Load history and first set of new messages with 1 API request

[nickvergessen]

Ref #8710

🚧 TODO

• Add endpoint to get the message context
  • Integration tests
• Use for first load of messages when entering a chat
• Revert not setting the read marker
• JS/Frontend Test
  • Check guests behaviour
  • Check self-joined users behaviour
  • Check revisiting a check room
  • Check behaviour with more than 100 unread messages (context end)
  • Check behaviour with more than 300 unread messages (first future end)

🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included
• 📘 API documentation in docs/ has been updated or is not required
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required
• 🔖 Capability is added or not needed

[nickvergessen]

Scenarios I tested:

🗯 Message 1-150
🗯 Message 151  === lastReadMessage (from API)
🗯 Message 152-170

🗯 Message 1-150
🗯 Message 151  === lastReadMessage (from API)
🗯 Message 152-300

🗯 Message 1-150
😄 Reactions 1-150 on Message 150
🗯 Message 151  === lastReadMessage (from API)
🗯 Message 152-300

🗯 Message 1-150
🗯 Message 151  === lastReadMessage (from API)
😄 Reactions 1-150 on Message 151
🗯 Message 152-300

🗯 Message 1-150
😄 Reactions 1-150 on Message 150
😄 Reactions 150  === lastReadMessage (from API)
🗯 Message 152-300

All of them produce an acceptable state after loading the chat (better or equal to the previous behaviour). Some could still be improved in terms of scrolling off-set but that was already the case before, so I think we can keep it like that for now.

Any (edge) cases I forgot?

[danxuliu]

Any (edge) cases I forgot?

I would also test the reaction scenarios with a deleted message instead of a reaction, and with a command from another participant that is not visible for the user loading the chat instead of a reaction.

[nickvergessen]

I would also test the reaction scenarios with a deleted message instead of a reaction

Deleted messages are in the DOM, so they are not any different from normal messages

and with a command from another participant that is not visible for the user loading the chat instead of a reaction.

Similar to messages that are not in the DOM but in the store, completely non-existing messages will just fall back to the previous visible one, so should be covered as well.

[SystemKeeper]

Could this be used (or easily extended) to solve #6046 and be used in mobile clients?

[nickvergessen]

We are doing it in the web now, if you did not open the conversation before :)
But otherwise we can't as it might create a hole in the list of loaded messages :(

[SystemKeeper]

But otherwise we can't as it might create a hole in the list of loaded messages :(

Could we remove the stored messages for that conversation when we open it from search to get the correct context ?

[nickvergessen]

Put as an idea into #6046 ?