[WIP] Add support for LNURL pay requests

[bumi]

Description

This adds a new prompt for LNURL pay requests. This is currently very experimental and this PR is opened to serve as a potential starting point around implementing LNURL features.

LNURL

https://github.com/btcontract/lnurl-rfc

LNURL is a bech32-encoded HTTPS/Onion query string which is supposed to help payer interact with payee and thus simplify a number of standard scenarios such as:

• Requesting incoming channels (LNURL-channel)
• Logging in (LNURL-auth)
• Withdrawing funds (LNURL-withdraw)
• Paying for a service (LNURL-pay)

ToDos

• [ ] add support for success actions
• [ ] validate payment request amount as described in the lnurl spec
• [ ] validate payment request description hash as described in the lnurl spec
• [ ] refactor all the things :)
• [ ] specify UX for the different LNURL scenarios

Discussion

• Support for LNURL requests should be added to webln?

Screenshots

[bumi]

experimenting on the flow:

https://vimeo.com/448816127

[wbobeirne]

This is an awesome start, thanks for being the first to look at LNURL in Joule!

My initial thoughts on the code is that it looks good, but there's quite a bit of overlap between this and prompts/payment.tsx, and it would be good to share more code between the two. Though perhaps this is what you had in mind for the refactor all the things :) TODO.

Looking forward to seeing where this one goes!

[githorray]

Is this error expected from Joule with LNURL-withdraw currently?

The payment request that was provided could not be looked up due to the following error: invoice not for current active network 'mainnet'

[bumi]

@githorray this PR so far only supports the LNURL-pay flow. And there are no checks to validate the lnurl response.

LNURL-withdraw is the next step. Can you maybe help with that?

[eza]

this is great! why was this never completed? Especially LNURL-Auth would be great to push a whole range of web-app authentications