# ViaVox

Sync Microsoft 365 calendar (and soon contacts) into Nextcloud.

ViaVox is the Nextcloud companion app for the **ViaVox Syncer** service: a
webhook-based Microsoft Graph → Nextcloud CalDAV bridge that keeps Outlook /
Exchange Online calendars in sync with each Nextcloud user's personal
calendar, both directions, in near-real-time.

This repo distributes the **Nextcloud app** half of the stack. The companion
syncer service is deployed separately (admins configure its URL + shared
token).

## What it does

- Each Nextcloud user can connect / disconnect their own Microsoft 365
  account from **Settings → Personal → ViaVox**.
- Once connected, Outlook events flow into the user's personal calendar via
  webhook notifications (no polling), and edits made in Nextcloud Calendar
  flow back to Outlook.
- Recurring meetings — including exceptions, cancellations, DST transitions,
  attendees and RSVPs — are handled end-to-end.
- **Duplicate cleanup**: surfaces meetings that Exchange minted twice (a fresh
  `vCal-Uid` per iTip round-trip, e.g. when a room is added to an existing
  meeting) and lets the user remove a copy. The delete is fail-closed and
  provenance-gated — only offered when every copy is provably a Microsoft 365
  item — with a per-user lock against concurrent deletes.
- An admin overview shows per-user connection status and sync health, plus an
  hourly watcher that notifies a user (bell + optional email) if their sync
  goes offline.

## Nextcloud scheduling / iTip is deliberately turned off

Microsoft 365 is the authoritative scheduler for connected users. If Nextcloud
*also* ran its own iTip scheduling, every cross-user meeting would get a second,
NC-minted copy and duplicate invitation emails would go out. ViaVox therefore
suppresses Nextcloud's built-in calendar scheduling on three layers:

1. **No iTip emails** — a repair step sets `dav.sendInvitations=no` on install
   and after every migration, so Nextcloud never emails iTip
   invitations/cancellations for connected users.
2. **No iTip on the CalDAV path** — a Sabre plugin sets `x-nc-scheduling: false`
   on every calendar-object `PUT`/`DELETE`, short-circuiting Nextcloud's
   scheduler. This also prevents the 403 ("event cannot be deleted") that NC's
   scheduler raises when a room/resource attendee is involved.
3. **No iTip on internal paths** — a listener covers the internal
   `ICreateFromString` paths (Talk-scheduled meetings, Calendar bookings /
   proposals) that bypass the standard CalDAV route.

Microsoft 365 owns invitations and cancellations end to end; Nextcloud mirrors
the result without generating its own scheduling traffic.

## Install

1. **Download** the latest `viavox-X.Y.Z.tgz` release asset (see the
   **Releases** page).
2. Extract into your Nextcloud installation's `apps/` directory so that
   `apps/viavox/appinfo/info.xml` exists:

   ```bash
   tar xzf viavox-0.8.22.tar.gz -C /var/www/nextcloud/apps/
   chown -R www-data:www-data /var/www/nextcloud/apps/viavox
   ```

3. Enable the app:

   ```bash
   occ app:enable viavox
   ```

4. As an admin, open **Settings → Administration → ViaVox**, enter the
   ViaVox Syncer base URL and shared NC-app token, hit *Save* and then
   *Test connection*.
5. Each user can now open **Settings → Personal → ViaVox** and click
   *Connect Microsoft 365* to start syncing.

## Requirements

- Nextcloud 32 – 34 (verified compatible with Nextcloud 34).
- PHP 8.1 – 8.4.
- A reachable ViaVox Syncer instance (separately deployed).
- A Microsoft 365 tenant with an App Registration that has
  `Calendars.ReadWrite` delegated permission.

> **Operator note:** keep `dav calendarRetentionObligation` unset (the default)
> while the duplicate-cleanup feature is in use, so a removed copy stays
> restorable from the Nextcloud trash bin.

## License

AGPL-3.0-or-later. See `COPYING` inside the package.

## Support

For installation help or to report issues, contact the maintainer (see
`appinfo/info.xml` for the e-mail address).