plebdevs/src/pages/api/lightning-address/callback/[slug].js

import axios from 'axios';
import crypto from 'crypto';
import { verifyEvent } from 'nostr-tools/pure';
import appConfig from '@/config/appConfig';
import { runMiddleware, corsMiddleware } from '@/utils/corsMiddleware';
import { getLightningAddressByName } from '@/db/models/lightningAddressModels';

const BACKEND_URL = process.env.BACKEND_URL;
const PLEBDEVS_API_KEY = process.env.PLEBDEVS_API_KEY;

export default async function handler(req, res) {
  await runMiddleware(req, res, corsMiddleware);
  const { slug, ...queryParams } = req.query;

  let foundAddress = null;
  const customAddress = appConfig.customLightningAddresses.find(addr => addr.name === slug);

  if (customAddress) {
    foundAddress = customAddress;
  } else {
    foundAddress = await getLightningAddressByName(slug);
  }

  if (!foundAddress) {
    res.status(404).json({ error: 'Lightning address not found' });
    return;
  }

  if (foundAddress) {
    if (queryParams.amount) {
      const amount = parseInt(queryParams.amount);
      let metadata, metadataString, hash, descriptionHash;

      if (queryParams?.nostr) {
        // This is a zap request
        const zapRequest = JSON.parse(decodeURIComponent(queryParams.nostr));

        // Verify the zap request
        if (!verifyEvent(zapRequest)) {
          res.status(400).json({ error: 'Invalid zap request' });
          return;
        }

        // Validate zap request
        if (zapRequest.kind !== 9734) {
          res.status(400).json({ error: 'Invalid zap request' });
          return;
        }

        metadataString = JSON.stringify(zapRequest);
        hash = crypto.createHash('sha256').update(metadataString).digest('hex');
        descriptionHash = Buffer.from(hash, 'hex').toString('base64');
      } else {
        // This is a regular lnurl-pay request
        metadata = [['text/plain', `${foundAddress.name}'s LNURL endpoint, CHEERS!`]];
        metadataString = JSON.stringify(metadata);
        hash = crypto.createHash('sha256').update(metadataString).digest('hex');
        descriptionHash = Buffer.from(hash, 'hex').toString('base64');
      }

      // Check amount against BigInt min/max values
      if (amount < foundAddress.minSendable) {
        res.status(400).json({ error: 'Amount too low' });
        return;
      } else if (amount > foundAddress.maxSendable) {
        res.status(400).json({ error: 'Amount too high' });
        return;
      } else {
        try {
          const response = await axios.post(
            `${BACKEND_URL}/api/lightning-address/lnd`,
            {
              amount: amount,
              description_hash: descriptionHash,
              name: slug,
              zap_request: queryParams?.nostr ? queryParams.nostr : null,
            },
            {
              headers: {
                Authorization: PLEBDEVS_API_KEY,
              },
            }
          );
          res.status(200).json({
            pr: response.data.invoice,
            verify: `${BACKEND_URL}/api/lightning-address/verify/${slug}/${response.data.payment_hash}`,
          });
        } catch (error) {
          console.error(error);
          res.status(500).json({ error: 'Failed to generate invoice' });
        }
      }
    } else {
      res.status(400).json({ error: 'Amount not specified' });
    }
  } else {
    res.status(404).json({ error: 'Lightning address not found' });
  }
}