{- git-annex remote repositories
 -
 - Copyright 2010 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remotes (
	list,
	keyPossibilities,
	tryGitConfigRead,
	inAnnex,
	same,
	commandLineRemote,
	byName,
	copyFromRemote,
	copyToRemote,
	onRemote
) where

import Control.Exception.Extensible
import Control.Monad.State (liftIO)
import qualified Data.Map as Map
import Data.String.Utils
import System.Cmd.Utils
import Data.List (intersect, sortBy)
import Control.Monad (when, unless, filterM)
import Data.Maybe

import Types
import qualified GitRepo as Git
import qualified Annex
import LocationLog
import Locations
import UUID
import Utility
import qualified Core
import Messages
import CopyFile
import RsyncFile

{- Human visible list of remotes. -}
list :: [Git.Repo] -> String
list remotes = join ", " $ map Git.repoDescribe remotes 

{- Cost ordered lists of remotes that the LocationLog indicate may have a key.
 -
 - The first list is of remotes that are trusted to have the key.
 -
 - The second is of untrusted remotes that may have the key.
 -
 - Also returns a list of UUIDs that are trusted to have the key
 - (some may not have configured remotes).
 -}
keyPossibilities :: Key -> Annex ([Git.Repo], [Git.Repo], [UUID])
keyPossibilities key = do
	allremotes <- remotesByCost
	-- To determine if a remote has a key, its UUID needs to be known.
	-- The locally cached UUIDs of remotes can fall out of date if
	-- eg, a different drive is mounted at the same location.
	-- But, reading the config of remotes can be expensive, so make
	-- sure we only do it once per git-annex run.
	remotesread <- Annex.flagIsSet "remotesread"
	if remotesread
		then partition allremotes
		else do
			-- We assume that it's cheap to read the config
			-- of non-URL remotes, so that is done each time.
			-- But reading the config of an URL remote is
			-- only done when there is no cached UUID value.
			let cheap = filter (not . Git.repoIsUrl) allremotes
			let expensive = filter Git.repoIsUrl allremotes
			doexpensive <- filterM cachedUUID expensive
			unless (null doexpensive) $
				showNote $ "getting UUID for " ++
					list doexpensive ++ "..."
			let todo = cheap ++ doexpensive
			if not $ null todo
				then do
					_ <- mapM tryGitConfigRead todo
					Annex.flagChange "remotesread" $ FlagBool True
					keyPossibilities key
				else partition allremotes
	where
		cachedUUID r = do
			u <- getUUID r
			return $ null u
		partition remotes = do
			g <- Annex.gitRepo
			u <- getUUID g
			trusted <- getTrusted
			-- get uuids of other repositories that are
			-- believed to have the key
			uuids <- liftIO $ keyLocations g key
			let validuuids = filter (/= u) uuids
			-- get uuids trusted to have the key
			-- note that validuuids is assumed to not have dups
			let validtrusteduuids = intersect validuuids trusted
			-- remotes that match uuids that have the key
			validremotes <- reposByUUID remotes validuuids
			-- partition out the trusted and untrusted remotes
			trustedremotes <- reposByUUID validremotes validtrusteduuids
			untrustedremotes <- reposWithoutUUID validremotes trusted
			return (trustedremotes, untrustedremotes, validtrusteduuids)

{- Checks if a given remote has the content for a key inAnnex.
 - If the remote cannot be accessed, returns a Left error.
 -}
inAnnex :: Git.Repo -> Key -> Annex (Either IOException Bool)
inAnnex r key = if Git.repoIsUrl r
		then checkremote
		else liftIO (try checklocal ::IO (Either IOException Bool))
	where
		checklocal = do
			-- run a local check inexpensively,
			-- by making an Annex monad using the remote
			a <- Annex.new r []
			Annex.eval a (Core.inAnnex key)
		checkremote = do
			showNote ("checking " ++ Git.repoDescribe r ++ "...")
			inannex <- onRemote r (boolSystem, False) "inannex" 
				["--backend=" ++ backendName key, keyName key]
			return $ Right inannex

