<?php

/*

 * This file is part of Twig.

 *

 * (c) 2009 Fabien Potencier

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

/**

 * Twig_NodeVisitor_Escaper implements output escaping.

 *

 * @package    twig

 * @author     Fabien Potencier <fabien@symfony.com>

 */

class Twig_NodeVisitor_Escaper implements Twig_NodeVisitorInterface

{

    protected $statusStack = array();

    protected $blocks = array();

    protected $safeAnalysis;

    protected $traverser;

    function __construct()

    {

        $this->safeAnalysis = new Twig_NodeVisitor_SafeAnalysis();

    }

    /**

     * Called before child nodes are visited.

     *

     * @param Twig_NodeInterface $node The node to visit

     * @param Twig_Environment   $env  The Twig environment instance

     *

     * @param Twig_NodeInterface The modified node

     */

    public function enterNode(Twig_NodeInterface $node, Twig_Environment $env)

    {

        if ($node instanceof Twig_Node_AutoEscape) {

            $this->statusStack[] = $node->getAttribute('value');

        } elseif ($node instanceof Twig_Node_Block) {

            $this->statusStack[] = isset($this->blocks[$node->getAttribute('name')]) ? $this->blocks[$node->getAttribute('name')] : $this->needEscaping($env);

        }

        return $node;

    }

    /**

     * Called after child nodes are visited.

     *

     * @param Twig_NodeInterface $node The node to visit

     * @param Twig_Environment   $env  The Twig environment instance

     *

     * @param Twig_NodeInterface The modified node

     */

    public function leaveNode(Twig_NodeInterface $node, Twig_Environment $env)

    {

        if ($node instanceof Twig_Node_Expression_Filter) {

            return $this->preEscapeFilterNode($node, $env);

        } elseif ($node instanceof Twig_Node_Print) {

            return $this->escapePrintNode($node, $env, $this->needEscaping($env));

        }

        if ($node instanceof Twig_Node_AutoEscape || $node instanceof Twig_Node_Block) {

            array_pop($this->statusStack);

        } elseif ($node instanceof Twig_Node_BlockReference) {

            $this->blocks[$node->getAttribute('name')] = $this->needEscaping($env);

        }

        return $node;

    }

    protected function escapePrintNode(Twig_Node_Print $node, Twig_Environment $env, $type)

    {

        if (false === $type) {

            return $node;

        }

        $expression = $node->getNode('expr');

        if ($this->isSafeFor($type, $expression, $env)) {

            return $node;

        }

        $class = get_class($node);

        return new $class(

            $this->getEscaperFilter($type, $expression),

            $node->getLine()

        );

    }

    protected function preEscapeFilterNode(Twig_Node_Expression_Filter $filter, Twig_Environment $env)

    {

        $name = $filter->getNode('filter')->getAttribute('value');

        if (false !== $f = $env->getFilter($name)) {

            $type = $f->getPreEscape();

            if (null === $type) {

                return $filter;

            }

            $node = $filter->getNode('node');

            if ($this->isSafeFor($type, $node, $env)) {

                return $filter;

            }

            $filter->setNode('node', $this->getEscaperFilter($type, $node));

            return $filter;

        }

        return $filter;

    }

    protected function isSafeFor($type, Twig_NodeInterface $expression, $env)

    {

        $safe = $this->safeAnalysis->getSafe($expression);

        if (null === $safe) {

            if (null === $this->traverser) {

                $this->traverser = new Twig_NodeTraverser($env, array($this->safeAnalysis));

            }

            $this->traverser->traverse($expression);

            $safe = $this->safeAnalysis->getSafe($expression);

        }

        return in_array($type, $safe) || in_array('all', $safe);

    }

    protected function needEscaping(Twig_Environment $env)

    {

        if (count($this->statusStack)) {

            return $this->statusStack[count($this->statusStack) - 1];

        }

        if ($env->hasExtension('escaper') && $env->getExtension('escaper')->isGlobal()) {

            return 'html';

        }

        return false;

    }

    protected function getEscaperFilter($type, Twig_NodeInterface $node)

    {

        $line = $node->getLine();

        $name = new Twig_Node_Expression_Constant('escape', $line);

        $args = new Twig_Node(array(new Twig_Node_Expression_Constant((string) $type, $line)));

        return new Twig_Node_Expression_Filter($node, $name, $args, $line);

    }

    /**

     * {@inheritdoc}

     */

    public function getPriority()

    {

        return 0;

    }

}