sample implementation of lnurl-pay and lightning address

index.js

const lnurl = require('lnurl')
const { v4: uuid4 } = require('uuid')
const express = require('express')
const { exec } = require('child_process')
const crypto = require('crypto')

const app = express()
const port = 7000
const users = ['godwin', 'bernard']

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.get('/user/:userid', (req, res) => {
  const url = lnurl.encode(`https://${req.hostname}/lnurlp?q=${req.params.userid}`)
  console.log(url)
  res.send(`<img src="https://chart.googleapis.com/chart?chs=500x500&cht=qr&chl=${url}" alt="${url}">`)
})

app.get('/lnurlp', (req, res) => {
  let response = {}
  if (users.includes(req.query.q) == true) {
    response = {
      callback: `https://${req.hostname}/pay?q=${req.query.q}`,
      tag: 'payRequest',
      minSendable: 10000,
      maxSendable: 10000,
      metadata: `[["text/plain", "send sats to ${req.query.q}"]]`
    }
  } else {
    response = {
      'status': 'ERROR',
      'reason': 'user not found'
    }
  }
  res.json(response)
})

app.get('/.well-known/lnurlp/:userid', (req, res) => {
  let response = {}
  if (users.includes(req.params.userid) == true) {
    response = {
      callback: `https://${req.hostname}/pay?q=${req.params.userid}`,
      tag: 'payRequest',
      minSendable: 1000,
      maxSendable: 5000000,
      metadata: `[["text/plain", "send sats to ${req.params.userid}"]]`
    }
  } else {
    response = {
      'status': 'ERROR',
      'reason': 'user not found'
    }
  }
  res.json(response)
})


app.get('/pay', (req, res) => {
  let recipient = req.query.q
  let amount_msats = parseInt(req.query.amount)
  let amount_sats = amount_msats / 1000
  let hash = crypto.createHash('sha256')
  hash.update(`[["text/plain", "send sats to ${recipient}"]]`)
  let desc = hash.digest('hex')
  console.log(`generating invoice of ${amount_msats}msats to ${recipient}`)
  exec(`lncli addinvoice --amt=${amount_sats} --description_hash=${desc}`, (err, stdout, sterr) => {
    let invoice = JSON.parse(stdout)
    console.log(`hash: ${invoice.r_hash} bolt11: ${invoice.payment_request}`)
    response = {
      pr: invoice.payment_request,
      routes: []
    }
    res.json(response)
  })
})

app.listen(port, () => {
  console.log(`Server listening on locahost:${port}`)
})