{- Credentials storage
 -
 - Copyright 2012-2014 Joey Hess <id@joeyh.name>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Creds (
	module Types.Creds,
	CredPairStorage(..),
	setRemoteCredPair,
	getRemoteCredPairFor,
	getRemoteCredPair,
	getEnvCredPair,
	writeCacheCreds,
	readCacheCreds,
	removeCreds,
	includeCredsInfo,
) where

import Common.Annex
import Types.Creds
import Annex.Perms
import Utility.FileMode
import Crypto
import Types.Remote (RemoteConfig, RemoteConfigKey)
import Remote.Helper.Encryptable (remoteCipher, remoteCipher', embedCreds, EncryptionIsSetup, extractCipher)
import Utility.Env (getEnv)

import qualified Data.ByteString.Lazy.Char8 as L
import qualified Data.Map as M
import Utility.Base64

{- A CredPair can be stored in a file, or in the environment, or perhaps
 - in a remote's configuration. -}
data CredPairStorage = CredPairStorage
	{ credPairFile :: FilePath
	, credPairEnvironment :: (String, String)
	, credPairRemoteKey :: Maybe RemoteConfigKey
	}

{- Stores creds in a remote's configuration, if the remote allows
 - that. Also caches them locally.
 -
 - The creds are found from the CredPairStorage storage if not provided,
 - so may be provided by an environment variable etc.
 -
 - The remote's configuration should have already had a cipher stored in it
 - if that's going to be done, so that the creds can be encrypted using the
 - cipher. The EncryptionIsSetup phantom type ensures that is the case.
 -}
setRemoteCredPair :: EncryptionIsSetup -> RemoteConfig -> CredPairStorage -> Maybe CredPair -> Annex RemoteConfig
setRemoteCredPair encsetup c storage Nothing = 
	maybe (return c) (setRemoteCredPair encsetup c storage . Just)
		=<< getRemoteCredPair c storage
setRemoteCredPair _ c storage (Just creds)
	| embedCreds c = case credPairRemoteKey storage of
		Nothing -> localcache
		Just key -> storeconfig key =<< remoteCipher =<< localcache
	| otherwise = localcache
  where
	localcache = do
		writeCacheCredPair creds storage
		return c

	storeconfig key (Just cipher) = do
		s <- liftIO $ encrypt (getGpgEncParams c) cipher
			(feedBytes $ L.pack $ encodeCredPair creds)
			(readBytes $ return . L.unpack)
		return $ M.insert key (toB64 s) c
	storeconfig key Nothing =
		return $ M.insert key (toB64 $ encodeCredPair creds) c

{- Gets a remote's credpair, from the environment if set, otherwise
 - from the cache in gitAnnexCredsDir, or failing that, from the
 - value in RemoteConfig. -}
getRemoteCredPairFor :: String -> RemoteConfig -> CredPairStorage -> Annex (Maybe CredPair)
getRemoteCredPairFor this c storage = maybe missing (return . Just) =<< getRemoteCredPair c storage
  where
	(loginvar, passwordvar) = credPairEnvironment storage
	missing = do
		warning $ unwords
			[ "Set both", loginvar
			, "and", passwordvar
			, "to use", this
			]
		return Nothing

