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

module Command where

import Control.Monad.State (liftIO)
import System.Directory
import System.Posix.Files
import Control.Monad (filterM)
import System.Path.WildMatch
import Text.Regex.PCRE.Light.Char8

import Types
import qualified Backend
import Messages
import qualified Annex
import qualified GitRepo as Git
import Locations

{- A subcommand runs in four stages.
 -
 - 0. The seek stage takes the parameters passed to the subcommand,
 -    looks through the repo to find the ones that are relevant
 -    to that subcommand (ie, new files to add), and generates
 -    a list of start stage actions. -}
type SubCmdSeek = [String] -> Annex [SubCmdStart]
{- 1. The start stage is run before anything is printed about the
  -   subcommand, is passed some input, and can early abort it
  -   if the input does not make sense. It should run quickly and
  -   should not modify Annex state. -}
type SubCmdStart = Annex (Maybe SubCmdPerform)
{- 2. The perform stage is run after a message is printed about the subcommand
 -    being run, and it should be where the bulk of the work happens. -}
type SubCmdPerform = Annex (Maybe SubCmdCleanup)
{- 3. The cleanup stage is run only if the perform stage succeeds, and it
 -    returns the overall success/fail of the subcommand. -}
type SubCmdCleanup = Annex Bool
{- Some helper functions are used to build up SubCmdSeek and SubCmdStart
 - functions. -}
type SubCmdSeekStrings = SubCmdStartString -> SubCmdSeek
type SubCmdStartString = String -> SubCmdStart
type BackendFile = (FilePath, Maybe Backend)
type SubCmdSeekBackendFiles = SubCmdStartBackendFile -> SubCmdSeek
type SubCmdStartBackendFile = BackendFile -> SubCmdStart
type AttrFile = (FilePath, String)
type SubCmdSeekAttrFiles = SubCmdStartAttrFile -> SubCmdSeek
type SubCmdStartAttrFile = AttrFile -> SubCmdStart
type SubCmdSeekNothing = SubCmdStart -> SubCmdSeek
type SubCmdStartNothing = SubCmdStart

data SubCommand = SubCommand {
	subcmdname :: String,
	subcmdparams :: String,
	subcmdseek :: [SubCmdSeek],
	subcmddesc :: String
}

{- Prepares a list of actions to run to perform a subcommand, based on
 - the parameters passed to it. -}
prepSubCmd :: SubCommand -> [String] -> Annex [Annex Bool]
prepSubCmd SubCommand { subcmdseek = seek } params = do
	lists <- mapM (\s -> s params) seek
	return $ map doSubCmd $ foldl (++) [] lists

{- Runs a subcommand through the start, perform and cleanup stages -}
doSubCmd :: SubCmdStart -> SubCmdCleanup
doSubCmd start = do
	s <- start
	case s of
		Nothing -> return True
		Just perform -> do
			p <- perform
			case p of
				Nothing -> do
					showEndFail
					return False
				Just cleanup -> do
					c <- cleanup
					if c
						then do
							showEndOk
							return True
						else do
							showEndFail
							return False

notAnnexed :: FilePath -> Annex (Maybe a) -> Annex (Maybe a)
notAnnexed file a = do
	r <- Backend.lookupFile file
	case r of
		Just _ -> return Nothing
		Nothing -> a

isAnnexed :: FilePath -> ((Key, Backend) -> Annex (Maybe a)) -> Annex (Maybe a)
isAnnexed file a = do
	r <- Backend.lookupFile file
	case r of
		Just v -> a v
		Nothing -> return Nothing

