<?php
defined('_JEXEC') or die('Restricted access');

/**
 * Source: http://code.google.com/p/oauth/
 *
 * Rename and move as needed, changing the require_once() call to the correct
 * name and path.
 */
require_once( JPATH_ROOT . '/components/com_easyblog/constants.php' );

// the PECL OAuth extension is not present, load our third-party OAuth library
require_once( EBLOG_CLASSES . '/oauth.php');


/**
 * This file defines the 'LinkedIn' class. This class is designed to be a 
 * simple, stand-alone implementation of the LinkedIn API functions.
 * 
 * COPYRIGHT:
 *   
 * Copyright (C) 2011, fiftyMission Inc.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a 
 * copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, including without limitation 
 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in 
 * all copies or substantial portions of the Software.  
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 
 * IN THE SOFTWARE.  
 *
 * SOURCE CODE LOCATION:
 * 
 * http://code.google.com/p/simple-linkedinphp/
 *    
 * REQUIREMENTS:
 * 
 * 1. You must have cURL installed on the server and available to PHP.
 * 2. You must be running PHP 5+.  
 *  
 * QUICK START:
 * 
 * There are two files needed to enable LinkedIn API functionality from PHP; the
 * stand-alone OAuth library, and this LinkedIn class. The latest version of 
 * the stand-alone OAuth library can be found on Google Code:
 * 
 * http://code.google.com/p/oauth/
 *   
 * Install these two files on your server in a location that is accessible to 
 * the scripts you wish to use them in. Make sure to change the file 
 * permissions such that your web server can read the files.
 * 
 * Next, make sure the path to the OAuth library is correct (you can change this 
 * as needed, depending on your file organization scheme, etc).
 * 
 * Finally, test the class by attempting to connect to LinkedIn using the 
 * associated demo.php page, also located at the Google Code location
 * referenced above.                   
 *   
 * RESOURCES:
 *    
 * REST API Documentation: http://developer.linkedin.com/rest
 *    
 * @version 3.2.0 - November 8, 2011
 * @author Paul Mennega <paul@fiftymission.net>
 * @copyright Copyright 2011, fiftyMission Inc. 
 * @license http://www.opensource.org/licenses/mit-license.php The MIT License 
 */

/**
 * 'LinkedInException' class declaration.
 *  
 * This class extends the base 'Exception' class.
 * 
 * @access public
 * @package classpackage
 */
class LinkedInException extends Exception {}

/**
 * 'LinkedIn' class declaration.
 *  
 * This class provides generalized LinkedIn oauth functionality.
 * 
 * @access public
 * @package classpackage
 */
class LinkedIn {
  // api/oauth settings
  const _API_OAUTH_REALM             = 'http://api.linkedin.com';
  const _API_OAUTH_VERSION           = '1.0';
  
  // the default response format from LinkedIn
  const _DEFAULT_RESPONSE_FORMAT     = 'xml';
    
  // helper constants used to standardize LinkedIn <-> API communication.  See demo page for usage.
  const _GET_RESPONSE                = 'lResponse';
  const _GET_TYPE                    = 'lType';
  
  // Invitation API constants.
  const _INV_SUBJECT                 = 'Invitation to connect';
  const _INV_BODY_LENGTH             = 200;
  
  // API methods
  const _METHOD_TOKENS               = 'POST';
  
  // Network API constants.
  const _NETWORK_LENGTH              = 1000;
  const _NETWORK_HTML                = '<a>';
  
  // response format type constants, see http://developer.linkedin.com/docs/DOC-1203
  const _RESPONSE_JSON               = 'JSON';
  const _RESPONSE_JSONP              = 'JSONP';
  const _RESPONSE_XML                = 'XML';
  
  // Share API constants
  const _SHARE_COMMENT_LENGTH        = 700;
  const _SHARE_CONTENT_TITLE_LENGTH  = 200;
  const _SHARE_CONTENT_DESC_LENGTH   = 400;
  
  // LinkedIn API end-points
  const _URL_ACCESS                  = 'https://api.linkedin.com/uas/oauth/accessToken';
  const _URL_API                     = 'https://api.linkedin.com';
  const _URL_AUTH                    = 'https://www.linkedin.com/uas/oauth/authenticate?oauth_token=';
  const _URL_REQUEST                 = 'https://api.linkedin.com/uas/oauth/requestToken';
  const _URL_REVOKE                  = 'https://api.linkedin.com/uas/oauth/invalidateToken';
  
  // Library version
  const _VERSION                     = '3.2.0';
  
  // oauth properties
  protected $callback;
  protected $token                   = NULL;
  
  // application properties
  protected $application_key, 
            $application_secret;
  
  // the format of the data to return
  protected $response_format         = self::_DEFAULT_RESPONSE_FORMAT;

  // last request fields
  public $last_request_headers, 
         $last_request_url;

  /**
   * Create a LinkedIn object, used for OAuth-based authentication and 
   * communication with the LinkedIn API.  
   * 
   * @param arr $config
   *    The 'start-up' object properties:
   *           - appKey       => The application's API key
   *           - appSecret    => The application's secret key
   *           - callbackUrl  => [OPTIONAL] the callback URL
   *                   
   * @return obj
   *    A new LinkedIn object.   
   */
  public function __construct($config) {
    if(!is_array($config)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->__construct(): bad data passed, $config must be of type array.');
    }
    $this->setApplicationKey($config['appKey']);
    $this->setApplicationSecret($config['appSecret']);
    $this->setCallbackUrl($config['callbackUrl']);
  }
  
  /**
   * The class destructor.
   * 
   * Explicitly clears LinkedIn object from memory upon destruction.
   */
  public function __destruct() {
    unset($this);
  }
  
  /**
   * Bookmark a job.
   * 
   * Calling this method causes the current user to add a bookmark for the 
   * specified job:
   * 
   *   http://developer.linkedin.com/docs/DOC-1323
   * 
   * @param str $jid
   *    Job ID you want to bookmark.
   *           
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function bookmarkJob($jid) {
    // check passed data
    if(!is_string($jid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->bookmarkJob(): bad data passed, $jid must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/job-bookmarks';
    $response = $this->fetch('POST', $query, '<job-bookmark><job><id>' . trim($jid) . '</id></job></job-bookmark>');
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Get list of jobs you have bookmarked.
   * 
   * Returns a list of jobs the current user has bookmarked, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1323   
   *  
   * @return arr
   *         Array containing retrieval success, LinkedIn response.
   */
  public function bookmarkedJobs() {  
    // construct and send the request  
    $query    = self::_URL_API . '/v1/people/~/job-bookmarks';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Used to check whether a response LinkedIn object has the required http_code or not and 
   * returns an appropriate LinkedIn object.
   * 
   * @param var $http_code_required
   *    The required http response from LinkedIn, passed in either as an integer, 
   *    or an array of integers representing the expected values.  
   * @param arr $response 
   *    An array containing a LinkedIn response.
   * 
   * @return boolean
   *    TRUE or FALSE depending on if the passed LinkedIn response matches the expected response.
   */
  private function checkResponse($http_code_required, $response) {
    // check passed data
    if(is_array($http_code_required)) {
    } else {
      if(!is_int($http_code_required)) {
        throw new LinkedInException('LinkedIn->checkResponse(): $http_code_required must be an integer or an array of integer values');
      } else {
        $http_code_required = array($http_code_required);
      }
    }
    if(!is_array($response)) {
      throw new LinkedInException('LinkedIn->checkResponse(): $response must be an array');
    }   
    
    // check for a match
    if(in_array($response['info']['http_code'], $http_code_required)) {
      // response found
      $response['success'] = TRUE;
    } else {
      // response not found
      $response['success'] = FALSE;
      $response['error']   = 'HTTP response from LinkedIn end-point was not code ' . implode(', ', $http_code_required);
    }
    return $response;
  }
  
