Gielert/NoodleJS

/**
 * A Map with additional utility methods. This is used throughout discord.js rather than Arrays for anything that has
 * an ID, for significantly improved performance and ease-of-use.
 * @extends {Map}
 */
class Collection extends Map {
  constructor(iterable) {
    super(iterable);

    /**
     * Cached array for the `array()` method - will be reset to `null` whenever `set()` or `delete()` are called
     * @name Collection#_array
     * @type {?Array}
     * @private
     */
    Object.defineProperty(this, '_array', { value: null, writable: true, configurable: true });

    /**
     * Cached array for the `keyArray()` method - will be reset to `null` whenever `set()` or `delete()` are called
     * @name Collection#_keyArray
     * @type {?Array}
     * @private
     */
    Object.defineProperty(this, '_keyArray', { value: null, writable: true, configurable: true });
  }

  set(key, val) {
    this._array = null;
    this._keyArray = null;
    return super.set(key, val);
  }

  delete(key) {
    this._array = null;
    this._keyArray = null;
    return super.delete(key);
  }

  /**
   * Creates an ordered array of the values of this collection, and caches it internally. The array will only be
   * reconstructed if an item is added to or removed from the collection, or if you change the length of the array
   * itself. If you don't want this caching behaviour, use `Array.from(collection.values())` instead.
   * @returns {Array}
   */
  array() {
    if (!this._array || this._array.length !== this.size) this._array = Array.from(this.values());
    return this._array;
  }

  /**
   * Searches for a single item where its specified property's value is identical to the given value
   * (`item[prop] === value`), or the given function returns a truthy value. In the latter case, this is identical to
   * [Array.find()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find).
   * <warn>All collections used in Discord.js are mapped using their `id` property, and if you want to find by id you
   * should use the `get` method. See
   * [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/get) for details.</warn>
   * @param {string|Function} propOrFn The property to test against, or the function to test with
   * @param {*} [value] The expected value - only applicable and required if using a property for the first argument
   * @returns {*}
   * @example
   * collection.find('username', 'Bob');
   * @example
   * collection.find(val => val.username === 'Bob');
   */
  find(propOrFn, value) {
    if (typeof propOrFn === 'string') {
      if (typeof value === 'undefined') throw new Error('Value must be specified.');
      for (const item of this.values()) {
        if (item[propOrFn] === value) return item;
      }
      return null;
    } else if (typeof propOrFn === 'function') {
      for (const [key, val] of this) {
        if (propOrFn(val, key, this)) return val;
      }
      return null;
    } else {
      throw new Error('First argument must be a property string or a function.');
    }
  }
}

module.exports = Collection;