// Query strings and list answers shared by the API modules.

/** "?a=1&b=x" from the defined, non-empty values. Empty when nothing is set. */
export function qs(params: Record<string, string | number | boolean | null | undefined>): string {
  const sp = new URLSearchParams();
  for (const [k, v] of Object.entries(params)) {
    if (v === undefined || v === null || v === "") continue;
    sp.set(k, String(v));
  }
  const s = sp.toString();
  return s ? `?${s}` : "";
}

/** A list answer may come bare or wrapped as {key: [...]}. Both give the array. */
export function asList<T>(raw: unknown, key: string): T[] {
  if (Array.isArray(raw)) return raw as T[];
  if (raw && typeof raw === "object" && Array.isArray((raw as Record<string, unknown>)[key])) {
    return (raw as Record<string, T[]>)[key] as T[];
  }
  return [];
}

/** The If-Match header for a version check. */
export function ifMatch(version: number): Record<string, string> {
  return { "If-Match": String(version) };
}