{- These functions find appropriate files or other things based on a
   user's parameters, and run a specified action on them. -}
withFilesInGit :: SubCmdSeekStrings
withFilesInGit a params = do
	repo <- Annex.gitRepo
	files <- liftIO $ Git.inRepo repo params
	files' <- filterFiles files
	return $ map a files'
withAttrFilesInGit :: String -> SubCmdSeekAttrFiles
withAttrFilesInGit attr a params = do
	repo <- Annex.gitRepo
	files <- liftIO $ Git.inRepo repo params
	files' <- filterFiles files
	pairs <- liftIO $ Git.checkAttr repo attr files'
	return $ map a pairs
withFilesMissing :: SubCmdSeekStrings
withFilesMissing a params = do
	files <- liftIO $ filterM missing params
	files' <- filterFiles files
	return $ map a files'
	where
		missing f = do
			e <- doesFileExist f
			return $ not e
withFilesNotInGit :: SubCmdSeekBackendFiles
withFilesNotInGit a params = do
	repo <- Annex.gitRepo
	newfiles <- liftIO $ Git.notInRepo repo params
	newfiles' <- filterFiles newfiles
	backendPairs a newfiles'
withString :: SubCmdSeekStrings
withString a params = return [a $ unwords params]
withStrings :: SubCmdSeekStrings
withStrings a params = return $ map a params
withFilesToBeCommitted :: SubCmdSeekStrings
withFilesToBeCommitted a params = do
	repo <- Annex.gitRepo
	tocommit <- liftIO $ Git.stagedFiles repo params
	tocommit' <- filterFiles tocommit
	return $ map a tocommit'
withFilesUnlocked :: SubCmdSeekBackendFiles
withFilesUnlocked = withFilesUnlocked' Git.typeChangedFiles
withFilesUnlockedToBeCommitted :: SubCmdSeekBackendFiles
withFilesUnlockedToBeCommitted = withFilesUnlocked' Git.typeChangedStagedFiles
withFilesUnlocked' :: (Git.Repo -> [FilePath] -> IO [FilePath]) -> SubCmdSeekBackendFiles
withFilesUnlocked' typechanged a params = do
	-- unlocked files have changed type from a symlink to a regular file
	repo <- Annex.gitRepo
	typechangedfiles <- liftIO $ typechanged repo params
	unlockedfiles <- liftIO $ filterM notSymlink $
		map (\f -> Git.workTree repo ++ "/" ++ f) typechangedfiles
	unlockedfiles' <- filterFiles unlockedfiles
	backendPairs a unlockedfiles'
withKeys :: SubCmdSeekStrings
withKeys a params = return $ map a params
withTempFile :: SubCmdSeekStrings
withTempFile a params = return $ map a params
withNothing :: SubCmdSeekNothing
withNothing a [] = return [a]
withNothing _ _ = return []

backendPairs :: SubCmdSeekBackendFiles
backendPairs a files = do
	pairs <- Backend.chooseBackends files
	return $ map a pairs

{- Default to acting on all files matching the seek action if
 - none are specified. -}
withAll :: (a -> SubCmdSeek) -> a -> SubCmdSeek
withAll w a [] = do
	g <- Annex.gitRepo
	w a [Git.workTree g]
withAll w a p = w a p

{- Provides a default parameter to act on if none is specified. -}
withDefault :: String-> (a -> SubCmdSeek) -> (a -> SubCmdSeek)
withDefault d w a [] = w a [d]
withDefault _ w a p = w a p

{- Filter out files from the state directory, and those matching the
 - exclude glob pattern, if it was specified. -}
filterFiles :: [FilePath] -> Annex [FilePath]
filterFiles l = do
	let l' = filter notState l
	exclude <- Annex.flagGet "exclude"
	if null exclude
		then return l'
		else do
			let regexp = compile ("^" ++ wildToRegex exclude) []
			return $ filter (notExcluded regexp) l'
	where
		notState f = stateLoc /= take stateLocLen f
		stateLocLen = length stateLoc
		notExcluded r f = case match r f [] of
			Nothing -> True
			Just _ -> False

{- filter out symlinks -}	
notSymlink :: FilePath -> IO Bool
notSymlink f = do
	s <- liftIO $ getSymbolicLinkStatus f
	return $ not $ isSymbolicLink s