Add / show user presence to map.
When users first open the map all present members must be shown using the new global channel.
Some users haven't yet identified themselves, they should still show on the map with an anonymous marker. Others can be shown simply by an avatar marker. Obviously avatar markers should be configured flexibly so that custom avatars could be introduced in the future.

Realtime pub functions are currently served through a wrapper that handles messages from Ably through callbacks. Create an alternative interface that will allow clients to call those functions using coroutines.

Suspending functions returning values that are currently passed to callback lambdas would be convenient. Interface for this one could wrap other realtime classes so that it can take advantage of them while saving some work time

RealtimePub class currently does not use channels very efficiently. Each message uses a unidirectional channel (from a user to another user) which is likely increasing the cost of using Ably.

Try to minimise these channels and use other means of filtering the messages. Maybe actions, events, anything that will help minimising number of channels.

Technical todo

• Create another class DefaultRealtimePub(again, could be changed) that implements RealtimePub and uses less channels
• Create a class that would provide those pubs using an interface (A factory)

Try to compare the cost of using those two. It could be a good example of efficient use of our platform

Currently when a user sends a chat message or offer a drink to another user, messages are shown as toasts. It proves the point but it's not a great UI

Create a chat interface that will hold and store chats during a pub session. In this first iteration of this work, it's not necessary to think about the details of storage. Ably functionalities must be used whenever possible (message history)

UI should be simple but reusable. Possibly a new activity or fragment that holds a UI representing conversation between two pub goers. Make sure that this UI is not coupled with details of realtime activity. In the future it could be used for group chats too