<?php

/**
 * @package   Functional-php
 * @author    Lars Strojny <lstrojny@php.net>
 * @copyright 2011-2017 Lars Strojny
 * @license   https://opensource.org/licenses/MIT MIT
 * @link      https://github.com/lstrojny/functional-php
 */

namespace Functional;

use ArrayAccess;
use Functional\Exceptions\InvalidArgumentException;

/**
 * Pick a single element from a collection of objects or arrays by index.
 * If no such index exists, return the default value.
 *
 * @param ArrayAccess|array $collection
 * @param mixed $index
 * @param mixed $default
 * @param callable $callback Custom function to check if index exists, default function is "isset"
 * @return mixed
 */
function pick($collection, $index, $default = null, callable $callback = null)
{
    InvalidArgumentException::assertArrayAccess($collection, __FUNCTION__, 1);

    if ($callback === null) {
        if (!isset($collection[$index])) {
            return $default;
        }
    } else {
        if (!$callback($collection, $index)) {
            return $default;
        }
    }

    return $collection[$index];
}