  /**
   * Close a job.
   * 
   * Calling this method causes the passed job to be closed, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1151   
   * 
   * @param str $jid
   *    Job ID you want to close.
   *              
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function closeJob($jid) {
    // check passed data
    if(!is_string($jid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->closeJob(): bad data passed, $jid must be of string value.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/jobs/partner-job-id=' . trim($jid);
    $response = $this->fetch('DELETE', $query);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Share comment posting method.
   * 
   * Post a comment on an existing connections shared content. API details can
   * be found here: 
   * 
   * http://developer.linkedin.com/docs/DOC-1043 
   * 
   * @param str $uid 
   *    The LinkedIn update ID.      
   * @param str $comment 
   *    The share comment to be posted.
   *               
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.         
   */
  public function comment($uid, $comment) {
    // check passed data
    if(!is_string($uid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->comment(): bad data passed, $uid must be of type string.');
    }
    if(!is_string($comment)) {
      // nothing/non-string passed, raise an exception
      throw new LinkedInException('LinkedIn->comment(): bad data passed, $comment must be a non-zero length string.');
    }
    
    /**
     * Share comment rules:
     * 
     * 1) No HTML permitted.
     * 2) Comment cannot be longer than 700 characters.     
     */
    $comment = substr(trim(htmlspecialchars(strip_tags($comment))), 0, self::_SHARE_COMMENT_LENGTH);
    $data    = '<?xml version="1.0" encoding="UTF-8"?>
                <update-comment>
                  <comment>' . $comment . '</comment>
                </update-comment>';

    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/network/updates/key=' . $uid . '/update-comments';
    $response = $this->fetch('POST', $query, $data);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Share comment retrieval.
   *     
   * Return all comments associated with a given network update:
   *   
   *   http://developer.linkedin.com/docs/DOC-1043
   * 
   * @param str $uid
   *    The LinkedIn update ID.
   *                       
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.                  
   */
  public function comments($uid) {
    // check passed data
    if(!is_string($uid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->comments(): bad data passed, $uid must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/network/updates/key=' . $uid . '/update-comments';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Company profile retrieval function.
   * 
   * Takes a string of parameters as input and requests company profile data 
   * from the LinkedIn Company Profile API. See the official documentation for 
   * $options 'field selector' formatting:
   * 
   *   http://developer.linkedin.com/docs/DOC-1014
   *   http://developer.linkedin.com/docs/DOC-1259   
   * 
   * @param str $options
   *    Data retrieval options. 
   * @param bool $by_email
   *    [OPTIONAL] Search by email domain?
   *   
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function company($options, $by_email = FALSE) {
    // check passed data
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->company(): bad data passed, $options must be of type string.');
    }
    if(!is_bool($by_email)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->company(): bad data passed, $by_email must be of type boolean.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/companies' . ($by_email ? '' : '/') . trim($options);

    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Company products and their associated recommendations.
   * 
   * The product data type contains details about a company's product or 
   * service, including recommendations from LinkedIn members, and replies from 
   * company representatives.
   * 
   *   http://developer.linkedin.com/docs/DOC-1327   
   * 
   * @param str $cid
   *    Company ID you want the producte for. 
   * @param str $options
   *    [OPTIONAL] Data retrieval options.
   *              
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function companyProducts($cid, $options = '') {
    // check passed data
    if(!is_string($cid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->companyProducts(): bad data passed, $cid must be of type string.');
    }
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->companyProducts(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/companies/' . trim($cid) . '/products' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
    
  /**
   * Connection retrieval function.
   * 
   * Takes a string of parameters as input and requests connection-related data 
   * from the Linkedin Connections API. See the official documentation for 
   * $options 'field selector' formatting:
   * 
   *   http://developer.linkedin.com/docs/DOC-1014         
   * 
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   *               
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function connections($options = '~/connections') {
    // check passed data
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->connections(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * This creates a post in the specified group with the specified title and specified summary.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * @param str $title
   *    The title of the post. This must be non-empty.
   * @param str $summary
   *    [OPTIONAL] The content or summary of the post. This can be empty.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function createPost($gid, $title, $summary = '') {
    if(!is_string($gid)) {
      throw new LinkedInException('LinkedIn->createPost(): bad data passed, $gid must be of type string.');
    }
    if(!is_string($title) || empty($title)) {
      throw new LinkedInException('LinkedIn->createPost(): bad data passed, $title must be a non-empty string.');
    }
    if(!is_string($summary)) {
      throw new LinkedInException('LinkedIn->createPost(): bad data passed, $summary must be of type string.');
    }
    
    // construct the XML
    $data = '<?xml version="1.0" encoding="UTF-8"?>
             <post>
               <title>'. $title . '</title>
               <summary>' . $summary . '</summary>
             </post>';
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/groups/' . trim($gid) . '/posts';
    $response = $this->fetch('POST', $query, $data);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(201, $response);
  }
  
  /**
   * This deletes the specified post if you are the owner or moderator that post.
   * Otherwise, it just flags the post as inappropriate.
   * 
   * https://developer.linkedin.com/documents/groups-api
   * 
   * @param str $pid
   *    The post id.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function deletePost($pid) {
    if(!is_string($pid)) {
      throw new LinkedInException('LinkedIn->deletePost(): bad data passed, $pid must be of type string');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/posts/' . trim($pid);
    $response = $this->fetch('DELETE', $query);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Edit a job.
   * 
   * Calling this method causes the passed job to be edited, with the passed
   * XML instructing which fields to change, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1154
   *   http://developer.linkedin.com/docs/DOC-1142      
   * 
   * @param str $jid
   *    Job ID you want to renew.
   * @param str $xml
   *    The XML containing the job fields to edit.   
   *              
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function editJob($jid, $xml) {
    // check passed data
    if(!is_string($jid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->editJob(): bad data passed, $jid must be of string value.');
    }
    if(is_string($xml)) {
      $xml = trim(stripslashes($xml));
    } else {
      // bad data passed
      throw new LinkedInException('LinkedIn->editJob(): bad data passed, $xml must be of string value.');
    }
               
    // construct and send the request
    $query    = self::_URL_API . '/v1/jobs/partner-job-id=' . trim($jid);
    $response = $this->fetch('PUT', $query, $xml);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * General data send/request method.
   * 
   * @param str $method 
   *    The data communication method.   
   * @param str $url 
   *    The Linkedin API endpoint to connect with.
   * @param str $data
   *    [OPTIONAL] The data to send to LinkedIn.
   * @param arr $parameters 
   *    [OPTIONAL] Addition OAuth parameters to send to LinkedIn.
   *        
   * @return arr 
   *    Array containing:
   * 
   *           array(
   *             'info'      => Connection information,
   *             'linkedin'  => LinkedIn response,  
   *             'oauth'     => The OAuth request string that was sent to LinkedIn   
   *           )   
   */
  protected function fetch($method, $url, $data = NULL, $parameters = array()) {
    // check for cURL
    if(!extension_loaded('curl')) {
      // cURL not present
      throw new LinkedInException('LinkedIn->fetch(): PHP cURL extension does not appear to be loaded/present.');
    }
    
    try {
      // generate OAuth values
      $oauth_consumer  = new OAuthConsumer($this->getApplicationKey(), $this->getApplicationSecret(), $this->getCallbackUrl());
      $oauth_token     = $this->getToken();
      $oauth_token     = (!is_null($oauth_token)) ? new OAuthToken($oauth_token['oauth_token'], $oauth_token['oauth_token_secret']) : NULL;
      $defaults        = array(
        'oauth_version' => self::_API_OAUTH_VERSION
      );
      $parameters    = array_merge($defaults, $parameters);
      
      // generate OAuth request
      $oauth_req = OAuthRequest::from_consumer_and_token($oauth_consumer, $oauth_token, $method, $url, $parameters);
      $oauth_req->sign_request(new OAuthSignatureMethod_HMAC_SHA1(), $oauth_consumer, $oauth_token);
      
      // start cURL, checking for a successful initiation
      if(!$handle = curl_init()) {
         // cURL failed to start
        throw new LinkedInException('LinkedIn->fetch(): cURL did not initialize properly.');
      }
      
      // set cURL options, based on parameters passed
      curl_setopt($handle, CURLOPT_CUSTOMREQUEST, $method);
      curl_setopt($handle, CURLOPT_RETURNTRANSFER, TRUE);
      curl_setopt($handle, CURLOPT_SSL_VERIFYPEER, FALSE);
      curl_setopt($handle, CURLOPT_URL, $url);
      curl_setopt($handle, CURLOPT_VERBOSE, FALSE);
      
