{- Amazon S3 remotes.
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

module Remote.S3 (remote) where

import Network.AWS.AWSConnection
import Network.AWS.S3Object
import Network.AWS.S3Bucket hiding (size)
import Network.AWS.AWSResult
import qualified Data.ByteString.Lazy.Char8 as L
import qualified Data.Map as M
import Data.Char
import System.Environment
import System.Posix.Env (setEnv)

import Common.Annex
import Types.Remote
import Types.Key
import qualified Git
import UUID
import Config
import Remote.Helper.Special
import Remote.Helper.Encryptable
import Crypto
import Annex.Content
import Utility.Base64

remote :: RemoteType Annex
remote = RemoteType {
	typename = "S3",
	enumerate = findSpecialRemotes "s3",
	generate = gen,
	setup = s3Setup
}

gen :: Git.Repo -> UUID -> Maybe RemoteConfig -> Annex (Remote Annex)
gen r u c = do
	cst <- remoteCost r expensiveRemoteCost
	return $ gen' r u c cst
gen' :: Git.Repo -> UUID -> Maybe RemoteConfig -> Int -> Remote Annex
gen' r u c cst =
	encryptableRemote c
		(storeEncrypted this)
		(retrieveEncrypted this)
		this
	where
		this = Remote {
			uuid = u,
			cost = cst,
			name = Git.repoDescribe r,
	 		storeKey = store this,
			retrieveKeyFile = retrieve this,
			removeKey = remove this,
			hasKey = checkPresent this,
			hasKeyCheap = False,
			config = c,
			repo = r
		}

s3Setup :: UUID -> RemoteConfig -> Annex RemoteConfig
s3Setup u c = handlehost $ M.lookup "host" c
	where
		remotename = fromJust (M.lookup "name" c)
		defbucket = remotename ++ "-" ++ u
		defaults = M.fromList
			[ ("datacenter", "US")
			, ("storageclass", "STANDARD")
			, ("host", defaultAmazonS3Host)
			, ("port", show defaultAmazonS3Port)
			, ("bucket", defbucket)
			]
		
		handlehost Nothing = defaulthost
		handlehost (Just h)
			| ".archive.org" `isSuffixOf` map toLower h = archiveorg
			| otherwise = defaulthost

		use fullconfig = do
			gitConfigSpecialRemote u fullconfig "s3" "true"
			s3SetCreds fullconfig	

		defaulthost = do
			c' <- encryptionSetup c
			let fullconfig = c' `M.union` defaults
			genBucket fullconfig
			use fullconfig

		archiveorg = do
			showNote "Internet Archive mode"
			maybe (error "specify bucket=") (const $ return ()) $
				M.lookup "bucket" archiveconfig
			use archiveconfig
			where
				archiveconfig =
					-- hS3 does not pass through
					-- x-archive-* headers
					M.mapKeys (replace "x-archive-" "x-amz-") $
					-- encryption does not make sense here
					M.insert "encryption" "none" $
					M.union c $
					-- special constraints on key names
					M.insert "mungekeys" "ia" $
					-- bucket created only when files
					-- are uploaded
					M.insert "x-amz-auto-make-bucket" "1" $
					-- no default bucket name; should
					-- be human-readable
					M.delete "bucket" defaults

store :: Remote Annex -> Key -> Annex Bool
store r k = s3Action r False $ \(conn, bucket) -> do
	g <- gitRepo
	res <- liftIO $ storeHelper (conn, bucket) r k $ gitAnnexLocation g k
	s3Bool res

storeEncrypted :: Remote Annex -> (Cipher, Key) -> Key -> Annex Bool
storeEncrypted r (cipher, enck) k = s3Action r False $ \(conn, bucket) -> 
	-- To get file size of the encrypted content, have to use a temp file.
	-- (An alternative would be chunking to to a constant size.)
	withTmp enck $ \tmp -> do
		g <- gitRepo
		let f = gitAnnexLocation g k
		liftIO $ withEncryptedContent cipher (L.readFile f) $ \s -> L.writeFile tmp s
		res <- liftIO $ storeHelper (conn, bucket) r enck tmp
		s3Bool res

storeHelper :: (AWSConnection, String) -> Remote Annex -> Key -> FilePath -> IO (AWSResult ())
storeHelper (conn, bucket) r k file = do
	content <- liftIO $ L.readFile file
	-- size is provided to S3 so the whole content does not need to be
	-- buffered to calculate it
	size <- maybe getsize (return . fromIntegral) $ keySize k
	let object = setStorageClass storageclass $ 
		S3Object bucket (bucketFile r k) ""
			(("Content-Length", show size) : xheaders) content
	sendObject conn object
	where
		storageclass =
			case fromJust $ M.lookup "storageclass" $ fromJust $ config r of
				"REDUCED_REDUNDANCY" -> REDUCED_REDUNDANCY
				_ -> STANDARD
		getsize = do
			s <- liftIO $ getFileStatus file
			return $ fileSize s
		
		xheaders = filter isxheader $ M.assocs $ fromJust $ config r
		isxheader (h, _) = "x-amz-" `isPrefixOf` h

retrieve :: Remote Annex -> Key -> FilePath -> Annex Bool
retrieve r k f = s3Action r False $ \(conn, bucket) -> do
	res <- liftIO $ getObject conn $ bucketKey r bucket k
	case res of
		Right o -> do
			liftIO $ L.writeFile f $ obj_data o
			return True
		Left e -> s3Warning e

retrieveEncrypted :: Remote Annex -> (Cipher, Key) -> FilePath -> Annex Bool
retrieveEncrypted r (cipher, enck) f = s3Action r False $ \(conn, bucket) -> do
	res <- liftIO $ getObject conn $ bucketKey r bucket enck
	case res of
		Right o -> liftIO $ 
			withDecryptedContent cipher (return $ obj_data o) $ \content -> do
				L.writeFile f content
				return True
		Left e -> s3Warning e