getRemoteCredPair :: RemoteConfig -> CredPairStorage -> Annex (Maybe CredPair)
getRemoteCredPair c storage = maybe fromcache (return . Just) =<< fromenv
  where
	fromenv = liftIO $ getEnvCredPair storage
	fromcache = maybe fromconfig (return . Just) =<< readCacheCredPair storage
	fromconfig = case credPairRemoteKey storage of
		Just key -> do
			mcipher <- remoteCipher' c
			case (M.lookup key c, mcipher) of
				(Nothing, _) -> return Nothing
				(Just enccreds, Just (cipher, storablecipher)) ->
					fromenccreds enccreds cipher storablecipher
				(Just bcreds, Nothing) ->
					fromcreds $ fromB64 bcreds
		Nothing -> return Nothing
	fromenccreds enccreds cipher storablecipher = do
		mcreds <- liftIO $ catchMaybeIO $ decrypt cipher
			(feedBytes $ L.pack $ fromB64 enccreds)
			(readBytes $ return . L.unpack)
		case mcreds of
			Just creds -> fromcreds creds
			Nothing -> do
				-- Work around un-encrypted creds storage
				-- bug in old S3 and glacier remotes.
				-- Not a problem for shared cipher.
				case storablecipher of
					SharedCipher {} -> showLongNote "gpg error above was caused by an old git-annex bug in credentials storage. Working around it.."
					_ -> error "*** Insecure credentials storage detected for this remote! See https://git-annex.branchable.com/upgrades/insecure_embedded_creds/"
				fromcreds $ fromB64 enccreds
	fromcreds creds = case decodeCredPair creds of
		Just credpair -> do
			writeCacheCredPair credpair storage

			return $ Just credpair
		_ -> error "bad creds"

{- Gets a CredPair from the environment. -}
getEnvCredPair :: CredPairStorage -> IO (Maybe CredPair)
getEnvCredPair storage = liftM2 (,)
	<$> getEnv uenv
	<*> getEnv penv
  where
	(uenv, penv) = credPairEnvironment storage

writeCacheCredPair :: CredPair -> CredPairStorage -> Annex ()
writeCacheCredPair credpair storage =
	writeCacheCreds (encodeCredPair credpair) (credPairFile storage)

{- Stores the creds in a file inside gitAnnexCredsDir that only the user
 - can read. -}
writeCacheCreds :: Creds -> FilePath -> Annex ()
writeCacheCreds creds file = do
	d <- fromRepo gitAnnexCredsDir
	createAnnexDirectory d
	liftIO $ writeFileProtected (d </> file) creds

readCacheCredPair :: CredPairStorage -> Annex (Maybe CredPair)
readCacheCredPair storage = maybe Nothing decodeCredPair
	<$> readCacheCreds (credPairFile storage)

readCacheCreds :: FilePath -> Annex (Maybe Creds)
readCacheCreds f = liftIO . catchMaybeIO . readFile =<< cacheCredsFile f

cacheCredsFile :: FilePath -> Annex FilePath
cacheCredsFile basefile = do
	d <- fromRepo gitAnnexCredsDir
	return $ d </> basefile

existsCacheCredPair :: CredPairStorage -> Annex Bool
existsCacheCredPair storage = 
	liftIO . doesFileExist =<< cacheCredsFile (credPairFile storage)

encodeCredPair :: CredPair -> Creds
encodeCredPair (l, p) = unlines [l, p]

decodeCredPair :: Creds -> Maybe CredPair
decodeCredPair creds = case lines creds of
	l:p:[] -> Just (l, p)
	_ -> Nothing

removeCreds :: FilePath -> Annex ()
removeCreds file = do
	d <- fromRepo gitAnnexCredsDir
	let f = d </> file
	liftIO $ nukeFile f

includeCredsInfo :: RemoteConfig -> CredPairStorage -> [(String, String)] -> Annex [(String, String)]
includeCredsInfo c storage info = do
	v <- liftIO $ getEnvCredPair storage
	case v of
		Just _ -> do
			let (uenv, penv) = credPairEnvironment storage
			ret $ "from environment variables (" ++ unwords [uenv, penv] ++ ")"
		Nothing -> case (\ck -> M.lookup ck c) =<< credPairRemoteKey storage of
			Nothing -> ifM (existsCacheCredPair storage)
				( ret "stored locally"
				, ret "not available"
				)
			Just _ -> case extractCipher c of
				Just (EncryptedCipher _ _ _) -> ret "embedded in git repository (gpg encrypted)"
				_ -> ret "embedded in git repository (not encrypted)"
  where
	ret s = return $ ("creds", s) : info