/**
 * Client for /api/suggest.
 *
 * No `cache: "no-store"`. The compare modal's search uses it, and copying that
 * here would discard both the browser cache and the ETag 304s the backend's
 * CacheAndETagMiddleware already provides — on the one endpoint where prefix
 * queries repeat most.
 */

export interface Suggestion {
  urn: number;
  school_name: string;
  local_authority: string;
  postcode: string;
  phase: string;
  school_type: string;
}

/** Below this the response is thousands of schools and worth no round trip. */
export const SUGGEST_MIN_QUERY = 2;

const API = process.env.NEXT_PUBLIC_API_URL || '/api';

/** Suggestions for `q`. Never throws: no suggestions is a fine outcome. */
export async function fetchSuggestions(
  q: string, signal?: AbortSignal,
): Promise<Suggestion[]> {
  if (q.trim().length < SUGGEST_MIN_QUERY) return [];
  try {
    const res = await fetch(`${API}/suggest?q=${encodeURIComponent(q.trim())}`,
      { signal });
    if (!res.ok) return [];
    const body = await res.json();
    return body.suggestions ?? [];
  } catch {
    // Includes AbortError, which is the normal path on every keystroke.
    return [];
  }
}