      // configure the header we are sending to LinkedIn - http://developer.linkedin.com/docs/DOC-1203
      $header = array($oauth_req->to_header(self::_API_OAUTH_REALM));
      if(is_null($data)) {
        // not sending data, identify the content type
        $header[] = 'Content-Type: text/plain; charset=UTF-8';
        switch($this->getResponseFormat()) {
          case self::_RESPONSE_JSON:
            $header[] = 'x-li-format: json';
            break;
          case self::_RESPONSE_JSONP:
            $header[] = 'x-li-format: jsonp';
            break;
        }
      } else {
        $header[] = 'Content-Type: text/xml; charset=UTF-8';
        curl_setopt($handle, CURLOPT_POSTFIELDS, $data);
      }
      curl_setopt($handle, CURLOPT_HTTPHEADER, $header);
    
      // set the last url, headers
      $this->last_request_url = $url;
      $this->last_request_headers = $header;
      
      // gather the response
      $return_data['linkedin']        = curl_exec($handle);
      $return_data['info']            = curl_getinfo($handle);
      $return_data['oauth']['header'] = $oauth_req->to_header(self::_API_OAUTH_REALM);
      $return_data['oauth']['string'] = $oauth_req->base_string;
            
      // check for throttling
      if(self::isThrottled($return_data['linkedin'])) {
        throw new LinkedInException('LinkedIn->fetch(): throttling limit for this user/application has been reached for LinkedIn resource - ' . $url);
      }
      
      //TODO - add check for NO response (http_code = 0) from cURL
      
      // close cURL connection
      curl_close($handle);
      
      // no exceptions thrown, return the data
      return $return_data;
    } catch(OAuthException $e) {
      // oauth exception raised
      throw new LinkedInException('OAuth exception caught: ' . $e->getMessage());
    }
  }
  
  /**
   * This flags a specified post as specified by type.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $pid
   *    The post id.
   * @param str $type
   *    The type to flag the post as.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function flagPost($pid, $type) {
    if(!is_string($pid)) {
      throw new LinkedInException('LinkedIn->flagPost(): bad data passed, $pid must be of type string');
    }
    if(!is_string($type)) {
      throw new LinkedInException('LinkedIn->flagPost(): bad data passed, $like must be of type string');
    }
    //Constructing the xml
    $data = '<?xml version="1.0" encoding="UTF-8"?>';
    switch($type) {
      case 'promotion':
        $data .= '<code>promotion</code>';
        break;
      case 'job':
        $data .= '<code>job</code>';
        break;
      default: 
        throw new LinkedInException('LinkedIn->flagPost(): invalid value for $type, must be one of: "promotion", "job"');
        break;  
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/posts/' . $pid . '/category/code';
    $response = $this->fetch('PUT', $query, $data);
      
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Follow a company.
   * 
   * Calling this method causes the current user to start following the 
   * specified company, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1324
   * 
   * @param str $cid
   *    Company ID you want to follow.
   *           
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function followCompany($cid) {
    // check passed data
    if(!is_string($cid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->followCompany(): bad data passed, $cid must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/following/companies';
    $response = $this->fetch('POST', $query, '<company><id>' . trim($cid) . '</id></company>');
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Follows/Unfollows the specified post.
   * 
   * https://developer.linkedin.com/documents/groups-api
   * 
   * @param str $pid
   *    The post id.
   * @param bool $follow
   *    Determines whether to follow or unfollow the post. TRUE = follow, FALSE = unfollow
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  
  public function followPost($pid, $follow) {
    if(!is_string($pid)) {
      throw new LinkedInException('LinkedIn->followPost(): bad data passed, $pid must be of type string');
    }
    if(!($follow === TRUE || $follow === FALSE)) {
      throw new LinkedInException('LinkedIn->followPost(): bad data passed, $follow must be of type boolean');
    }
    
    // construct the XML
    $data = '<?xml version="1.0" encoding="UTF-8"?>
             <is-following>'. (($follow) ? 'true' : 'false'). '</is-following>';
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/posts/' . trim($pid) . '/relation-to-viewer/is-following';
    $response = $this->fetch('PUT', $query, $data);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Get list of companies you follow.
   * 
   * Returns a list of companies the current user is currently following, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1324   
   *  
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function followedCompanies() {   
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/following/companies';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Get the application_key property.
   * 
   * @return str 
   *    The application key.         
   */
  public function getApplicationKey() {
    return $this->application_key;
  }
  
  /**
   * Get the application_secret property.
   * 
   * @return str 
   *    The application secret.          
   */
  public function getApplicationSecret() {
    return $this->application_secret;
  }
  
  /**
   * Get the callback property.
   * 
   * @return str 
   *    The callback url.          
   */
  public function getCallbackUrl() {
    return $this->callback;
  }
  
  /**
   * Get the response_format property.
   * 
   * @return str 
   *    The response format.         
   */
  public function getResponseFormat() {
    return $this->response_format;
  }
  
  /**
   * Get the token_access property.
   * 
   * @return arr 
   *    The access token.          
   */
  public function getToken() {
    return $this->token;
  }
  
  /**
   * [DEPRECATED] Get the token_access property.
   * 
   * @return arr 
   *    The access token.          
   */
  public function getTokenAccess() {
    return $this->getToken();
  }
  
  /**
   * 
   * Get information about a specific group.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   *  
   * @param str $options
   *    [OPTIONAL] Field selectors for the group.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  
  public function group($gid, $options = '') {
    if(!is_string($gid)){
      throw new LinkedInException('LinkedIn->group(): bad data passed, $gid must be of type string.');
    }
    if(!is_string($options)) {
      throw new LinkedInException('LinkedIn->group(): bad data passed, $options must be of type string');
    }
  
    // construct and send the request
    $query    = self::_URL_API . '/v1/groups/' . trim($gid) . trim($options); 
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * This returns all the groups the user is a member of.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $options
   *    [OPTIONAL] Field selectors for the groups.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function groupMemberships($options = '') {
    if(!is_string($options)) {
      throw new LinkedInException('LinkedIn->groupMemberships(): bad data passed, $options must be of type string');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/group-memberships' . trim($options) . '?membership-state=member';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * This gets a specified post made within a group.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $pid
   *    The post id.
   * @param str $options
   *    [OPTIONAL] Field selectors for the post.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function groupPost($pid, $options = '') {
    if(!is_string($pid)) {
      throw new LinkedInException('LinkedIn->groupPost(): bad data passed, $pid must be of type string.');
    }
    if(!is_string($options)) {
      throw new LinkedInException('LinkedIn->groupPost(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/posts/' . trim($pid) . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * This returns all the comments made on the specified post within a group.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $pid
   *    The post id.
   * @param str $options
   *    [OPTIONAL] Field selectors for the post comments.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function groupPostComments($pid, $options = ''){ 
    if(!is_string($pid)){
      throw new LinkedInException('LinkedIn->groupPostComments(): bad data passed, $pid must be of type string.');
    }
    if(!is_string($options)) {
      throw new LinkedInException('LinkedIn->groupPostComments(): bad data passed, $options must be of type string.');
    }   
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/posts/' . trim($pid) . '/comments' . trim($options);
    $response = $this->fetch('GET', $query);

