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/ImportFeed.hs

@@ -33,6 +33,9 @@ import Annex.Quvi
 import qualified Utility.Quvi as Quvi
 import Command.AddUrl (addUrlFileQuvi)
 #endif
+import Types.MetaData
+import Logs.MetaData
+import Annex.MetaData
 
 def :: [Command]
 def = [notBareRepo $ withOptions [templateOption, relaxedOption] $
@@ -165,12 +168,14 @@ performDownload relaxed cache todownload = case location todownload of
 			Nothing -> return True
 			Just f -> do
 				showStart "addurl" f
-				ok <- getter f
-				if ok
-					then do
+				mk <- getter f
+				case mk of
+					Just key -> do
+						whenM (annexGenMetaData <$> Annex.getGitConfig) $
+							addMetaData key $ extractMetaData todownload
 						showEndOk
 						return True
-					else do
+					Nothing -> do
 						showEndFail
 						checkFeedBroken (feedurl todownload)
 
@@ -198,32 +203,19 @@ performDownload relaxed cache todownload = case location todownload of
 			( return Nothing
 			, tryanother
 			)
-	
+
 defaultTemplate :: String
 defaultTemplate = "${feedtitle}/${itemtitle}${extension}"
 
 {- Generates a filename to use for a feed item by filling out the template.
  - The filename may not be unique. -}
 feedFile :: Utility.Format.Format -> ToDownload -> String -> FilePath
-feedFile tmpl i extension = Utility.Format.format tmpl $ M.fromList
-	[ field "feedtitle" $ getFeedTitle $ feed i
-	, fieldMaybe "itemtitle" $ getItemTitle $ item i
-	, fieldMaybe "feedauthor" $ getFeedAuthor $ feed i
-	, fieldMaybe "itemauthor" $ getItemAuthor $ item i
-	, fieldMaybe "itemsummary" $ getItemSummary $ item i
-	, fieldMaybe "itemdescription" $ getItemDescription $ item i
-	, fieldMaybe "itemrights" $ getItemRights $ item i
-	, fieldMaybe "itemid" $ snd <$> getItemId (item i)
-	, fieldMaybe "itempubdate" $ pubdate $ item i
-	, ("extension", sanitizeFilePath extension)
-	]
+feedFile tmpl i extension = Utility.Format.format tmpl $
+	M.map sanitizeFilePath $ M.fromList $ extractFields i ++
+		[ ("extension", extension)
+		, extractField "itempubdate" [pubdate $ item i]
+		]
   where
-	field k v = 
-		let s = sanitizeFilePath v in
-		if null s then (k, "none") else (k, s)
-	fieldMaybe k Nothing = (k, "none")
-	fieldMaybe k (Just v) = field k v
-
 #if MIN_VERSION_feed(0,3,9)
 	pubdate itm = case getItemPublishDate itm :: Maybe (Maybe UTCTime) of
 		Just (Just d) -> Just $
@@ -234,6 +226,41 @@ feedFile tmpl i extension = Utility.Format.format tmpl $ M.fromList
 	pubdate _ = Nothing
 #endif
 
+extractMetaData :: ToDownload -> MetaData
+extractMetaData i = case getItemPublishDate (item i) :: Maybe (Maybe UTCTime) of
+	Just (Just d) -> addDateMetaData d meta
+	_ -> meta
+  where
+	tometa (k, v) = (mkMetaFieldUnchecked k, S.singleton (toMetaValue v))
+	meta = MetaData $ M.fromList $ map tometa $ extractFields i
+
+{- Extract fields from the feed and item, that are both used as metadata,
+ - and to generate the filename. -}
+extractFields :: ToDownload -> [(String, String)]
+extractFields i = map (uncurry extractField)
+	[ ("feedtitle", [feedtitle])
+	, ("itemtitle", [itemtitle])
+	, ("feedauthor", [feedauthor])
+	, ("itemauthor", [itemauthor])
+	, ("itemsummary", [getItemSummary $ item i])
+	, ("itemdescription", [getItemDescription $ item i])
+	, ("itemrights", [getItemRights $ item i])
+	, ("itemid", [snd <$> getItemId (item i)])
+	, ("title", [itemtitle, feedtitle])
+	, ("author", [itemauthor, feedauthor])
+	]
+  where
+	feedtitle = Just $ getFeedTitle $ feed i
+	itemtitle = getItemTitle $ item i
+	feedauthor = getFeedAuthor $ feed i
+	itemauthor = getItemAuthor $ item i
+
+extractField :: String -> [Maybe String] -> (String, String)
+extractField k [] = (k, "none")
+extractField k (Just v:_)
+	| not (null v) = (k, v)
+extractField k (_:rest) = extractField k rest
+
 {- Called when there is a problem with a feed.
  - Throws an error if the feed is broken, otherwise shows a warning. -}
 feedProblem :: URLString -> String -> Annex ()