Proper conflict handling in the backend

Signed-off-by: Julius Härtl <jus@bitgrid.net>

5 files changed, 128 insertions, 26 deletions

diff --git a/lib/Controller/SessionController.php b/lib/Controller/SessionController.php
index 671c47078..58a2dd7d4 100644
--- a/lib/Controller/SessionController.php
+++ b/lib/Controller/SessionController.php
@@ -7,6 +7,7 @@ namespace OCA\Text\Controller;
 use OC\Files\Node\File;
 use OCA\Text\Service\DocumentService;
 use OCA\Text\Service\SessionService;
+use OCA\Text\VersionMismatchException;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\DataResponse;
 use OCP\AppFramework\Http\FileDisplayResponse;
@@ -85,8 +86,8 @@ class SessionController extends Controller {
 		if ($this->sessionService->isValidSession($documentId, $sessionId, $token)) {
 			try {
 				$steps = $this->documentService->addStep($documentId, $sessionId, $steps, $version);
-			} catch (\Exception $e) {
-				return new DataResponse($e->getMessage(), 500);
+			} catch (VersionMismatchException $e) {
+				return new DataResponse($e->getMessage(), $e->getStatus());
 			}
 			return new DataResponse($steps);
 		}
diff --git a/lib/Db/Document.php b/lib/Db/Document.php
index 5c1e30c06..07a1e64ce 100644
--- a/lib/Db/Document.php
+++ b/lib/Db/Document.php
@@ -33,6 +33,8 @@ class Document extends Entity implements \JsonSerializable {
 	protected $lastSavedVersion = 0;
 	protected $initialVersion = 0;
 	protected $lastSavedVersionTime = 0;
+	protected $lastSavedVersionEtag = '';
+	protected $baseVersionEtag = '';
 
 	public function __construct() {
 		$this->addType('id', 'integer');
diff --git a/lib/Db/StepMapper.php b/lib/Db/StepMapper.php
index 847409750..6b580ee9b 100644
--- a/lib/Db/StepMapper.php
+++ b/lib/Db/StepMapper.php
@@ -34,13 +34,20 @@ class StepMapper extends QBMapper {
 		parent::__construct($db, 'text_steps', Step::class);
 	}
 
-	public function find($documentId, $fromVersion) {
+	public function find($documentId, $fromVersion, $lastAckedVersion = null) {
 		/* @var $qb IQueryBuilder */
 		$qb = $this->db->getQueryBuilder();
 		$qb->select('*')
 			->from($this->getTableName())
 			->where($qb->expr()->eq('document_id', $qb->createNamedParameter($documentId)))
-			->andWhere($qb->expr()->gt('version', $qb->createNamedParameter($fromVersion)))
+			->andWhere($qb->expr()->gt('version', $qb->createNamedParameter($fromVersion)));
+		// WIP: only return steps that were persisted completely
+		if ($lastAckedVersion) {
+			$qb->andWhere($qb->expr()->lte('version', $qb->createNamedParameter($lastAckedVersion)));
+		}
+		$qb
+		// TODO: limiting results currently causes the loading detection to fail
+		//	->setMaxResults(500)
 			->execute();
 
 		return $this->findEntities($qb);
diff --git a/lib/Service/DocumentService.php b/lib/Service/DocumentService.php
index e8e605c86..d07aa8cb2 100644
--- a/lib/Service/DocumentService.php
+++ b/lib/Service/DocumentService.php
@@ -23,6 +23,8 @@
 
 namespace OCA\Text\Service;
 
+use http\Exception\InvalidArgumentException;
+use function json_encode;
 use OC\Files\Node\File;
 use OCA\Text\Db\Document;
 use OCA\Text\Db\DocumentMapper;
@@ -30,26 +32,32 @@ use OCA\Text\Db\SessionMapper;
 use OCA\Text\Db\Step;
 use OCA\Text\Db\StepMapper;
 use OCA\Text\DocumentSaveConflictException;
+use OCA\Text\VersionMismatchException;
 use OCP\AppFramework\Db\DoesNotExistException;
+use OCP\AppFramework\Db\Entity;
 use OCP\Files\IAppData;
 use OCP\Files\InvalidPathException;
 use OCP\Files\IRootFolder;
 use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
+use OCP\Files\SimpleFS\ISimpleFile;
 use OCP\ICacheFactory;
+use OCP\ILogger;
+use OCP\Lock\ILockingProvider;
 
 class DocumentService {
 
 	/**
 	 * Delay to wait for between autosave versions
 	 */
-	const AUTOSAVE_MINIMUM_DELAY = 10;
+	const AUTOSAVE_MINIMUM_DELAY = 60;
 
 	private $sessionMapper;
 	private $userId;
 	private $documentMapper;
+	private $logger;
 
