import * as https from "https";
import * as http from "http";
import { URL } from "url";

const MAX_FILE_SIZE = 100 * 1024 * 1024; // 100 MB
const TIMEOUT_MS = 30000; // 30 seconds

export async function downloadFile(
  urlStr: string,
  options?: {
    method?: string;
    headers?: Record<string, string>;
    body?: string;
  },
): Promise<Buffer> {
  const url = new URL(urlStr);
  const protocol = url.protocol === "https:" ? https : http;
  const method = options?.method ?? "GET";
  const headers = options?.headers ?? {};

  return new Promise((resolve, reject) => {
    const req = protocol.request(
      {
        hostname: url.hostname,
        port: url.port,
        path: url.pathname + url.search,
        method,
        headers,
        timeout: TIMEOUT_MS,
      },
      (res) => {
        // Follow redirects
        if (res.statusCode && res.statusCode >= 300 && res.statusCode < 400 && res.headers.location) {
          downloadFile(res.headers.location, options).then(resolve).catch(reject);
          return;
        }

        if (res.statusCode && res.statusCode !== 200) {
          reject(new Error(`HTTP ${res.statusCode}: ${res.statusMessage}`));
          return;
        }

        const chunks: Buffer[] = [];
        let totalSize = 0;

        res.on("data", (chunk: Buffer) => {
          totalSize += chunk.length;
          if (totalSize > MAX_FILE_SIZE) {
            req.destroy();
            reject(new Error(`File exceeds maximum size of ${MAX_FILE_SIZE} bytes`));
            return;
          }
          chunks.push(chunk);
        });

        res.on("end", () => {
          resolve(Buffer.concat(chunks));
        });

        res.on("error", reject);
      },
    );

    req.on("timeout", () => {
      req.destroy();
      reject(new Error("Download timeout"));
    });

    req.on("error", reject);

    if (options?.body && (method === "POST" || method === "PUT")) {
      req.write(options.body);
    }

    req.end();
  });
}