plebdevs/src/utils/lightning.js

import Bolt11Decoder from 'light-bolt11-decoder';

export const getSatAmountFromInvoice = invoice => {
  const decoded = Bolt11Decoder.decode(invoice);
  return decoded.sections[2].value / 1000;
};

export const getTotalFromZaps = (zaps, event) => {
  let total = 0;
  let uniqueZaps = new Set();
  zaps.forEach(zap => {
    // If the zap matches the event or the parameterized event, then add the zap to the total
    if (
      (zap.tags.find(tag => tag[0] === 'e' && tag[1] === event.id) ||
        zap.tags.find(
          tag => tag[0] === 'a' && tag[1] === `${event.kind}:${event.pubkey}:${event.d}`
        )) &&
      !uniqueZaps.has(zap.id)
    ) {
      uniqueZaps.add(zap.id);
      const bolt11Tag = zap.tags.find(tag => tag[0] === 'bolt11');
      const invoice = bolt11Tag ? bolt11Tag[1] : null;
      if (invoice) {
        const amount = getSatAmountFromInvoice(invoice);
        total += amount;
      }
    }
  });
  return total;
};