    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * This returns all the posts within a group.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function groupPosts($gid, $options = '') {
    if(!is_string($gid)){
      throw new LinkedInException('LinkedIn->groupPosts(): bad data passed, $gid must be of type string');
    }
    if(!is_string($options)){
      throw new LinkedInException('LinkedIn->groupPosts(): bad data passed, $options must be of type string');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/groups/' . trim($gid)  .'/posts' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * This returns the group settings of the specified group
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * @param str $options
   *    [OPTIONAL] Field selectors for the group.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function groupSettings($gid, $options = '') {
    if(!is_string($gid)) {
      throw new LinkedInException('LinkedIn->groupSettings(): bad data passed, $gid must be of type string');
    }
    if(!is_string($options)) {
      throw new LinkedInException('LinkedIn->groupSettings(): bad data passed, $options must be of type string');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/group-memberships/' . trim($gid) . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Send connection invitations.
   *     
   * Send an invitation to connect to your network, either by email address or 
   * by LinkedIn ID. Details on the API here: 
   * 
   *   http://developer.linkedin.com/docs/DOC-1012
   * 
   * @param str $method 
   *    The invitation method to process.  
   * @param str $recipient 
   *    The email/id to send the invitation to.    
   * @param str $subject 
   *    The subject of the invitation to send.
   * @param str $body 
   *    The body of the invitation to send.
   * @param str $type 
   *    [OPTIONAL] The invitation request type (only friend is supported at this time by the Invite API).
   * 
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.     
   */
  public function invite($method, $recipient, $subject, $body, $type = 'friend') {
    /**
     * Clean up the passed data per these rules:
     * 
     * 1) Message must be sent to one recipient (only a single recipient permitted for the Invitation API)
     * 2) No HTML permitted
     * 3) 200 characters max in the invitation subject
     * 4) Only able to connect as a friend at this point     
     */
    // check passed data
    if(empty($recipient)) {
      throw new LinkedInException('LinkedIn->invite(): you must provide an invitation recipient.');
    }
    switch($method) {
      case 'email':
        if(is_array($recipient)) {
          $recipient = array_map('trim', $recipient);
        } else {
          // bad format for recipient for email method
          throw new LinkedInException('LinkedIn->invite(): invitation recipient email/name array is malformed.');
        }
        break;
      case 'id':
        $recipient = trim($recipient);
        if(!self::isId($recipient)) {
          // bad format for recipient for id method
          throw new LinkedInException('LinkedIn->invite(): invitation recipient ID does not match LinkedIn format.');
        }
        break;
      default:
        throw new LinkedInException('LinkedIn->invite(): bad invitation method, must be one of: email, id.');
        break;
    }
    if(!empty($subject)) {
      $subject = trim(htmlspecialchars(strip_tags(stripslashes($subject))));
    } else {
      throw new LinkedInException('LinkedIn->invite(): message subject is empty.');
    }
    if(!empty($body)) {
      $body = trim(htmlspecialchars(strip_tags(stripslashes($body))));
      if(strlen($body) > self::_INV_BODY_LENGTH) {
        throw new LinkedInException('LinkedIn->invite(): message body length is too long - max length is ' . self::_INV_BODY_LENGTH . ' characters.');
      }
    } else {
      throw new LinkedInException('LinkedIn->invite(): message body is empty.');
    }
    switch($type) {
      case 'friend':
        break;
      default:
        throw new LinkedInException('LinkedIn->invite(): bad invitation type, must be one of: friend.');
        break;
    }
    
    // construct the xml data
    $data   = '<?xml version="1.0" encoding="UTF-8"?>
               <mailbox-item>
                 <recipients>
                   <recipient>';
                     switch($method) {
                       case 'email':
                         // email-based invitation
                         $data .= '<person path="/people/email=' . $recipient['email'] . '">
                                     <first-name>' . htmlspecialchars($recipient['first-name']) . '</first-name>
                                     <last-name>' . htmlspecialchars($recipient['last-name']) . '</last-name>
                                   </person>';
                         break;
                       case 'id':
                         // id-based invitation
                         $data .= '<person path="/people/id=' . $recipient . '"/>';
                         break;
                     }
    $data  .= '    </recipient>
                 </recipients>
                 <subject>' . $subject . '</subject>
                 <body>' . $body . '</body>
                 <item-content>
                   <invitation-request>
                     <connect-type>';
                       switch($type) {
                         case 'friend':
                           $data .= 'friend';
                           break;
                       }
    $data  .= '      </connect-type>';
                     switch($method) {
                       case 'id':
                         // id-based invitation, we need to get the authorization information
                         $query                 = 'id=' . $recipient . ':(api-standard-profile-request)';
                         $response              = self::profile($query);
                         if($response['info']['http_code'] == 200) {
                           $response['linkedin'] = self::xmlToArray($response['linkedin']);
                           if($response['linkedin'] === FALSE) {
                             // bad XML data
                             throw new LinkedInException('LinkedIn->invite(): LinkedIn returned bad XML data.');
                           }
                           $authentication = explode(':', $response['linkedin']['person']['children']['api-standard-profile-request']['children']['headers']['children']['http-header']['children']['value']['content']);
                           
                           // complete the xml        
                           $data .= '<authorization>
                                       <name>' . $authentication[0] . '</name>
                                       <value>' . $authentication[1] . '</value>
                                     </authorization>';
                         } else {
                           // bad response from the profile request, not a valid ID?
                           throw new LinkedInException('LinkedIn->invite(): could not send invitation, LinkedIn says: ' . print_r($response['linkedin'], TRUE));
                         }
                         break;
                     }
    $data  .= '    </invitation-request>
                 </item-content>
               </mailbox-item>';
    
    // send request
    $query    = self::_URL_API . '/v1/people/~/mailbox';
    $response = $this->fetch('POST', $query, $data);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * LinkedIn ID validation.
   *   
   * Checks the passed string $id to see if it has a valid LinkedIn ID format, 
   * which is, as of October 15th, 2010:
   * 
   *   10 alpha-numeric mixed-case characters, plus underscores and dashes.            
   * 
   * @param str $id 
   *    A possible LinkedIn ID.            
   * 
   * @return bool 
   *    TRUE/FALSE depending on valid ID format determination.                  
   */
  public static function isId($id) {
    // check passed data
    if(!is_string($id)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->isId(): bad data passed, $id must be of type string.');
    }
    
    $pattern = '/^[a-z0-9_\-]{10}$/i';
    if($match = preg_match($pattern, $id)) {
      // we have a match
      $return_data = TRUE;
    } else {
      // no match
      $return_data = FALSE;
    }
    return $return_data;
  }
  
  /**
   * Throttling check.
   * 
   * Checks the passed LinkedIn response to see if we have hit a throttling 
   * limit:
   * 
   * http://developer.linkedin.com/docs/DOC-1112
   * 
   * @param arr $response 
   *    The LinkedIn response.
   *                       
   * @return bool
   *    TRUE/FALSE depending on content of response.                  
   */
  public static function isThrottled($response) {
    $return_data = FALSE;
    
    // check the variable
    if(!empty($response) && is_string($response)) {
      // we have an array and have a properly formatted LinkedIn response
         
      // store the response in a temp variable
      $temp_response = self::xmlToArray($response);
      if($temp_response !== FALSE) {
        // check to see if we have an error
        if(array_key_exists('error', $temp_response) && ($temp_response['error']['children']['status']['content'] == 403) && preg_match('/throttle/i', $temp_response['error']['children']['message']['content'])) {
          // we have an error, it is 403 and we have hit a throttle limit
          $return_data = TRUE;
        }
      }
    }
    return $return_data;
  }
  
  /**
   * Job posting detail info retrieval function.
   * 
   * The Jobs API returns detailed information about job postings on LinkedIn. 
   * Find the job summary, description, location, and apply our professional graph 
   * to present the relationship between the current member and the job poster or 
   * hiring manager.
   * 
   *   http://developer.linkedin.com/docs/DOC-1322  
   * 
   * @param str $jid 
   *    ID of the job you want to look up.
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   *              
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function job($jid, $options = '') {
    // check passed data
    if(!is_string($jid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->job(): bad data passed, $jid must be of type string.');
    }
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->job(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/jobs/' . trim($jid) . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Join the specified group, per: 
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.     
   */
  public function joinGroup($gid) {
    if(!is_string($gid)) {
      throw new LinkedInException('LinkedIn->joinGroup(): bad data passed, $gid must be of type string.');
    }
    
    // constructing the XML
    $data = '<?xml version="1.0" encoding="UTF-8"?>
             <group-membership>
               <membership-state>
                 <code>member</code>
               </membership-state>
             </group-membership>';
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/group-memberships/' . trim($gid);
    $response = $this->fetch('PUT', $query, $data);
    
    /**
     * Check for successful request (a 200 or 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(array(200, 201), $response);
  }
  
