Include support for X-LOOL-WOPI-Timestamp

See for more detailed message:
https://github.com/owncloud/richdocuments/pull/178

lib/Controller/WopiController.php

@@ -38,6 +38,9 @@ class WopiController extends Controller {
 	/** @var IRootFolder */
 	private $rootFolder;
 
+	// Signifies LOOL that document has been changed externally in this storage
+	const LOOL_STATUS_DOC_CHANGED = 1010;
+
 	/**
 	 * @param string $appName
 	 * @param IRequest $request
@@ -95,6 +98,7 @@ class WopiController extends Controller {
 				'UserFriendlyName' => $res['editor'] !== '' ? \OC_User::getDisplayName($res['editor']) : 'Guest user',
 				'UserCanWrite' => $res['canwrite'] ? true : false,
 				'PostMessageOrigin' => $res['server_host'],
+				'LastModifiedTime' => Helper::toISO8601($file->getMtime())
 			]
 		);
 	}
@@ -169,10 +173,23 @@ class WopiController extends Controller {
 			return new JSONResponse([], Http::STATUS_FORBIDDEN);
 		}
 
+
+
 		try {
 			/** @var File $file */
 			$userFolder = $this->rootFolder->getUserFolder($res['owner']);
 			$file = $userFolder->getById($fileId)[0];
+
+			$wopiHeaderTime = $this->request->getHeader('X-LOOL-WOPI-Timestamp');
+			if (!is_null($wopiHeaderTime) && $wopiHeaderTime != Helper::toISO8601($file->getMTime())) {
+				\OC::$server->getLogger()->debug('Document timestamp mismatch ! WOPI client says mtime {headerTime} but storage says {storageTime}', [
+					'headerTime' => $wopiHeaderTime,
+					'storageTime' => Helper::toISO8601($file->getMtime())
+				]);
+				// Tell WOPI client about this conflict.
+				return new JSONResponse(['LOOLStatusCode' => self::LOOL_STATUS_DOC_CHANGED], Http::STATUS_CONFLICT);
+			}
+
 			$content = fopen('php://input', 'rb');
 			// Setup the FS which is needed to emit hooks (versioning).
 			\OC_Util::tearDownFS();
@@ -185,7 +202,7 @@ class WopiController extends Controller {
 			}
 
 			$file->putContent($content);
-			return new JSONResponse();
+			return new JSONResponse(['LastModifiedTime' => Helper::toISO8601($file->getMtime())]);
 		} catch (\Exception $e) {
 			return new JSONResponse([], Http::STATUS_INTERNAL_SERVER_ERROR);
 		}

lib/helper.php

@@ -11,6 +11,9 @@
 
 namespace OCA\Richdocuments;
 
+use \DateTime;
+use \DateTimeZone;
+
 class Helper {
 	const APP_ID = 'richdocuments';
 
@@ -41,6 +44,19 @@ class Helper {
 		];
 	}
 
+	/**
+	 * WOPI helper function to convert to ISO 8601 round-trip format.
+	 * @param integer $time Must be seconds since unix epoch
+	 */
+	public static function toISO8601($time)
+	{
+		// TODO: Be more precise and don't ignore milli, micro seconds ?
+		$datetime = DateTime::createFromFormat('U', $time, new DateTimeZone('UTC'));
+		if ($datetime)
+			return $datetime->format('Y-m-d\TH:i:s.u\Z');
+
+		return false;
+	}
 
 	public static function getNewFileName($view, $path, $prepend = ' '){
 		$fileNum = 1;