fix(caldav): rename default calendar to keep it in the trashbin instead of purging it

apps/dav/lib/CalDAV/Schedule/Plugin.php

@@ -138,7 +138,7 @@ protected function getAddressesForPrincipal($principal) {
 		if ($result === null) {
 			$result = [];
 		}
-		
+
 		// iterate through items and html decode values
 		foreach ($result as $key => $value) {
 			$result[$key] = urldecode($value);
@@ -197,12 +197,12 @@ public function calendarObjectChange(RequestInterface $request, ResponseInterfac
 			}
 			// process request
 			$this->processICalendarChange($currentObject, $vCal, $addresses, [], $modified);
-	
+
 			if ($currentObject) {
 				// Destroy circular references so PHP will GC the object.
 				$currentObject->destroy();
 			}
-			
+
 		} catch (SameOrganizerForAllComponentsException $e) {
 			$this->handleSameOrganizerException($e, $vCal, $calendarPath);
 		}
@@ -430,12 +430,20 @@ public function propFindDefaultCalendarUrl(PropFind $propFind, INode $node) {
 						} else {
 							// Otherwise if we have really nothing, create a new calendar
 							if ($currentCalendarDeleted) {
-								// If the calendar exists but is deleted, we need to purge it first
-								// This may cause some issues in a non synchronous database setup
+								// If the calendar exists but is in the trash bin, we try to rename its uri
+								// so that we can create the new one and still restore the previous one
+								// otherwise we just purge the calendar by removing it before recreating it
 								$calendar = $this->getCalendar($calendarHome, $uri);
 								if ($calendar instanceof Calendar) {
-									$calendar->disableTrashbin();
-									$calendar->delete();
+									$backend = $calendarHome->getCalDAVBackend();
+									if ($backend instanceof CalDavBackend) {
+										// If the CalDAV backend supports moving calendars
+										$this->moveCalendar($backend, $principalUrl, $uri, $uri . '-back-' . time());
+									} else {
+										// Otherwise just purge the calendar
+										$calendar->disableTrashbin();
+										$calendar->delete();
+									}
 								}
 							}
 							$this->createCalendar($calendarHome, $principalUrl, $uri, $displayName);
@@ -572,7 +580,7 @@ private function isAvailableAtTime(string $email, \DateTimeInterface $start, \Da
 		$homePath = $result[0][200]['{' . self::NS_CALDAV . '}calendar-home-set']->getHref();
 		/** @var Calendar $node */
 		foreach ($this->server->tree->getNodeForPath($homePath)->getChildren() as $node) {
-			
+
 			if (!$node instanceof ICalendar) {
 				continue;
 			}
@@ -704,6 +712,10 @@ private function createCalendar(CalendarHome $calendarHome, string $principalUri
 		]);
 	}
 
+	private function moveCalendar(CalDavBackend $calDavBackend, string $principalUri, string $oldUri, string $newUri): void {
+		$calDavBackend->moveCalendar($oldUri, $principalUri, $principalUri, $newUri);
+	}
+
 	/**
 	 * Try to handle the given exception gracefully or throw it if necessary.
 	 *

apps/dav/tests/unit/CalDAV/Schedule/PluginTest.php

@@ -353,7 +353,7 @@ public function testPropFindDefaultCalendarUrl(string $principalUri, ?string $ca
 						'{DAV:}displayname' => $displayName,
 					]);
 
-				$calendarHomeObject->expects($this->once())
+				$calendarHomeObject->expects($this->exactly($deleted ? 2 : 1))
 					->method('getCalDAVBackend')
 					->with()
 					->willReturn($calendarBackend);