<?php

/*
 * This file is part of Twig.
 *
 * (c) Fabien Potencier
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Twig_SupTwgSgg_NodeVisitor_Optimizer tries to optimizes the AST.
 *
 * This visitor is always the last registered one.
 *
 * You can configure which optimizations you want to activate via the
 * optimizer mode.
 *
 * @final
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class Twig_SupTwgSgg_NodeVisitor_Optimizer extends Twig_SupTwgSgg_BaseNodeVisitor
{
  const OPTIMIZE_ALL = -1;
  const OPTIMIZE_NONE = 0;
  const OPTIMIZE_FOR = 2;
  const OPTIMIZE_RAW_FILTER = 4;
  const OPTIMIZE_VAR_ACCESS = 8;

  protected $loops = [];
  protected $loopsTargets = [];
  protected $optimizers;
  protected $prependedNodes = [];
  protected $inABody = false;

  /**
   * @param int $optimizers The optimizer mode
   */
  public function __construct($optimizers = -1)
  {
    if (!is_int($optimizers) || $optimizers > (self::OPTIMIZE_FOR | self::OPTIMIZE_RAW_FILTER | self::OPTIMIZE_VAR_ACCESS)) {
      throw new InvalidArgumentException(sprintf('Optimizer mode "%s" is not valid.', $optimizers));
    }

    $this->optimizers = $optimizers;
  }

  protected function doEnterNode(Twig_SupTwgSgg_Node $node, Twig_SupTwgSgg_Environment $env)
  {
    if (self::OPTIMIZE_FOR === (self::OPTIMIZE_FOR & $this->optimizers)) {
      $this->enterOptimizeFor($node, $env);
    }

    if (PHP_VERSION_ID < 50400 && self::OPTIMIZE_VAR_ACCESS === (self::OPTIMIZE_VAR_ACCESS & $this->optimizers) && !$env->isStrictVariables() && !$env->hasExtension('Twig_SupTwgSgg_Extension_Sandbox')) {
      if ($this->inABody) {
        if (!$node instanceof Twig_SupTwgSgg_Node_Expression) {
          if (get_class($node) !== 'Twig_SupTwgSgg_Node') {
            array_unshift($this->prependedNodes, []);
          }
        } else {
          $node = $this->optimizeVariables($node, $env);
        }
      } elseif ($node instanceof Twig_SupTwgSgg_Node_Body) {
        $this->inABody = true;
      }
    }

    return $node;
  }

  protected function doLeaveNode(Twig_SupTwgSgg_Node $node, Twig_SupTwgSgg_Environment $env)
  {
    $expression = $node instanceof Twig_SupTwgSgg_Node_Expression;

    if (self::OPTIMIZE_FOR === (self::OPTIMIZE_FOR & $this->optimizers)) {
      $this->leaveOptimizeFor($node, $env);
    }

    if (self::OPTIMIZE_RAW_FILTER === (self::OPTIMIZE_RAW_FILTER & $this->optimizers)) {
      $node = $this->optimizeRawFilter($node, $env);
    }

    $node = $this->optimizePrintNode($node, $env);

    if (self::OPTIMIZE_VAR_ACCESS === (self::OPTIMIZE_VAR_ACCESS & $this->optimizers) && !$env->isStrictVariables() && !$env->hasExtension('Twig_SupTwgSgg_Extension_Sandbox')) {
      if ($node instanceof Twig_SupTwgSgg_Node_Body) {
        $this->inABody = false;
      } elseif ($this->inABody) {
        if (!$expression && get_class($node) !== 'Twig_SupTwgSgg_Node' && ($prependedNodes = array_shift($this->prependedNodes))) {
          $nodes = [];
          foreach (array_unique($prependedNodes) as $name) {
            $nodes[] = new Twig_SupTwgSgg_Node_SetTemp($name, $node->getTemplateLine());
          }

          $nodes[] = $node;
          $node = new Twig_SupTwgSgg_Node($nodes);
        }
      }
    }

    return $node;
  }

  protected function optimizeVariables(Twig_SupTwgSgg_NodeInterface $node, Twig_SupTwgSgg_Environment $env)
  {
    if ('Twig_SupTwgSgg_Node_Expression_Name' === get_class($node) && $node->isSimple()) {
      $this->prependedNodes[0][] = $node->getAttribute('name');

      return new Twig_SupTwgSgg_Node_Expression_TempName($node->getAttribute('name'), $node->getTemplateLine());
    }

    return $node;
  }

  /**
   * Optimizes print nodes.
   *
   * It replaces:
   *
   *   * "echo $this->render(Parent)Block()" with "$this->display(Parent)Block()"
   *
   * @return Twig_SupTwgSgg_NodeInterface
   */
  protected function optimizePrintNode(Twig_SupTwgSgg_NodeInterface $node, Twig_SupTwgSgg_Environment $env)
  {
    if (!$node instanceof Twig_SupTwgSgg_Node_Print) {
      return $node;
    }

