import { fetch, Agent, setGlobalDispatcher } from "undici";
import dns from "dns/promises";

export async function byDNS(domain: string): Promise<string | any> {
  const txt = `_atproto.${domain}`;
  let records: string[][];

  try {
    records = await dns.resolveTxt(txt);
  } catch (e) {
    return null;
  }

  for (const chunks of records) {
    const record = chunks.join("");
    const trimmed = record.trim();

    if (trimmed.toLowerCase().startsWith("did=")) {
      const candidate = trimmed.slice(4).trim();

      if (candidate) return candidate;
    }
  }

  return null;
}

export async function byHTTP(domain: string, secure: boolean = true): Promise<string | any> {
  const agent = new Agent({ keepAliveTimeout: 10000 });
  setGlobalDispatcher(agent);

  let url;

  if (secure) {
    url = `https://${domain}/.well-known/atproto-did`;
  } else {
    url = `http://${domain}/.well-known/atproto-did`;
  }

  try {
    const response = await fetch(url);
    const data = await response.text();

    if (!data) {
      return null;
    } else {
      return data.trim();
    }
  } catch (e) {
    return null;
  }
}

export async function getPLC(did: string, endpoint: string = "https://plc.directory"): Promise<any> {
  const agent = new Agent({ keepAliveTimeout: 10000 });
  setGlobalDispatcher(agent);

  try {
    const response = await fetch(`${endpoint}/${did}`);
    const data = await response.json();

    if (!data) {
      return null;
    } else {
      return data;
    }
  } catch (e) {
    return null;
  }
}

export async function byPLC(did: string) {
  const didDoc = await getPLC(did);
  return didDoc.id;
}

export async function getPDS(did: string) {
  const didDoc = await getPLC(did);
  return didDoc.service[0].serviceEndpoint;
}