-	public function __construct(SessionMapper $sessionMapper, DocumentMapper $documentMapper, StepMapper $stepMapper, IAppData $appData, $userId, IRootFolder $rootFolder, ICacheFactory $cacheFactory) {
+	public function __construct(SessionMapper $sessionMapper, DocumentMapper $documentMapper, StepMapper $stepMapper, IAppData $appData, $userId, IRootFolder $rootFolder, ICacheFactory $cacheFactory, ILogger $logger) {
 		$this->sessionMapper = $sessionMapper;
 		$this->documentMapper = $documentMapper;
 		$this->stepMapper = $stepMapper;
@@ -57,6 +65,7 @@ class DocumentService {
 		$this->appData = $appData;
 		$this->rootFolder = $rootFolder;
 		$this->cache = $cacheFactory->createDistributed('text');
+		$this->logger = $logger;
 
 		try {
 			$this->appData->getFolder('documents');
@@ -67,10 +76,10 @@ class DocumentService {
 
 	/**
 	 * @param $path
-	 * @return \OCP\AppFramework\Db\Entity
+	 * @return Entity
 	 * @throws NotFoundException
-	 * @throws \OCP\Files\InvalidPathException
-	 * @throws \OCP\Files\NotPermittedException
+	 * @throws InvalidPathException
+	 * @throws NotPermittedException
 	 */
 	public function createDocumentByPath($path) {
 		/** @var File $file */
@@ -80,10 +89,10 @@ class DocumentService {
 
 	/**
 	 * @param $fileId
-	 * @return \OCP\AppFramework\Db\Entity
+	 * @return Entity
 	 * @throws NotFoundException
-	 * @throws \OCP\Files\InvalidPathException
-	 * @throws \OCP\Files\NotPermittedException
+	 * @throws InvalidPathException
+	 * @throws NotPermittedException
 	 */
 	public function getDocumentById($fileId) {
 		return $this->createDocument($this->getFile($fileId));
@@ -94,23 +103,44 @@ class DocumentService {
 		return $this->rootFolder->getUserFolder($this->userId)->getById($fileId)[0];
 	}
 
+	public function getFileForShare($token) {
+
+		$userFolder = $this->rootFolder->getUserFolder($share->getShareOwner());
+		$originalSharePath = $userFolder->getRelativePath($share->getNode()->getPath());
+
+
+		// Single file share
+		if ($share->getNode() instanceof \OCP\Files\File) {
+			// Single file download
+			return $share->getNode();
+		}
+
+		return null;
+	}
+
 	/**
 	 * @param File $file
-	 * @return \OCP\AppFramework\Db\Entity
+	 * @return Entity
 	 * @throws NotFoundException
-	 * @throws \OCP\Files\InvalidPathException
-	 * @throws \OCP\Files\NotPermittedException
+	 * @throws InvalidPathException
+	 * @throws NotPermittedException
 	 */
 	protected function createDocument(File $file) {
 		try {
 			$document = $this->documentMapper->find($file->getFileInfo()->getId());
 
-			// TODO: do not hard reset if changed from outside since this will throw away possible steps
+			// Do not hard reset if changed from outside since this will throw away possible steps
+			// This way the user can still resolve conflicts in the editor view
+			if ($document->getLastSavedVersion() !== $document->getCurrentVersion()) {
+				$this->logger->debug('Unsaved steps but collission with file, continue collaborative editing');
+				return $document;
+			}
+
 			// TODO: Only do this when no sessions active, otherise we need to resolve the conflict differently
 			$lastMTime = $document->getLastSavedVersionTime();
 			if ($file->getMTime() > $lastMTime && $lastMTime > 0) {
 				$this->resetDocument($document->getId());
-				throw  new NotFoundException();
+				throw new NotFoundException();
 			}
 
 			return $document;
@@ -131,28 +161,37 @@ class DocumentService {
 		$document->setCurrentVersion(0);
 		$document->setLastSavedVersion(0);
 		$document->setLastSavedVersionTime($file->getFileInfo()->getMtime());
+		$document->setLastSavedVersionEtag($file->getEtag());
+		$document->setBaseVersionEtag($file->getEtag());
 		$document = $this->documentMapper->insert($document);
 		$this->cache->set('document-version-'.$document->getId(), 0);
 		return $document;
 	}
 