{- Cost Ordered list of remotes. -}
remotesByCost :: Annex [Git.Repo]
remotesByCost = do
	g <- Annex.gitRepo
	reposByCost $ Git.remotes g

{- Orders a list of git repos by cost. Throws out ignored ones. -}
reposByCost :: [Git.Repo] -> Annex [Git.Repo]
reposByCost l = do
	notignored <- filterM repoNotIgnored l
	costpairs <- mapM costpair notignored
	return $ fst $ unzip $ sortBy cmpcost costpairs
	where
		costpair r = do
			cost <- repoCost r
			return (r, cost)
		cmpcost (_, c1) (_, c2) = compare c1 c2

{- Calculates cost for a repo.
 -
 - The default cost is 100 for local repositories, and 200 for remote
 - repositories; it can also be configured by remote.<name>.annex-cost
 -}
repoCost :: Git.Repo -> Annex Int
repoCost r = do
	cost <- repoConfig r "cost" ""
	if not $ null cost
		then return $ read cost
		else if Git.repoIsUrl r
			then return 200
			else return 100

{- Checks if a repo should be ignored, based either on annex-ignore
 - setting, or on command-line options. Allows command-line to override
 - annex-ignore. -}
repoNotIgnored :: Git.Repo -> Annex Bool
repoNotIgnored r = do
	ignored <- repoConfig r "ignore" "false"
	fromName <- Annex.flagGet "fromrepository"
	toName <- Annex.flagGet "torepository"
	let name = if null fromName then toName else fromName
	if not $ null name
		then return $ match name
		else return $ not $ Git.configTrue ignored
	where
		match name = name == Git.repoRemoteName r

{- Checks if two repos are the same, by comparing their remote names. -}
same :: Git.Repo -> Git.Repo -> Bool
same a b = Git.repoRemoteName a == Git.repoRemoteName b

{- Returns the remote specified by --from or --to, may fail with error. -}
commandLineRemote :: Annex Git.Repo
commandLineRemote = do
	fromName <- Annex.flagGet "fromrepository"
	toName <- Annex.flagGet "torepository"
	let name = if null fromName then toName else fromName
	byName name

{- Looks up a remote by name. -}
byName :: String -> Annex Git.Repo
byName name = do
	when (null name) $ error "no remote specified"
	g <- Annex.gitRepo
	let match = filter (\r -> name == Git.repoRemoteName r) $
		Git.remotes g
	when (null match) $ error $
		"there is no git remote named \"" ++ name ++ "\""
	return $ head match

{- The git configs for the git repo's remotes is not read on startup
 - because reading it may be expensive. This function tries to read the
 - config for a specified remote, and updates state. If successful, it
 - returns the updated git repo. -}
tryGitConfigRead :: Git.Repo -> Annex (Either Git.Repo Git.Repo)
tryGitConfigRead r 
	| not $ Map.null $ Git.configMap r = return $ Right r -- already read
	| Git.repoIsSsh r = store $ onRemote r (pipedconfig, r) "configlist" []
	| Git.repoIsUrl r = return $ Left r
	| otherwise = store $ safely $ Git.configRead r
	where
		-- Reading config can fail due to IO error or
		-- for other reasons; catch all possible exceptions.
		safely a = do
			result <- liftIO (try (a)::IO (Either SomeException Git.Repo))
			case result of
				Left _ -> return r
				Right r' -> return r'
		pipedconfig cmd params = safely $
			pOpen ReadFromPipe cmd params $
				Git.hConfigRead r
		store a = do
			r' <- a
			g <- Annex.gitRepo
			let l = Git.remotes g
			let g' = Git.remotesAdd g $ exchange l r'
			Annex.gitRepoChange g'
			return $ Right r'
		exchange [] _ = []
		exchange (old:ls) new =
			if Git.repoRemoteName old == Git.repoRemoteName new
				then new : exchange ls new
				else old : exchange ls new

