starting work on import from S3

Not in a usuable state yet.

Remote/S3.hs

@@ -40,12 +40,14 @@ import Annex.Common
 import Types.Remote
 import Types.Export
 import qualified Git
+import qualified Annex
 import Config
 import Config.Cost
 import Remote.Helper.Special
 import Remote.Helper.Http
 import Remote.Helper.Messages
 import Remote.Helper.ExportImport
+import Types.Import
 import qualified Remote.Helper.AWS as AWS
 import Creds
 import Annex.UUID
@@ -71,7 +73,7 @@ remote = RemoteType
 	, generate = gen
 	, setup = s3Setup
 	, exportSupported = exportIsSupported
-	, importSupported = importUnsupported
+	, importSupported = importIsSupported
 	}
 
 gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
@@ -112,7 +114,14 @@ gen r u c gc = do
 				, removeExportDirectory = Nothing
 				, renameExport = renameExportS3 hdl this info
 				}
-			, importActions = importUnsupported
+			, importActions = ImportActions
+                                { listImportableContents = listImportableContentsS3 hdl this info
+                                , retrieveExportWithContentIdentifier = retrieveExportWithContentIdentifierS3 hdl info
+                                , storeExportWithContentIdentifier = storeExportWithContentIdentifierS3 hdl this info magic
+                                , removeExportWithContentIdentifier = removeExportWithContentIdentifierS3 hdl info
+                                , removeExportDirectoryWhenEmpty = Nothing
+                                , checkPresentExportWithContentIdentifier = checkPresentExportWithContentIdentifierS3 hdl info
+                                }
 			, whereisKey = Just (getPublicWebUrls u info c)
 			, remoteFsck = Nothing
 			, repairRepo = Nothing
@@ -150,8 +159,8 @@ s3Setup' ss u mcreds c gc
 		, ("bucket", defbucket)
 		]
 		
-	use fullconfig = do
+	use fullconfig info = do
-		enableBucketVersioning ss fullconfig gc u
+		enableBucketVersioning ss info fullconfig gc u
 		gitConfigSpecialRemote u fullconfig [("s3", "true")]
 		return (fullconfig, u)
 
@@ -159,10 +168,12 @@ s3Setup' ss u mcreds c gc
 		(c', encsetup) <- encryptionSetup c gc
 		c'' <- setRemoteCredPair encsetup c' gc (AWS.creds u) mcreds
 		let fullconfig = c'' `M.union` defaults
+		info <- extractS3Info fullconfig
+		checkexportimportsafe fullconfig info
 		case ss of
 			Init -> genBucket fullconfig gc u
 			_ -> return ()
-		use fullconfig
+		use fullconfig info
 
 	archiveorg = do
 		showNote "Internet Archive mode"
@@ -182,10 +193,26 @@ s3Setup' ss u mcreds c gc
 			-- special constraints on key names
 			M.insert "mungekeys" "ia" defaults
 		info <- extractS3Info archiveconfig
+		checkexportimportsafe archiveconfig info
 		hdl <- mkS3HandleVar archiveconfig gc u
 		withS3HandleOrFail u hdl $
 			writeUUIDFile archiveconfig u info
-		use archiveconfig
+		use archiveconfig info
+	
+	checkexportimportsafe c' info = 
+		checkexportimportsafe' c' info
+			=<< Annex.getState Annex.force
+	checkexportimportsafe' c' info force
+		| force = return ()
+		| versioning info = return ()
+		| exportTree c' && importTree c' = giveup $ unwords
+			[ "Combining exporttree=yes and importtree=yes"
+			, "with an unversioned S3 bucket is not safe;"
+			, "exporting can overwrite other modifications"
+			, "to files in the bucket."
+			, "Recommend you add versioning=yes."
+			, "(Or use --force if you don't mind possibly losing data.)"
+			]
 
 store :: S3HandleVar -> Remote -> S3Info -> Maybe Magic -> Storer
 store mh r info magic = fileStorer $ \k f p -> withS3HandleOrFail (uuid r) mh $ \h -> do
@@ -346,17 +373,21 @@ checkKeyHelper info h loc = liftIO $ runResourceT $ do
 #endif
 
 storeExportS3 :: S3HandleVar -> Remote -> S3Info -> Maybe Magic -> FilePath -> Key -> ExportLocation -> MeterUpdate -> Annex Bool
-storeExportS3 hv r info magic f k loc p = withS3Handle hv $ \case
+storeExportS3 hv r info magic f k loc p = fst
-	Just h -> catchNonAsync (go h) (\e -> warning (show e) >> return False)
+	<$> storeExportS3' hv r info magic f k loc p
+
+storeExportS3' :: S3HandleVar -> Remote -> S3Info -> Maybe Magic -> FilePath -> Key -> ExportLocation -> MeterUpdate -> Annex (Bool, Maybe S3VersionID)
+storeExportS3' hv r info magic f k loc p = withS3Handle hv $ \case
+	Just h -> catchNonAsync (go h) (\e -> warning (show e) >> return (False, Nothing))
 	Nothing -> do
 		warning $ needS3Creds (uuid r)
-		return False
+		return (False, Nothing)
   where
 	go h = do
 		let o = T.pack $ bucketExportLocation info loc
-		storeHelper info h magic f o p
+		mvid <- storeHelper info h magic f o p
-			>>= setS3VersionID info (uuid r) k
+		setS3VersionID info (uuid r) k mvid
-		return True
+		return (True, mvid)
 
