))

--test function 
test_concSumB :: IO Integer
test_concSumB = concSumB treeb