// PDS cache TTL: 1 hour (PDS endpoints rarely change)

const PDS_CACHE_TTL_MS = 60 * 60 * 1000;

function isPdsCacheValid(cachedAt: string | null): boolean {

  if (!cachedAt) return false;

  const cacheTime = new Date(cachedAt).getTime();

  return Date.now() - cacheTime < PDS_CACHE_TTL_MS;

}

export async function resolvePds(

  db: D1Database,

  did: string

): Promise<string | null> {

  const cached = await db

    .prepare("SELECT pds_endpoint, cached_at FROM pds_cache WHERE did = ?")

    .bind(did)

    .first<{ pds_endpoint: string; cached_at: string }>();

  if (cached && isPdsCacheValid(cached.cached_at)) {

    return cached.pds_endpoint;

  }

  try {

    const response = await fetch(`https://plc.directory/${did}`);

    if (!response.ok) return null;

    const doc = (await response.json()) as {

      service?: Array<{ id: string; type: string; serviceEndpoint: string }>;

    };

    const pds = doc.service?.find((s) => s.id === "#atproto_pds");

    if (pds?.serviceEndpoint) {

      await db

        .prepare(

          `INSERT INTO pds_cache (did, pds_endpoint, cached_at)

           VALUES (?, ?, datetime('now'))

           ON CONFLICT(did) DO UPDATE SET pds_endpoint = ?, cached_at = datetime('now')`

        )

        .bind(did, pds.serviceEndpoint, pds.serviceEndpoint)

        .run();

      return pds.serviceEndpoint;

    }

    return null;

  } catch {

    return null;

  }

}