DatasheetParser.hs

module DatasheetParser
       ( parseDatasheet
       , Datasheet (..)
       , Table (..)
       , Row (..)
       , Cell (..)
       , Column (columnName)
       , ColumnType
       ) where

import qualified Data.ByteString as BS
import qualified Data.Attoparsec.ByteString as A
import qualified Data.Attoparsec.Binary as B
import Data.Word
import Control.Monad (forM)
import GHC.Float (castWord32ToFloat)

getString :: BS.ByteString -> Int -> BS.ByteString
getString dat offset = BS.takeWhile (/= 0) $ BS.drop (offset) dat

data DatasheetHeader 
       = DatasheetHeader { headerRevision        :: Word32
                         , headerUniqueIdOffset  :: Word32
                         , headerTypeOffset      :: Word32
                         , headerRowNumber       :: Word32 
                         , headerPlainTextLen    :: Word32
                         , headerPlainTextOffset :: Word32
                         , headerSig             :: Word32
                         , headerColumnCount     :: Word32
                         , headerRowCount        :: Word32
                         } deriving (Show)

data DatasheetHeaderStrings 
       = DatasheetHeaderStrings { headerUniqueId :: BS.ByteString
                                , headerType     :: BS.ByteString 
                                } deriving (Show)

data ColumnType = TString
                | TFloat
                | TBool 
                deriving (Show)

data Column 
       = Column { columnName :: BS.ByteString 
                , columnType :: ColumnType
                }
              deriving (Show)

data Cell = CString BS.ByteString 
          | CFloat Float
          | CBool Bool
          deriving (Show)

newtype Row = Row [Cell]
       deriving (Show)
newtype Table = Table [Row]
       deriving (Show)

data Datasheet = Datasheet DatasheetHeader DatasheetHeaderStrings [Column] Table
       deriving (Show)

datasheetHeaderParser :: A.Parser DatasheetHeader 
datasheetHeaderParser = do
       revision             <- B.anyWord32le
       _                    <- A.take 4
       uniqueIdOffset       <- B.anyWord32le
       _                    <- A.take 4
       typeOffset           <- B.anyWord32le
       rowNumber            <- B.anyWord32le
       plainTextLength      <- B.anyWord32le
       _                    <- A.take 28
       plainTextOffset      <- B.anyWord32le >>= return . (+ 60)
       hSig                 <- B.anyWord32be
       _                    <- A.take 4
       columnCount          <- B.anyWord32le
       rowCount             <- B.anyWord32le
       _                    <- A.take 16
       return 
              $ DatasheetHeader
                revision
                uniqueIdOffset
                typeOffset
                rowNumber
                plainTextLength
                plainTextOffset
                hSig
                columnCount
                rowCount

datasheetHeaderStrings :: DatasheetHeader -> BS.ByteString -> DatasheetHeaderStrings
datasheetHeaderStrings h d 
       = DatasheetHeaderStrings
         (getString d (fromIntegral $ headerUniqueIdOffset h))
         (getString d (fromIntegral $ headerTypeOffset h))

parseColumn :: BS.ByteString -> A.Parser Column
parseColumn s = do
       _                    <- A.take 4
       columnNameOffset     <- B.anyWord32le
       columnType           <- B.anyWord32le
       return 
              $ Column
                (getString s (fromIntegral columnNameOffset))
                (case fromIntegral columnType of
                       1 -> TString
                       2 -> TFloat
                       3 -> TBool
                       _ -> error $ show columnType)

parseCell :: BS.ByteString -> ColumnType -> A.Parser Cell
parseCell s t = do
       so    <- B.anyWord32le
       value <- B.anyWord32le
       return (case t of
              TString -> CString (getString s $ fromIntegral value)
              TFloat  -> CFloat $ castWord32ToFloat value
              TBool   -> CBool (if (fromIntegral value) == 0 then False else True))

datasheetParser :: BS.ByteString -> A.Parser Datasheet
datasheetParser d = do
       header               <- datasheetHeaderParser
       let plen             = fromIntegral $ headerPlainTextLen header
           strings          = BS.drop (BS.length d - plen) d
           headerStrings    = datasheetHeaderStrings header strings
       columns              <- forM [1..fromIntegral $ headerColumnCount header] (const $ parseColumn strings)
       rows                 <- forM [1..fromIntegral $ headerRowCount header] (const (forM columns ((parseCell strings) . columnType) >>= return . Row))
       return 
              $ Datasheet
                header
                headerStrings
                columns
                (Table rows)

parseDatasheet :: BS.ByteString -> Maybe Datasheet
parseDatasheet d = case A.parse (datasheetParser d) d of 
       A.Done _ x -> Just x
       _          -> Nothing