Hi @rkfg,

I recently ran into an issue that seems to be preventing the invoice subscription via the invoice r_hash you added. This prevents the notification code from being triggered. This issue seemingly appeared without code changes from my end. When /v2/invoices/subscribe is run the invoice subscription response indicates &{Status:404 Not Found StatusCode:404......

If you got a minute could you confirm if notifications are working for you? I could send you test payments to your lightningaddress.

It's currently hard to find if you've been paid. The only way is listing all paid invoices and look for those you don't remember creating yourself. A simple abstract notification interface with few implementations would be great to have (I might implement it myself if I find time). For example, it could be e-mail notification and http hook. I like how lightningtip does it. Shouldn't be hard to do.

This is currently WIP but mail notifications should work now. I plan to add HTTP as well. I extracted the make invoice dependency because it's not possible to get r_hash (that we need to subscribe to settlements) from the encoded invoice without admin macaroon and that's a dangerous requirement. Make invoice doesn't return r_hash even though the underlying REST API provides it so I made appropriate changes and removed the dead code that's not relevant to lnd (we don't support anything else anyway). This also greatly reduced the amount of dependencies to just gjson.

I also fixed macaroon loading so it's not loaded from disk every time the invoice is created. Comments were previously completely ignored even when allowed in config. Now they're properly used in notifications. Added optional private channels hints (for nodes with no or small public channels), TLS certificate support (for REST API connection). Refactored repeating error reporting code.

So it's a draft for now, feel free to test and review.

Right now nothing prevents someone from calling the callback https://site.com/invoice?amount=1000 unreasonably often and spam the system. @rkfg Do you think it would make sense to add a spam protection here like a Timeout/IPFilter etc.?

As per https://github.com/hieblmi/go-host-lnaddr/pull/6#issuecomment-945098227 here's a new option to only permit notifications (currently by mail) if the amount is above the threshold. You'll still be able to see all of them in the system log. Also I changed the amount type to uint64 because uint is 32 bit long and, while unlikely, big enough amount of sats might overflow it.

Currently the invoice macaroon is generated via: "InvoiceMacaroon": Generate the hex encoded invoice macaroon : xxd -ps -u -c 1000 $HOME/.lnd/data/chain/bitcoin/mainnet/invoice.macaroon

This should be done in code.

Right now the server just exits without notification when an instance of go-host-lnaddr is already active. In case of an already active instance print an error log.

It would be nice to have tiered payment confirmation messages (0-10, 10-100, 100-1000, 1000-10000 sats etc.) instead of the generic "thank you" as well as notification templates using Go's text/template.