{- git-annex webapp launcher
 -
 - Copyright 2012 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Command.WebApp where

import Common.Annex
import Command
import Assistant
import Assistant.Common
import Assistant.NamedThread
import Assistant.Threads.WebApp
import Assistant.WebApp
import Assistant.Install
import Annex.Environment
import Utility.WebApp
import Utility.Daemon (checkDaemon)
#ifdef __ANDROID__
import Utility.Env
#endif
import Annex.Init
import qualified Git
import qualified Git.Config
import qualified Git.CurrentRepo
import qualified Annex
import Config.Files
import Upgrade
import Annex.Version

import Control.Concurrent
import Control.Concurrent.STM
import Network.Socket (HostName)
import System.Environment (getArgs)

cmd :: [Command]
cmd = [ withOptions [listenOption] $
	noCommit $ noRepo startNoRepo $ dontCheck repoExists $ notBareRepo $
	command "webapp" paramNothing seek SectionCommon "launch webapp"]

listenOption :: Option
listenOption = fieldOption [] "listen" paramAddress
	"accept connections to this address"

seek :: CommandSeek
seek ps = do
	listenhost <- getOptionField listenOption return
	withNothing (start listenhost) ps

start :: Maybe HostName -> CommandStart
start = start' True

start' :: Bool -> Maybe HostName -> CommandStart
start' allowauto listenhost = do
	liftIO ensureInstalled
	ifM isInitialized 
		( maybe notinitialized (go <=< needsUpgrade) =<< getVersion
		, if allowauto
			then liftIO $ startNoRepo []
			else notinitialized
		)
	stop
  where
	go cannotrun = do
		browser <- fromRepo webBrowser
		f <- liftIO . absPath =<< fromRepo gitAnnexHtmlShim
		listenhost' <- if isJust listenhost
			then pure listenhost
			else annexListen <$> Annex.getGitConfig
		ifM (checkpid <&&> checkshim f)
			( if isJust listenhost
				then error "The assistant is already running, so --listen cannot be used."
				else do
					url <- liftIO . readFile
						=<< fromRepo gitAnnexUrlFile
					liftIO $ if isJust listenhost'
						then putStrLn url
						else liftIO $ openBrowser browser f url Nothing Nothing
			, do
				startDaemon True True Nothing cannotrun listenhost' $ Just $ 
					\origout origerr url htmlshim ->
						if isJust listenhost'
							then maybe noop (`hPutStrLn` url) origout
							else openBrowser browser htmlshim url origout origerr
			)
	checkpid = do
		pidfile <- fromRepo gitAnnexPidFile
		liftIO $ isJust <$> checkDaemon pidfile
	checkshim f = liftIO $ doesFileExist f
	notinitialized = do
		g <- Annex.gitRepo
		liftIO $ cannotStartIn (Git.repoLocation g) "repository has not been initialized by git-annex"
		liftIO $ firstRun listenhost

{- When run without a repo, start the first available listed repository in
 - the autostart file. If none, it's our first time being run! -}
startNoRepo :: CmdParams -> IO ()
startNoRepo _ = do
	-- FIXME should be able to reuse regular getopt, but 
	-- it currently runs in the Annex monad.
	args <- getArgs
	let listenhost = headMaybe $ map (snd . separate (== '=')) $ 
		filter ("--listen=" `isPrefixOf`) args

	go listenhost =<< liftIO (filterM doesDirectoryExist =<< readAutoStartFile)
  where
	go listenhost [] = firstRun listenhost
	go listenhost (d:ds) = do
		v <- tryNonAsync $ do
			setCurrentDirectory d
			Annex.new =<< Git.CurrentRepo.get
		case v of
			Left e -> do
				cannotStartIn d (show e)
				go listenhost ds
			Right state -> void $ Annex.eval state $ do
				whenM (fromRepo Git.repoIsLocalBare) $
					error $ d ++ " is a bare git repository, cannot run the webapp in it"
				callCommandAction $
					start' False listenhost

cannotStartIn :: FilePath -> String -> IO ()
cannotStartIn d reason = warningIO $ "unable to start webapp in repository " ++ d ++ ": " ++ reason

