From ea8ccaa3d5416044ca69e4a3dcb7b879aec0ff4c Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Sun, 7 Nov 2010 17:26:21 -0400
Subject: rough in fsck

---
 Command/Fsck.hs | 46 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 8 deletions(-)

(limited to 'Command/Fsck.hs')

diff --git a/Command/Fsck.hs b/Command/Fsck.hs
index bd5a9ad7f..c86f30ff8 100644
--- a/Command/Fsck.hs
+++ b/Command/Fsck.hs
@@ -7,15 +7,10 @@
 
 module Command.Fsck where
 
-import Control.Monad.State (liftIO)
-import System.Posix.Files
-import System.Directory
-
 import Command
-import qualified Annex
 import Types
-import Utility
 import Core
+import qualified Data.Map as M
 
 {- Checks the whole annex for problems. -}
 start :: SubCmdStart
@@ -35,5 +30,40 @@ perform = do
 checkUnused :: Annex Bool
 checkUnused = do
 	showNote "checking for unused data..."
-	-- TODO
-	return False
+	unused <- unusedKeys
+	if (null unused)
+		then return True
+		else do
+			showLongNote $ w unused
+			return False
+	where
+		w u = unlines $ [
+			"Some annexed data is no longer pointed to by any file.",
+			"If this data is no longer needed, it can be removed using git-annex dropkey:"
+			] ++ map show u
+
+unusedKeys :: Annex [Key]
+unusedKeys = do
+	present <- getKeysPresent
+	referenced <- getKeysReferenced
+	
+	-- Constructing a single map, of the set that tends to be smaller,
+	-- appears more efficient in both memory and CPU than constructing
+	-- and taking the M.difference of two maps.
+	let present_m = existsMap present
+	let unused_m = remove referenced present_m
+	return $ M.keys unused_m
+	where
+		remove [] m = m
+		remove (x:xs) m = remove xs $ M.delete x m
+
+existsMap :: Ord k => [k] -> M.Map k Int
+existsMap l = M.fromList $ map (\k -> (k, 1)) l
+
+getKeysPresent :: Annex [Key]
+getKeysPresent = do
+	return []
+
+getKeysReferenced :: Annex [Key]
+getKeysReferenced = do
+	return []
-- 
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