Calendar invitation time proposals

[ChristophWurst]

This is related to nextcloud/calendar#5697.

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Problem Statement

As a calendar user, scheduling events with both internal and external parties can be challenging due to the lack of free-busy information for external attendees. This often results in a time-consuming back-and-forth process to find a suitable time slot for all participants.

Proposed Solution

Implement a feature that allows users to suggest multiple time slots for an event based on the availability of internal attendees and send personalized links to external attendees to select their preferred time slots.

Work packages

• feat: Meeting Proposals #53831
• feat: Meeting Proposals calendar#7072
• fix: actually create a talk room when converting proposal calendar#7398
• feat: Meeting proposals calendar time blockers calendar#7315
• fix: meeting proposals participant no reponse calendar#7396
• feat: meeting proposals documentation#13690

User Flow

1. Create Event:

   • User creates a new event with both internal and external attendees.

2. Find Available Time Slots:

   • System checks the free-busy information of internal attendees to suggest 3 (or more) available time slots.

3. Create Blocker Events:

   • System creates blocker events in the calendars of internal attendees for the suggested time slots.

4. Notify Internal Attendees:

   • Send an email to internal attendees informing them about the blocker events and the upcoming event.

5. Notify External Attendees:

   • Send an email to external attendees with personalized links to select their preferred time slots. They can select multiple slots or indicate that none of the slots work for them.

6. Store Responses:

   • Store the responses from external attendees and notify the organizer via email.

Happy Case Scenario:

7. Consensus on Time Slot:

   • If all external attendees agree on a time slot, create the actual event for that time slot.

8. Invite All Attendees:

   • Send invitations to all internal and external attendees for the confirmed event.

9. Remove Blocker Events:

   • Delete the blocker events from the calendars of internal attendees.

10. Notify Completion:

    • Send an email to all attendees confirming the event details and the removal of blocker events for internal attendees.

Unhappy Case Scenario:

7. No Consensus:

   • If no time slot works for all attendees (e.g., Bob cannot attend any slot), the organizer decides whether to proceed without Bob or reschedule the event.

8. Notify Decision:

   • Send an email to all attendees informing them of the organizer's decision.

Technical Considerations:

• Create a new database table in Nextcloud Calendar to manage event proposals.
• Each event proposal should have the following attributes:
  • Name
  • Description
  • Duration
  • Timezone
  • Date picker (for the earliest date)
  • List of attendees

[ericfischereu]

Here's a reference how others do it: https://support.microsoft.com/en-us/office/create-a-scheduling-poll-in-outlook-for-windows-34176e59-c87a-4a19-85a4-bb35050ace02

[SebastianKrupinski]

Feature Design Discussion Notes

User Experience - Organizer Creating Proposal

1. User clicks button in calendar left side bar "Meeting Proposal" (this opens a modal)
2. User selects meeting length, title, desciption and attendees (attendees should have option to be mandatory or optional)
3. As user adds attendees, available times are retrieved, filtered for common availability and displayed in a week view
4. Once user is done adding attendees, user can select the available times to propose for meetings
5. User clicks propose, which generates an email to all attendees with links to selection page (and ics event with tentative status?), and adds the selected time blocks to the calendar as tentative. This also adds calendar event to internal attendees calendars

User Experience - Organizer List/Modify/Delete Proposals

1. User would need a way to manage existing proposals?

User Experience - Attendee (using link)

1. User receives email and clicks link
2. Link opens informational page with proposed times, title and description
3. User selects a single proposed time
4. User confirms selection

User Experience - Attendee (using calendar)

1. User see tentative meeting in calendar and accepts or declines any the instance.

Technical - Organizer Creating Proposal

1. Generate free/busy array for organizer and attendees, when adding attendees on the fly and calculate available times in browser as attendees get added
2. On proposal submit, generate emails and tentative events for internal users (re-use iMip for both if possible, might need a flag in the event to disable emails, if not possible to reuse the existing emailing function)
3. Use recurring instances for selected dates to keep all information in one record

Technical - Attendee (using link)

1. When user confirms time, generate updated iMip, with attendee status confirmed (and send status to external users if we initially sent a ics).
2. Update proposal with user status

Technical - Attendee (using calendar)

1. Listen for CalendarUpdateEvent filter processing by custom property "X-SCHEDULING-PROPOSAL" and organizer

Technical - General

1. add field to calendar objects table to mark event as proposal
2. add custom property to calendar object to mark it as a proposal (until event is confirmed)
3. When all required attendees have a attending status, delete all other instances and send out imip update.