<?php
/**
 * @file
 *
 * PseudoClass class.
 *
 * This is the first pass in an experiment to break PseudoClass handling
 * out of the normal traversal. Eventually, this should become a
 * top-level pluggable registry that will allow custom pseudoclasses.
 * For now, though, we just handle the core pseudoclasses.
 */
namespace QueryPath\CSS\DOMTraverser;

use \QueryPath\CSS\NotImplementedException;
use \QueryPath\CSS\EventHandler;
/**
 *  The PseudoClass handler.
 *
 */
class PseudoClass {

  /**
   * Tests whether the given element matches the given pseudoclass.
   *
   * @param string $pseudoclass
   *   The string name of the pseudoclass
   * @param resource $node
   *   The DOMNode to be tested.
   * @param resource $scope
   *   The DOMElement that is the active root for this node.
   * @param mixed $value
   *   The optional value string provided with this class. This is
   *   used, for example, in an+b psuedoclasses.
   * @retval boolean
   *   TRUE if the node matches, FALSE otherwise.
   */
  public function elementMatches($pseudoclass, $node, $scope, $value = NULL) {
    $name = strtolower($pseudoclass);
    // Need to handle known pseudoclasses.
    switch($name) {
      case 'current':
      case 'past':
      case 'future':
      case 'visited':
      case 'hover':
      case 'active':
      case 'focus':
      case 'animated': //  Last 3 are from jQuery
      case 'visible':
      case 'hidden':
        // These require a UA, which we don't have.
      case 'valid':
      case 'invalid':
      case 'required':
      case 'optional':
      case 'read-only':
      case 'read-write':
        // Since we don't know how to validate elements,
        // we can't supply these.
      case 'dir':
        // FIXME: I don't know how to get directionality info.
      case 'nth-column':
      case 'nth-last-column':
        // We don't know what a column is in most documents.
        // FIXME: Can we do this for HTML?
      case 'target':
        // This requires a location URL, which we don't have.
        return FALSE;
      case 'indeterminate':
        // Because sometimes screwing with people is fun.
        return (boolean) mt_rand(0, 1);
      case 'lang':
        // No value = exception.
        if (!isset($value)) {
          throw new NotImplementedException(":lang() requires a value.");
        }
        return $this->lang($node, $value);
      case 'any-link':
        return Util::matchesAttribute($node, 'href')
          || Util::matchesAttribute($node, 'src')
          || Util::matchesAttribute($node, 'link');
      case 'link':
        return Util::matchesAttribute($node, 'href');
      case 'local-link':
        return $this->isLocalLink($node);
      case 'root':
        return $node->isSameNode($node->ownerDocument->documentElement);

        // CSS 4 declares the :scope pseudo-class, which describes what was
        // the :x-root QueryPath extension.
      case 'x-root':
      case 'x-reset':
      case 'scope':
        return $node->isSameNode($scope);
      // NON-STANDARD extensions for simple support of even and odd. These
      // are supported by jQuery, FF, and other user agents.
      case 'even':
        return $this->isNthChild($node, 'even');
      case 'odd':
        return $this->isNthChild($node, 'odd');
      case 'nth-child':
        return $this->isNthChild($node, $value);
      case 'nth-last-child':
        return $this->isNthChild($node, $value, TRUE);
      case 'nth-of-type':
        return $this->isNthChild($node, $value, FALSE, TRUE);
      case 'nth-last-of-type':
        return $this->isNthChild($node, $value, TRUE, TRUE);
      case 'first-of-type':
        return $this->isFirstOfType($node);
      case 'last-of-type':
        return $this->isLastOfType($node);
      case 'only-of-type':
        return $this->isFirstOfType($node) && $this->isLastOfType($node);

