<?php

/**
 * GET and POST form on drupal, preserving existing form data
 */
class DrupalUserAgent {
  private $handle;
  private $base_url;
    
  public function __construct($base_url = '') {
    $this->handle = curl_init();
    $this->set_base_url($base_url);
  }

  /**
   * Utility function to set the client's base-url.
   *
   * This is needed because on some installations we use SSL, and cURL changes
   * POST requests to GET after redirects.
   */
  public function set_base_url($base_url) {
    
    $this->curlOpen($base_url);
    // Do *not* follow redirects - we want to analyse the server's response.
    curl_setopt($this->handle, CURLOPT_FOLLOWLOCATION, FALSE);

    $this->curlExecute();
    $info = curl_getinfo($this->handle);

    if ($info['http_code'] == 301) {
	// Redirect detected
	// Get the headers & extract the goto - URL
        $headers = get_headers($info['url']);

        $location = "";
        foreach( $headers as $value ) {
            if ( substr( strtolower($value), 0, 9 ) == "location:" ) {
              $redirected_base_url= trim( substr( $value, 9, strlen($value)));
	      // Use the found values as base-url.
              $this->base_url= $redirected_base_url;
              return;
            }
        }
    }

    // Default: use the provided url
    $this->base_url =  $base_url;
  }


  public function close() {
    curl_close($this->handle);
    unset($this->handle);
  }
  
  static public function asDom($content) {
    $html = DOMDocument::loadHTML($content);
    if (is_null($html)) {
      throw new Exception("Could not parse HTML at url ". $url);
    }
    return simplexml_import_dom($html);
  }

  public function getDom($url) {
    $content = $this->get($url);
    return self::asDom($content);    
  }

  public function get($url) {   
    $this->curlOpen($url);
    curl_setopt($this->handle, CURLOPT_HTTPGET, True);

    return $this->curlExecute();
  }  
  
  public function post($url, $params) {         
    $this->curlOpen($url);
    curl_setopt($this->handle, CURLOPT_POST, count($params));
    curl_setopt($this->handle, CURLOPT_POSTFIELDS, DrupalUserAgent::paramString($params));
    return $this->curlExecute();      
  }
  
  public static function paramString($params) {
    $post = array();
    foreach($params as $field => $value) {
      $post[] = urlencode($field) .'='. urlencode($value); 
    }
    
    return implode($post, '&'); 
  }
  
  public function curlOpen($url) {
    // echo $url ."\n";
    $options = array(
      CURLOPT_URL => $this->absoluteUrl($url),
      //CURLOPT_VERBOSE => TRUE,
      CURLOPT_COOKIEJAR => NULL, // accepts session cookie, just not on disk
      CURLOPT_TIMEOUT => 300, 
      CURLOPT_FOLLOWLOCATION => TRUE,
      CURLOPT_RETURNTRANSFER => TRUE,
      CURLOPT_SSL_VERIFYPEER => FALSE,
      CURLOPT_USERAGENT => 'drupal-user-agent');
    curl_setopt_array($this->handle, $options);
  }
  
  public function setCookies($cookies) {
    curl_setopt($this->handle, CURLOPT_COOKIE, DrupalUserAgent::paramString($params));
  }

  public function curlExecute() {
    $content = curl_exec($this->handle);      
    $err_id = curl_errno($this->handle);
    if ($err_id != 0) {
      throw new Exception(curl_error($this->handle));
    }
    
    return $content;
  }

  public function absoluteUrl($url) {
    if (empty($url)) {
      return $this->base_url;
    }
    if (empty($this->base_url) || strpos($url, $this->base_url) === 0) {
      return $url;
    }
    
    return $this->base_url . $url;
  }  
}

class DrupalFormLoader {
  private $form;
  private $params = array();

  public function __construct($form) {
    $this->form = $form;
  }
  
  public static function findById($dom, $id) {
    $elems = $dom->elements->xpath("//form[@id='" . $id ."']");
    return empty($elems) ? NULL : new DrupalFormLoader($elems[0]);
  }
  
  public static function findBySubmitValue($dom, $submit) {
    $elems = $dom->elements->xpath("//input[@type='submit' and @value='" . $submit ."']");
    if (!$elems) {
      return NULL;
    }
    
    foreach ($elems as $elem) {
      $form = $elem->xpath('ancestor::form');
      if (!empty($form)) {
        return new DrupalFormLoader($form);
      }
    }    
  }
  
  public function setValue($name, $value) {
    $this->params[$name] = $value;
  }
  
  public function getAction() {
    return (string)$this->form['action'];
  }
  
  public function getParams() {
    
    // surely there is more types, only understand these at the moment
    $elements = $this->form->xpath("descendant::input|descendant::textarea");
    
    foreach ($elements as $element) {
       // SimpleXML objects need string casting all the time.
      $name = (string)$element['name'];
      
      // ignore preset parameters
      if (empty($name) || array_key_exists($name, $this->params)) {
        continue;
      }
      
      switch ($element->getName()) {
        case 'input':
          $type = $element['type'];
          switch ($type) {
            case 'radio':
            case 'checkbox':
              if (!isset($element['checked'])) {
                break;
              }
              // Deliberate no break.
              
            default:
              $value = isset($element['value']) ? (string)$element['value'] : '';
              break;
          }
          break;
        case 'textarea':
          $value = (string)$element;
          break;
        case 'select':
          throw new Exception('select element not supported yet');
      }
      $this->params[$name] = $value;
    }
    
    return $this->params;      
  }  
}

?>