/**
 * Handle-based actor search for the DID lookup form.
 *
 * Primary service is waow.tech's typeahead (https://typeahead.waow.tech/docs),
 * which mirrors bluesky's `app.bsky.actor.searchActorsTypeahead` endpoint.
 * Bluesky's public API is the fallback when waow looks like it's having
 * server trouble (a 5xx status, or unreachable entirely).
 */

export type TypeaheadActor = {
  did: string;
  handle: string;
  displayName?: string;
};

const ENDPOINT = '/xrpc/app.bsky.actor.searchActorsTypeahead';
const WAOW_API = 'https://typeahead.waow.tech';
const BSKY_API = 'https://public.api.bsky.app';
const LIMIT = 8;

function endpointUrl(base: string, q: string): string {
  const params = new URLSearchParams({ q, limit: String(LIMIT) });
  return `${base}${ENDPOINT}?${params}`;
}

function parseActors(body: unknown): TypeaheadActor[] {
  if (typeof body !== 'object' || body === null) return [];
  const actors = (body as { actors?: unknown }).actors;
  if (!Array.isArray(actors)) return [];
  return actors.flatMap((actor: unknown) => {
    if (typeof actor !== 'object' || actor === null) return [];
    const { did, handle, displayName } = actor as Record<string, unknown>;
    if (typeof did !== 'string' || typeof handle !== 'string') return [];
    return [
      {
        did,
        handle,
        displayName: typeof displayName === 'string' ? displayName : undefined,
      },
    ];
  });
}

/**
 * Search actors by (partial) handle or display name.
 *
 * Makes at most one request to each service per call — no retry loops. The
 * caller is expected to abort superseded queries via `signal`; an abort
 * throws, every other failure resolves to an empty list.
 */
export async function searchActorsTypeahead(
  q: string,
  signal: AbortSignal,
): Promise<TypeaheadActor[]> {
  let res: Response | undefined;
  try {
    res = await fetch(endpointUrl(WAOW_API, q), {
      signal,
      // their docs ask clients to identify themselves (header is in their
      // CORS allow-list, verified 2026-08)
      headers: { 'X-Client': 'web.hubble.microcosm.blue' },
    });
  } catch (err) {
    if (signal.aborted) throw err;
    // network-level failure: fall through to the bluesky attempt
  }
  // a 4xx means waow rejected this query; don't shop it around
  if (res && !res.ok && res.status < 500) return [];
  if (!res || !res.ok) {
    res = await fetch(endpointUrl(BSKY_API, q), { signal });
    if (!res.ok) return [];
  }
  return parseActors(await res.json());
}