{- git-annex command
 -
 - Copyright 2013 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Command.ImportFeed where

import Text.Feed.Import
import Text.Feed.Query
import Text.Feed.Types
import qualified Data.Set as S
import qualified Data.Map as M
import Data.Time.Clock

import Common.Annex
import qualified Annex
import Command
import qualified Annex.Url as Url
import Logs.Web
import qualified Utility.Format
import Utility.Tmp
import Command.AddUrl (addUrlFile, relaxedOption)
import Annex.Perms
import Backend.URL (fromUrl)
#ifdef WITH_QUVI
import Annex.Quvi
import qualified Utility.Quvi as Quvi
import Command.AddUrl (addUrlFileQuvi)
#endif

def :: [Command]
def = [notBareRepo $ withOptions [templateOption, relaxedOption] $
	command "importfeed" (paramRepeating paramUrl) seek
		SectionCommon "import files from podcast feeds"]

templateOption :: Option
templateOption = fieldOption [] "template" paramFormat "template for filenames"

seek :: CommandSeek
seek ps = do
	tmpl <- getOptionField templateOption return
	relaxed <- getOptionFlag relaxedOption
	cache <- getCache tmpl
	withStrings (start relaxed cache) ps

start :: Bool -> Cache -> URLString -> CommandStart
start relaxed cache url = do
	showStart "importfeed" url
	next $ perform relaxed cache url

perform :: Bool -> Cache -> URLString -> CommandPerform
perform relaxed cache url = do
	v <- findDownloads url
	case v of
		[] -> do
			feedProblem url "bad feed content"
			next $ return True
		l -> do
			ok <- and <$> mapM (performDownload relaxed cache) l
			unless ok $
				feedProblem url "problem downloading item"
			next $ cleanup url True

cleanup :: URLString -> Bool -> CommandCleanup
cleanup url ok = do
	when ok $
		clearFeedProblem url
	return ok

data ToDownload = ToDownload
	{ feed :: Feed
	, feedurl :: URLString
	, item :: Item
	, location :: DownloadLocation
	}

data DownloadLocation = Enclosure URLString | QuviLink URLString

data Cache = Cache
	{ knownurls :: S.Set URLString
	, template :: Utility.Format.Format
	}

getCache :: Maybe String -> Annex Cache
getCache opttemplate = ifM (Annex.getState Annex.force)
	( ret S.empty
	, do
		showSideAction "checking known urls"
		ret =<< S.fromList <$> knownUrls
	)
  where
	tmpl = Utility.Format.gen $ fromMaybe defaultTemplate opttemplate
	ret s = return $ Cache s tmpl

findDownloads :: URLString -> Annex [ToDownload]
findDownloads u = go =<< downloadFeed u
  where
	go Nothing = pure []
	go (Just f) = catMaybes <$> mapM (mk f) (feedItems f)

	mk f i = case getItemEnclosure i of
		Just (enclosureurl, _, _) -> return $ 
			Just $ ToDownload f u i $ Enclosure enclosureurl
		Nothing -> mkquvi f i
#ifdef WITH_QUVI
	mkquvi f i = case getItemLink i of
		Just link -> ifM (liftIO $ Quvi.supported link)
			( return $ Just $ ToDownload f u i $ QuviLink link
			, return Nothing
			)
		Nothing -> return Nothing
#else
	mkquvi = return Nothing
#endif

{- Feeds change, so a feed download cannot be resumed. -}
downloadFeed :: URLString -> Annex (Maybe Feed)
downloadFeed url = do
	showOutput
	ua <- Url.getUserAgent
	liftIO $ withTmpFile "feed" $ \f h -> do
		fileEncoding h
		ifM (Url.download url [] [] f ua)
			( parseFeedString <$> hGetContentsStrict h
			, return Nothing
			)

performDownload :: Bool -> Cache -> ToDownload -> Annex Bool
performDownload relaxed cache todownload = case location todownload of
	Enclosure url -> checkknown url $
		rundownload url (takeExtension url) $ 
			addUrlFile relaxed url
	QuviLink pageurl -> do
		let quviurl = setDownloader pageurl QuviDownloader
		checkknown quviurl $ do
			mp <- withQuviOptions Quvi.query [Quvi.quiet, Quvi.httponly] pageurl
			case mp of
				Nothing -> return False
				Just page -> case headMaybe $ Quvi.pageLinks page of
					Nothing -> return False
					Just link -> do
						let videourl = Quvi.linkUrl link
						checkknown videourl $
							rundownload videourl ("." ++ Quvi.linkSuffix link) $
								addUrlFileQuvi relaxed quviurl videourl
  where
  	forced = Annex.getState Annex.force

	{- Avoids downloading any urls that are already known to be
	 - associated with a file in the annex, unless forced. -}
	checkknown url a
		| S.member url (knownurls cache) = ifM forced (a, return True)
		| otherwise = a

	rundownload url extension getter = do
		dest <- makeunique url (1 :: Integer) $
			feedFile (template cache) todownload extension
		case dest of
			Nothing -> return True
			Just f -> do
				showStart "addurl" f
				ok <- getter f
				if ok
					then do
						showEndOk
						return True
					else do
						showEndFail
						checkFeedBroken (feedurl todownload)

	{- Find a unique filename to save the url to.
	 - If the file exists, prefixes it with a number.
	 - When forced, the file may already exist and have the same
	 - url, in which case Nothing is returned as it does not need
	 - to be re-downloaded. -}
	makeunique url n file = ifM alreadyexists
		( ifM forced
			( ifAnnexed f checksameurl tryanother
			, tryanother
			)
		, return $ Just f
		)
	  where
	  	f = if n < 2
			then file
			else
				let (d, base) = splitFileName file
				in d </> show n ++ "_" ++ base
		tryanother = makeunique url (n + 1) file
		alreadyexists = liftIO $ isJust <$> catchMaybeIO (getSymbolicLinkStatus f)
		checksameurl (k, _) = ifM (elem url <$> getUrls k)
			( 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)
	, ("extension", sanitizeFilePath extension)
	]
  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

{- 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 ()
feedProblem url message = ifM (checkFeedBroken url)
	( error $ message ++ " (having repeated problems with this feed!)"
	, warning $ "warning: " ++ message
	)

{- A feed is only broken if problems have occurred repeatedly, for at
 - least 23 hours. -}
checkFeedBroken :: URLString -> Annex Bool
checkFeedBroken url = checkFeedBroken' url =<< feedState url
checkFeedBroken' :: URLString -> FilePath -> Annex Bool
checkFeedBroken' url f = do
	prev <- maybe Nothing readish <$> liftIO (catchMaybeIO $ readFile f)
	now <- liftIO getCurrentTime
	case prev of
		Nothing -> do
			createAnnexDirectory (parentDir f)
			liftIO $ writeFile f $ show now
			return False
		Just prevtime -> do
			let broken = diffUTCTime now prevtime > 60 * 60 * 23
			when broken $
				-- Avoid repeatedly complaining about
				-- broken feed.
				clearFeedProblem url
			return broken

clearFeedProblem :: URLString -> Annex ()
clearFeedProblem url = void $ liftIO . tryIO . removeFile =<< feedState url

feedState :: URLString -> Annex FilePath
feedState url = fromRepo . gitAnnexFeedState =<< fromUrl url Nothing