remove :: Remote Annex -> Key -> Annex Bool
remove r k = s3Action r False $ \(conn, bucket) -> do
	res <- liftIO $ deleteObject conn $ bucketKey r bucket k
	s3Bool res

checkPresent :: Remote Annex -> Key -> Annex (Either IOException Bool)
checkPresent r k = s3Action r noconn $ \(conn, bucket) -> do
	showAction $ "checking " ++ name r
	res <- liftIO $ getObjectInfo conn $ bucketKey r bucket k
	case res of
		Right _ -> return $ Right True
		Left (AWSError _ _) -> return $ Right False
		Left e -> return $ Left (s3Error e)
	where
		noconn = Left $ error "S3 not configured"
			
s3Warning :: ReqError -> Annex Bool
s3Warning e = do
	warning $ prettyReqError e
	return False

s3Error :: ReqError -> a
s3Error e = error $ prettyReqError e

s3Bool :: AWSResult () -> Annex Bool
s3Bool (Right _) = return True
s3Bool (Left e) = s3Warning e

s3Action :: Remote Annex -> a -> ((AWSConnection, String) -> Annex a) -> Annex a
s3Action r noconn action = do
	when (isNothing $ config r) $
		error $ "Missing configuration for special remote " ++ name r
	let bucket = M.lookup "bucket" $ fromJust $ config r
	conn <- s3Connection $ fromJust $ config r
	case (bucket, conn) of
		(Just b, Just c) -> action (c, b)
		_ -> return noconn

bucketFile :: Remote Annex -> Key -> FilePath
bucketFile r = munge . show
	where
		munge s = case M.lookup "mungekeys" $ fromJust $ config r of
			Just "ia" -> iaMunge s
			_ -> s

bucketKey :: Remote Annex -> String -> Key -> S3Object
bucketKey r bucket k = S3Object bucket (bucketFile r k) "" [] L.empty

{- Internet Archive limits filenames to a subset of ascii,
 - with no whitespace. Other characters are xml entity
 - encoded. -}
iaMunge :: String -> String
iaMunge = (>>= munge)
	where
		munge c
			| isAsciiUpper c || isAsciiLower c || isNumber c = [c]
			| c `elem` "_-.\"" = [c]
			| isSpace c = []
			| otherwise = "&" ++ show (ord c) ++ ";"

genBucket :: RemoteConfig -> Annex ()
genBucket c = do
	conn <- s3ConnectionRequired c
	showAction "checking bucket"
	loc <- liftIO $ getBucketLocation conn bucket 
	case loc of
		Right _ -> return ()
		Left err@(NetworkError _) -> s3Error err
		Left (AWSError _ _) -> do
			showAction $ "creating bucket in " ++ datacenter
			res <- liftIO $ createBucketIn conn bucket datacenter
			case res of
				Right _ -> return ()
				Left err -> s3Error err
	where
		bucket = fromJust $ M.lookup "bucket" c
		datacenter = fromJust $ M.lookup "datacenter" c

s3ConnectionRequired :: RemoteConfig -> Annex AWSConnection
s3ConnectionRequired c =
	maybe (error "Cannot connect to S3") return =<< s3Connection c

s3Connection :: RemoteConfig -> Annex (Maybe AWSConnection)
s3Connection c = do
	creds <- s3GetCreds c
	case creds of
		Just (ak, sk) -> return $ Just $ AWSConnection host port ak sk
		_ -> do
			warning $ "Set both " ++ s3AccessKey ++ " and " ++ s3SecretKey  ++ " to use S3"
			return Nothing
	where
		host = fromJust $ M.lookup "host" c
		port = let s = fromJust $ M.lookup "port" c in
			case reads s of
			[(p, _)] -> p
			_ -> error $ "bad S3 port value: " ++ s

{- S3 creds come from the environment if set. 
 - Otherwise, might be stored encrypted in the remote's config. -}
s3GetCreds :: RemoteConfig -> Annex (Maybe (String, String))
s3GetCreds c = do
	ak <- getEnvKey s3AccessKey
	sk <- getEnvKey s3SecretKey
	if null ak || null sk
		then do
			mcipher <- remoteCipher c
			case (M.lookup "s3creds" c, mcipher) of
				(Just encrypted, Just cipher) -> do
					s <- liftIO $ withDecryptedContent cipher
						(return $ L.pack $ fromB64 encrypted)
						(return . L.unpack)
					let [ak', sk', _rest] = lines s
					liftIO $ do
						setEnv s3AccessKey ak True
						setEnv s3SecretKey sk True
					return $ Just (ak', sk')
				_ -> return Nothing
		else return $ Just (ak, sk)
	where
		getEnvKey s = liftIO $ catch (getEnv s) (const $ return "")

{- Stores S3 creds encrypted in the remote's config if possible. -}
s3SetCreds :: RemoteConfig -> Annex RemoteConfig
s3SetCreds c = do
	creds <- s3GetCreds c
	case creds of
		Just (ak, sk) -> do
			mcipher <- remoteCipher c
			case mcipher of
				Just cipher -> do
					s <- liftIO $ withEncryptedContent cipher
						(return $ L.pack $ unlines [ak, sk])
						(return . L.unpack)
					return $ M.insert "s3creds" (toB64 s) c
				Nothing -> return c
		_ -> return c

s3AccessKey :: String
s3AccessKey = "AWS_ACCESS_KEY_ID"
s3SecretKey :: String
s3SecretKey = "AWS_SECRET_ACCESS_KEY"