export class ExtendedArray<T> extends Array<T> {
  constructor(data?: Array<T>) {
    super();
    Object.setPrototypeOf(this, ExtendedArray.prototype);
    this.addRange(data);
  }

  addRange(data: Array<T>) {
    if (!data) {
      return;
    }
    data.map(item => this.push(item));
  }

  chunkify(size: number): Array<Array<T>> {
    size = size !== undefined && size !== null && size > 0 ? size : 10;
    let groups = [],
      i;
    for (i = 0; i < this.length; i += size) {
      groups.push(this.slice(i, i + size));
    }
    return groups;
  }

  groupBy(prop: any) {
    return this.reduce((grouped, item) => {
      let key = this.isFunction(prop) ? prop.apply(this, [item]) : item[prop];
      grouped[key] = grouped[key] || [];
      grouped[key].push(item);
      return grouped;
    }, {});
  }

  private isFunction(obj: any) {
    return !!(obj && obj.constructor && obj.call && obj.apply);
  }
}