From 4fa67d25dd5c23e2fff3fd7b5ad9468f1ba1ebad Mon Sep 17 00:00:00 2001
From: Stefan Ollinger <Stefan.Ollinger@gmx.de>
Date: Tue, 30 Apr 2024 16:57:00 +0200
Subject: [PATCH] Fixed duplicate RECURRENCE-ID when expanding events

---
 caldav/objects.py    |  3 ++-
 tests/test_caldav.py | 56 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/caldav/objects.py b/caldav/objects.py
index a08a808..9e14022 100644
--- a/caldav/objects.py
+++ b/caldav/objects.py
@@ -2027,7 +2027,8 @@ def expand_rrule(self, start: datetime, end: datetime) -> None:
         calendar = self.icalendar_instance
         calendar.subcomponents = []
         for occurrence in recurrings:
-            occurrence.add("RECURRENCE-ID", occurrence.get("DTSTART"))
+            if "RECURRENCE-ID" not in occurrence:
+                occurrence.add("RECURRENCE-ID", occurrence.get("DTSTART"))
             calendar.add_component(occurrence)
         # add other components (except for the VEVENT itself and VTIMEZONE which is not allowed on occurrence events)
         for component in stripped_event.icalendar_instance.subcomponents:
diff --git a/tests/test_caldav.py b/tests/test_caldav.py
index c6dfb21..b0efa1b 100644
--- a/tests/test_caldav.py
+++ b/tests/test_caldav.py
@@ -21,6 +21,7 @@
 from datetime import timedelta
 from datetime import timezone
 
+import icalendar
 import pytest
 import requests
 import vobject
@@ -174,6 +175,35 @@
 END:VEVENT
 END:VCALENDAR"""
 
+# example created by editing a specific occurrence of a recurrent event via Thunderbird
+evr2 = """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN
+BEGIN:VEVENT
+UID:c26921f4-0653-11ef-b756-58ce2a14e2e5
+DTSTART;VALUE=DATE:20240411
+DTEND;VALUE=DATE:20240412
+DTSTAMP:20240429T181103Z
+LAST-MODIFIED:20240429T181103Z
+RRULE:FREQ=WEEKLY;INTERVAL=2
+SEQUENCE:1
+SUMMARY:Test
+X-MOZ-GENERATION:1
+END:VEVENT
+BEGIN:VEVENT
+UID:c26921f4-0653-11ef-b756-58ce2a14e2e5
+RECURRENCE-ID;VALUE=DATE:20240425
+DTSTART;VALUE=DATE:20240425
+DTEND;VALUE=DATE:20240426
+CREATED:20240429T181031Z
+DTSTAMP:20240429T181103Z
+LAST-MODIFIED:20240429T181103Z
+SEQUENCE:1
+SUMMARY:Test (edited)
+X-MOZ-GENERATION:1
+END:VEVENT
+END:VCALENDAR"""
+
 # example from http://www.rfc-editor.org/rfc/rfc5545.txt
 todo = """BEGIN:VCALENDAR
 VERSION:2.0
@@ -2505,7 +2535,7 @@ def testRecurringDateSearch(self):
         self.skip_on_compatibility_flag("no_search")
         c = self._fixCalendar()
 
-        # evr is a yearly event starting at 1997-02-11
+        # evr is a yearly event starting at 1997-11-02
         e = c.save_event(evr)
 
         ## Without "expand", we should still find it when searching over 2008 ...
@@ -2583,6 +2613,30 @@ def testRecurringDateSearch(self):
             assert len(r) == 1
         assert r[0].data.count("END:VEVENT") == 1
 
+    def testRecurringDateWithExceptionSearch(self):
+        c = self._fixCalendar()
+
+        # evr2 is a bi-weekly event starting 2024-04-11
+        e = c.save_event(evr2)
+
+        r = c.search(
+            start=datetime(2024, 3, 31, 0, 0),
+            end=datetime(2024, 5, 4, 0, 0, 0),
+            event=True,
+            expand=True,
+        )
+
+        assert len(r) == 2
+
+        assert 'RRULE' not in r[0].data
+        assert 'RRULE' not in r[1].data
+
+        assert isinstance(r[0].icalendar_component['RECURRENCE-ID'], icalendar.vDDDTypes)
+        assert r[0].icalendar_component['RECURRENCE-ID'].dt == date(2024, 4, 11)
+
+        assert isinstance(r[1].icalendar_component['RECURRENCE-ID'], icalendar.vDDDTypes)
+        assert r[1].icalendar_component['RECURRENCE-ID'].dt == date(2024, 4, 25)
+
     def testOffsetURL(self):
         """
         pass a URL pointing to a calendar or a user to the DAVClient class,