<?php

/*
 * This file is part of Twig.
 *
 * (c) 2009 Fabien Potencier
 * (c) 2009 Armin Ronacher
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Loops over each item of a sequence.
 *
 * <pre>
 * <ul>
 *  {% for user in users %}
 *    <li>{{ user.username|e }}</li>
 *  {% endfor %}
 * </ul>
 * </pre>
 */
class Twig_TokenParser_For extends Twig_TokenParser
{
  /**
   * Parses a token and returns a node.
   *
   * @param Twig_Token $token A Twig_Token instance
   *
   * @return Twig_NodeInterface A Twig_NodeInterface instance
   */
  public function parse(Twig_Token $token)
  {
    $lineno = $token->getLine();
    $stream = $this->parser->getStream();
    $targets = $this->parser->getExpressionParser()->parseAssignmentExpression();
    $stream->expect(Twig_Token::OPERATOR_TYPE, 'in');
    $seq = $this->parser->getExpressionParser()->parseExpression();

    $ifexpr = null;
    if ($stream->nextIf(Twig_Token::NAME_TYPE, 'if')) {
      $ifexpr = $this->parser->getExpressionParser()->parseExpression();
    }

    $stream->expect(Twig_Token::BLOCK_END_TYPE);
    $body = $this->parser->subparse([$this, 'decideForFork']);
    if ($stream->next()->getValue() == 'else') {
      $stream->expect(Twig_Token::BLOCK_END_TYPE);
      $else = $this->parser->subparse([$this, 'decideForEnd'], true);
    } else {
      $else = null;
    }
    $stream->expect(Twig_Token::BLOCK_END_TYPE);

    if (count($targets) > 1) {
      $keyTarget = $targets->getNode(0);
      $keyTarget = new Twig_Node_Expression_AssignName($keyTarget->getAttribute('name'), $keyTarget->getLine());
      $valueTarget = $targets->getNode(1);
      $valueTarget = new Twig_Node_Expression_AssignName($valueTarget->getAttribute('name'), $valueTarget->getLine());
    } else {
      $keyTarget = new Twig_Node_Expression_AssignName('_key', $lineno);
      $valueTarget = $targets->getNode(0);
      $valueTarget = new Twig_Node_Expression_AssignName($valueTarget->getAttribute('name'), $valueTarget->getLine());
    }

    if ($ifexpr) {
      $this->checkLoopUsageCondition($stream, $ifexpr);
      $this->checkLoopUsageBody($stream, $body);
    }

    return new Twig_Node_For($keyTarget, $valueTarget, $seq, $ifexpr, $body, $else, $lineno, $this->getTag());
  }

  public function decideForFork(Twig_Token $token)
  {
    return $token->test(['else', 'endfor']);
  }

  public function decideForEnd(Twig_Token $token)
  {
    return $token->test('endfor');
  }

  // the loop variable cannot be used in the condition
  protected function checkLoopUsageCondition(Twig_TokenStream $stream, Twig_NodeInterface $node)
  {
    if ($node instanceof Twig_Node_Expression_GetAttr && $node->getNode('node') instanceof Twig_Node_Expression_Name && 'loop' == $node->getNode('node')->getAttribute('name')) {
      throw new Twig_Error_Syntax('The "loop" variable cannot be used in a looping condition', $node->getLine(), $stream->getFilename());
    }

    foreach ($node as $n) {
      if (!$n) {
        continue;
      }

      $this->checkLoopUsageCondition($stream, $n);
    }
  }

  // check usage of non-defined loop-items
  // it does not catch all problems (for instance when a for is included into another or when the variable is used in an include)
  protected function checkLoopUsageBody(Twig_TokenStream $stream, Twig_NodeInterface $node)
  {
    if ($node instanceof Twig_Node_Expression_GetAttr && $node->getNode('node') instanceof Twig_Node_Expression_Name && 'loop' == $node->getNode('node')->getAttribute('name')) {
      $attribute = $node->getNode('attribute');
      if ($attribute instanceof Twig_Node_Expression_Constant && in_array($attribute->getAttribute('value'), ['length', 'revindex0', 'revindex', 'last'])) {
        throw new Twig_Error_Syntax(sprintf('The "loop.%s" variable is not defined when looping with a condition', $attribute->getAttribute('value')), $node->getLine(), $stream->getFilename());
      }
    }

    // should check for parent.loop.XXX usage
    if ($node instanceof Twig_Node_For) {
      return;
    }

    foreach ($node as $n) {
      if (!$n) {
        continue;
      }

      $this->checkLoopUsageBody($stream, $n);
    }
  }

  /**
   * Gets the tag name associated with this token parser.
   *
   * @return string The tag name
   */
  public function getTag()
  {
    return 'for';
  }
}
