feat: Google calendar sync

[PavloNetrebchuk]

Fix Google Calendar Integration

Problem

Calendar events were not appearing in Google Calendar. 441

Root Cause

The code was attempting to use CALLER_IS_SYNCADAPTER=true URI parameter, which is only available to actual sync adapters, not regular Android applications. This caused calendar and event operations to fail silently.

Why Regular Apps Can't Use CALLER_IS_SYNCADAPTER

The CALLER_IS_SYNCADAPTER parameter is a security and permission mechanism in Android's Calendar Provider:

1. Security Model: Sync adapters are system-level components that must be declared in AndroidManifest.xml with specific permissions and metadata. They are granted elevated privileges to modify calendar data across accounts.

2. Permission Requirements: To use CALLER_IS_SYNCADAPTER, an app must:

   • Be declared as a sync adapter in the manifest
   • Have a corresponding AccountAuthenticator
   • Be registered with the system's sync framework
   • Have the android.permission.WRITE_SYNC_SETTINGS permission

3. Regular App Limitations: Regular applications (like our OpenEdX app) cannot:

   • Create calendars in Google accounts using sync adapter URIs
   • Use sync adapter URIs for event operations
   • Delete Google calendars (only Google's sync adapter can do this)

4. What Happens When Used Incorrectly: When a regular app tries to use CALLER_IS_SYNCADAPTER=true:

   • The Calendar Provider ignores the parameter or rejects the operation
   • Operations fail silently without throwing exceptions
   • No calendar/events are created, but no error is reported

Solution

1. Fixed Calendar Creation

• Before: Attempted to create calendars using sync adapter URI (failed silently)
• After:
  • First tries to find an existing Google Calendar (primary or any writable)
  • If found, uses that calendar ID so events sync to Google Calendar
  • If no Google Calendar exists, creates a local calendar
  • Uses standard CalendarContract.Calendars.CONTENT_URI instead of sync adapter URI

2. Fixed Event Operations

• Before: Attempted to use sync adapter URI for adding/deleting events
• After: Uses standard CalendarContract.Events.CONTENT_URI
  • Events automatically sync to Google Calendar if the calendar is a Google Calendar
  • Works correctly for both Google and local calendars

3. Fixed Calendar Deletion

• Before: Only deleted calendar, leaving events behind
• After:
  • First deletes all events in the calendar
  • For Google Calendars: Only deletes events (cannot delete the calendar itself)
  • For local calendars: Deletes both events and the calendar
  • Uses proper ContentUris.withAppendedId() for URI construction

Limitation ⚠️

Because the application lacks permissions to create calendars and can only insert events into the user’s default calendar, it is not possible to customize calendar properties such as name or color.

---

Creating google calendar:

Screen.Recording.2025-12-05.at.13.56.40.mov

Creating local calendar:

Screen.Recording.2025-12-15.at.15.30.07.mov

[openedx-webhooks]

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[volodymyr-chekyrta]

LGTM

[IvanStepanok]

LGTM