{- Tries to copy a key's content from a remote's annex to a file. -}
copyFromRemote :: Git.Repo -> Key -> FilePath -> Annex Bool
copyFromRemote r key file
	| not $ Git.repoIsUrl r = liftIO $ copyFile (annexLocation r key) file
	| Git.repoIsSsh r = rsynchelper r True key file
	| otherwise = error "copying from non-ssh repo not supported"

{- Tries to copy a key's content to a remote's annex. -}
copyToRemote :: Git.Repo -> Key -> Annex Bool
copyToRemote r key
	| not $ Git.repoIsUrl r = do
		g <- Annex.gitRepo
		let keysrc = annexLocation g key
		let keydest = annexLocation r key
		liftIO $ copyFile keysrc keydest
	| Git.repoIsSsh r = do
		g <- Annex.gitRepo
		let keysrc = annexLocation g key
		rsynchelper r False key keysrc
	| otherwise = error "copying to non-ssh repo not supported"

rsynchelper :: Git.Repo -> Bool -> Key -> FilePath -> Annex (Bool)
rsynchelper r sending key file = do
	showProgress -- make way for progress bar
	p <- rsyncParams r sending key file
	res <- liftIO $ boolSystem "rsync" p
	if res
		then return res
		else do
			showLongNote "rsync failed -- run git annex again to resume file transfer"
			return res

{- Generates rsync parameters that ssh to the remote and asks it
 - to either receive or send the key's content. -}
rsyncParams :: Git.Repo -> Bool -> Key -> FilePath -> Annex [String]
rsyncParams r sending key file = do
	-- Note that the command is terminated with "--", because
	-- rsync will tack on its own options to this command,
	-- and they need to be ignored.
	shellcmd <- git_annex_shell r
		(if sending then "sendkey" else "recvkey")
		["--backend=" ++ backendName key, keyName key, "--"]
	-- Convert the ssh command into rsync command line.
	let eparam = rsyncShell $ fromJust shellcmd
	o <- repoConfig r "rsync-options" ""
	let base = options ++ words o ++ eparam
	if sending
		then return $ base ++ [dummy, file]
		else return $ base ++ [file, dummy]
	where
		-- inplace makes rsync resume partial files
		options = ["-p", "--progress", "--inplace"]
		-- the rsync shell parameter controls where rsync
		-- does, so the source/dest parameter can be a dummy value,
		-- that just enables remote rsync mode.
		dummy = ":"

{- Uses a supplied function to run a git-annex-shell command on a remote.
 -
 - Or, if the remote does not support running remote commands, returns
 - a specified error value. -}
onRemote 
	:: Git.Repo
	-> (String -> [String] -> IO a, a)
	-> String
	-> [String]
	-> Annex a
onRemote r (with, errorval) command params = do
	s <- git_annex_shell r command params
	case s of
		Just shellcmd -> liftIO $ with (shellcmd !! 0) (tail shellcmd)
		Nothing -> return errorval

{- Generates parameters to run a git-annex-shell command on a remote. -}
git_annex_shell :: Git.Repo -> String -> [String] -> Annex (Maybe [String])
git_annex_shell r command params
	| not $ Git.repoIsUrl r = return $ Just (shellcmd:shellopts)
	| Git.repoIsSsh r = do
		sshoptions <- repoConfig r "ssh-options" ""
		return $ Just $ ["ssh"] ++ words sshoptions ++ 
			[Git.urlHost r, sshcmd]
	| otherwise = return Nothing
	where
		dir = Git.workTree r
		shellcmd = "git-annex-shell"
		shellopts = command:dir:params
		sshcmd = shellcmd ++ " " ++ unwords (map shellEscape shellopts)

{- Looks up a per-remote config option in git config.
 - Failing that, tries looking for a global config option. -}
repoConfig :: Git.Repo -> String -> String -> Annex String
repoConfig r key def = do
	g <- Annex.gitRepo
	let def' = Git.configGet g global def
	return $ Git.configGet g local def'
	where
		local = "remote." ++ Git.repoRemoteName r ++ ".annex-" ++ key
		global = "annex." ++ key