{- git-annex assistant git pushing thread
 -
 - Copyright 2012 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Assistant.Threads.Pusher where

import Assistant.Common
import Assistant.Commits
import Assistant.Pushes
import Assistant.Alert
import Assistant.ThreadedMonad
import Assistant.DaemonStatus
import Assistant.Sync
import Utility.ThreadScheduler
import qualified Remote
import qualified Types.Remote as Remote

import Data.Time.Clock

thisThread :: ThreadName
thisThread = "Pusher"

{- This thread retries pushes that failed before. -}
pushRetryThread :: ThreadState -> DaemonStatusHandle -> FailedPushMap -> NamedThread
pushRetryThread st dstatus pushmap = thread $ runEvery (Seconds halfhour) $ do
	-- We already waited half an hour, now wait until there are failed
	-- pushes to retry.
	topush <- getFailedPushesBefore pushmap (fromIntegral halfhour)
	unless (null topush) $ do
		debug thisThread
			[ "retrying"
			, show (length topush)
			, "failed pushes"
			]
		now <- getCurrentTime
		void $ alertWhile dstatus (pushRetryAlert topush) $
			pushToRemotes thisThread now st (Just pushmap) topush
	where
		halfhour = 1800
		thread = NamedThread thisThread

{- This thread pushes git commits out to remotes soon after they are made. -}
pushThread :: ThreadState -> DaemonStatusHandle -> CommitChan -> FailedPushMap -> NamedThread
pushThread st dstatus commitchan pushmap = thread $ runEvery (Seconds 2) $ do
	-- We already waited two seconds as a simple rate limiter.
	-- Next, wait until at least one commit has been made
	commits <- getCommits commitchan
	-- Now see if now's a good time to push.
	now <- getCurrentTime
	if shouldPush now commits
		then do
			remotes <- filter pushable . knownRemotes
				<$> getDaemonStatus dstatus
			unless (null remotes) $ 
				void $ alertWhile dstatus (pushAlert remotes) $
					pushToRemotes thisThread now st (Just pushmap) remotes
		else do
			debug thisThread
				[ "delaying push of"
				, show (length commits)
				, "commits"
				]
			refillCommits commitchan commits
	where
		thread = NamedThread thisThread
		pushable r
			| Remote.specialRemote r = False
			| Remote.readonly r = False
			| otherwise = True

{- Decide if now is a good time to push to remotes.
 -
 - Current strategy: Immediately push all commits. The commit machinery
 - already determines batches of changes, so we can't easily determine
 - batches better.
 -}
shouldPush :: UTCTime -> [Commit] -> Bool
shouldPush _now commits
	| not (null commits) = True
	| otherwise = False