import type { Express, RequestHandler } from "express";
import http from "node:http";
import https from "node:https";

function createMediaProxy(targetUrl: string): RequestHandler {
  const target = new URL(targetUrl);
  const transport = target.protocol === "https:" ? https : http;

  return (req, res) => {
    const upstreamUrl = new URL(req.originalUrl, target);
    const proxyRequest = transport.request(
      upstreamUrl,
      {
        method: req.method,
        headers: {
          ...req.headers,
          host: target.host,
          connection: "keep-alive",
        },
      },
      (proxyResponse) => {
        if (proxyResponse.statusCode) {
          res.status(proxyResponse.statusCode);
        }
        Object.entries(proxyResponse.headers).forEach(([key, value]) => {
          if (value !== undefined) {
            res.setHeader(key, value);
          }
        });
        proxyResponse.pipe(res);
      }
    );

    proxyRequest.on("error", (error) => {
      if (!res.headersSent) {
        res.status(502).json({
          error: "media_service_unavailable",
          message: error.message,
        });
      } else {
        res.end();
      }
    });

    req.pipe(proxyRequest);
  };
}

export function registerMediaProxy(app: Express) {
  const mediaServiceUrl = process.env.MEDIA_SERVICE_URL;
  if (!mediaServiceUrl) {
    return;
  }

  app.use("/media", createMediaProxy(mediaServiceUrl));
}