Thunderbird: How to access the calendar?

Question

I'm planning to develop a tool (running on the Windows PC) which allows comparing and merging calendar events between different calendars. My mobile device and my Lightning calendar should be supported.

The idea is to write an App for my mobile device connecting to the tool via TCP or UDP so the tool is able to modify the mobile device's calendar by sending commands to the App.

Unfortunately I'm not aware on how I can access the Thunderbird Lightning calendar with my tool.

Question 1: (Possibility 1)

Is it possible to access the Thunderbird (Lightning) calendar read/write from another application (e.g. by directly accessing the SQLite archive) in a safe way?

"In a safe way" means: No risk that the calendar format changes in the next Lightning release and writing events will destroy it!

Question 2: (Possibility 2)

Is there a possibility to access the Lightning calendar data from another Thunderbird plug-in?

(I was searching about this in Google for 2 hours and found nothing!)

Is it possible to create a "permanent" TCP connection from a Thunderbird plug-in (running some operations in the background)?

Answer 1

I would advise against option 1, but if you must then you can check the version table to see if the storage version has changed. This doesn't happen very often. As for accessing calendar data, you can reach the calendar manager and events as follows:

Components.utils.import("resource://calendar/modules/calUtils.jsm"); 

let calmgr = cal.getCalendarManager();
let calendars = calmgr.getCalendars({});
let mycal = calendars[0]; // pick one

The calendar in mycal will follow the calICalendar interface, which you can read about here. The most important methods are addItem, modifyItem, deleteItem, getItem and getItems.

As for creating a permanent connection from within Thunderbird, it is probably best to use web sockets, which you should be able to use from any DOM window. It might make sense to create your own e.g. with an iframe.