/**
 * Local Zapier interface simulator + trace console.
 * Default http://0.0.0.0:3847
 */
import http from 'node:http';
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { ACTIONS, Simulator } from './pipeline.js';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const PUBLIC = path.join(__dirname, '..', 'public');
const PORT = Number(process.env.SIM_PORT || 3847);
const BIND = process.env.SIM_BIND || '0.0.0.0';
const world = new Simulator();

const mime = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript; charset=utf-8',
  '.css': 'text/css; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.svg': 'image/svg+xml',
};

function send(res, code, body, type = 'application/json; charset=utf-8') {
  const buf = typeof body === 'string' ? body : JSON.stringify(body, null, 2);
  res.writeHead(code, { 'content-type': type, 'cache-control': 'no-store' });
  res.end(buf);
}

function readBody(req) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    req.on('data', (c) => chunks.push(c));
    req.on('end', () => {
      const raw = Buffer.concat(chunks).toString('utf8');
      if (!raw) return resolve({});
      try {
        resolve(JSON.parse(raw));
      } catch (err) {
        reject(err);
      }
    });
    req.on('error', reject);
  });
}

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, `http://127.0.0.1:${PORT}`);
  try {
    if (req.method === 'GET' && url.pathname === '/health') {
      return send(res, 200, { ok: true, port: PORT });
    }
    if (req.method === 'GET' && url.pathname === '/api/actions') {
      return send(res, 200, { actions: ACTIONS, state: world.snapshot() });
    }
    if (req.method === 'GET' && url.pathname === '/api/state') {
      return send(res, 200, world.snapshot());
    }
    if (req.method === 'POST' && url.pathname === '/api/reset') {
      world.reset();
      return send(res, 200, { ok: true, state: world.snapshot() });
    }
    if (req.method === 'POST' && url.pathname === '/api/run') {
      const body = await readBody(req);
      const result = await world.run(body);
      return send(res, 200, result);
    }
    let file = url.pathname === '/' ? '/index.html' : url.pathname;
    const dest = path.normalize(path.join(PUBLIC, file));
    if (!dest.startsWith(PUBLIC)) {
      return send(res, 403, { error: 'forbidden' });
    }
    if (!fs.existsSync(dest) || fs.statSync(dest).isDirectory()) {
      return send(res, 404, { error: 'not found' });
    }
    const ext = path.extname(dest);
    res.writeHead(200, { 'content-type': mime[ext] || 'application/octet-stream' });
    fs.createReadStream(dest).pipe(res);
  } catch (err) {
    send(res, 500, { error: err.message });
  }
});

server.listen(PORT, BIND, () => {
  process.stdout.write(`Zapier simulator http://${BIND}:${PORT}/\n`);
});