<?php
/**
 * Joomla! Content Management System
 *
 * @copyright  Copyright (C) 2005 - 2020 Open Source Matters, Inc. All rights reserved.
 * @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\Filesystem\Path;
use Joomla\CMS\Form\Form;
use Joomla\CMS\Form\FormRule;
use Joomla\Registry\Registry;

/**
 * Form Rule class for the Joomla Platform.
 *
 * @since  3.9.21
 */
class FilePathRule extends FormRule
{
	/**
	 * Method to test if the file path is valid
	 *
	 * @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   3.9.21
	 */
	public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
	{
		$value = trim($value);

		// If the field is empty and not required, the field is valid.
		$required = ((string) $element['required'] == 'true' || (string) $element['required'] == 'required');

		if (!$required && empty($value))
		{
			return true;
		}

		// Get the exclude setting from the xml
		$exclude = (array) explode('|', (string) $element['exclude']);

		// Exclude current folder '.' to be safe from full path disclosure
		$exclude[] = '.';

		// Check the exclude setting
		$path = preg_split('/[\/\\\\]/', $value);

		if (in_array(strtolower($path[0]), $exclude) || empty($path[0]))
		{
			return false;
		}

		// Prepend the root path
		$value = JPATH_ROOT . '/' . $value;

		// Check if $value is a valid path, which includes not allowing to break out of the current path
		try
		{
			Path::check($value);
		}
		catch (\Exception $e)
		{
			// When there is an exception in the check path this is not valid
			return false;
		}

		// When there are no exception this rule should pass.
		// See: https://github.com/joomla/joomla-cms/issues/30500#issuecomment-683290162
		return true;
	}
}