class Cache {
  constructor() {
    this.kv = {};
  }

  /**
   * @param {string} key
   * @param {string} value
   * @param {boolean?} noOverride
   */
  set(key, value, noOverride) {
    if (noOverride && key in this.kv) {
      throw new Error("key exists");
    }

    this.kv[key] = value;
  }

  /**
   * @param {string} key
   * @return {string?}
   */
  get(key) {
    return this.kv[key] || null;
  }

  /**
   * @param {string[]} keys
   */
  del(...keys) {
    for (const key of keys) {
      delete this.kv[key];
    }
  }
}

let cache = null;

exports.new = function () {
  if (cache) throw new Error("cache already initiate");
  cache = new Cache();
  return cache;
};

exports.get = function () {
  if (!cache) throw new Error("cache not initiate");
  return cache;
};