  /**
   * Returns the last request header from the previous call to the 
   * LinkedIn API.
   * 
   * @returns str
   *    The header, in string format.
   */             
  public function lastRequestHeader() {
     return $this->last_request_headers;
  }
  
  /**
   * Returns the last request url from the previous call to the 
   * LinkedIn API.
   * 
   * @returns str
   *    The url, in string format.
   */             
  public function lastRequestUrl() {
     return $this->last_request_url;
  }
  
  /**
   * Leave the specified group, per:.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function leaveGroup($gid){
    if(!is_string($gid)) {
      throw new LinkedInException('LinkedIn->leaveGroup(): bad data passed, $gid must be of type string');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/group-memberships/'  .trim($gid);
    $response = $this->fetch('DELETE', $query);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Like another user's network update, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1043
   * 
   * @param str $uid
   *    The LinkedIn update ID.
   *                       
   * @return arr
   *    Array containing retrieval success, LinkedIn response.                  
   */
  public function like($uid) {
    // check passed data
    if(!is_string($uid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->like(): bad data passed, $uid must be of type string.');
    }
    
    // construct the XML
    $data = '<?xml version="1.0" encoding="UTF-8"?>
             <is-liked>true</is-liked>';
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/network/updates/key=' . $uid . '/is-liked';
    $response = $this->fetch('PUT', $query, $data);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Likes/unlikes the specified post, per:
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $pid
   *    The post id.
   * @param bool $like
   *    Determines whether to like or unlike. TRUE = like, FALSE = unlike.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function likePost($pid, $like) {
    if(!is_string($pid)) {
      throw new LinkedInException ('LinkedIn->likePost(): bad data passed, $pid must be of type string');
    }
    if(!($like === TRUE || $like === FALSE)) {
      throw new LinkedInException('LinkedIn->likePost(): bad data passed, $like must be of type boolean');
    }
    
    // construct the XML
    $data = '<?xml version="1.0" encoding="UTF-8"?>
             <is-liked>'.(($like) ? 'true': 'false').'</is-liked>';
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/posts/' . trim($pid) . '/relation-to-viewer/is-liked';
    $response = $this->fetch('PUT', $query, $data);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Retrieve network update likes.
   *    
   * Return all likes associated with a given network update:
   * 
   * http://developer.linkedin.com/docs/DOC-1043
   * 
   * @param str $uid
   *    The LinkedIn update ID.
   *                       
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.                  
   */
  public function likes($uid) {
    // check passed data
    if(!is_string($uid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->likes(): bad data passed, $uid must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/network/updates/key=' . $uid . '/likes';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Connection messaging method.
   *   
   * Send a message to your network connection(s), optionally copying yourself.  
   * Full details from LinkedIn on this functionality can be found here: 
   * 
   *   http://developer.linkedin.com/docs/DOC-1044
   * 
   * @param arr $recipients 
   *    The connection(s) to send the message to.    
   * @param str $subject 
   *    The subject of the message to send.
   * @param str $body 
   *    The body of the message to send.
   * @param bool $copy_self 
   *    [OPTIONAL] Also update the teathered Twitter account.
   *       
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.         
   */
  public function message($recipients, $subject, $body, $copy_self = FALSE) {
    /**
     * Clean up the passed data per these rules:
     * 
     * 1) Message must be sent to at least one recipient
     * 2) No HTML permitted
     */
    if(!empty($subject) && is_string($subject)) {
      $subject = trim(strip_tags(stripslashes($subject)));
    } else {
      throw new LinkedInException('LinkedIn->message(): bad data passed, $subject must be of type string.');
    }
    if(!empty($body) && is_string($body)) {
      $body = trim(strip_tags(stripslashes($body)));
    } else {
      throw new LinkedInException('LinkedIn->message(): bad data passed, $body must be of type string.');
    }
    if(!is_array($recipients) || count($recipients) < 1) {
      // no recipients, and/or bad data
      throw new LinkedInException('LinkedIn->message(): at least one message recipient required.');
    }
    
    // construct the xml data
    $data   = '<?xml version="1.0" encoding="UTF-8"?>
               <mailbox-item>
                 <recipients>';
    $data  .=     ($copy_self) ? '<recipient><person path="/people/~"/></recipient>' : '';
                  for($i = 0; $i < count($recipients); $i++) {
                    if(is_string($recipients[$i])) {
                      $data .= '<recipient><person path="/people/' . trim($recipients[$i]) . '"/></recipient>';
                    } else {
                      throw new LinkedInException ('LinkedIn->message(): bad data passed, $recipients must be an array of type string.');
                    }
                  }
    $data  .= '  </recipients>
                 <subject>' . htmlspecialchars($subject) . '</subject>
                 <body>' . htmlspecialchars($body) . '</body>
               </mailbox-item>';
    
    // send request
    $query    = self::_URL_API . '/v1/people/~/mailbox';
    $response = $this->fetch('POST', $query, $data);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Job posting method.
   *   
   * Post a job to LinkedIn, assuming that you have access to this feature. 
   * Full details from LinkedIn on this functionality can be found here: 
   * 
   *   http://developer.linkedin.com/community/jobs?view=documents
   * 
   * @param str $xml 
   *    The XML defining a job to post.    
   *       
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.         
   */
  public function postJob($xml) {
    // check passed data
    if(is_string($xml)) {
      $xml = trim(stripslashes($xml));
    } else {
      throw new LinkedInException('LinkedIn->postJob(): bad data passed, $xml must be of type string.');
    }
   
    // construct and send the request
    $query    = self::_URL_API . '/v1/jobs';
    $response = $this->fetch('POST', $query, $xml);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * General profile retrieval function.
   * 
   * Takes a string of parameters as input and requests profile data from the 
   * Linkedin Profile API. See the official documentation for $options
   * 'field selector' formatting:
   * 
   *   http://developer.linkedin.com/docs/DOC-1014
   *   http://developer.linkedin.com/docs/DOC-1002    
   * 
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   *               
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function profile($options = '~') {
    // check passed data
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->profile(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Manual API call method, allowing for support for un-implemented API
   * functionality to be supported.
   * 
   * @param str $method 
   *    The data communication method.   
   * @param str $url 
   *    The Linkedin API endpoint to connect with - should NOT include the 
   *    leading https://api.linkedin.com/v1.
   * @param str $body
   *    [OPTIONAL] The URL-encoded body data to send to LinkedIn with the request.
   * 
   * @return arr
   *    Array containing retrieval information, LinkedIn response. Note that you
   *    must manually check the return code and compare this to the expected 
   *    API response to determine  if the raw call was successful.
   */
  public function raw($method, $url, $body = NULL) {
    if(!is_string($method)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->raw(): bad data passed, $method must be of string value.');
    }
    if(!is_string($url)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->raw(): bad data passed, $url must be of string value.');
    }
    if(!is_null($body) && !is_string($url)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->raw(): bad data passed, $body must be of string value.');
    }
    
    // construct and send the request
    $query = self::_URL_API . '/v1' . trim($url);
    return $this->fetch($method, $query, $body);
  }
  
  /**
   * This removes the specified group from the group suggestions, per:
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function removeSuggestedGroup($gid) {
    if(!is_string($gid)) {
      throw new LinkedInException('LinkedIn->removeSuggestedGroup(): bad data passed, $gid must be of type string');
    } 
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/suggestions/groups/'  .trim($gid);
    $response = $this->fetch('DELETE', $query);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Renew a job.
   * 
   * Calling this method causes the passed job to be renewed, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1154   
   * 
   * @param str $jid
   *    Job ID you want to renew.
   * @param str $cid
   *    Contract ID that covers the passed Job ID.   
   *              
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function renewJob($jid, $cid) {
    // check passed data
    if(!is_string($jid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->renewJob(): bad data passed, $jid must be of string value.');
    }
    if(!is_string($cid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->renewJob(): bad data passed, $cid must be of string value.');
    }
    
    // construct the xml data
    $data   = '<?xml version="1.0" encoding="UTF-8"?>
               <job>
                 <contract-id>' . trim($cid) . '</contract-id>
                 <renewal/>
               </job>';
               
