type Value = string | number | boolean | null | undefined | Value[] | { [key: string]: Value };

export function arrayDedup<T extends Value>(arr: T[]): T[] {
  const seen = new Map<string, T>();

  for (const item of arr) {
    const key = stableStringify(item);
    if (!seen.has(key)) {
      seen.set(key, item);
    }
  }

  return Array.from(seen.values());
}

/**
 * Deterministic stringify:
 * - sorts object keys
 * - preserves arrays order
 * - distinguishes undefined/null
 */
function stableStringify(value: Value): string {
  if (value === undefined) return 'undefined';
  if (value === null) return 'null';

  if (Array.isArray(value)) {
    return `[${value.map(stableStringify).join(',')}]`;
  }

  if (typeof value === 'object') {
    const keys = Object.keys(value).sort();
    return `{${keys.map((k) => `${k}:${stableStringify(value[k])}`).join(',')}}`;
  }

  return `${typeof value}:${String(value)}`;
}