const fs = require('fs');
const https = require('https');
const WebSocket = require('ws');
const axios = require('axios');
require('dotenv').config();

const WS_URL = process.env.WS_URL;
const WS_TOKEN = process.env.WS_TOKEN;

if (!WS_URL) {
  console.error('❌ WS_URL is not set in .env');
  process.exit(1);
}

const INITIAL_BACKOFF_MS = 2000;
const MAX_BACKOFF_MS = 60000;
const PROXY_TIMEOUT_MS = 30000;

let ws = null;
let reconnectAttempts = 0;
let shuttingDown = false;

/**
 * TLS options for wss:// and for HTTPS calls the agent proxies (SIW, MDM, …).
 *
 * Preferred: mount your corporate root + intermediate CA(s) as a PEM bundle
 * and point WS_TLS_CA_FILE at it. That keeps verification on.
 *
 * Escape hatch (trusted networks only): WS_TLS_REJECT_UNAUTHORIZED=false
 */
function readTlsOptions() {
  const tls = {};

  const caFile = process.env.WS_TLS_CA_FILE;
  if (caFile) {
    try {
      tls.ca = fs.readFileSync(caFile, 'utf8');
      console.log(`🔒 Using custom CA bundle: ${caFile}`);
    } catch (err) {
      console.error(`❌ Failed to read WS_TLS_CA_FILE (${caFile}): ${err.message}`);
      process.exit(1);
    }
  }

  if (process.env.WS_TLS_REJECT_UNAUTHORIZED !== undefined) {
    const reject =
      process.env.WS_TLS_REJECT_UNAUTHORIZED !== 'false' &&
      process.env.WS_TLS_REJECT_UNAUTHORIZED !== '0';
    tls.rejectUnauthorized = reject;
    if (!reject) {
      console.warn(
        '⚠️  WS_TLS_REJECT_UNAUTHORIZED=false — TLS certificate verification is DISABLED.'
      );
    }
  }

  return Object.keys(tls).length ? tls : null;
}

const TLS_OPTIONS = readTlsOptions();
const HTTPS_AGENT = TLS_OPTIONS ? new https.Agent(TLS_OPTIONS) : undefined;

/**
 * WebSocket client options: optional Bearer auth + optional TLS trust config.
 */
function buildClientOptions() {
  const options = {};

  if (WS_TOKEN) {
    options.headers = { Authorization: `Bearer ${WS_TOKEN}` };
  }

  if (TLS_OPTIONS) {
    Object.assign(options, TLS_OPTIONS);
  }

  return Object.keys(options).length ? options : undefined;
}

function connect() {
  console.log(`🔄 Connecting to ${WS_URL}...`);

  ws = new WebSocket(WS_URL, buildClientOptions());

  ws.on('open', () => {
    console.log('✅ Remote Agent connected to StoreHealthAnalyzer');
    reconnectAttempts = 0;
  });

  ws.on('message', async data => {
    let request;
    try {
      request = JSON.parse(data);
      if (request.action !== 'proxyRequest') return;

      console.log(`🔄 Proxying ${request.method || 'GET'} ${request.url}`);

      const response = await axios({
        method: request.method || 'GET',
        url: request.url,
        headers: request.headers || {},
        auth: request.auth || undefined,
        data: request.body || undefined,
        timeout: PROXY_TIMEOUT_MS,
        httpsAgent: HTTPS_AGENT,
      });

      ws.send(
        JSON.stringify({
          requestId: request.requestId,
          status: response.status,
          data: response.data,
          headers: response.headers,
        })
      );
    } catch (err) {
      console.error('Proxy error:', err.message);
      ws.send(
        JSON.stringify({
          requestId: request ? request.requestId : null,
          error: err.message,
          status: err.response?.status || 500,
          data: err.response?.data || null,
        })
      );
    }
  });

  ws.on('close', code => {
    console.log(`❌ Disconnected (code: ${code}).`);
    if (!shuttingDown) scheduleReconnect();
  });

  ws.on('error', err => {
    console.error('WebSocket error:', err.message);
  });
}

function scheduleReconnect() {
  reconnectAttempts++;

  const backoff = Math.min(
    INITIAL_BACKOFF_MS * Math.pow(1.5, reconnectAttempts - 1),
    MAX_BACKOFF_MS
  );

  console.log(
    `⏳ Reconnecting in ${Math.round(backoff / 1000)}s... (attempt ${reconnectAttempts})`
  );

  setTimeout(connect, backoff);
}

connect();

function shutdownRemote(signal) {
  console.log(`🛑 ${signal} received. Shutting down remote agent...`);
  shuttingDown = true;
  if (ws) {
    try {
      ws.close();
    } catch (_e) {
      // ignore close errors during shutdown
    }
  }
  process.exit(0);
}

process.on('SIGINT', () => shutdownRemote('SIGINT'));
process.on('SIGTERM', () => shutdownRemote('SIGTERM'));