<?php
declare(strict_types=1);

/**
 * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 * @link          https://cakephp.org CakePHP(tm) Project
 * @since         3.0.0
 * @license       https://opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\Collection;

use ArrayIterator;
use IteratorIterator;
use SplFixedArray;

/**
 * A collection is an immutable list of elements with a handful of functions to
 * iterate, group, transform and extract information from it.
 *
 * @template TKey
 * @template TValue
 * @extends \IteratorIterator<TKey, TValue, \Traversable<TKey, TValue>>
 * @implements \Cake\Collection\CollectionInterface<TKey, TValue>
 */
class Collection extends IteratorIterator implements CollectionInterface
{
    /** @use \Cake\Collection\CollectionTrait<TKey, TValue> */
    use CollectionTrait;

    /**
     * Whether or not the items in this collection are an array.
     *
     * @var bool
     */
    protected bool $innerIsArray = false;

    /**
     * Constructor. You can provide an array or any traversable object
     *
     * @param iterable<TKey, TValue> $items Items.
     * @throws \InvalidArgumentException If passed incorrect type for items.
     */
    public function __construct(iterable $items)
    {
        if (is_array($items)) {
            $items = new ArrayIterator($items);
        }

        $this->innerIsArray = $items instanceof ArrayIterator || $items instanceof SplFixedArray;

        parent::__construct($items);
    }

    /**
     * Returns an array for serializing this object.
     *
     * @return array
     */
    public function __serialize(): array
    {
        return $this->buffered()->toArray();
    }

    /**
     * Rebuilds the Collection instance.
     *
     * @param array $data Data array.
     * @return void
     */
    public function __unserialize(array $data): void
    {
        /** @phpstan-ignore argument.type (unserialize rebuilds from array) */
        $this->__construct($data);
    }

    /**
     * Returns an array that can be used to describe the internal state of this
     * object.
     *
     * @return array<string, mixed>
     */
    public function __debugInfo(): array
    {
        if ($this->innerIsArray) {
            $index = $this->key();
            $items = $this->toArray();

            $this->rewind();
            while ($this->key() !== $index) {
                $this->next();
            }

            return [
                'count' => count($items),
                'items' => $items,
            ];
        }

        return [
            'innerIterator' => $this->unwrap(),
        ];
    }
}