{- Run the webapp without a repository, which prompts the user, makes one,
 - changes to it, starts the regular assistant, and redirects the
 - browser to its url.
 -
 - This is a very tricky dance -- The first webapp calls the signaler,
 - which signals the main thread when it's ok to continue by writing to a
 - MVar. The main thread starts the second webapp, and uses its callback
 - to write its url back to the MVar, from where the signaler retrieves it,
 - returning it to the first webapp, which does the redirect.
 -
 - Note that it's important that mainthread never terminates! Much
 - of this complication is due to needing to keep the mainthread running.
 -}
firstRun :: Maybe HostName -> IO ()
firstRun listenhost = do
	checkEnvironmentIO
	{- Without a repository, we cannot have an Annex monad, so cannot
	 - get a ThreadState. Using undefined is only safe because the
	 - webapp checks its noAnnex field before accessing the
	 - threadstate. -}
	let st = undefined
	{- Get a DaemonStatus without running in the Annex monad. -}
	dstatus <- atomically . newTMVar =<< newDaemonStatus
	d <- newAssistantData st dstatus
	urlrenderer <- newUrlRenderer
	v <- newEmptyMVar
	let callback a = Just $ a v
	runAssistant d $ do
		startNamedThread urlrenderer $
			webAppThread d urlrenderer True Nothing
				(callback signaler)
				listenhost
				(callback mainthread)
		waitNamedThreads
  where
	signaler v = do
		putMVar v ""
		takeMVar v
	mainthread v url htmlshim
		| isJust listenhost = do
			putStrLn url
			hFlush stdout
			go
		| otherwise = do
			browser <- maybe Nothing webBrowser
				<$> catchDefaultIO Nothing Git.Config.global
			openBrowser browser htmlshim url Nothing Nothing
			go
	  where
		go = do
			_wait <- takeMVar v
			state <- Annex.new =<< Git.CurrentRepo.get
			Annex.eval state $
				startDaemon True True Nothing Nothing listenhost $ Just $
					sendurlback v
	sendurlback v _origout _origerr url _htmlshim = do
		recordUrl url
		putMVar v url

recordUrl :: String -> IO ()
#ifdef __ANDROID__
{- The Android app has a menu item that opens the url recorded
 - in this file. -}
recordUrl url = writeFile "/sdcard/git-annex.home/.git-annex-url" url
#else
recordUrl _ = noop
#endif

openBrowser :: Maybe FilePath -> FilePath -> String -> Maybe Handle -> Maybe Handle -> IO ()
openBrowser mcmd htmlshim realurl outh errh = do
	htmlshim' <- absPath htmlshim
	openBrowser' mcmd htmlshim' realurl outh errh

openBrowser' :: Maybe FilePath -> FilePath -> String -> Maybe Handle -> Maybe Handle -> IO ()
#ifndef __ANDROID__
openBrowser' mcmd htmlshim _realurl outh errh = runbrowser
#else
openBrowser' mcmd htmlshim realurl outh errh = do
	recordUrl url
	{- Android's `am` command does not work reliably across the
	 - wide range of Android devices. Intead, FIFO should be set to 
	 - the filename of a fifo that we can write the URL to. -}
	v <- getEnv "FIFO"
	case v of
		Nothing -> runbrowser
		Just f -> void $ forkIO $ do
			fd <- openFd f WriteOnly Nothing defaultFileFlags
			void $ fdWrite fd url
			closeFd fd
#endif
  where
	p = case mcmd of
		Just c -> proc c [htmlshim]
		Nothing -> 
#ifndef mingw32_HOST_OS
			browserProc url
#else
			{- Windows hack to avoid using the full path,
			 - which might contain spaces that cause problems
			 - for browserProc. -}
			(browserProc (takeFileName htmlshim))
				{ cwd = Just (takeDirectory htmlshim) } 
#endif
#ifdef __ANDROID__
	{- Android does not support file:// urls, but neither is
	 - the security of the url in the process table important
	 - there, so just use the real url. -}
	url = realurl
#else
	url = fileUrl htmlshim
#endif
	runbrowser = do
		hPutStrLn (fromMaybe stdout outh) $ "Launching web browser on " ++ url
		hFlush stdout
		environ <- cleanEnvironment
		(_, _, _, pid) <- createProcess p
			{ env = environ
			, std_out = maybe Inherit UseHandle outh
			, std_err = maybe Inherit UseHandle errh
			}
		exitcode <- waitForProcess pid
		unless (exitcode == ExitSuccess) $
			hPutStrLn (fromMaybe stderr errh) "failed to start web browser"

{- web.browser is a generic git config setting for a web browser program -}
webBrowser :: Git.Repo -> Maybe FilePath
webBrowser = Git.Config.getMaybe "web.browser"

fileUrl :: FilePath -> String
fileUrl file = "file://" ++ file
