'use strict';

const { EachSeries } = require('./eachSeries');

class ConcatSeries extends EachSeries {
  constructor(collection, iterator) {
    super(collection, iterator);
    this._result = [];
  }

  _callResolve(value) {
    if (Array.isArray(value)) {
      this._result.push(...value);
    } else if (value !== undefined) {
      this._result.push(value);
    }
    if (--this._rest === 0) {
      this._promise._resolve(this._result);
    } else {
      this._iterate();
    }
  }
}

module.exports = { concatSeries, ConcatSeries };

/**
 * `Aigle.concatSeries` is almost the as [`Aigle.concat`](https://suguru03.github.io/aigle/docs/Aigle.html#concat), but it will work in series.
 * @param {Array|Object} collection
 * @param {Function} iterator
 * @return {Aigle} Returns an Aigle instance
 * @example
 * const order = [];
 * const collection = [1, 4, 2];
 * const iterator = (num, index, collection) => {
 *   return Aigle.delay(num * 10)
 *     .then(() => {
 *       order.push(num);
 *       return num;
 *     });
 * };
 * Aigle.concatSeries(collection, iterator)
 *   .then(array => {
 *     console.log(array); // [1, 4, 2];
 *     console.log(order); // [1, 4, 2];
 *   });
 *
 * @example
 * const order = [];
 * const collection = { a: 1, b: 4, c: 2 };
 * const iterator = (num, key, collection) => {
 *   return Aigle.delay(num * 10)
 *     .then(() => {
 *       order.push(num);
 *       return num;
 *     });
 * };
 * Aigle.concatSeries(collection, iterator)
 *   .then(array => {
 *     console.log(array); // [1, 4, 2];
 *     console.log(order); // [1, 4, 2];
 *   });
 */
function concatSeries(collection, iterator) {
  return new ConcatSeries(collection, iterator)._execute();
}