import crypto from 'node:crypto';
import { execFile } from 'node:child_process';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import express from 'express';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const app = express();
const port = Number(process.env.PORT || 3020);
const webhookPath = process.env.WEBHOOK_PATH || '/webhook/github';
const webhookSecret = process.env.WEBHOOK_SECRET || '';
const pm2AppName = process.env.PM2_APP_NAME || 'linkweb';
const pm2Command = process.env.PM2_BIN || (process.platform === 'win32' ? 'pm2.cmd' : 'pm2');

function verifyGitHubSignature(req) {
  if (!webhookSecret) {
    return true;
  }

  const signature = req.get('x-hub-signature-256');
  if (!signature?.startsWith('sha256=')) {
    return false;
  }

  const digest = `sha256=${crypto
    .createHmac('sha256', webhookSecret)
    .update(req.body)
    .digest('hex')}`;

  const received = Buffer.from(signature);
  const expected = Buffer.from(digest);

  return received.length === expected.length && crypto.timingSafeEqual(received, expected);
}

app.post(webhookPath, express.raw({ type: '*/*' }), (req, res) => {
  if (!verifyGitHubSignature(req)) {
    res.status(401).json({ ok: false, error: 'Invalid webhook signature' });
    return;
  }

  res.status(202).json({ ok: true, restarting: pm2AppName });

  execFile(pm2Command, ['restart', pm2AppName], (error, stdout, stderr) => {
    if (error) {
      console.error('PM2 restart failed:', error.message);
      if (stderr) {
        console.error(stderr);
      }
      return;
    }

    if (stdout) {
      console.log(stdout);
    }
  });
});

app.get('/healthz', (_req, res) => {
  res.json({ ok: true });
});

app.use(express.static(path.join(__dirname, 'dist')));

app.use((_req, res) => {
  res.sendFile(path.join(__dirname, 'dist', 'index.html'));
});

app.listen(port, () => {
  console.log(`Toothless' Bot Home listening on port ${port}`);
});