    module Propellor.CmdLine (
    	defaultMain,
    	processCmdLine,
    ) where

    import System.Environment (getArgs)
    import Data.List
    import System.Exit
    import System.PosixCompat
    import Network.Socket

    import Propellor.Base
    import Propellor.Gpg
    import Propellor.Git
    import Propellor.Git.VerifiedBranch
    import Propellor.Bootstrap
    import Propellor.Spin
    import Propellor.Types.CmdLine
    import qualified Propellor.Property.Docker as Docker
    import qualified Propellor.Property.Chroot as Chroot
    import qualified Propellor.Shim as Shim
    import Utility.FileSystemEncoding

    usage :: Handle -> IO ()
    usage h = hPutStrLn h $ unlines
    	[ "Usage:"
    	, "  with no arguments, provision the current host"
    	, ""
    	, "  --init"
    	, "      initialize ~/.propellor"
    	, "  hostname"
    	, "      provision the current host as if it had the specified hostname"
    	, "  --spin targethost [--via relayhost]"
    	, "      provision the specified host"
    	, "  --build"
    	, "      recompile using your current config"
    	, "  --add-key keyid"
    	, "      add an additional signing key to the private data"
    	, "  --rm-key keyid"
    	, "      remove a signing key from the private data"
    	, "  --list-fields"
    	, "      list private data fields"
    	, "  --set field context"
    	, "      set a private data field"
    	, "  --unset field context"
    	, "      clear a private data field"
    	, "  --unset-unused"
    	, "      clear unused fields from the private data"
    	, "  --dump field context"
    	, "      show the content of a private data field"
    	, "  --edit field context"
    	, "      edit the content of a private data field"
    	, "  --merge"
    	, "      combine multiple spins into a single git commit"
    	, "  --check"
    	, "      double-check that propellor can actually run here"]

    usageError :: [String] -> IO a
    usageError ps = do
    	usage stderr
    	error ("(Unexpected: " ++ show ps)

    processCmdLine :: IO CmdLine
    processCmdLine = go =<< getArgs
      where
    	go ("--check":_) = return Check
    	go ("--spin":ps) = case reverse ps of
    		(r:"--via":hs) -> Spin
    			<$> mapM hostname (reverse hs)
    			<*> pure (Just r)
    		_ -> Spin <$> mapM hostname ps <*> pure Nothing
    	go ("--build":[]) = return Build
    	go ("--add-key":k:[]) = return $ AddKey k
    	go ("--rm-key":k:[]) = return $ RmKey k
    	go ("--set":f:c:[]) = withprivfield f c Set
    	go ("--unset":f:c:[]) = withprivfield f c Unset
    	go ("--unset-unused":[]) = return UnsetUnused
    	go ("--dump":f:c:[]) = withprivfield f c Dump
    	go ("--edit":f:c:[]) = withprivfield f c Edit
    	go ("--list-fields":[]) = return ListFields
    	go ("--merge":[]) = return Merge
    	go ("--help":_) = do
    		usage stdout
    		exitFailure
    	go ("--boot":_:[]) = return $ Update Nothing -- for back-compat
    	go ("--serialized":s:[]) = serialized Serialized s
    	go ("--continue":s:[]) = serialized Continue s
    	go ("--gitpush":fin:fout:_) = return $ GitPush (Prelude.read fin) (Prelude.read fout)
    	go ("--run":h:[]) = go [h]
    	go (h:[])
    		| "--" `isPrefixOf` h = usageError [h]
    		| otherwise = Run <$> hostname h
    	go [] = do
    		s <- takeWhile (/= '\n') <$> readProcess "hostname" ["-f"]
    		if null s
    			then errorMessage "Cannot determine hostname! Pass it on the command line."
    			else return $ Run s
    	go v = usageError v

    	withprivfield s c f = case readish s of
    		Just pf -> return $ f pf (Context c)
    		Nothing -> errorMessage $ "Unknown privdata field " ++ s

    	serialized mk s = case readish s of
    		Just cmdline -> return $ mk cmdline
    		Nothing -> errorMessage $ "serialization failure (" ++ s ++ ")"

