import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'flatten'
})
export class FlattenPipe implements PipeTransform {

  transform(input: any, available: boolean = false): any[] {
    
    function convertToArray(object) {

      return Array.isArray(object) ? object : Object.keys(object).map(function (key) {

        return object[key];

      });

    }

    function flatten(array, index) {

      index = index || 0;

      if (index >= array.length)
        return array;

      if (Array.isArray(array[index])) {

        return flatten(array.slice(0, index).concat(array[index], array.slice(index + 1)), index);

      }

      return flatten(array, index + 1);

    }

    function isObject(object) {

      return (typeof object === "object" && object !== null) || typeof object === "function";

    }

    available = available || false;

    input = isObject(input) ? convertToArray(input) : input;

    if (!Array.isArray(input)) {

      return input;

    }

    return !available ? flatten(input, 0) : [].concat.apply([], input);
  }

}