 retrieveExportS3 :: S3HandleVar -> Remote -> S3Info -> Key -> ExportLocation -> FilePath -> MeterUpdate -> Annex Bool
 retrieveExportS3 hv r info _k loc f p =
@@ -420,6 +451,93 @@ renameExportS3 hv r info k src dest = Just <$> go
 	srcobject = T.pack $ bucketExportLocation info src
 	dstobject = T.pack $ bucketExportLocation info dest
 
+listImportableContentsS3 :: S3HandleVar -> Remote -> S3Info -> Annex (Maybe (ImportableContents (ContentIdentifier, ByteSize)))
+listImportableContentsS3 hv r info =
+	withS3Handle hv $ \case
+		Nothing -> do
+			warning $ needS3Creds (uuid r)
+			return Nothing
+		Just h -> catchMaybeIO $ liftIO $ runResourceT $ startlist h
+  where
+	startlist h
+		| versioning info = do
+			rsp <- sendS3Handle h $ 
+				S3.getBucketObjectVersions (bucket info)
+			liftIO $ print rsp
+			continuelistversioned h [] rsp
+		| otherwise = do
+			rsp <- sendS3Handle h $ 
+				S3.getBucket (bucket info)
+			liftIO $ print rsp
+			continuelistunversioned h [] rsp
+
+	continuelistunversioned h l rsp
+		| S3.gbrIsTruncated rsp = do
+			rsp' <- sendS3Handle h $
+				(S3.getBucket (bucket info))
+					{ S3.gbMarker = S3.gbrNextMarker rsp
+					}
+			liftIO $ print rsp'
+			continuelistunversioned h (rsp:l) rsp'
+		| otherwise = return (mklistunversioned (reverse (rsp:l)))
+	
+	continuelistversioned h l rsp
+		| S3.gbovrIsTruncated rsp = do
+			rsp' <- sendS3Handle h $
+				(S3.getBucketObjectVersions (bucket info))
+					{ S3.gbovKeyMarker = S3.gbovrNextKeyMarker rsp
+					, S3.gbovVersionIdMarker = S3.gbovrNextVersionIdMarker rsp
+					}
+			liftIO $ print rsp
+			continuelistversioned h (rsp:l) rsp'
+		| otherwise = return (mklistversioned (reverse (rsp:l)))
+	
+	mklistunversioned l = ImportableContents 
+		{ importableContents =
+			concatMap (mapMaybe go . S3.gbrContents) l
+		, importableHistory = []
+		}
+	  where
+	  	go oi = do
+			loc <- bucketImportLocation info $
+				T.unpack $ S3.objectKey oi
+			let sz  = S3.objectSize oi
+			let cid = mkS3UnversionedContentIdentifier $
+				S3.objectETag oi
+			return (loc, (cid, sz))
+	
+	mklistversioned l = ImportableContents [] [] -- FIXME
+
+retrieveExportWithContentIdentifierS3 :: S3HandleVar -> S3Info -> ExportLocation -> ContentIdentifier -> FilePath -> Annex (Maybe Key) -> MeterUpdate -> Annex (Maybe Key)
+retrieveExportWithContentIdentifierS3 hv info loc cid dest mkkey p = undefined
+
+-- Does not check if content on S3 is safe to overwrite, because there
+-- is no atomic way to do so. When the bucket is versioned, this is
+-- acceptable because listImportableContentsS3 will find versions
+-- of files that were overwritten by this and no data is lost.
+--
+-- When the bucket is not versioned, data loss can result.
+-- This is why that configuration requires --force to enable.
+storeExportWithContentIdentifierS3 :: S3HandleVar -> Remote -> S3Info -> Maybe Magic -> FilePath -> Key -> ExportLocation -> [ContentIdentifier] -> MeterUpdate -> Annex (Maybe ContentIdentifier)
+storeExportWithContentIdentifierS3 hv r info magic src k loc _overwritablecids p = 
+	storeExportS3' hv r info magic src k loc p >>= \case
+		(False, _) -> return Nothing
+		(True, Just vid) -> return $ Just $
+			mkS3VersionedContentIdentifier vid
+		(True, Nothing) -> return $ Just $
+			-- FIXME for an unversioned bucket, should use the etag
+			-- of the file, which is its md5sum, as the ContentIdentifier
+			-- NOT mempty!
+			-- This is blocked by 
+			-- https://github.com/aristidb/aws/issues/258
+			mkS3UnversionedContentIdentifier mempty
+
+removeExportWithContentIdentifierS3 :: S3HandleVar -> S3Info -> Key -> ExportLocation -> [ContentIdentifier] -> Annex Bool
+removeExportWithContentIdentifierS3 hv info k loc removeablecids = undefined
+
+checkPresentExportWithContentIdentifierS3 :: S3HandleVar -> S3Info -> Key -> ExportLocation -> [ContentIdentifier] -> Annex Bool
+checkPresentExportWithContentIdentifierS3 hv info _k loc knowncids = undefined
+
 {- Generate the bucket if it does not already exist, including creating the
  - UUID file within the bucket.
  -
@@ -611,6 +729,7 @@ data S3Info = S3Info
 	, storageClass :: S3.StorageClass
 	, bucketObject :: Key -> BucketObject
 	, bucketExportLocation :: ExportLocation -> BucketObject
+	, bucketImportLocation :: BucketObject -> Maybe ImportLocation
 	, metaHeaders :: [(T.Text, T.Text)]
 	, partSize :: Maybe Integer
 	, isIA :: Bool
@@ -631,6 +750,7 @@ extractS3Info c = do
 		, storageClass = getStorageClass c
 		, bucketObject = getBucketObject c
 		, bucketExportLocation = getBucketExportLocation c
+		, bucketImportLocation = getBucketImportLocation c
 		, metaHeaders = getMetaHeaders c
 		, partSize = getPartSize c
 		, isIA = configIA c
@@ -690,6 +810,19 @@ getBucketObject c = munge . serializeKey
 getBucketExportLocation :: RemoteConfig -> ExportLocation -> BucketObject
 getBucketExportLocation c loc = getFilePrefix c ++ fromExportLocation loc
 
