{- 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 Control.Exception.Extensible (IOException)
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.Maybe
import Control.Monad (when)
import Control.Monad.State (liftIO)
import System.Environment
import System.Posix.Files
import System.Posix.Env (setEnv)

import RemoteClass
import Types
import qualified GitRepo as Git
import qualified Annex
import UUID
import Messages
import Locations
import Config
import Remote.Special
import Remote.Encryptable
import Crypto
import Key
import Content
import 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 = do
	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
		}

s3Setup :: UUID -> RemoteConfig -> Annex RemoteConfig
s3Setup u c = do
	-- verify configuration is sane
	c' <- encryptionSetup c
	let fullconfig = M.union c' defaults

	-- check bucket location to see if the bucket exists, and create it
	let datacenter = fromJust $ M.lookup "datacenter" fullconfig
	conn <- s3ConnectionRequired fullconfig
	showNote "checking bucket"
	loc <- liftIO $ getBucketLocation conn bucket 
	case loc of
		Right _ -> return ()
		Left err@(NetworkError _) -> s3Error err
		Left (AWSError _ _) -> do
			showNote $ "creating bucket in " ++ datacenter
			res <- liftIO $ createBucketIn conn bucket datacenter
			case res of
				Right _ -> return ()
				Left err -> s3Error err

	gitConfigSpecialRemote u fullconfig "s3" "true"
	s3SetCreds fullconfig
	where
		remotename = fromJust (M.lookup "name" c)
		bucket = remotename ++ "-" ++ u
		defaults = M.fromList
			[ ("datacenter", "US")
			, ("storageclass", "STANDARD")
			, ("host", defaultAmazonS3Host)
			, ("port", show defaultAmazonS3Port)
			, ("bucket", bucket)
			]

store :: Remote Annex -> Key -> Annex Bool
store r k = s3Action r False $ \(conn, bucket) -> do
	g <- Annex.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 <- Annex.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 <- case keySize k of
		Just s -> return $ fromIntegral s
		Nothing -> do
			s <- liftIO $ getFileStatus file
			return $ fileSize s
	let object = setStorageClass storageclass $ 
		S3Object bucket (show k) ""
			[("Content-Length",(show size))] content
	sendObject conn object
	where
		storageclass =
			case fromJust $ M.lookup "storageclass" $ fromJust $ config r of
				"REDUCED_REDUNDANCY" -> REDUCED_REDUNDANCY
				_ -> STANDARD

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

checkPresent :: Remote Annex -> Key -> Annex (Either IOException Bool)
checkPresent r k = s3Action r noconn $ \(conn, bucket) -> do
	showNote ("checking " ++ name r ++ "...")
	res <- liftIO $ getObjectInfo conn $ bucketKey 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 res = do
	case res of
		Right _ -> return True
		Left e -> s3Warning e

s3Action :: Remote Annex -> a -> ((AWSConnection, String) -> Annex a) -> Annex a
s3Action r noconn action = do
	when (config r == Nothing) $
		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

bucketKey :: String -> Key -> S3Object
bucketKey bucket k = S3Object bucket (show k) "" [] L.empty

s3ConnectionRequired :: RemoteConfig -> Annex AWSConnection
s3ConnectionRequired c = do
	conn <- s3Connection c
	case conn of
		Nothing -> error "Cannot connect to S3"
		Just conn' -> return conn'

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 line = lines s
					let ak' = line !! 0
					let sk' = line !! 1
					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"