export type SetItemComparator<T> = (a: T, b: T) => boolean;

/**
 *
 */
export class ComparableSet<T> {
  items: Array<T>;
  comparator: SetItemComparator<T>;

  /**
   *
   * @param items
   * @param comparator
   */
  constructor(items: Array<T> = [], comparator?: SetItemComparator<T>) {
    this.items = items;

    if (comparator) {
      this.comparator = comparator;
    } else {
      // Default comparator
      this.comparator = (a: T, b: T): boolean => a === b;
    }
  }

  /**
   *
   * @param item
   */
  add(item: T): void {
    if (!this.has(item)) {
      this.items.push(item);
    }
  }

  /**
   *
   * @param newSet
   */
  concat(newSet: ComparableSet<T>) {
    newSet.items.forEach(newItem => {
      this.add(newItem);
    });
  }

  /**
   *
   */
  copy(): ComparableSet<T> {
    return new ComparableSet(this.items.slice(0), this.comparator);
  }

  /**
   *
   * @param item
   */
  has(item: T): boolean {
    return this.items.find(setItem => this.comparator(item, setItem)) !== undefined;
  }

  list(): Array<T> {
    return this.items.slice(0);
  }
}