    // construct and send the request
    $query    = self::_URL_API . '/v1/jobs/partner-job-id=' . trim($jid);
    $response = $this->fetch('PUT', $query, $data);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Access token retrieval.
   *
   * Request the user's access token from the Linkedin API.
   * 
   * @param str $token
   *    The token returned from the user authorization stage.
   * @param str $secret
   *    The secret returned from the request token stage.
   * @param str $verifier
   *    The verification value from LinkedIn.
   *       
   * @return arr 
   *    The Linkedin OAuth/http response, in array format.         
   */
  public function retrieveTokenAccess($token, $secret, $verifier) {
    // check passed data
    if(!is_string($token) || !is_string($secret) || !is_string($verifier)) {
      // nothing passed, raise an exception
      throw new LinkedInException('LinkedIn->retrieveTokenAccess(): bad data passed, string type is required for $token, $secret and $verifier.');
    }
    
    // start retrieval process
    $this->setToken(array('oauth_token' => $token, 'oauth_token_secret' => $secret));
    $parameters = array(
      'oauth_verifier' => $verifier
    );
    $response = $this->fetch(self::_METHOD_TOKENS, self::_URL_ACCESS, NULL, $parameters);
    parse_str($response['linkedin'], $response['linkedin']);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    if($response['info']['http_code'] == 200) {
      // tokens retrieved
      $this->setToken($response['linkedin']);
      
      // set the response
      $return_data            = $response;
      $return_data['success'] = TRUE;
    } else {
      // error getting the request tokens
       $this->setToken(NULL);
       
      // set the response
      $return_data            = $response;
      $return_data['error']   = 'HTTP response from LinkedIn end-point was not code 200';
      $return_data['success'] = FALSE;
    }
    return $return_data;
  }
  
  /**
   * Request token retrieval.
   * 
   * Get the request token from the Linkedin API.
   * 
   * @return arr
   *    The Linkedin OAuth/http response, in array format.         
   */
  public function retrieveTokenRequest() {
    $parameters = array(
      'oauth_callback' => $this->getCallbackUrl()
    );
    $response = $this->fetch(self::_METHOD_TOKENS, self::_URL_REQUEST, NULL, $parameters);
    parse_str($response['linkedin'], $response['linkedin']);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    if(($response['info']['http_code'] == 200) && (array_key_exists('oauth_callback_confirmed', $response['linkedin'])) && ($response['linkedin']['oauth_callback_confirmed'] == 'true')) {
      // tokens retrieved
      $this->setToken($response['linkedin']);
      
      // set the response
      $return_data            = $response;
      $return_data['success'] = TRUE;        
    } else {
      // error getting the request tokens
      $this->setToken(NULL);
      
      // set the response
      $return_data = $response;
      if((array_key_exists('oauth_callback_confirmed', $response['linkedin'])) && ($response['linkedin']['oauth_callback_confirmed'] == 'true')) {
        $return_data['error'] = 'HTTP response from LinkedIn end-point was not code 200';
      } else {
        $return_data['error'] = 'OAuth callback URL was not confirmed by the LinkedIn end-point';
      }
      $return_data['success'] = FALSE;
    }
    return $return_data;
  }
  
  /**
   * User authorization revocation.
   * 
   * Revoke the current user's access token, clear the access token's from 
   * current LinkedIn object. The current documentation for this feature is 
   * found in a blog entry from April 29th, 2010:
   * 
   *   http://developer.linkedin.com/community/apis/blog/2010/04/29/oauth--now-for-authentication  
   * 
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.     
   */
  public function revoke() {
    // construct and send the request
    $response = $this->fetch('GET', self::_URL_REVOKE);

    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */                   
    return $this->checkResponse(200, $response);
  }
  
  /**
   * [DEPRECATED] General people search function.
   * 
   * Takes a string of parameters as input and requests profile data from the 
   * Linkedin People Search API.  See the official documentation for $options
   * querystring formatting:
   * 
   *   http://developer.linkedin.com/docs/DOC-1191 
   * 
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   *               
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function search($options = NULL) {
    return searchPeople($options);
  }
  
  /**
   * Company search.
   * 
   * Uses the Company Search API to find companies using keywords, industry, 
   * location, or some other criteria. It returns a collection of matching 
   * companies.
   * 
   *   http://developer.linkedin.com/docs/DOC-1325  
   * 
   * @param str $options
   *    [OPTIONAL] Search options.  
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function searchCompanies($options = '') {
    // check passed data
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->searchCompanies(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/company-search' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Jobs search.
   * 
   * Use the Job Search API to find jobs using keywords, company, location, 
   * or some other criteria. It returns a collection of matching jobs. Each 
   * entry can contain much of the information available on the job listing.
   * 
   *   http://developer.linkedin.com/docs/DOC-1321  
   * 
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   *              
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function searchJobs($options = '') {
    // check passed data
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->jobsSearch(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/job-search' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * General people search function.
   * 
   * Takes a string of parameters as input and requests profile data from the 
   * Linkedin People Search API.  See the official documentation for $options
   * querystring formatting:
   * 
   *   http://developer.linkedin.com/docs/DOC-1191 
   * 
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   *               
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function searchPeople($options = NULL) {
    // check passed data
    if(!is_null($options) && !is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->search(): bad data passed, $options must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people-search' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Set the application_key property.
   * 
   * @param str $key 
   *    The application key.         
   */
  public function setApplicationKey($key) {
    $this->application_key = $key;
  }
  
  /**
   * Set the application_secret property.
   * 
   * @param str $secret 
   *    The application secret.          
   */
  public function setApplicationSecret($secret) {
    $this->application_secret = $secret;
  }
  
  /**
   * Set the callback property.
   * 
   * @param str $url 
   *    The callback url.          
   */
  public function setCallbackUrl($url) {
    $this->callback = $url;
  }
  
  /**
   * This sets the group settings of the specified group.
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @param str $gid
   *    The group id.
   * @param str $xml
   *    The group settings to set. The settings are:
   *      -<show-group-logo-in-profle>
   *      -<contact-email>
   *      -<email-digest-frequency>
   *      -<email-annoucements-from-managers>
   *      -<allow-messages-from-members>
   *      -<email-for-every-new-post>
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function setGroupSettings($gid, $xml) {
    if(!is_string ($gid)) {
      throw new LinkedInException('LinkedIn->setGroupSettings(): bad data passed, $token_access should be in array format.');
    }
    if(!is_string ($xml)) {
      throw new LinkedInException('LinkedIn->setGroupSettings(): bad data passed, $token_access should be in array format.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/group-memberships/' . trim($gid);
    $response = $this->fetch('PUT', $query, $xml);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Set the response_format property.
   * 
   * @param str $format 
   *    [OPTIONAL] The response format to specify to LinkedIn.         
   */
  public function setResponseFormat($format = self::_DEFAULT_RESPONSE_FORMAT) {
    $this->response_format = $format;
  }
  
  /**
   * Set the token property.
   * 
   * @return arr $token 
   *    The LinkedIn OAuth token.
   */
  public function setToken($token) {
    // check passed data
    if(!is_null($token) && !is_array($token)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->setToken(): bad data passed, $token_access should be in array format.');
    }
    
    // set token
    $this->token = $token;
  }
  
  /**
   * [DEPRECATED] Set the token_access property.
   * 
   * @return arr $token_access 
   *    [OPTIONAL] The LinkedIn OAuth access token.
   */
  public function setTokenAccess($token_access) {
    $this->setToken($token_access);
  }

  public function sharePost($action, $content, $private = TRUE, $twitter = FALSE , $companies = array() ) {

