import dns from "dns/promises";
import https from "https";
import axios from "axios";

/**
 * Purges a specific path from all cache nodes behind a hostname.
 *
 * @param {string} host - The public hostname of the site (e.g. "example.com")
 * @param {string} [protocol="https"] - The protocol to use ("http" or "https")
 * @param {string} [path="/"] - The path that should be purged (e.g. "/blog/my-post")
 *
 * @returns {Promise<Array>}
 * Returns an array of results for each resolved cache node, including
 * HTTP status codes or error messages.
 *
 * @example
 * await purgeHost("www.example.com", "https", "/blog/page");
 */
export async function purgeHost(host, protocol = "https", path = "/") {
  const ips = [];

  // Resolve IPv4 addresses
  try {
    ips.push(...await dns.resolve4(host));
  } catch {}

  // Resolve IPv6 addresses
  try {
    ips.push(...await dns.resolve6(host));
  } catch {}

  if (!ips.length) {
    throw new Error(`No IPs found for ${host}`);
  }

  // Send parallel PURGE requests to all resolved IPs
  const results = await Promise.all(
    ips.map(async (ip) => {
      const targetHost = ip.includes(":") ? `[${ip}]` : ip;
      const url = `${protocol}://${targetHost}${path}`;

      const config = {
        method: "PURGE",
        url,
        timeout: 5000,
        headers: {
          Host: host,
          "User-Agent": "Cache-Purge-Agent",
        },
        validateStatus: () => true,
      };

      // Required for HTTPS when using direct IP + hostname routing
      if (protocol === "https") {
        config.httpsAgent = new https.Agent({
          servername: host,
          rejectUnauthorized: false,
        });
      }

      try {
        const res = await axios(config);
        return { ip, status: res.status };
      } catch (err) {
        return { ip, error: err.message };
      }
    })
  );

  return results;
}