<?php
/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2020 Open Source Matters, Inc. <https://www.joomla.org>
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace Joomla\CMS\Form\Rule;

\defined('JPATH_PLATFORM') or die;

use Joomla\CMS\Factory;
use Joomla\CMS\Form\Form;
use Joomla\CMS\Form\FormRule;
use Joomla\Database\ParameterType;
use Joomla\Registry\Registry;

/**
 * Form Rule class for the Joomla Platform.
 *
 * @since  4.0.0
 */
class UserIdRule extends FormRule
{
	/**
	 * Method to test the validity of a Joomla User.
	 *
	 * @param   \SimpleXMLElement  $element  The SimpleXMLElement object representing the `<field>` tag for the form field object.
	 * @param   mixed              $value    The form field value to validate.
	 * @param   ?string            $group    The field name group control value. This acts as an array container for the field.
	 *                                       For example if the field has name="foo" and the group value is set to "bar" then the
	 *                                       full field name would end up being "bar[foo]".
	 * @param   ?Registry          $input    An optional Registry object with the entire data set to validate against the entire form.
	 * @param   ?Form              $form     The form object for which the field is being tested.
	 *
	 * @return  boolean  True if the value is valid, false otherwise.
	 *
	 * @since   4.0.0
	 */
	public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
	{
		// Check if the field is required.
		$required = ((string) $element['required'] === 'true' || (string) $element['required'] === 'required');

		// If the value is empty, null or has the value 0 and the field is not required return true else return false
		if (($value === '' || $value === null || (string) $value === '0'))
		{
			return !$required;
		}

		// Get the database object and a new query object.
		$db = Factory::getDbo();
		$query = $db->getQuery(true);

		// Build the query.
		$query->select('COUNT(*)')
			->from($db->quoteName('#__users'))
			->where($db->quoteName('id') . ' = :userId')
			->bind(':userId', $value, ParameterType::INTEGER);

		// Set and query the database.
		return (bool) $db->setQuery($query)->loadResult();
	}
}
