Introducing metadata collections in dav

This change is to have metadata collection
in dav app. This will help users to:
1) Create fileid with a UUID
2) Create subfolder "p" inside "meta" folder
3) Create subfolder "v" inside "meta" folder
The "p" folder stands for preview and "v"
folder stands for version.

Signed-off-by: Sujith H <sharidasan@owncloud.com>

apps/dav/lib/MetaData/MetaDataHome.php

@@ -0,0 +1,102 @@
+<?php
+/**
+ * @author Sujith Haridasan <shariadsan@owncloud.com>
+ *
+ * @copyright Copyright (c) 2017, ownCloud GmbH
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+
+namespace OCA\DAV\MetaData;
+
+
+use OC\Files\Meta\MetaVersionCollection;
+use OCP\IMetaData;
+use Sabre\DAV\Exception\Forbidden;
+use Sabre\DAV\Exception\MethodNotAllowed;
+use Sabre\DAV\Exception\NotFound;
+use Sabre\DAV\ICollection;
+use Sabre\HTTP\URLUtil;
+
+class MetaDataHome implements ICollection {
+
+	/** @var array */
+
+	private $metaData;
+
+	/**
+	 * MetaDataHome constructor.
+	 */
+	public function __construct() {
+	}
+
+	function createFile($name, $data = null) {
+		throw new Forbidden('Permission denied to create a file');
+	}
+
+	function createDirectory($name) {
+		throw new Forbidden('Permission denied to create a folder');
+	}
+
+	function getChild($name) {
+		$metaVersion = new MetaVersionCollection('');
+		return new MetaDataNode($metaVersion);
+	}
+
+	function getChildren() {
+		try {
+			return [
+				$this->getChild('')
+			];
+		} catch(NotFound $exception) {
+			return [];
+		}
+	}
+
+	function childExists($name) {
+		try {
+			$ret = $this->getChild($name);
+			return !is_null($ret);
+		} catch (NotFound $ex) {
+			return false;
+		} catch (MethodNotAllowed $ex) {
+			return false;
+		}
+	}
+
+	function delete() {
+		throw new Forbidden('Permission denied to delete this folder');
+	}
+
+	function getName() {
+		return "meta";
+	}
+
+	function setName($name) {
+		throw new Forbidden('Permission denied to rename this folder');
+	}
+
+	/**
+	 * Returns the last modification time, as a unix timestamp
+	 *
+	 * @return int
+	 */
+	function getLastModified() {
+		return null;
+	}
+
+
+}

apps/dav/lib/MetaData/MetaDataNode.php

@@ -0,0 +1,89 @@
+<?php
+/**
+ * @author Sujith Haridasan <sharidasan@owncloud.com>
+ *
+ * @copyright Copyright (c) 2017, ownCloud GmbH
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+
+namespace OCA\DAV\MetaData;
+
+
+use OC\Files\Meta\MetaVersionCollection;
+use OCP\IMetaData;
+use Sabre\DAV\File;
+
+class MetaDataNode {
+
+	private $metaVersionCollection;
+	/**
+	 * MetaDataNode constructor.
+	 *
+	 */
+	public function __construct(MetaVersionCollection $metaVersionCollection) {
+		$this->metaVersionCollection = $metaVersionCollection;
+	}
+
+	/**
+	 * Get the fileVersion Node
+	 *
+	 * @param $fileName
+	 * @return \OCP\Files\Node
+	 */
+	public function getFileVersion($fileName) {
+		return $this->metaVersionCollection->get($fileName);
+	}
+
+	/**
+	 * Get the name of the file
+	 *
+	 * @return string
+	 */
+	public function getName() {
+		return $this->metaVersionCollection->getName();
+	}
+
+	/**
+	 * Returns the content of the file version
+	 *
+	 * @param $fileName
+	 * @return false|string
+	 */
+	public function getFileVersionContent($fileName) {
+		$getVersion = $this->getFileVersion($fileName);
+		$path = $getVersion->getPath();
+		return $this->metaVersionCollection->getStorage()->file_get_contents($path);
+	}
+
+	/**
+	 * Returns a list of versions (path) associated with file
+	 *
+	 * @param $fileName
+	 * @return array
+	 */
+	public function getVersionsOfFile() {
+		$nodeVersionList = [];
+		$fileList = $this->metaVersionCollection->getDirectoryListing();
+
+		foreach ($fileList as $file) {
+			array_push($nodeVersionList, $file->getInternalPath());
+		}
+
+		return $nodeVersionList;
+	}
+
+}

apps/dav/lib/RootCollection.php

@@ -92,6 +92,8 @@ public function __construct() {
 		$avatarCollection = new Avatars\RootCollection($userPrincipalBackend, 'principals/users');
 		$avatarCollection->disableListing = $disableListing;
 
+		$metaDataCollection = new MetaData\MetaDataHome();
+
 		$children = [
 				new SimpleCollection('principals', [
 						$userPrincipals,
@@ -106,7 +108,8 @@ public function __construct() {
 				$systemTagCollection,
 				$systemTagRelationsCollection,
 				$uploadCollection,
-				$avatarCollection
+				$metaDataCollection,
+				$avatarCollection,
 		];
 
 		parent::__construct('root', $children);