From 34a2c840cd211e6eaadff0b700f4f6d135623462 Mon Sep 17 00:00:00 2001
From: Kevin Alberts <kevin@kevinalberts.nl>
Date: Thu, 12 Nov 2020 13:28:39 +0100
Subject: [PATCH] Do not re-upload events if they aren't changed.

---
 davinci/caldav/models.py                      | 28 ++++++++++++++-----
 .../management/commands/gcal_sync.py          |  4 +--
 .../management/commands/ical_sync.py          |  4 +--
 3 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/davinci/caldav/models.py b/davinci/caldav/models.py
index 677fd7b..ad0ef46 100644
--- a/davinci/caldav/models.py
+++ b/davinci/caldav/models.py
@@ -65,7 +65,7 @@ class CalDAVCalendar(models.Model):
                 return cal
         return None
 
-    def upload_events(self, events: List[Event], purge: bool = True, ignore_invalid_recurring: bool = False) -> Tuple[int, int, int]:
+    def upload_events(self, events: List[Event], purge: bool = True, ignore_invalid_recurring: bool = False) -> Tuple[int, int, int, int]:
         """
         Upload events to this calendar. If purge is True, all old events will be removed.
         :param events: The events to upload
@@ -74,8 +74,8 @@ class CalDAVCalendar(models.Model):
         :type purge: bool
         :param ignore_invalid_recurring: Whether to ignore errors when adding invalid recurring events (GCalendar does this)
         :type ignore_invalid_recurring: bool
-        :return Amount of events added, updated, and deleted
-        :rtype Tuple[int, int, int]
+        :return Amount of events added, updated, unchanged, and deleted
+        :rtype Tuple[int, int, int, int]
         """
         logger = logging.getLogger("davinci.icalendar.CalDAVCalendar.upload_events")
         calendar = self.get_calendar()
@@ -88,6 +88,7 @@ class CalDAVCalendar(models.Model):
 
         updated = 0
         added = 0
+        unchanged = 0
 
         # Import events
         for event in events:
@@ -102,8 +103,22 @@ class CalDAVCalendar(models.Model):
                 # Need to overwrite
                 try:
                     cevent = calendar.event_by_uid(event.uid)
-                    cevent.data = vcal.fix(ev)
-                    cevent.save()
+
+                    replace = False
+
+                    # If a sequence number is available, only overwrite if it is higher in the ICS event.
+                    if hasattr(cevent.vobject_instance.vevent, 'sequence') and any([x.name == "SEQUENCE" for x in event.extra]):
+                        ics_sequence = [x.value for x in event.extra if x.name == "SEQUENCE"][0]
+                        dav_sequence = cevent.vobject_instance.vevent.sequence.value
+                        if int(ics_sequence) > int(dav_sequence):
+                            replace = True
+
+                    if replace:
+                        cevent.data = vcal.fix(ev)
+                        cevent.save()
+                        updated += 1
+                    else:
+                        unchanged += 1
                 except Exception as e:
                     if ignore_invalid_recurring and len([x for x in event.extra if x.name == "RECURRENCE-ID"]) > 0:
                         # Recurring event from GCal, ignore
@@ -113,7 +128,6 @@ class CalDAVCalendar(models.Model):
                         logger.error(f"======EVENT======\n{ev}\n=================")
 
                 purge_uids.remove(event.uid)
-                updated += 1
 
             else:
                 try:
@@ -131,4 +145,4 @@ class CalDAVCalendar(models.Model):
         else:
             deleted = 0
 
-        return added, updated, deleted
+        return added, updated, unchanged, deleted
diff --git a/davinci/gcalendar/management/commands/gcal_sync.py b/davinci/gcalendar/management/commands/gcal_sync.py
index d2308b8..7096219 100644
--- a/davinci/gcalendar/management/commands/gcal_sync.py
+++ b/davinci/gcalendar/management/commands/gcal_sync.py
@@ -21,10 +21,10 @@ class Command(BaseCommand):
                 logger.debug(f"Synchronizing {sync.name}...")
 
                 events = sync.get_events()
-                added, existing, deleted = sync.target.upload_events(events, purge=sync.purge, ignore_invalid_recurring=True)
+                added, existing, unchanged, deleted = sync.target.upload_events(events, purge=sync.purge, ignore_invalid_recurring=True)
 
                 sync.last_sync = timezone.now()
                 sync.save()
-                logger.debug(f"Sync for {sync.name} done! {added} events added, {existing} updated, and {deleted} purged.")
+                logger.debug(f"Sync for {sync.name} done! {added} events added, {existing} updated, {unchanged} unchanged, and {deleted} purged.")
 
         logger.debug("iCal sync complete!")
diff --git a/davinci/icalendar/management/commands/ical_sync.py b/davinci/icalendar/management/commands/ical_sync.py
index f3000eb..b3bc44b 100644
--- a/davinci/icalendar/management/commands/ical_sync.py
+++ b/davinci/icalendar/management/commands/ical_sync.py
@@ -21,10 +21,10 @@ class Command(BaseCommand):
                 logger.debug(f"Synchronizing {sync.name}...")
 
                 events = sync.get_events()
-                added, existing, deleted = sync.target.upload_events(events, purge=sync.purge)
+                added, existing, unchanged, deleted = sync.target.upload_events(events, purge=sync.purge)
 
                 sync.last_sync = timezone.now()
                 sync.save()
-                logger.debug(f"Sync for {sync.name} done! {added} events added, {existing} updated, and {deleted} purged.")
+                logger.debug(f"Sync for {sync.name} done! {added} events added, {existing} updated. {unchanged} unchanged, and {deleted} purged.")
 
         logger.debug("iCal sync complete!")