/**
 * modem-bridge.js — Client for the modem-bridge Playwright service
 *
 * DEPENDENCY: modem-bridge container (port 3301 on Docker proxy network)
 *
 * Provides targo-hub with access to TP-Link ONU web GUI data
 * by proxying requests to the modem-bridge headless Chromium service.
 *
 * ENDPOINTS EXPOSED (on targo-hub, port 3300):
 *   GET  /modem/status?ip=X&user=Y&pass=Z      — Full status (auto-login)
 *   GET  /modem/dm/:oid?ip=X&user=Y&pass=Z      — Raw DM read
 *   GET  /modem/diagnostic?ip=X&user=Y&pass=Z    — Full WiFi/mesh/WAN diagnostic
 *   GET  /modem/screenshot?ip=X&user=Y&pass=Z   — PNG screenshot
 *   GET  /modem/sessions                         — List active sessions
 *   POST /modem/close                            — Close a session
 */

const http = require('http');
const { log, json: jsonResp, parseBody } = require('./helpers');

const BRIDGE_HOST = process.env.BRIDGE_HOST || 'modem-bridge';
const BRIDGE_PORT = parseInt(process.env.BRIDGE_PORT || '3301');
const BRIDGE_TOKEN = process.env.BRIDGE_TOKEN || '';

/**
 * Make HTTP request to modem-bridge service
 */
function bridgeRequest(method, path, body = null) {
  return new Promise((resolve, reject) => {
    const opts = {
      hostname: BRIDGE_HOST,
      port: BRIDGE_PORT,
      path,
      method,
      headers: {
        'Content-Type': 'application/json',
      }
    };
    if (BRIDGE_TOKEN) {
      opts.headers['Authorization'] = `Bearer ${BRIDGE_TOKEN}`;
    }

    const bodyStr = body ? JSON.stringify(body) : '';
    if (body) opts.headers['Content-Length'] = Buffer.byteLength(bodyStr);

    const req = http.request(opts, res => {
      let data = '';
      res.on('data', c => data += c);
      res.on('end', () => {
        try {
          // Screenshots return binary
          if (res.headers['content-type']?.includes('image/png')) {
            resolve({ status: res.statusCode, body: Buffer.from(data, 'binary'), isPng: true });
          } else {
            resolve({ status: res.statusCode, body: JSON.parse(data) });
          }
        } catch(e) {
          resolve({ status: res.statusCode, body: data });
        }
      });
    });
    req.on('error', reject);
    if (body) req.write(bodyStr);
    req.end();
  });
}

/**
 * Ensure a session exists for the given modem, login if needed
 */
async function ensureSession(ip, user, pass, path) {
  // Check if session already exists
  const listRes = await bridgeRequest('GET', '/session/list');
  if (listRes.status === 200 && Array.isArray(listRes.body)) {
    const existing = listRes.body.find(s => s.ip === ip && s.loggedIn);
    if (existing) return existing;
  }

  // Login
  const loginRes = await bridgeRequest('POST', '/session/login', {
    ip, user, pass, path: path || '/superadmin'
  });

  if (loginRes.status !== 200) {
    throw new Error(`Modem login failed: ${loginRes.body?.error || 'Unknown error'}`);
  }

  return loginRes.body;
}

/**
 * Route handler for targo-hub
 */
async function handleModemRequest(req, res, path) {
  try {
    // GET /modem/sessions — list active sessions
    if (path === '/modem/sessions' && req.method === 'GET') {
      const result = await bridgeRequest('GET', '/session/list');
      return jsonResp(res, result.status, result.body);
    }

    // POST /modem/close — close a session
    if (path === '/modem/close' && req.method === 'POST') {
      const body = await parseBody(req);
      if (!body.ip) return jsonResp(res, 400, { error: 'Missing ip' });
      const result = await bridgeRequest('DELETE', `/session/${body.ip}`);
      return jsonResp(res, result.status, result.body);
    }

    // GET /modem/health — bridge health (no auth needed)
    if (path === '/modem/health' && req.method === 'GET') {
      const result = await bridgeRequest('GET', '/health');
      return jsonResp(res, result.status, result.body);
    }

    // All other /modem/* routes need ip, user, pass
    const url = new URL(req.url, `http://${req.headers.host}`);
    const ip = url.searchParams.get('ip');
    const user = url.searchParams.get('user') || 'superadmin';
    const pass = url.searchParams.get('pass');
    const loginPath = url.searchParams.get('path') || '/superadmin';

    if (!ip || !pass) {
      return jsonResp(res, 400, { error: 'Missing required params: ip, pass' });
    }

    // Ensure session exists
    await ensureSession(ip, user, pass, loginPath);

    // GET /modem/status — full status
    if (path === '/modem/status' && req.method === 'GET') {
      const result = await bridgeRequest('GET', `/modem/${ip}/status`);
      return jsonResp(res, result.status, result.body);
    }

    // GET /modem/dm/:oid — raw data manager read
    const dmMatch = path.match(/^\/modem\/dm\/(.+)$/);
    if (dmMatch && req.method === 'GET') {
      const oid = dmMatch[1];
      let queryStr = `?`;
      if (url.searchParams.get('stack')) queryStr += `stack=${url.searchParams.get('stack')}&`;
      if (url.searchParams.get('attrs')) queryStr += `attrs=${url.searchParams.get('attrs')}&`;
      const result = await bridgeRequest('GET', `/modem/${ip}/dm/${oid}${queryStr}`);
      return jsonResp(res, result.status, result.body);
    }

    // GET /modem/diagnostic — full WiFi/mesh/WAN diagnostic
    if (path === '/modem/diagnostic' && req.method === 'GET') {
      const result = await bridgeRequest('GET', `/modem/${ip}/wifi/diagnostic`);
      return jsonResp(res, result.status, result.body);
    }

    // GET /modem/screenshot — PNG
    if (path === '/modem/screenshot' && req.method === 'GET') {
      const result = await bridgeRequest('GET', `/modem/${ip}/screenshot`);
      if (result.isPng) {
        res.writeHead(200, { 'Content-Type': 'image/png', 'Content-Length': result.body.length });
        return res.end(result.body);
      }
      return jsonResp(res, result.status, result.body);
    }

    return jsonResp(res, 404, { error: 'Unknown modem endpoint' });

  } catch(e) {
    log('modem-bridge error:', e.message);
    return jsonResp(res, 502, { error: e.message });
  }
}

module.exports = { handleModemRequest };