<?php
/** @file
 * A selector.
 */

namespace QueryPath\CSS;

/**
 * A CSS Selector.
 *
 * A CSS selector is made up of one or more Simple Selectors
 * (SimpleSelector).
 *
 * @attention
 * The Selector data structure is a LIFO (Last in, First out). This is
 * because CSS selectors are best processed "bottom up". Thus, when
 * iterating over 'a>b>c', the iterator will produce:
 * - c
 * - b
 * - a
 * It is assumed, therefore, that any suitable querying engine will
 * traverse from the bottom (`c`) back up.
 *
 * @b Usage
 *
 * This class is an event handler. It can be plugged into an Parser and 
 * receive the events the Parser generates.
 *
 * This class is also an iterator. Once the parser has completed, the
 * captured selectors can be iterated over.
 *
 * @code
 * <?php
 * $selectorList = new \QueryPath\CSS\Selector();
 * $parser = new \QueryPath\CSS\Parser($selector, $selectorList);
 *
 * $parser->parse();
 *
 * foreach ($selectorList as $simpleSelector) {
 *   // Do something with the SimpleSelector.
 *   print_r($simpleSelector);
 * }
 * ?>
 * @endode
 *
 *
 * @since QueryPath 3.0.0
 */
class Selector implements EventHandler, \IteratorAggregate, \Countable {
  protected $selectors = array();
  protected $currSelector;
  protected $selectorGroups = array();
  protected $groupIndex = 0;

  public function __construct() {
    $this->currSelector = new SimpleSelector();

    $this->selectors[$this->groupIndex][] = $this->currSelector;
  }

  public function getIterator() {
    return new \ArrayIterator($this->selectors);
  }

  /**
   * Get the array of SimpleSelector objects.
   *
   * Normally, one iterates over a Selector. However, if it is
   * necessary to get the selector array and manipulate it, this
   * method can be used.
   */
  public function toArray() {
    return $this->selectors;
  }

  public function count() {
    return count($this->selectors);
  }

  public function elementID($id) {
    $this->currSelector->id = $id;
  }
  public function element($name) {
    $this->currSelector->element = $name;
  }
  public function elementNS($name, $namespace = NULL) {
    $this->currSelector->ns = $namespace;
    $this->currSelector->element = $name;
  }
  public function anyElement() {
    $this->currSelector->element = '*';
  }
  public function anyElementInNS($ns) {
    $this->currSelector->ns = $ns;
    $this->currSelector->element = '*';
  }
  public function elementClass($name) {
    $this->currSelector->classes[] = $name;
  }
  public function attribute($name, $value = NULL, $operation = EventHandler::isExactly) {
    $this->currSelector->attributes[] = array(
      'name'  => $name,
      'value' => $value,
      'op'    => $operation,
    );
  }
  public function attributeNS($name, $ns, $value = NULL, $operation = EventHandler::isExactly) {
    $this->currSelector->attributes[] = array(
      'name'  => $name,
      'value' => $value,
      'op'    => $operation,
      'ns'    => $ns,
    );
  }
  public function pseudoClass($name, $value = NULL) {
    $this->currSelector->pseudoClasses[] = array('name' => $name, 'value' => $value);
  }
  public function pseudoElement($name) {
    $this->currSelector->pseudoElements[] = $name;
  }
  public function combinator($combinatorName) {
    $this->currSelector->combinator = $combinatorName;
    $this->currSelector = new SimpleSelector();
    array_unshift($this->selectors[$this->groupIndex], $this->currSelector);
    //$this->selectors[]= $this->currSelector;
  }
  public function directDescendant() {
    $this->combinator(SimpleSelector::directDescendant);
  }
  public function adjacent() {
    $this->combinator(SimpleSelector::adjacent);
  }
  public function anotherSelector() {
    $this->groupIndex++;
    $this->currSelector = new SimpleSelector();
    $this->selectors[$this->groupIndex] = array($this->currSelector);
  }
  public function sibling() {
    $this->combinator(SimpleSelector::sibling);
  }
  public function anyDescendant() {
    $this->combinator(SimpleSelector::anyDescendant);
  }
}