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diff --git a/src/System/Torrent/Tree.hs b/src/System/Torrent/Tree.hs
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+-- |
+--   Copyright   :  (c) Sam Truzjan 2013
+--   License     :  BSD3
+--   Maintainer  :  pxqr.sta@gmail.com
+--   Stability   :  experimental
+--   Portability :  portable
+--
+--   Directory tree can be used to easily manipulate file layout info.
+--
+{-# LANGUAGE FlexibleInstances  #-}
+{-# LANGUAGE TemplateHaskell    #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+module System.Torrent.Tree
+       ( -- * Directory tree
+         DirTree (..)
+
+         -- * Construction
+       , build
+
+         -- * Query
+       , System.Torrent.Tree.lookup
+       , lookupDir
+       , fileNumber
+       , dirNumber
+       ) where
+
+import Data.ByteString as BS
+import Data.ByteString.Char8 as BC
+import Data.Foldable
+import Data.List as L
+import Data.Map  as M
+import Data.Monoid
+
+import Data.Torrent
+
+
+-- | 'DirTree' is more convenient form of 'LayoutInfo'.
+data DirTree a = Dir  { children :: Map ByteString (DirTree a) }
+               | File { node     :: FileInfo a                 }
+                 deriving Show
+
+-- | Build directory tree from a list of files.
+build :: LayoutInfo -> DirTree ()
+build SingleFile {liFile = FileInfo {..}} = Dir
+    { children = M.singleton fiName (File fi) }
+  where
+    fi = FileInfo fiLength fiMD5Sum ()
+build MultiFile {..} = Dir $ M.singleton liDirName files
+  where
+    files = Dir $ M.fromList $ L.map mkFileEntry liFiles
+    mkFileEntry FileInfo {..} = (L.head fiName, ent) -- TODO FIXME
+      where
+        ent = File $ FileInfo fiLength fiMD5Sum ()
+
+--decompress :: DirTree () -> [FileInfo ()]
+--decompress = undefined
+
+-- TODO pretty print
+
+-- | Lookup file by path.
+lookup :: [FilePath] -> DirTree a -> Maybe (DirTree a)
+lookup []        t      = Just t
+lookup (p : ps) (Dir m) | Just subTree <- M.lookup (BC.pack p) m
+                        = System.Torrent.Tree.lookup ps subTree
+lookup _         _      = Nothing
+
+-- | Lookup directory by path.
+lookupDir :: [FilePath] -> DirTree a -> Maybe [(ByteString, DirTree a)]
+lookupDir ps d = do
+  subTree <- System.Torrent.Tree.lookup ps d
+  case subTree of
+    File _  -> Nothing
+    Dir  es -> Just $ M.toList es
+
+-- | Get total count of files in directory and subdirectories.
+fileNumber :: DirTree a -> Sum Int
+fileNumber File {..} = Sum 1
+fileNumber Dir  {..} = foldMap fileNumber children
+
+-- | Get total count of directories in the directory and subdirectories.
+dirNumber :: DirTree a -> Sum Int
+dirNumber File {..} = Sum 0
+dirNumber Dir  {..} = Sum 1 <> foldMap dirNumber children