From 0747d038452babeefcb9b6faf0925aa7828f77a3 Mon Sep 17 00:00:00 2001
From: Thomas Citharel <tcit@tcit.fr>
Date: Fri, 3 Jan 2025 20:15:35 +0100
Subject: [PATCH] fix(caldav): rename default calendar to keep it in the
 trashbin instead of purging it

When doing a PROPFIND on default-calendar-url, if the current default calendar (fallbacking on personal uri)
is in the trashbin, it's being purged so that it's recreated.

This leads to loss of data.

We can simply rename the calendar URI and add a unique suffix so that it doesn't conflict with the new calendar
being created.
Shares are fine because they reference the resourceid and not the calendar URI.

Signed-off-by: Thomas Citharel <tcit@tcit.fr>
---
 apps/dav/lib/CalDAV/Schedule/Plugin.php       | 28 +++++++++++++------
 .../tests/unit/CalDAV/Schedule/PluginTest.php |  2 +-
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/apps/dav/lib/CalDAV/Schedule/Plugin.php b/apps/dav/lib/CalDAV/Schedule/Plugin.php
index d7c2a735dae5e..1574792c6f06f 100644
--- a/apps/dav/lib/CalDAV/Schedule/Plugin.php
+++ b/apps/dav/lib/CalDAV/Schedule/Plugin.php
@@ -143,7 +143,7 @@ protected function getAddressesForPrincipal($principal) {
 		if ($result === null) {
 			$result = [];
 		}
-		
+
 		// iterate through items and html decode values
 		foreach ($result as $key => $value) {
 			$result[$key] = urldecode($value);
@@ -202,12 +202,12 @@ 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);
 		}
@@ -435,12 +435,20 @@ 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);
@@ -577,7 +585,7 @@ private function isAvailableAtTime(string $email, \DateTimeInterface $start, \Da
 		$homePath = $result[0][200]['{' . self::NS_CALDAV . '}calendar-home-set']->getHref();
 		/** @var \OCA\DAV\CalDAV\Calendar $node */
 		foreach ($this->server->tree->getNodeForPath($homePath)->getChildren() as $node) {
-			
+
 			if (!$node instanceof ICalendar) {
 				continue;
 			}
@@ -709,6 +717,10 @@ 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.
 	 *
diff --git a/apps/dav/tests/unit/CalDAV/Schedule/PluginTest.php b/apps/dav/tests/unit/CalDAV/Schedule/PluginTest.php
index 15e598389c142..7a1d61a083b25 100644
--- a/apps/dav/tests/unit/CalDAV/Schedule/PluginTest.php
+++ b/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);