    data CanRebuild = CanRebuild | NoRebuild

    -- | Runs propellor on hosts, as controlled by command-line options.
    defaultMain :: [Host] -> IO ()
    defaultMain hostlist = withConcurrentOutput $ do
    	useFileSystemEncoding
    	setupGpgEnv
    	Shim.cleanEnv
    	checkDebugMode
    	cmdline <- processCmdLine
    	debug ["command line: ", show cmdline]
    	go CanRebuild cmdline
      where
    	go cr (Serialized cmdline) = go cr cmdline
    	go _ Check = return ()
    	go cr Build = buildFirst Nothing cr Build $ return ()
    	go _ (Set field context) = setPrivData field context
    	go _ (Unset field context) = unsetPrivData field context
    	go _ (UnsetUnused) = unsetPrivDataUnused hostlist
    	go _ (Dump field context) = dumpPrivData field context
    	go _ (Edit field context) = editPrivData field context
    	go _ ListFields = listPrivDataFields hostlist
    	go _ (AddKey keyid) = addKey keyid
    	go _ (RmKey keyid) = rmKey keyid
    	go _ c@(ChrootChain _ _ _ _) = Chroot.chain hostlist c
    	go _ (DockerChain hn cid) = Docker.chain hostlist hn cid
    	go _ (DockerInit hn) = Docker.init hn
    	go _ (GitPush fin fout) = gitPushHelper fin fout
    	go cr (Relay h) = forceConsole >>
    		updateFirst Nothing cr (Update (Just h)) (update (Just h))
    	go _ (Update Nothing) = forceConsole >>
    		fetchFirst (onlyprocess (update Nothing))
    	go _ (Update (Just h)) = update (Just h)
    	go _ Merge = mergeSpin
    	go cr cmdline@(Spin hs mrelay) = buildFirst Nothing cr cmdline $ do
    		unless (isJust mrelay) commitSpin
    		forM_ hs $ \hn -> withhost hn $ spin mrelay hn
    	go cr cmdline@(Run hn) = ifM ((==) 0 <$> getRealUserID)
    		( updateFirst (findHost hostlist hn) cr cmdline $ runhost hn
    		, fetchFirst $ go cr (Spin [hn] Nothing)
    		)
    	go cr cmdline@(SimpleRun hn) = forceConsole >>
    		fetchFirst (buildFirst (findHost hostlist hn) cr cmdline (runhost hn))
    	-- When continuing after a rebuild, don't want to rebuild again.
    	go _ (Continue cmdline) = go NoRebuild cmdline

    	withhost :: HostName -> (Host -> IO ()) -> IO ()
    	withhost hn a = maybe (unknownhost hn hostlist) a (findHost hostlist hn)

    	runhost hn = onlyprocess $ withhost hn mainProperties

    	onlyprocess = onlyProcess (localdir </> ".lock")

    unknownhost :: HostName -> [Host] -> IO a
    unknownhost h hosts = errorMessage $ unlines
    	[ "Propellor does not know about host: " ++ h
    	, "(Perhaps you should specify the real hostname on the command line?)"
    	, "(Or, edit propellor's config.hs to configure this host)"
    	, "Known hosts: " ++ unwords (map hostName hosts)
    	]

    -- Builds propellor (when allowed) and if it looks like a new binary,
    -- re-execs it to continue.
    -- Otherwise, runs the IO action to continue.
    --
    -- The Host should only be provided when dependencies should be installed
    -- as needed to build propellor.
    buildFirst :: Maybe Host -> CanRebuild -> CmdLine -> IO () -> IO ()
    buildFirst h CanRebuild cmdline next = do
    	oldtime <- getmtime
    	buildPropellor h
    	newtime <- getmtime
    	if newtime == oldtime
    		then next
    		else continueAfterBuild cmdline
      where
    	getmtime = catchMaybeIO $ getModificationTime "propellor"
    buildFirst _ NoRebuild _ next = next

    continueAfterBuild :: CmdLine -> IO a
    continueAfterBuild cmdline = go =<< boolSystem "./propellor"
    	[ Param "--continue"
    	, Param (show cmdline)
    	]
      where
    	go True = exitSuccess
    	go False = exitWith (ExitFailure 1)

    fetchFirst :: IO () -> IO ()
    fetchFirst next = do
    	whenM hasOrigin $
    		void fetchOrigin
    	next

    updateFirst :: Maybe Host -> CanRebuild -> CmdLine -> IO () -> IO ()
    updateFirst h canrebuild cmdline next = ifM hasOrigin
    	( updateFirst' h canrebuild cmdline next
    	, next
    	)

    -- If changes can be fetched from origin, builds propellor (when allowed)
    -- and re-execs the updated propellor binary to continue.
    -- Otherwise, runs the IO action to continue.
    updateFirst' :: Maybe Host -> CanRebuild -> CmdLine -> IO () -> IO ()
    updateFirst' h CanRebuild cmdline next = ifM fetchOrigin
    	( do
    		buildPropellor h
    		continueAfterBuild cmdline
    	, next
    	)
    updateFirst' _ NoRebuild _ next = next

    -- Gets the fully qualified domain name, given a string that might be
    -- a short name to look up in the DNS.
    hostname :: String -> IO HostName
    hostname s = go =<< catchDefaultIO [] dnslookup
      where
    	dnslookup = getAddrInfo (Just canonname) (Just s) Nothing
    	canonname = defaultHints { addrFlags = [AI_CANONNAME] }
    	go (AddrInfo { addrCanonName = Just v } : _) = pure v
    	go _
    		| "." `isInfixOf` s = pure s -- assume it's a fqdn
    		| otherwise =
    			error $ "cannot find host " ++ s ++ " in the DNS"