NUT-4/NUT-5: Method-unit pair is object with settings

[callebtc]

This PR changes the "settings" for NUT-4/NUT-5 (minting and melting) that are shown in the /v1/info response.

The unit pairs are changed from an array ["method", "unit"] to an object that now also carries settings for the endpoints.

Example:

{
  "method": "bolt11",
  "unit": "sat",
  "min_amount": 0,
  "max_amount": 10000        
}

[ngutech21]

LGTM

Just one suggestion. I would like to rename method to payment_method, since this is more precise. If I read the term method in a Rest-Api my first thought is http-method.

[ngutech21]

Update: In the nut the struct is described as settings but in the json it's called method. Having method or payment_method twice feels redundant.

How about this:

 "4": {
      "settings": [
        {
          "payment_method": "bolt11",
          "unit": "sat",
          "min_amount": 0,
          "max_amount": 10000        
        }
      ],
      "disabled": false
    },

[thunderbiscuit]

I think it makes sense to have a more complex object for settings, and might even be a place where mints can add custom things that are useful for them/their users without breaking anything, because the wallet parsing could simply discard any field it does not know (I don't do that in my lib yet and the parsing errors out if there are extra fields on the response object but might turn that on if it's useful for people).

A few comments below.

[thunderbiscuit]

I liked the wording you had above, and could combine both like so:

Here, methods is an array of MintMethodSetting. MintMethodSetting indicates supported method and unit pairs and additional settings of the mint. disabled indicates whether this minting is disabled.

[ngutech21]

Since cashu-ts is migrating to v1 api and this is only a small change, I think we should get this PR ready to merge before the wallets adopt the new api. Any thoughts on this? @gandlafbtc @callebtc

[gandlafbtc]

looks good to me

[thesimplekid]

Agree with tb's small points but overall LGTM

[callebtc]

In the nut the struct is described as settings but in the json it's called method. Having method or payment_method twice feels redundant.

It feels appropriate to me that there is an array "methods" with entries that have a "method". Since we speak of "method-unit" pairs in the spec, I think the labels are ok or at least clear enough as is.

I have added all remaining suggestions and I think we are ready to merge this.