/**
 * API proxy for development — forwards /api/* to flights.test.aeroflot.ru
 * through the system HTTPS proxy (GOST at 127.0.0.1:8888).
 *
 * Run: node scripts/api-proxy.mjs
 * Listens on port 4201.
 */
import http from "node:http";
import https from "node:https";
import { URL } from "node:url";

const TARGET = "flights.test.aeroflot.ru";
const PORT = 4201;
const SYSTEM_PROXY = process.env.https_proxy || process.env.HTTPS_PROXY || "";

function proxyViaConnect(req, res) {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS");
  res.setHeader("Access-Control-Allow-Headers", "*");

  if (req.method === "OPTIONS") {
    res.writeHead(204);
    res.end();
    return;
  }

  if (SYSTEM_PROXY) {
    // Use HTTP CONNECT tunnel through system proxy
    const proxyUrl = new URL(SYSTEM_PROXY);
    const connectReq = http.request({
      host: proxyUrl.hostname,
      port: parseInt(proxyUrl.port || "8888"),
      method: "CONNECT",
      path: `${TARGET}:443`,
    });

    connectReq.on("connect", (_connectRes, socket) => {
      const options = {
        hostname: TARGET,
        path: req.url,
        method: req.method,
        headers: {
          host: TARGET,
          accept: "application/json, text/plain, */*",
          "accept-language": "ru",
        },
        socket,
        agent: false,
      };

      const targetReq = https.request(options, (targetRes) => {
        const headers = { ...targetRes.headers, "access-control-allow-origin": "*" };
        delete headers["transfer-encoding"];
        res.writeHead(targetRes.statusCode ?? 200, headers);
        targetRes.pipe(res, { end: true });
      });

      targetReq.on("error", (err) => {
        res.writeHead(502, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ error: err.message }));
      });

      req.pipe(targetReq, { end: true });
    });

    connectReq.on("error", (err) => {
      res.writeHead(502, { "Content-Type": "application/json" });
      res.end(JSON.stringify({ error: `Proxy connect error: ${err.message}` }));
    });

    connectReq.end();
  } else {
    // Direct HTTPS without system proxy
    const options = {
      hostname: TARGET,
      port: 443,
      path: req.url,
      method: req.method,
      headers: {
        host: TARGET,
        accept: "application/json, text/plain, */*",
        "accept-language": "ru",
      },
    };

    const targetReq = https.request(options, (targetRes) => {
      res.writeHead(targetRes.statusCode ?? 200, {
        ...targetRes.headers,
        "access-control-allow-origin": "*",
      });
      targetRes.pipe(res, { end: true });
    });

    targetReq.on("error", (err) => {
      res.writeHead(502, { "Content-Type": "application/json" });
      res.end(JSON.stringify({ error: err.message }));
    });

    req.pipe(targetReq, { end: true });
  }
}

const server = http.createServer(proxyViaConnect);
server.listen(PORT, () => {
  console.log(`API proxy on http://localhost:${PORT} → https://${TARGET}`);
  if (SYSTEM_PROXY) console.log(`Using system proxy: ${SYSTEM_PROXY}`);
});