<?php

/**
 * Joomla! Content Management System
 *
 * @copyright  (C) 2018 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;

use Joomla\CMS\Form\Form;
use Joomla\CMS\Form\FormRule;
use Joomla\Database\DatabaseAwareInterface;
use Joomla\Database\DatabaseAwareTrait;
use Joomla\Registry\Registry;

// phpcs:disable PSR1.Files.SideEffects
\defined('JPATH_PLATFORM') or die;
// phpcs:enable PSR1.Files.SideEffects

/**
 * Form rule class to determine if a value exists in a database table.
 *
 * @since  3.9.0
 */
class ExistsRule extends FormRule implements DatabaseAwareInterface
{
    use DatabaseAwareTrait;

    /**
     * Method to test the username for uniqueness.
     *
     * @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   3.9.0
     */
    public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
    {
        $value = trim($value);

        $existsTable  = (string) $element['exists_table'];
        $existsColumn = (string) $element['exists_column'];

        // We cannot validate without a table name
        if ($existsTable === '') {
            return true;
        }

        // Assume a default column name of `id`
        if ($existsColumn === '') {
            $existsColumn = 'id';
        }

        $db = $this->getDatabase();

        // Set and query the database.
        $exists = $db->setQuery(
            $db->getQuery(true)
                ->select('COUNT(*)')
                ->from($db->quoteName($existsTable))
                ->where($db->quoteName($existsColumn) . ' = ' . $db->quote($value))
        )->loadResult();

        return (int) $exists > 0;
    }
}