+ mk newtype for info hash

2 files changed, 46 insertions, 4 deletions

diff --git a/src/Data/Torrent.hs b/src/Data/Torrent.hs
index 128c1c7c..57831acf 100644
--- a/src/Data/Torrent.hs
+++ b/src/Data/Torrent.hs
@@ -2,7 +2,8 @@
 {-# LANGUAGE OverloadedStrings #-}
 -- | This module provides torrent metainfo serialization.
 module Data.Torrent
-       ( Torrent(..), TorrentInfo(..), TorrentFile(..)
+       ( module Data.Torrent.InfoHash
+       , Torrent(..), TorrentInfo(..), TorrentFile(..)
        , fromFile
        ) where
 
@@ -13,8 +14,8 @@ import           Data.ByteString (ByteString)
 import qualified Data.ByteString as B
 import qualified Data.ByteString.Char8 as BC (pack, unpack)
 import           Data.Text (Text)
-import Crypto.Hash.SHA1
 import Data.BEncode
+import Data.Torrent.InfoHash
 import Network.URI
 
 type Time = Text
@@ -22,7 +23,7 @@ type Time = Text
 -- TODO comment fields
 -- TODO more convenient form of torrent info.
 data Torrent = Torrent {
-      tInfoHash     :: ByteString
+      tInfoHash     :: InfoHash
     , tAnnounce     ::       URI
     , tAnnounceList :: Maybe [[URI]]
     , tComment      :: Maybe Text
@@ -148,4 +149,4 @@ instance BEncodable TorrentFile where
 
 
 fromFile :: FilePath -> IO (Result Torrent)
-fromFile path = (fromBEncode <=< decode) <$> B.readFile path
+fromFile filepath = (fromBEncode <=< decode) <$> B.readFile filepath
diff --git a/src/Data/Torrent/InfoHash.hs b/src/Data/Torrent/InfoHash.hs
new file mode 100644
index 00000000..448e9a5a
--- /dev/null
+++ b/src/Data/Torrent/InfoHash.hs
@@ -0,0 +1,41 @@
+module Data.Torrent.InfoHash
+       ( InfoHash (getInfoHash)
+
+         -- ^ Construction
+       , hash, hashlazy
+
+         -- ^ Extra
+       , ppHex
+       ) where
+
+import Control.Applicative
+import Data.Foldable
+import           Data.ByteString (ByteString)
+import qualified Data.ByteString as B
+import qualified Data.ByteString.Char8 as BC
+import qualified Data.ByteString.Builder as B
+import qualified Data.ByteString.Builder.Prim as B
+import qualified Data.ByteString.Lazy as Lazy
+import Data.Serialize
+import qualified Crypto.Hash.SHA1 as C
+
+-- | Exactly 20 bytes long SHA1 hash.
+newtype InfoHash = InfoHash { getInfoHash :: ByteString }
+                   deriving (Eq, Ord)
+
+instance Show InfoHash where
+  show = BC.unpack . ppHex
+
+instance Serialize InfoHash where
+  put = putByteString . getInfoHash
+  get = InfoHash <$> getBytes 20
+
+hash :: ByteString -> InfoHash
+hash = InfoHash . C.hash
+
+hashlazy :: Lazy.ByteString -> InfoHash
+hashlazy = InfoHash . C.hashlazy
+
+ppHex :: InfoHash -> ByteString
+ppHex = Lazy.toStrict . B.toLazyByteString .
+        foldMap (B.primFixed B.word8HexFixed) . B.unpack . getInfoHash