Wallet Activity Notification Feature

[pxsocs]

@ben-kaufman @k9ert

Looking into creating a wallet activity notification feature. Wanted to get your guidance on best way to implement this. This is something I've implemented in the WARden and think could be a useful feature for Specter. Quick overview on how this could work.

1. When application launches, start a background job that checks for activity every [n] seconds
   . Does the app already have any background jobs method that could be reused / based off?
   Suggestion would be to do something along these lines:

   def check_activity_bk():
       # include check here
       pass
   
   from apscheduler.schedulers.background import BackgroundScheduler
   app = Flask(__name__)
   app.scheduler = BackgroundScheduler()
   app.scheduler.add_job(check_activity_bk, 'interval', seconds=10)

2. A dictionary is saved as a pickle on default home folder (i.e. ~/specter ?):

{'wallet_alias_1' : 
    {
    'last_tx_hash' : '------',
    'last_balance_hash': '----',
     }, 
 'wallet_alias_2': ... 
}

3. When checking for activity, the latest hashes are checked against the pkl file. If changes detected, an icon appears by the wallet name on the menu bar: 'Activity Detected since last checkpoint'. A 'dismiss' button would save the pkl file with the latest checkpoint and stop notifying the user. Notification will keep being displayed until 'dismiss' is clicked.

4. Include in the specter class, a new dictionary: wallet_activity so it's easily accessible across html jinja2 templates:

{
    'activity_detected': False,
    'latest_status' : {...}, 
    'pkl_status': {...}
}

latest_status and pkl_status are dictionaries in the format listed at (2). Saving both will make it easy to check which wallets have balance change and/or txs.

If this is acceptable and you believe this to be a useful feature, I'm happy to work on some initial code and submit a PR.

This could also be enhanced later to send e-mail notifications, etc. But would need to consider potential risks.

[k9ert]

Well, that sounds cool :-).

When application launches, start a background job that checks for activity every [n] seconds

That's one possibility but Bitcoin-core has a better one: ZeroMQ. We can have nearly instant notification and don't have to rely on pulling with ZMQ.
Have a look e.g. here:
https://bitcoindev.network/accessing-bitcoins-zeromq-interface/
This is based on nodejs. Here is a python-example:
https://github.com/bitcoin/bitcoin/blob/master/contrib/zmq/zmq_sub.py

A dictionary is saved as a pickle on default home folder (i.e. ~/specter ?):

We should imho store wallet-specific stuff in the wallet-folder. Check ~/.specter/wallets/main/...

Include in the specter class, a new dictionary: wallet_activity so it's easily accessible across html jinja2 templates:

I'd suggest a new Manager similiar to WalletManager, UserManager and so on. Check src/cryptoadvance/specter/managers. Initialize them in the init-method of specter similiar to the other managers. Maybe you can call it ZmqManager so that it receives all events from BitcoinCore (and later maybe Liquid) coming via ZMQ. There are then one method which is storing the pickles and a method which checks for activity and reads the corresponding pickles and returns the result.

If this is acceptable and you believe this to be a useful feature, I'm happy to work on some initial code and submit a PR.

Looking forward to your PR. In the meantime i'll try to get the API ready :-).

But maybe let's wait also on comments from @stepansnigirev and @ben-kaufman