import http from "node:http";
import https from "node:https";

/** Bounded GET with no redirects, no response-body errors, and loopback proxy bypass. */
export function getCatalogText(
  url: URL,
  signal: AbortSignal,
  headers: Record<string, string> = {},
  maxBytes = 5 * 1024 * 1024,
): Promise<string> {
  return new Promise((resolve, reject) => {
    const transport = url.protocol === "http:" ? http : url.protocol === "https:" ? https : undefined;
    if (!transport || url.username || url.password) {
      reject(new Error("Invalid catalog URL"));
      return;
    }
    const loopback = ["localhost", "127.0.0.1", "::1", "[::1]"].includes(url.hostname);
    const req = transport.get(url, {
      signal,
      headers: { Accept: "application/json, text/html, application/javascript", ...headers },
      ...(loopback ? { agent: false } : {}),
    }, res => {
      if (res.statusCode !== 200) {
        res.destroy();
        reject(new Error(`HTTP ${res.statusCode ?? 0}`));
        return;
      }
      const chunks: Buffer[] = [];
      let bytes = 0;
      res.on("data", (chunk: Buffer) => {
        bytes += chunk.length;
        if (bytes > maxBytes) {
          reject(new Error("Catalog response too large"));
          res.destroy();
          return;
        }
        chunks.push(chunk);
      });
      res.on("end", () => resolve(Buffer.concat(chunks).toString("utf8")));
      res.on("error", reject);
      res.on("aborted", () => reject(new Error("Catalog response interrupted")));
    });
    req.on("error", reject);
  });
}

export function modelsUrl(baseUrl: string): URL {
  const url = new URL(baseUrl.trim());
  let path = url.pathname.replace(/\/+$/, "");
  path = path.replace(/\/v1\/(?:chat\/completions|responses|models)$/, "/v1");
  if (!path.endsWith("/v1")) path += "/v1";
  url.pathname = `${path}/models`;
  url.search = "";
  url.hash = "";
  return url;
}