+	/**
+	 * @param $document
+	 * @return ISimpleFile
+	 * @throws NotFoundException
+	 */
 	public function getBaseFile($document) {
 		return $this->appData->getFolder('documents')->getFile($document);
 	}
 
 	/**
-	 * @param Document $document
+	 * @param $documentId
+	 * @param $sessionId
 	 * @param $steps
 	 * @param $version
 	 * @return array
-	 * @throws \Exception
+	 * @throws DoesNotExistException
+	 * @throws VersionMismatchException
 	 */
 	public function addStep($documentId, $sessionId, $steps, $version) {
 		// TODO lock for other step adding
 		// TODO check cache
 		$document = $this->documentMapper->find($documentId);
 		if ($version !== $document->getCurrentVersion()) {
-			throw new \Exception('Version does not match');
+			throw new VersionMismatchException('Version does not match');
 		}
 		$step = new Step();
 		$step->setData(\json_encode($steps));
@@ -172,30 +211,49 @@ class DocumentService {
 		return $this->stepMapper->find($documentId, $lastVersion);
 	}
 
+	/**
+	 * @param $documentId
+	 * @param $version
+	 * @param $autoaveDocument
+	 * @param bool $force
+	 * @param bool $manualSave
+	 * @return Document
+	 * @throws DocumentSaveConflictException
+	 * @throws DoesNotExistException
+	 * @throws InvalidPathException
+	 * @throws NotFoundException
+	 * @throws NotPermittedException
+	 * @throws \OCP\Files\GenericFileException
+	 */
 	public function autosave($documentId, $version, $autoaveDocument, $force = false, $manualSave = false) {
 		/** @var Document $document */
 		$document = $this->documentMapper->find($documentId);
-		if ($autoaveDocument === null) {
-			return $document;
-		}
-		$lastMTime = $document->getLastSavedVersionTime();
+
 		/** @var File $file */
 		$file = $this->rootFolder->getUserFolder($this->userId)->getById($documentId)[0];
-		if ($file->getMTime() > $lastMTime && $lastMTime > 0 && $force === false) {
+
+		$lastMTime = $document->getLastSavedVersionTime();
+		if ($lastMTime > 0 && $file->getEtag() !== $document->getLastSavedVersionEtag() && $force === false) {
 			throw new DocumentSaveConflictException('File changed in the meantime from outside');
 		}
+
+		if ($autoaveDocument === null) {
+			return $document;
+		}
+
 		// TODO: check for etag rather than mtime
 		// Do not save if version already saved
 		if (!$force && $version <= (string)$document->getLastSavedVersion()) {
 			return $document;
 		}
 		// Only save once every AUTOSAVE_MINIMUM_DELAY seconds
-		if ($file->getMTime() === $lastMTime && $lastMTime > time()- self::AUTOSAVE_MINIMUM_DELAY && $manualSave === false) {
+		if ($file->getMTime() === $lastMTime && $lastMTime > time() - self::AUTOSAVE_MINIMUM_DELAY && $manualSave === false) {
 			return $document;
 		}
 		$file->putContent($autoaveDocument);
 		$document->setLastSavedVersion($version);
 		$document->setLastSavedVersionTime(time());
+		$document->setLastSavedVersionEtag($file->getEtag());
 		$this->documentMapper->update($document);
 		return $document;
 	}
diff --git a/lib/VersionMismatchException.php b/lib/VersionMismatchException.php
new file mode 100644
index 000000000..b4b1ea1ad
--- /dev/null
+++ b/lib/VersionMismatchException.php
@@ -0,0 +1,34 @@
+<?php
+/**
+ * @copyright Copyright (c) 2019 Julius Härtl <jus@bitgrid.net>
+ *
+ * @author Julius Härtl <jus@bitgrid.net>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Text;
+
+
+use OCP\AppFramework\Http;
+
+class VersionMismatchException extends \Exception {
+
+	public function getStatus() {
+		return Http::STATUS_PRECONDITION_FAILED;
+	}
+}