+getBucketImportLocation :: RemoteConfig -> BucketObject -> Maybe ImportLocation
+getBucketImportLocation c obj
+	-- The uuidFile should not be imported.
+	| obj == uuidfile = Nothing
+	-- Only import files that are under the fileprefix, when
+	-- one is configured.
+	| prefix `isPrefixOf` obj = Just $ mkImportLocation $ drop prefixlen obj
+	| otherwise = Nothing
+  where
+	prefix = getFilePrefix c
+	prefixlen = length prefix
+	uuidfile = uuidFile c
+
 {- Internet Archive documentation limits filenames to a subset of ascii.
  - While other characters seem to work now, this entity encodes everything
  - else to avoid problems. -}
@@ -804,7 +937,11 @@ getPublicUrlMaker info = case publicurl info of
 				Just (iaPublicUrl info)
 		_ -> Nothing
 
-
+-- S3 uses a unique version id for each object stored on it.
+--
+-- The Object is included in this because retrieving a particular
+-- version id involves a request for an object, so this keeps track of what
+-- the object is.
 data S3VersionID = S3VersionID S3.Object T.Text
 	deriving (Show)
 
@@ -834,6 +971,20 @@ parseS3VersionID b = do
 	o <- eitherToMaybe $ T.decodeUtf8' $ BS.drop 1 rest
 	mkS3VersionID o (eitherToMaybe $ T.decodeUtf8' v)
 
+-- For a versioned bucket, the S3VersionID is used as the
+-- ContentIdentifier.
+mkS3VersionedContentIdentifier :: S3VersionID -> ContentIdentifier
+mkS3VersionedContentIdentifier (S3VersionID _ v) = 
+	ContentIdentifier $ T.encodeUtf8 v
+
+type S3Etag = T.Text
+
+-- For an unversioned bucket, the S3Etag is instead used as the
+-- ContentIdentifier.
+mkS3UnversionedContentIdentifier :: S3Etag -> ContentIdentifier
+mkS3UnversionedContentIdentifier t =
+	ContentIdentifier $ T.encodeUtf8 t
+
 setS3VersionID :: S3Info -> UUID -> Key -> Maybe S3VersionID -> Annex ()
 setS3VersionID info u k vid
 	| versioning info = maybe noop (setS3VersionID' u k) vid
@@ -881,13 +1032,12 @@ getS3VersionIDPublicUrls mk info u k =
 -- Enable versioning on the bucket can only be done at init time;
 -- setting versioning in a bucket that git-annex has already exported
 -- files to risks losing the content of those un-versioned files.
-enableBucketVersioning :: SetupStage -> RemoteConfig -> RemoteGitConfig -> UUID -> Annex ()
+enableBucketVersioning :: SetupStage -> S3Info -> RemoteConfig -> RemoteGitConfig -> UUID -> Annex ()
 #if MIN_VERSION_aws(0,21,1)
-enableBucketVersioning ss c gc u = do
+enableBucketVersioning ss info c gc u = do
 #else
-enableBucketVersioning ss c _ _ = do
+enableBucketVersioning ss info _ _ _ = do
 #endif
-	info <- extractS3Info c
 	case ss of
 		Init -> when (versioning info) $
 			enableversioning (bucket info)