      // Additional pseudo-classes defined in jQuery:
      case 'lt':
        // I'm treating this as "less than or equal to".
        $rule = sprintf('-n + %d', (int) $value);
        // $rule = '-n+15';
        return $this->isNthChild($node, $rule);
      case 'gt':
        // I'm treating this as "greater than"
        // return $this->nodePositionFromEnd($node) > (int) $value;
        return $this->nodePositionFromStart($node) > (int) $value;
      case 'nth':
      case 'eq':
        $rule = (int)$value;
        return $this->isNthChild($node, $rule);
      case 'first':
        return $this->isNthChild($node, 1);
      case 'first-child':
        return $this->isFirst($node);
      case 'last':
      case 'last-child':
        return $this->isLast($node);
      case 'only-child':
        return $this->isFirst($node) && $this->isLast($node);
      case 'empty':
        return $this->isEmpty($node);
      case 'parent':
        return !$this->isEmpty($node);

      case 'enabled':
      case 'disabled':
      case 'checked':
        return Util::matchesAttribute($node, $name);
      case 'text':
      case 'radio':
      case 'checkbox':
      case 'file':
      case 'password':
      case 'submit':
      case 'image':
      case 'reset':
      case 'button':
        return Util::matchesAttribute($node, 'type', $name);

      case 'header':
        return $this->header($node);
      case 'has':
      case 'matches':
        return $this->has($node, $value);
        break;
      case 'not':
        if (empty($value)) {
          throw new ParseException(":not() requires a value.");
        }
        return $this->isNot($node, $value);
      // Contains == text matches.
      // In QP 2.1, this was changed.
      case 'contains':
        return $this->contains($node, $value);
      // Since QP 2.1
      case 'contains-exactly':
        return $this->containsExactly($node, $value);
      default:
        throw new \QueryPath\CSS\ParseException("Unknown Pseudo-Class: " . $name);
    }
    $this->findAnyElement = FALSE;
  }

  /**
   * Pseudo-class handler for :lang
   *
   * Note that this does not implement the spec in its entirety because we do
   * not presume to "know the language" of the document. If anyone is interested
   * in making this more intelligent, please do so.
   */
  protected function lang($node, $value) {
    // TODO: This checks for cases where an explicit language is
    // set. The spec seems to indicate that an element should inherit
    // language from the parent... but this is unclear.
    $operator = (strpos($value, '-') !== FALSE) ? EventHandler::isExactly : EventHandler::containsWithHyphen;

    $match = TRUE;
    foreach ($node->attributes as $attrNode) {
      if ($attrNode->localName == 'lang') {

        if ($attrNode->nodeName == $attrNode->localName) {
          // fprintf(STDOUT, "%s in NS %s\n", $attrNode->name, $attrNode->nodeName);
          return Util::matchesAttribute($node, 'lang', $value, $operator);
        }
        else {
          $nsuri = $attrNode->namespaceURI;
          // fprintf(STDOUT, "%s in NS %s\n", $attrNode->name, $nsuri);
          return Util::matchesAttributeNS($node, 'lang', $nsuri, $value, $operator);
        }

      }
    }
    return FALSE;
  }

  /**
   * Provides jQuery pseudoclass ':header'.
   */
  protected function header($node) {
    return preg_match('/^h[1-9]$/i', $node->tagName) == 1;
  }

  /**
   * Provides pseudoclass :empty.
   */
  protected function isEmpty($node) {
    foreach ($node->childNodes as $kid) {
      // We don't want to count PIs and comments. From the spec, it
      // appears that CDATA is also not counted.
      if ($kid->nodeType == XML_ELEMENT_NODE || $kid->nodeType == XML_TEXT_NODE) {
        // As soon as we hit a FALSE, return.
        return FALSE;
      }
    }
    return TRUE;
  }

