'use strict';

var _arrayPush = require('./_arrayPush.js');
var _isFlattenable = require('./_isFlattenable.js');

/**
 * The base implementation of `_.flatten` with support for restricting flattening.
 *
 * @private
 * @param {Array} array The array to flatten.
 * @param {number} depth The maximum recursion depth.
 * @param {boolean} [predicate=isFlattenable] The function invoked per iteration.
 * @param {boolean} [isStrict] Restrict to values that pass `predicate` checks.
 * @param {Array} [result=[]] The initial result value.
 * @returns {Array} Returns the new flattened array.
 */
function baseFlatten(array, depth, predicate, isStrict, result) {
  var index = -1,
      length = array.length;

  predicate || (predicate = _isFlattenable);
  result || (result = []);

  while (++index < length) {
    var value = array[index];
    if (predicate(value)) {
      {
        _arrayPush(result, value);
      }
    } else if (!isStrict) {
      result[result.length] = value;
    }
  }
  return result;
}

module.exports = baseFlatten;
