import metadata from feeds

When annex.genmetadata is set, metadata from the feed is added to files
that are imported from it.

Reused the same feedtitle and itemtitle, feedauthor, itemauthor, etc names
that are used in --template.

Also added title and author, which are the item title/author if available,
falling back to the feed title/author. These are more likely to be common
metadata fields.

(There is a small bit of dupication here, but once git gets
around to packing the object, it will compress it away.)

The itempubdate field is not included in the metadata as a string; instead
it is used to generate year and month fields, same as is done when adding
files with annex.genmetadata set.

This commit was sponsored by Amitai Schlair, who cooincidentially
is responsible for ikiwiki generating nice feed metadata!

Command/AddUrl.hs

@@ -97,15 +97,17 @@ performQuvi relaxed pageurl videourl file = ifAnnexed file addurl geturl
   where
   	quviurl = setDownloader pageurl QuviDownloader
   	addurl key = next $ cleanup quviurl file key Nothing
-	geturl = next $ addUrlFileQuvi relaxed quviurl videourl file
+	geturl = next $ isJust <$> addUrlFileQuvi relaxed quviurl videourl file
 #endif
 
 #ifdef WITH_QUVI
-addUrlFileQuvi :: Bool -> URLString -> URLString -> FilePath -> Annex Bool
+addUrlFileQuvi :: Bool -> URLString -> URLString -> FilePath -> Annex (Maybe Key)
 addUrlFileQuvi relaxed quviurl videourl file = do
 	key <- Backend.URL.fromUrl quviurl Nothing
 	ifM (pure relaxed <||> Annex.getState Annex.fast)
-		( cleanup quviurl file key Nothing
+		( do
+			cleanup' quviurl file key Nothing
+			return (Just key)
 		, do
 			{- Get the size, and use that to check
 			 - disk space. However, the size info is not
@@ -113,7 +115,7 @@ addUrlFileQuvi relaxed quviurl videourl file = do
 			 - might change and we want to be able to download
 			 - it later. -}
 			sizedkey <- addSizeUrlKey videourl key
-			prepGetViaTmpChecked sizedkey $ do
+			prepGetViaTmpChecked sizedkey Nothing $ do
 				tmp <- fromRepo $ gitAnnexTmpObjectLocation key
 				showOutput
 				ok <- Transfer.notifyTransfer Transfer.Download (Just file) $
@@ -121,15 +123,17 @@ addUrlFileQuvi relaxed quviurl videourl file = do
 						liftIO $ createDirectoryIfMissing True (parentDir tmp)
 						downloadUrl [videourl] tmp
 				if ok
-					then cleanup quviurl file key (Just tmp)
-					else return False
+					then do
+						cleanup' quviurl file key (Just tmp)
+						return (Just key)
+					else return Nothing
 		)
 #endif
 
 perform :: Bool -> URLString -> FilePath -> CommandPerform
 perform relaxed url file = ifAnnexed file addurl geturl
   where
-	geturl = next $ addUrlFile relaxed url file
+	geturl = next $ isJust <$> addUrlFile relaxed url file
 	addurl key
 		| relaxed = do
 			setUrlPresent key url
@@ -149,7 +153,7 @@ perform relaxed url file = ifAnnexed file addurl geturl
 						stop
 			)
 
-addUrlFile :: Bool -> URLString -> FilePath -> Annex Bool
+addUrlFile :: Bool -> URLString -> FilePath -> Annex (Maybe Key)
 addUrlFile relaxed url file = do
 	liftIO $ createDirectoryIfMissing True (parentDir file)
 	ifM (Annex.getState Annex.fast <||> pure relaxed)
@@ -159,13 +163,13 @@ addUrlFile relaxed url file = do
 			download url file
 		)
 
-download :: URLString -> FilePath -> Annex Bool
+download :: URLString -> FilePath -> Annex (Maybe Key)
 download url file = do
 	{- Generate a dummy key to use for this download, before we can
 	 - examine the file and find its real key. This allows resuming
 	 - downloads, as the dummy key for a given url is stable. -}
 	dummykey <- addSizeUrlKey url =<< Backend.URL.fromUrl url Nothing
-	prepGetViaTmpChecked dummykey $ do
+	prepGetViaTmpChecked dummykey Nothing $ do
 		tmp <- fromRepo $ gitAnnexTmpObjectLocation dummykey
 		showOutput
 		ifM (runtransfer dummykey tmp)
@@ -178,9 +182,11 @@ download url file = do
 					}
 				k <- genKey source backend
 				case k of
-					Nothing -> return False
-					Just (key, _) -> cleanup url file key (Just tmp)
-			, return False
+					Nothing -> return Nothing
+					Just (key, _) -> do
+						cleanup' url file key (Just tmp)
+						return (Just key)
+			, return Nothing
 			)
   where
   	runtransfer dummykey tmp =  Transfer.notifyTransfer Transfer.Download (Just file) $
@@ -200,6 +206,11 @@ addSizeUrlKey url key = do
 
 cleanup :: URLString -> FilePath -> Key -> Maybe FilePath -> Annex Bool
 cleanup url file key mtmp = do
+	cleanup' url file key mtmp
+	return True
+
+cleanup' :: URLString -> FilePath -> Key -> Maybe FilePath -> Annex ()
+cleanup' url file key mtmp = do
 	when (isJust mtmp) $
 		logStatus key InfoPresent
 	setUrlPresent key url
@@ -210,9 +221,8 @@ cleanup url file key mtmp = do
 		 - must already exist, so flush the queue. -}
 		Annex.Queue.flush
 	maybe noop (moveAnnex key) mtmp
-	return True
 
-nodownload :: Bool -> URLString -> FilePath -> Annex Bool
+nodownload :: Bool -> URLString -> FilePath -> Annex (Maybe Key)
 nodownload relaxed url file = do
 	(exists, size) <- if relaxed
 		then pure (True, Nothing)
@@ -220,10 +230,11 @@ nodownload relaxed url file = do
 	if exists
 		then do
 			key <- Backend.URL.fromUrl url size
-			cleanup url file key Nothing
+			cleanup' url file key Nothing
+			return (Just key)
 		else do
 			warning $ "unable to access url: " ++ url
-			return False
+			return Nothing
 
 url2file :: URI -> Maybe Int -> Int -> FilePath
 url2file url pathdepth pathmax = case pathdepth of