<?php

namespace Symfony\Components\CssSelector\Node;

use Symfony\Components\CssSelector\SyntaxError;
use Symfony\Components\CssSelector\XPathExpr;

/*
 * This file is part of the symfony package.
 *
 * (c) Fabien Potencier <fabien.potencier@symfony-project.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * FunctionNode represents a "selector:name(expr)" node.
 *
 * This component is a port of the Python lxml library,
 * which is copyright Infrae and distributed under the BSD license.
 *
 * @package    symfony
 * @subpackage css_selector
 * @author     Fabien Potencier <fabien.potencier@symfony-project.com>
 */
class FunctionNode implements NodeInterface
{
  static protected $unsupported = array('target', 'lang', 'enabled', 'disabled');

  protected $selector;
  protected $type;
  protected $name;
  protected $expr;

  public function __construct($selector, $type, $name, $expr)
  {
    $this->selector = $selector;
    $this->type = $type;
    $this->name = $name;
    $this->expr = $expr;
  }

  public function __toString()
  {
    return sprintf('%s[%s%s%s(%s)]', __CLASS__, $this->selector, $this->type, $this->name, $this->expr);
  }

  public function toXpath()
  {
    $sel_path = $this->selector->toXpath();
    if (in_array($this->name, self::$unsupported))
    {
      throw new SyntaxError(sprintf("The pseudo-class %s is not supported", $this->name));
    }
    $method = '_xpath_'.str_replace('-', '_', $this->name);
    if (!method_exists($this, $method))
    {
      throw new SyntaxError(sprintf("The pseudo-class %s is unknown", $this->name));
    }

    return $this->$method($sel_path, $this->expr);
  }

  protected function _xpath_nth_child($xpath, $expr, $last = false, $addNameTest = true)
  {
    list($a, $b) = $this->parseSeries($expr);
    if (!$a && !$b && !$last)
    {
      // a=0 means nothing is returned...
      $xpath->addCondition('false() and position() = 0');

      return $xpath;
    }

    if ($addNameTest)
    {
      $xpath->addNameTest();
    }

    $xpath->addStarPrefix();
    if ($a == 0)
    {
      if ($last)
      {
        $b = sprintf('last() - %s', $b);
      }
      $xpath->addCondition(sprintf('position() = %s', $b));

      return $xpath;
    }

    if ($last)
    {
      // FIXME: I'm not sure if this is right
      $a = -$a;
      $b = -$b;
    }

    if ($b > 0)
    {
      $b_neg = -$b;
    }
    else
    {
      $b_neg = sprintf('+%s', -$b);
    }

    if ($a != 1)
    {
      $expr = array(sprintf('(position() %s) mod %s = 0', $b_neg, $a));
    }
    else
    {
      $expr = array();
    }

    if ($b >= 0)
    {
      $expr[] = sprintf('position() >= %s', $b);
    }
    elseif ($b < 0 && $last)
    {
      $expr[] = sprintf('position() < (last() %s)', $b);
    }
    $expr = implode($expr, ' and ');

    if ($expr)
    {
      $xpath->addCondition($expr);
    }

    return $xpath;
    /* FIXME: handle an+b, odd, even
       an+b means every-a, plus b, e.g., 2n+1 means odd
       0n+b means b
       n+0 means a=1, i.e., all elements
       an means every a elements, i.e., 2n means even
       -n means -1n
       -1n+6 means elements 6 and previous */
  }

  protected function _xpath_nth_last_child($xpath, $expr)
  {
    return $this->_xpath_nth_child($xpath, $expr, true);
  }

  protected function _xpath_nth_of_type($xpath, $expr)
  {
    if ($xpath->getElement() == '*')
    {
      throw new SyntaxError("*:nth-of-type() is not implemented");
    }

    return $this->_xpath_nth_child($xpath, $expr, false, false);
  }

  protected function _xpath_nth_last_of_type($xpath, $expr)
  {
    return $this->_xpath_nth_child($xpath, $expr, true, false);
  }

  protected function _xpath_contains($xpath, $expr)
  {
    // text content, minus tags, must contain expr
    if ($expr instanceof ElementNode)
    {
      $expr = $expr->formatElement();
    }
    $xpath->addCondition(sprintf('contains(css:lower-case(string(.)), %s)', XPathExpr::xpathLiteral(strtolower($expr))));
    // FIXME: Currently case insensitive matching doesn't seem to be happening

    return $xpath;
  }

  protected function _xpath_not($xpath, $expr)
  {
    // everything for which not expr applies
    $expr = $expr->toXpath();
    $cond = $expr->getCondition();
    // FIXME: should I do something about element_path?
    $xpath->addCondition(sprintf('not(%s)', $cond));

    return $xpath;
  }

  // Parses things like '1n+2', or 'an+b' generally, returning (a, b)
  protected function parseSeries($s)
  {
    if ($s instanceof ElementNode)
    {
      $s = $s->formatElement();
    }

    if (!$s || $s == '*')
    {
      // Happens when there's nothing, which the CSS parser thinks of as *
      return array(0, 0);
    }

    if (is_string($s))
    {
      // Happens when you just get a number
      return array(0, $s);
    }

    if ($s == 'odd')
    {
      return array(2, 1);
    }
    elseif ($s == 'even')
    {
      return array(2, 0);
    }
    elseif ($s == 'n')
    {
      return array(1, 0);
    }

    if (false === strpos($s, 'n'))
    {
      // Just a b

      return array(0, intval((string) $s));
    }

    list($a, $b) = explode('n', $s);
    if (!$a)
    {
      $a = 1;
    }
    elseif ($a == '-' || $a == '+')
    {
      $a = intval($a.'1');
    }
    else
    {
      $a = intval($a);
    }

    if (!$b)
    {
      $b = 0;
    }
    elseif ($b == '-' || $b == '+')
    {
      $b = intval($b.'1');
    }
    else
    {
      $b = intval($b);
    }

    return array($a, $b);
  }
}