lnurl-pay.me/src/payflow.js

import { bech32 } from 'bech32'
import UTF8 from 'utf-8'

function getDomain(url) {
  return url
    .split('://')[1]
    .split('/')[0]
    .split('@')
    .slice(-1)[0]
    .split(':')[0]
}

export function decodeLnurl(lnurl) {
  let obj = bech32.decode(lnurl,20000)
  if (obj.prefix!="lnurl")
    throw new Error("bad prefix")
  return UTF8.getStringFromBytes(bech32.fromWords(obj.words))
}

export async function payStep1(url) {
  const r = await fetch(url)
  if (r.status >= 300) {
    throw new Error(await r.text())
  }
  let res = await r.json()
  if (res.status == "ERROR")
    return res;
  if (res.tag != "payRequest") {
    throw new Error(`LNURL type ${r.tag}, expected: payRequest`)
  }
  try {
    res.decodedMetadata = JSON.parse(res.metadata)
  } catch (err) {
    res.decodedMetadata = []
  }
  return res
}

export async function payStep2(url, res, msat, comment) {
  let cb = res.callback;
  let params = new URLSearchParams();
  params.set("amount",msat);
  cb = cb+(cb.includes("?")?"&":"?")+params.toString()
  const r = await fetch(cb)
  if (r.status >= 300) {
    throw new Error(await r.text())
  }
  let res2 = await r.json()
  return res2
}