Allow editing on publicly shared calendars

Public calendar links are great, but would be even better if there was a possibility for the external (guest) user to add items and edit the calendar in the same way as with files and folders.

This would be useful for example a collaborative booking calendar, where customers could see availible times and choose a time to book. (Add but not delete) Or if you and a friend would like to collaborate on a schedule for a vacation, or whatever. (Full permissions)

Idk if it's possible, but would it be doable to generate several public links to the same calendar? In that case give full permissions, send a temporary generated link to 1 external user that expires in lets say 15 minutes, where that user only can edit/delete his/her own stuff but add on all the available times.

It would also be nice to password protect public calendars.

What do you think @georgehrke and others?

The issue names no files, tests, or entry points to start from. First clarify whether the goal is guest editing, add-only booking, per-user ownership, expiring links, password protection, or several separate features; done would require an agreed scope and permissions model.