From 0cacd98f23287edb4aa2b8b0d6cfda185f2dde52 Mon Sep 17 00:00:00 2001
From: Kevin Alberts <kevin@kevinalberts.nl>
Date: Wed, 11 Nov 2020 21:20:45 +0100
Subject: [PATCH] Add padding to each event UID to avoid conflicts when adding
 same events/icalendars to caldav calendars.

---
 davinci/icalendar/ical_utils.py | 19 +++++++++++++++++++
 davinci/icalendar/models.py     |  6 +++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/davinci/icalendar/ical_utils.py b/davinci/icalendar/ical_utils.py
index 25cc53c..39c0017 100644
--- a/davinci/icalendar/ical_utils.py
+++ b/davinci/icalendar/ical_utils.py
@@ -1,6 +1,11 @@
+from typing import List
 from urllib.request import urlopen
 
 import ics
+from django.utils.text import slugify
+from ics import Event
+
+from davinci.caldav.models import CalDAVCalendar
 
 
 def get_ical_from_url(ical_url):
@@ -11,3 +16,17 @@ def get_ical_from_url(ical_url):
 def split_events(data):
     c = ics.Calendar(data.decode('utf-8'))
     return c.events
+
+
+def fix_ical_uid(event: Event, padding: str):
+    e = event.clone()
+    e.uid = f"{event.uid}{padding}"
+    return e
+
+
+def fix_ical_uids(events: List[Event], calendar: CalDAVCalendar):
+    # Pad the uids with some string related to the calendar
+    # So that if someone wants to sync the same .ics to two calendars, the UIDs are different. We will do this by
+    # appending the string "@slugified-server-name+slugified-username+slugified-calendar-name" to each uid.
+    padding = f"@{slugify(calendar.server.name)}+{slugify(calendar.server.username)}+{slugify(calendar.name)}"
+    return [fix_ical_uid(event, padding) for event in events]
diff --git a/davinci/icalendar/models.py b/davinci/icalendar/models.py
index 485b288..1e48a9a 100644
--- a/davinci/icalendar/models.py
+++ b/davinci/icalendar/models.py
@@ -30,4 +30,8 @@ class ICalSync(models.Model):
 
     def get_events(self):
         data = ical_utils.get_ical_from_url(self.ical_url)
-        return ical_utils.split_events(data)
+        events = ical_utils.split_events(data)
+        # We have to pad the uids with some string related to the target calendar,
+        # So that if someone wants to sync the same .ics to two calendars, the UIDs are different.
+        fixed_events = ical_utils.fix_ical_uids(events, self.target)
+        return fixed_events