<?php declare(strict_types=1);

namespace EmsApi;

use Iterator;

/**
 * Class ParamsIterator
 * @package EmsApi
 *
 * Implementation based on CMapIterator class file from the Yii framework, as follows:
 *
 * CMapIterator implements an iterator for {@link CMap}.
 *
 * It allows CMap to return a new iterator for traversing the items in the map.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.collections
 * @since 1.0
 */
class ParamsIterator implements Iterator
{
    /**
     * @var array the data to be iterated through
     */
    private $_data = [];
    
    /**
     * @var array list of keys in the map
     */
    private $_keys = [];
    
    /**
     * @var mixed current key
     */
    private $_key;

    /**
     * Constructor.
     * @param array $data the data to be iterated through
     */
    public function __construct(array &$data = [])
    {
        $this->_data =& $data;
        $this->_keys = array_keys($data);
        $this->_key = reset($this->_keys);
    }

    /**
     * Rewinds internal array pointer.
     * This method is required by the interface Iterator.
     *
     * @return void
     */
    #[\ReturnTypeWillChange]
    public function rewind()
    {
        $this->_key = reset($this->_keys);
    }

    /**
     * Returns the key of the current array element.
     * This method is required by the interface Iterator.
     * @return mixed the key of the current array element
     */
    #[\ReturnTypeWillChange]
    public function key()
    {
        return $this->_key;
    }

    /**
     * Returns the current array element.
     * This method is required by the interface Iterator.
     * @return mixed the current array element
     */
    #[\ReturnTypeWillChange]
    public function current()
    {
        return $this->_data[$this->_key];
    }

    /**
     * Moves the internal pointer to the next array element.
     * This method is required by the interface Iterator.
     *
     * @return void
     */
    #[\ReturnTypeWillChange]
    public function next()
    {
        $this->_key = next($this->_keys);
    }

    /**
     * Returns whether there is an element at current position.
     * This method is required by the interface Iterator.
     * @return boolean
     */
    #[\ReturnTypeWillChange]
    public function valid()
    {
        return $this->_key !== false;
    }
}