Split up this project into a REST API and thin command line tool

[apoelstra]

For Simplicity manipulation people make want to work programmatically or in an automated way. a REST or JSONRPC API would be better for this.

IMO we should copy Core's architecture and have a "daemon" and a "cli tool".

Because this should also work as a standalone "swiss army knife" cli tool we should have a mode where, if no daemon is running, we should just spawn one in a local thread or process.

Maybe we want to fold this into https://github.com/apoelstra/simplicity-unchained and/or want to extend "simplicity-unchained" to add a bunch of "pure function" endpoints.

[ivanlele]

Hi @apoestra, I was wondering if you might have some time to take a look at PR #36 when it fits into your time constraints. I figured out that it’s quite a large one and may be a bit heavyto review in a single pass. If that makes sense, I can split it into smaller PRs and integrate the features gradually. We could keep the existing logic for now and, down the line, potentially deprecate it once the new implementation is fully in place. I would be glad to hear your opinion

[apoelstra]

Sorry for missing your PR when you opened it on Thursday! I realized I am not subscribed to this repo (even though I created it ... kinda a dumb default on Github's part). I subscribed now.

[ivanlele]

Thank you for the response! I’m planning to split the large PR into several smaller ones. The small PRs will be:

1. Introduce custom error types for each command and use them instead of panicking throughout the code.
2. Move the command execution logic into a separate actions module and have commands delegate to it.
3. Add a daemon module that listens for HTTP connections and routes JSON-RPC method calls to the appropriate actions.
4. Implement a JSON-RPC client with predefined, named methods for calling the daemon.
5. Add an optional CLI feature that when enabled, routes execution through the JSON-RPC client instead of calling actions directly.

If you have any comments, I would be glad to hear

[apoelstra]

These steps sound great to me.