    // check the status itself
    if(!empty($action) && !empty($content)) {

      // prepare the share data per the rules above
      $share_flag   = FALSE;
      $content_xml  = NULL;
      switch($action) {
        case 'new':
          // share can be an article
          if(array_key_exists('title', $content) && array_key_exists('submitted-url', $content)) {
            // we have shared content, format it as needed per rules above
            $content_title = trim(htmlspecialchars(strip_tags(stripslashes($content['title']))));
            if(strlen($content_title) > self::_SHARE_CONTENT_TITLE_LENGTH) {
              throw new LinkedInException('LinkedIn->share(): title length is too long - max length is ' . self::_SHARE_CONTENT_TITLE_LENGTH . ' characters.');
            }
            $content_xml .= '<content>
                               <title>' . $content_title . '</title>
                               <submitted-url>' . trim(htmlspecialchars($content['submitted-url'])) . '</submitted-url>';
            if(array_key_exists('submitted-image-url', $content)) {
              $content_xml .= '<submitted-image-url>' . trim(htmlspecialchars($content['submitted-image-url'])) . '</submitted-image-url>';
            }
            if(array_key_exists('description', $content)) {
              $content_desc = trim(htmlspecialchars(strip_tags(stripslashes($content['description']))));
              if(strlen($content_desc) > self::_SHARE_CONTENT_DESC_LENGTH) {
                throw new LinkedInException('LinkedIn->share(): description length is too long - max length is ' . self::_SHARE_CONTENT_DESC_LENGTH . ' characters.');
              }
              $content_xml .= '<description>' . $content_desc . '</description>';
            }
            $content_xml .= '</content>';
            
            $share_flag = TRUE;
          }
          
          // share can be just a comment
          if(array_key_exists('comment', $content)) {
            // comment located
            $comment = htmlspecialchars(trim(strip_tags(stripslashes($content['comment']))));
            if(strlen($comment) > self::_SHARE_COMMENT_LENGTH) {
              throw new LinkedInException('LinkedIn->share(): comment length is too long - max length is ' . self::_SHARE_COMMENT_LENGTH . ' characters.');
            }
            $content_xml .= '<comment>' . $comment . '</comment>';
            
            $share_flag = TRUE; 
          }
          break;
        case 'reshare':
          if(array_key_exists('id', $content)) {
            // put together the re-share attribution XML
            $content_xml .= '<attribution>
                               <share>
                                 <id>' . trim($content['id']) . '</id>
                               </share>
                             </attribution>';
            
            // optional additional comment
            if(array_key_exists('comment', $content)) {
              // comment located
              $comment = htmlspecialchars(trim(strip_tags(stripslashes($content['comment']))));
              if(strlen($comment) > self::_SHARE_COMMENT_LENGTH) {
                throw new LinkedInException('LinkedIn->share(): comment length is too long - max length is ' . self::_SHARE_COMMENT_LENGTH . ' characters.');
              }
              $content_xml .= '<comment>' . $comment . '</comment>';
            }
            
            $share_flag = TRUE;
          }
          break;
        default:
          // bad action passed
          throw new LinkedInException('LinkedIn->share(): share action is an invalid value, must be one of: share, reshare.');
          break;
      }
      
      // should we proceed?
      if($share_flag)
      {
        // put all of the xml together
        $visibility = ($private) && !$companies ? 'connections-only' : 'anyone';
        $data       = '<?xml version="1.0" encoding="UTF-8"?>
                       <share>
                         ' . $content_xml . '
                         <visibility>
                           <code>' . $visibility . '</code>
                         </visibility>
                       </share>';
        
        if( !empty( $companies ) )
        {
          foreach( $companies as $company )
          {
            $share_url = self::_URL_API . '/v1/companies/' . $company . '/shares';
          }
        }
        else
        {
          // create the proper url
          $share_url = self::_URL_API . '/v1/people/~/shares'; 
        }

        if($twitter) {
          // update twitter as well
          $share_url .= '?twitter-post=true';
        }
        
        // send request
        $response = $this->fetch('POST', $share_url, $data);
      } else {
        // data contraints/rules not met, raise an exception
        throw new LinkedInException('LinkedIn->share(): sharing data constraints not met; check that you have supplied valid content and combinations of content to share.');
      }
    } else {
      // data missing, raise an exception
      throw new LinkedInException('LinkedIn->share(): sharing action or shared content is missing.');
    }
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }

  /**
   * Post a share. 
   * 
   * Create a new or reshare another user's shared content. Full details from 
   * LinkedIn on this functionality can be found here: 
   * 
   *   http://developer.linkedin.com/docs/DOC-1212 
   * 
   *   $action values: ('new', 'reshare')        
   *   $content format: 
   *     $action = 'new'; $content => ('comment' => 'xxx', 'title' => 'xxx', 'submitted-url' => 'xxx', 'submitted-image-url' => 'xxx', 'description' => 'xxx')
   *     $action = 'reshare'; $content => ('comment' => 'xxx', 'id' => 'xxx')  
   * 
   * @param str $action
   *    The sharing action to perform.   
   * @param str $content
   *    The share content.
   * @param bool $private 
   *    [OPTIONAL] Should we restrict this shared item to connections only?  
   * @param bool $twitter 
   *    [OPTIONAL] Also update the teathered Twitter account.
   *       
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.         
   */
  public function share($action, $content, $private = TRUE, $twitter = FALSE) {
    // check the status itself
    if(!empty($action) && !empty($content)) {
      /**
       * Status is not empty, wrap a cleaned version of it in xml.  Status
       * rules:
       * 
       * 1) Comments are 700 chars max (if this changes, change _SHARE_COMMENT_LENGTH constant)
       * 2) Content/title 200 chars max (if this changes, change _SHARE_CONTENT_TITLE_LENGTH constant)
       * 3) Content/description 400 chars max (if this changes, change _SHARE_CONTENT_DESC_LENGTH constant)
       * 4a) New shares must contain a comment and/or (content/title and content/submitted-url)
       * 4b) Reshared content must contain an attribution id.
       * 4c) Reshared content must contain actual content, not just a comment.             
       * 5) No HTML permitted in comment, content/title, content/description.
       */

      // prepare the share data per the rules above
      $share_flag   = FALSE;
      $content_xml  = NULL;
      switch($action) {
        case 'new':
          // share can be an article
          if(array_key_exists('title', $content) && array_key_exists('submitted-url', $content)) {
            // we have shared content, format it as needed per rules above
            $content_title = trim(htmlspecialchars(strip_tags(stripslashes($content['title']))));
            if(strlen($content_title) > self::_SHARE_CONTENT_TITLE_LENGTH) {
              throw new LinkedInException('LinkedIn->share(): title length is too long - max length is ' . self::_SHARE_CONTENT_TITLE_LENGTH . ' characters.');
            }
            $content_xml .= '<content>
                               <title>' . $content_title . '</title>
                               <submitted-url>' . trim(htmlspecialchars($content['submitted-url'])) . '</submitted-url>';
            if(array_key_exists('submitted-image-url', $content)) {
              $content_xml .= '<submitted-image-url>' . trim(htmlspecialchars($content['submitted-image-url'])) . '</submitted-image-url>';
            }
            if(array_key_exists('description', $content)) {
              $content_desc = trim(htmlspecialchars(strip_tags(stripslashes($content['description']))));
              if(strlen($content_desc) > self::_SHARE_CONTENT_DESC_LENGTH) {
                throw new LinkedInException('LinkedIn->share(): description length is too long - max length is ' . self::_SHARE_CONTENT_DESC_LENGTH . ' characters.');
              }
              $content_xml .= '<description>' . $content_desc . '</description>';
            }
            $content_xml .= '</content>';
            
            $share_flag = TRUE;
          }
          
          // share can be just a comment
          if(array_key_exists('comment', $content)) {
            // comment located
            $comment = htmlspecialchars(trim(strip_tags(stripslashes($content['comment']))));
            if(strlen($comment) > self::_SHARE_COMMENT_LENGTH) {
              throw new LinkedInException('LinkedIn->share(): comment length is too long - max length is ' . self::_SHARE_COMMENT_LENGTH . ' characters.');
            }
            $content_xml .= '<comment>' . $comment . '</comment>';
            
            $share_flag = TRUE; 
          }
          break;
        case 'reshare':
          if(array_key_exists('id', $content)) {
            // put together the re-share attribution XML
            $content_xml .= '<attribution>
                               <share>
                                 <id>' . trim($content['id']) . '</id>
                               </share>
                             </attribution>';
            