  /**
   * Provides jQuery pseudoclass :first.
   *
   * @todo
   *   This can be replaced by isNthChild().
   */
  protected function isFirst($node) {
    while (isset($node->previousSibling)) {
      $node = $node->previousSibling;
      if ($node->nodeType == XML_ELEMENT_NODE) {
        return FALSE;
      }
    }
    return TRUE;
  }
  /**
   * Fast version of first-of-type.
   */
  protected function isFirstOfType($node) {
    $type = $node->tagName;
    while (isset($node->previousSibling)) {
      $node = $node->previousSibling;
      if ($node->nodeType == XML_ELEMENT_NODE && $node->tagName == $type) {
        return FALSE;
      }
    }
    return TRUE;
  }
  /**
   * Fast version of jQuery :last.
   */
  protected function isLast($node) {
    while (isset($node->nextSibling)) {
      $node = $node->nextSibling;
      if ($node->nodeType == XML_ELEMENT_NODE) {
        return FALSE;
      }
    }
    return TRUE;
  }
  /**
   * Provides last-of-type.
   */
  protected function isLastOfType($node) {
    $type = $node->tagName;
    while (isset($node->nextSibling)) {
      $node = $node->nextSibling;
      if ($node->nodeType == XML_ELEMENT_NODE && $node->tagName == $type) {
        return FALSE;
      }
    }
    return TRUE;
  }
  /**
   * Provides :contains() as the original spec called for.
   *
   * This is an INEXACT match.
   */
  protected function contains($node, $value) {
    $text = $node->textContent;
    $value = Util::removeQuotes($value);
    return isset($text) && (stripos($text, $value) !== FALSE);
  }
  /**
   * Provides :contains-exactly QueryPath pseudoclass.
   *
   * This is an EXACT match.
   */
  protected function containsExactly($node, $value) {
    $text = $node->textContent;
    $value = Util::removeQuotes($value);
    return isset($text) && $text == $value;
  }

  /**
   * Provides :has pseudoclass.
   */
  protected function has($node, $selector) {
    $splos = new \SPLObjectStorage();
    $splos->attach($node);
    $traverser = new \QueryPath\CSS\DOMTraverser($splos, TRUE);
    $results = $traverser->find($selector)->matches();
    return count($results) > 0;
  }

  /**
   * Provides :not pseudoclass.
   */
  protected function isNot($node, $selector) {
    return !$this->has($node, $selector);
  }

  /**
   * Get the relative position of a node in its sibling set.
   */
  protected function nodePositionFromStart($node, $byType = FALSE) {
    $i = 1;
    $tag = $node->tagName;
    while (isset($node->previousSibling)) {
      $node = $node->previousSibling;
      if ($node->nodeType == XML_ELEMENT_NODE && (!$byType || $node->tagName == $tag)) {
        ++$i;
      }
    }
    return $i;
  }
  /**
   * Get the relative position of a node in its sibling set.
   */
  protected function nodePositionFromEnd($node, $byType = FALSE) {
    $i = 1;
    $tag = $node->tagName;
    while (isset($node->nextSibling)) {
      $node = $node->nextSibling;
      if ($node->nodeType == XML_ELEMENT_NODE && (!$byType || $node->tagName == $tag)) {
        ++$i;
      }
    }
    return $i;
  }

  /**
   * Provides functionality for all "An+B" rules.
   * Provides nth-child and also the functionality required for:
   *
   *- nth-last-child
   *- even
   *- odd
   *- first
   *- last
   *- eq
   *- nth
   *- nth-of-type
   *- first-of-type
   *- last-of-type
   *- nth-last-of-type
   *
   * See also QueryPath::CSS::DOMTraverser::Util::parseAnB().
   */
  protected function isNthChild($node, $value, $reverse = FALSE, $byType = FALSE) {
    list($groupSize, $elementInGroup) = Util::parseAnB($value);
    $parent = $node->parentNode;
    if (empty($parent)
      || ($groupSize == 0 && $elementInGroup == 0)
      || ($groupSize > 0 && $elementInGroup > $groupSize)
    ) {
      return FALSE;
    }

    // First we need to find the position of $node in other elements.
    if ($reverse) {
      $pos = $this->nodePositionFromEnd($node, $byType);
    }
    else {
      $pos = $this->nodePositionFromStart($node, $byType);
    }

    // If group size is 0, we just check to see if this
    // is the nth element:
    if ($groupSize == 0) {
      return $pos == $elementInGroup;
    }

    // Next, we normalize $elementInGroup
    if ($elementInGroup < 0) {
      $elementInGroup = $groupSize + $elementInGroup;
    }


    $prod = ($pos - $elementInGroup) / $groupSize;
    // fprintf(STDOUT, "%d n + %d on %d is %3.5f\n", $groupSize, $elementInGroup, $pos, $prod);

    return is_int($prod) && $prod >= 0;
  }

  protected function isLocalLink($node) {
    if (!$node->hasAttribute('href')) {
      return FALSE;
    }
    $url = $node->getAttribute('href');
    $scheme = parse_url($url, PHP_URL_SCHEME);
    return empty($scheme) || $scheme == 'file';
  }

}
