module Info ( identify
            ) where

import           Compression
import           Data.ByteString as BS

identify :: BS.ByteString -> Compression
identify bs | lzipMagicBytes `isPrefixOf` bs = Lzip
            | lzopMagicBytes `isPrefixOf` bs = Lzo
#ifdef SNAPPY
            | snappyStreamIdentifier `isPrefixOf` bs = Snappy
#endif
            | lz4Magic `isPrefixOf` bs = Lz4
            | gzipId `isPrefixOf` bs = GZip
            | xzMagic `isPrefixOf` bs = Lzma
            | zstdMagic `isPrefixOf` bs = Zstd
            | bzMagic `isPrefixOf` bs = BZip
            | otherwise = None

-- lrzipMagic :: BS.ByteString
-- lrzipMagic = BS.pack [0x4c, 0x52, 0x5a, 0x49]

zstdMagic :: BS.ByteString
zstdMagic = BS.pack [0x28, 0xb5, 0x2f, 0xfd]

lzipMagicBytes :: BS.ByteString
lzipMagicBytes = BS.pack [0x4c, 0x5a, 0x49, 0x50]

lzopMagicBytes :: BS.ByteString
lzopMagicBytes = BS.pack [0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a]

snappyStreamIdentifier :: BS.ByteString
snappyStreamIdentifier = BS.pack [0xff, 0x06, 0x00, 0x00, 0x73, 0x4e, 0x61, 0x50, 0x70, 0x59]

gzipId :: BS.ByteString
gzipId = BS.pack [0x1f, 0x8b]

bzMagic :: BS.ByteString
bzMagic = BS.pack [0x42, 0x5a]

lz4Magic :: BS.ByteString
lz4Magic = BS.pack [0x04, 0x22, 0x4d, 0x18]

xzMagic :: BS.ByteString
xzMagic = BS.pack [0xfd, 0x37, 0x7a, 0x58, 0x5a, 0x00]