From: Ramakrishnan Muthukrishnan <ram@rkrishnan.org>
Date: Mon, 18 Jul 2016 03:57:00 +0000 (+0530)
Subject: beginning of the filesystem module
X-Git-Url: https://git.rkrishnan.org/pf/content/en/seg/bcase/status?a=commitdiff_plain;h=refs%2Fheads%2Fnext;p=functorrent.git

beginning of the filesystem module
---

diff --git a/functorrent.cabal b/functorrent.cabal
index 63ce6d2..69d7722 100644
--- a/functorrent.cabal
+++ b/functorrent.cabal
@@ -20,6 +20,7 @@ library
   hs-source-dirs:      src
   exposed-modules:     FuncTorrent.Bencode
                      , FuncTorrent.Metainfo
+                     , FuncTorrent.Filesystem
   build-depends:       base >= 4.7 && < 5
                      , bytestring
                      , containers
diff --git a/src/FuncTorrent/Filesystem.hs b/src/FuncTorrent/Filesystem.hs
index 66468c4..cc757d4 100644
--- a/src/FuncTorrent/Filesystem.hs
+++ b/src/FuncTorrent/Filesystem.hs
@@ -16,15 +16,69 @@
  - You should have received a copy of the GNU General Public License
  - along with FuncTorrent; if not,  see <http://www.gnu.org/licenses/>
  -}
+{-# LANGUAGE OverloadedStrings #-}
 
 module FuncTorrent.Filesystem
        (new
        , FilesystemState
-       , getBlock
-       , putBlock
        , getStats
        ) where
 
-data Filesystem = Filesystem { pieces :: [Piece]
+import Data.ByteString (ByteString)
+import qualified Data.ByteString.Char8 as BC (take, drop, null)
+import Control.Concurrent.MVar (MVar, newMVar, readMVar)
+import System.IO (FilePath)
+import System.Environment (getEnv)
+
+import FuncTorrent.Metainfo (Metainfo(..), Info(..), FileInfo(..))
+
+data Filesystem = Filesystem { fs :: [File]
                              , stats :: Stats
-            
+                             }
+
+newtype FilesystemState = FilesystemState (MVar Filesystem)
+
+data File = File { name :: FilePath
+                 , ps :: [Piece]
+                 }
+
+data Piece = Piece { hash :: ByteString
+                   }
+
+data Block = Block { offset :: Integer
+                   , len :: Integer
+                   }
+
+data Stats = Stats { read :: Integer
+                   , written :: Integer
+                   }
+
+new :: Metainfo -> IO FilesystemState
+new m = do
+  home <- getEnv "HOME"
+  let baseDir = home ++ "/Downloads/"
+      files' = files (info m)
+      pieceLen = pieceLength (info m)
+      h = infoHash m
+      numPiecesList = map (\f -> numPieces (lengthInBytes f) pieceLen) files'
+      hashes    = snd $ foldl (\(bs, b) a -> (BC.drop (fromIntegral a) bs, b ++ [BC.take (fromIntegral a) bs])) (h, [] :: [ByteString]) (map (* 20) numPiecesList)
+      hss = map (splitN 20) hashes
+      newFile p hs = File { name = p, ps = map Piece hs }
+      fs = map (\(f, hs) -> let p = baseDir ++ (path f)
+                      in newFile p hs) (zip files' hss)
+  v <- newMVar (Filesystem fs (Stats 0 0))
+  return (FilesystemState v)
+
+getStats :: FilesystemState -> IO Stats
+getStats (FilesystemState fsState) = do
+  (Filesystem _ stats') <- readMVar fsState
+  return stats'
+
+numPieces :: Integer -> Integer -> Integer
+numPieces fileLen pieceLen | fileLen `mod` pieceLen == 0 = (fileLen `div` pieceLen)
+                           | otherwise = (fileLen `div` pieceLen) + 1
+
+splitN :: Int -> ByteString -> [ByteString]
+splitN n bs | BC.null bs = []
+            | otherwise = BC.take n bs : splitN n (BC.drop n bs)
+