    $exprNode = $node->getNode('expr');
    if ($exprNode instanceof Twig_SupTwgSgg_Node_Expression_BlockReference || $exprNode instanceof Twig_SupTwgSgg_Node_Expression_Parent) {
      $exprNode->setAttribute('output', true);

      return $exprNode;
    }

    return $node;
  }

  /**
   * Removes "raw" filters.
   *
   * @return Twig_SupTwgSgg_NodeInterface
   */
  protected function optimizeRawFilter(Twig_SupTwgSgg_NodeInterface $node, Twig_SupTwgSgg_Environment $env)
  {
    if ($node instanceof Twig_SupTwgSgg_Node_Expression_Filter && 'raw' == $node->getNode('filter')->getAttribute('value')) {
      return $node->getNode('node');
    }

    return $node;
  }

  /**
   * Optimizes "for" tag by removing the "loop" variable creation whenever possible.
   */
  protected function enterOptimizeFor(Twig_SupTwgSgg_NodeInterface $node, Twig_SupTwgSgg_Environment $env)
  {
    if ($node instanceof Twig_SupTwgSgg_Node_For) {
      // disable the loop variable by default
      $node->setAttribute('with_loop', false);
      array_unshift($this->loops, $node);
      array_unshift($this->loopsTargets, $node->getNode('value_target')->getAttribute('name'));
      array_unshift($this->loopsTargets, $node->getNode('key_target')->getAttribute('name'));
    } elseif (!$this->loops) {
      // we are outside a loop
      return;
    }

    // when do we need to add the loop variable back?
    // the loop variable is referenced for the current loop
    elseif ($node instanceof Twig_SupTwgSgg_Node_Expression_Name && 'loop' === $node->getAttribute('name')) {
      $node->setAttribute('always_defined', true);
      $this->addLoopToCurrent();
    }

    // optimize access to loop targets
    elseif ($node instanceof Twig_SupTwgSgg_Node_Expression_Name && in_array($node->getAttribute('name'), $this->loopsTargets)) {
      $node->setAttribute('always_defined', true);
    }

    // block reference
    elseif ($node instanceof Twig_SupTwgSgg_Node_BlockReference || $node instanceof Twig_SupTwgSgg_Node_Expression_BlockReference) {
      $this->addLoopToCurrent();
    }

    // include without the only attribute
    elseif ($node instanceof Twig_SupTwgSgg_Node_Include && !$node->getAttribute('only')) {
      $this->addLoopToAll();
    }

    // include function without the with_context=false parameter
    elseif ($node instanceof Twig_SupTwgSgg_Node_Expression_Function && 'include' === $node->getAttribute('name') && (!$node->getNode('arguments')->hasNode('with_context') || false !== $node->getNode('arguments')->getNode('with_context')->getAttribute('value'))) {
      $this->addLoopToAll();
    }

    // the loop variable is referenced via an attribute
    elseif (
      $node instanceof Twig_SupTwgSgg_Node_Expression_GetAttr &&
      (!$node->getNode('attribute') instanceof Twig_SupTwgSgg_Node_Expression_Constant || 'parent' === $node->getNode('attribute')->getAttribute('value')) &&
      (true === $this->loops[0]->getAttribute('with_loop') || ($node->getNode('node') instanceof Twig_SupTwgSgg_Node_Expression_Name && 'loop' === $node->getNode('node')->getAttribute('name')))
    ) {
      $this->addLoopToAll();
    }
  }

  /**
   * Optimizes "for" tag by removing the "loop" variable creation whenever possible.
   */
  protected function leaveOptimizeFor(Twig_SupTwgSgg_NodeInterface $node, Twig_SupTwgSgg_Environment $env)
  {
    if ($node instanceof Twig_SupTwgSgg_Node_For) {
      array_shift($this->loops);
      array_shift($this->loopsTargets);
      array_shift($this->loopsTargets);
    }
  }

  protected function addLoopToCurrent()
  {
    $this->loops[0]->setAttribute('with_loop', true);
  }

  protected function addLoopToAll()
  {
    foreach ($this->loops as $loop) {
      $loop->setAttribute('with_loop', true);
    }
  }

  public function getPriority()
  {
    return 255;
  }
}
