module Session
where
import IO
import System
import IOExts
import Array
import Foreign
import CForeign

data Session = Session {stockId, date, sessionId :: Int,
			lowestValue, highestValue, lastValue, averageValue,
			lot, volume :: Float} deriving (Eq, Show)

emptySession = Session {
			stockId = 0,
			date = 0,
			sessionId = 0,
			lowestValue = 0,
			highestValue = 0,
			lastValue = 0,
			averageValue = 0,
			lot = 0,
			volume = 0
		       }

readSession :: Handle -> IO (Maybe Session)
readSession h = 
 do eof <- hIsEOF h
    if eof then return Nothing else 
      do buf <- mallocArray 73:: IO (Ptr CChar)
	 readChars <- hGetBuf h buf 73
-- 	 putStrLn ("read " ++ (show readChars))
	 let sidptr = castPtr buf :: Ptr CShort
	     dateptr = castPtr (plusPtr buf 2) :: Ptr CUInt
	     sesptr = (plusPtr buf 6) :: Ptr CChar
	     ptr = castPtr (plusPtr buf 7) :: Ptr CLLong
          in do stockid <- peek sidptr
		date <- peek dateptr
		sessid <- peek sesptr
		rec <- peekArray 8 ptr
--  		destructArray 73 buf
		let list  = map (\x -> (fromIntegral x) / 10000) rec
			  :: [Float]
 		    vals = array (1,8) (zip [1..8] list)
   		    in return (Just Session {stockId = (fromIntegral stockid),
   					     date = (fromIntegral date),
   					     sessionId = (fromIntegral sessid),
   					     lowestValue = vals!1,
   					     highestValue = vals!2,
   					     lastValue = vals!3,
   					     averageValue = vals!4,
   					     lot = vals!5,
   					     volume = vals!6
   					    })