            // optional additional comment
            if(array_key_exists('comment', $content)) {
              // comment located
              $comment = htmlspecialchars(trim(strip_tags(stripslashes($content['comment']))));
              if(strlen($comment) > self::_SHARE_COMMENT_LENGTH) {
                throw new LinkedInException('LinkedIn->share(): comment length is too long - max length is ' . self::_SHARE_COMMENT_LENGTH . ' characters.');
              }
              $content_xml .= '<comment>' . $comment . '</comment>';
            }
            
            $share_flag = TRUE;
          }
          break;
        default:
          // bad action passed
          throw new LinkedInException('LinkedIn->share(): share action is an invalid value, must be one of: share, reshare.');
          break;
      }
      
      // should we proceed?
      if($share_flag) {
        // put all of the xml together
        $visibility = ($private) ? 'connections-only' : 'anyone';
        $data       = '<?xml version="1.0" encoding="UTF-8"?>
                       <share>
                         ' . $content_xml . '
                         <visibility>
                           <code>' . $visibility . '</code>
                         </visibility>
                       </share>';
        
        // create the proper url
        $share_url = self::_URL_API . '/v1/people/~/shares';
        if($twitter) {
          // update twitter as well
          $share_url .= '?twitter-post=true';
        }
        
        // send request
        $response = $this->fetch('POST', $share_url, $data);
      } else {
        // data contraints/rules not met, raise an exception
        throw new LinkedInException('LinkedIn->share(): sharing data constraints not met; check that you have supplied valid content and combinations of content to share.');
      }
    } else {
      // data missing, raise an exception
      throw new LinkedInException('LinkedIn->share(): sharing action or shared content is missing.');
    }
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Network statistics.
   * 
   * General network statistics retrieval function, returns the number of connections, 
   * second-connections an authenticated user has. More information here:
   * 
   *   http://developer.linkedin.com/docs/DOC-1006
   * 
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.
   */
  public function statistics() {
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/network/network-stats';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Companies you may want to follow.
   * 
   * Returns a list of companies the current user may want to follow, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1324   
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function suggestedCompanies() {
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/suggestions/to-follow/companies';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Retrieves suggested groups for the user, per:
   * 
   *   http://developer.linkedin.com/documents/groups-api
   * 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function suggestedGroups() {
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/suggestions/groups:(id,name,is-open-to-non-members)';
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse (200, $response);
  }

  /**
   * Jobs you may be interested in.
   * 
   * Returns a list of jobs the current user may be interested in, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1323   
   * 
   * @param str $options
   *    [OPTIONAL] Data retrieval options.  
   *             
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function suggestedJobs($options = ':(jobs)') {
    // check passed data
    if(!is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->suggestedJobs(): bad data passed, $options must be of type string.');
    }
  
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/suggestions/job-suggestions' . trim($options);
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Unbookmark a job.
   * 
   * Calling this method causes the current user to remove a bookmark for the 
   * specified job:
   * 
   *   http://developer.linkedin.com/docs/DOC-1323   
   * 
   * @param str $jid
   *    Job ID you want to unbookmark.
   *              
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function unbookmarkJob($jid) {
    // check passed data
    if(!is_string($jid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->unbookmarkJob(): bad data passed, $jid must be of type string.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/job-bookmarks/' . trim($jid);
    $response = $this->fetch('DELETE', $query);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Unfollow a company.
   * 
   * Calling this method causes the current user to stop following the specified 
   * company, per:
   * 
   *   http://developer.linkedin.com/docs/DOC-1324   
   * 
   * @param str $cid
   *    Company ID you want to unfollow.  
   *           
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function unfollowCompany($cid) {
    // check passed data
    if(!is_string($cid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->unfollowCompany(): bad data passed, $cid must be of string value.');
    }
    
    // construct and send the request
    $query    = self::_URL_API . '/v1/people/~/following/companies/id=' . trim($cid);
    $response = $this->fetch('DELETE', $query);
    
    /**
     * Check for successful request (a 204 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(204, $response);
  }
  
  /**
   * Unlike a network update.
   *     
   * Unlike another user's network update:
   * 
   *   http://developer.linkedin.com/docs/DOC-1043
   * 
   * @param str $uid 
   *    The LinkedIn update ID.
   *                       
   * @return arr
   *    Array containing retrieval success, LinkedIn response.                  
   */
  public function unlike($uid) {
    // check passed data
    if(!is_string($uid)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->unlike(): bad data passed, $uid must be of type string.');
    }
    
    // construct the xml data
    $data = '<?xml version="1.0" encoding="UTF-8"?>
             <is-liked>false</is-liked>';
    
    // send request
    $query    = self::_URL_API . '/v1/people/~/network/updates/key=' . $uid . '/is-liked';
    $response = $this->fetch('PUT', $query, $data);
    
    /**
     * Check for successful request (a 201 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */ 
    return $this->checkResponse(201, $response);
  }
  
  /**
   * Post network update.
   * 
   * Update the user's Linkedin network status. Full details from LinkedIn 
   * on this functionality can be found here: 
   * 
   *   http://developer.linkedin.com/docs/DOC-1009
   *   http://developer.linkedin.com/docs/DOC-1009#comment-1077 
   * 
   * @param str $update
   *    The network update.  
   * 
   * @return arr 
   *    Array containing retrieval success, LinkedIn response.         
   */
  public function updateNetwork($update) {
    // check passed data
    if(!is_string($update)) {
      // nothing/non-string passed, raise an exception
      throw new LinkedInException('LinkedIn->updateNetwork(): bad data passed, $update must be a non-zero length string.');
    }
    
    /**
     * Network update is not empty, wrap a cleaned version of it in xml.  
     * Network update rules:
     * 
     * 1) No HTML permitted except those found in _NETWORK_HTML constant
     * 2) Update cannot be longer than 140 characters.     
     */
    // get the user data
    $response = self::profile('~:(first-name,last-name,site-standard-profile-request)');
    if($response['success'] === TRUE) {
      /** 
       * We are converting response to usable data.  I'd use SimpleXML here, but
       * to keep the class self-contained, we will use a portable XML parsing
       * routine, self::xmlToArray.       
       */
      $person = self::xmlToArray($response['linkedin']);
      if($person === FALSE) {
        // bad xml data
        throw new LinkedInException('LinkedIn->updateNetwork(): LinkedIn returned bad XML data.');
      }
      $fields = $person['person']['children'];
  
      // prepare user data
      $first_name   = trim($fields['first-name']['content']);
      $last_name    = trim($fields['last-name']['content']);
      $profile_url  = trim($fields['site-standard-profile-request']['children']['url']['content']);
  
      // create the network update 
      $update = trim(htmlspecialchars(strip_tags($update, self::_NETWORK_HTML)));
      if(strlen($update) > self::_NETWORK_LENGTH) {
        throw new LinkedInException('LinkedIn->share(): update length is too long - max length is ' . self::_NETWORK_LENGTH . ' characters.');
      }
      $user   = htmlspecialchars('<a href="' . $profile_url . '">' . $first_name . ' ' . $last_name . '</a>');
      $data   = '<activity locale="en_US">
                   <content-type>linkedin-html</content-type>
                   <body>' . $user . ' ' . $update . '</body>
                 </activity>';
  
      // send request
      $query    = self::_URL_API . '/v1/people/~/person-activities';
      $response = $this->fetch('POST', $query, $data);
      
      /**
       * Check for successful request (a 201 response from LinkedIn server) 
       * per the documentation linked in method comments above.
       */ 
      return $this->checkResponse(201, $response);
    } else {
      // profile retrieval failed
      throw new LinkedInException('LinkedIn->updateNetwork(): profile data could not be retrieved.');
    }
  }
  
  /**
   * General network update retrieval function.
   * 
   * Takes a string of parameters as input and requests update-related data 
   * from the Linkedin Network Updates API. See the official documentation for 
   * $options parameter formatting:
   * 
   *   http://developer.linkedin.com/docs/DOC-1006
   * 
   * For getting more comments, likes, etc, see here:
   * 
   *   http://developer.linkedin.com/docs/DOC-1043           
   * 
   * @param str $options 
   *    [OPTIONAL] Data retrieval options.
   * @param str $id 
   *    [OPTIONAL] The LinkedIn ID to restrict the updates for.
   *                 
   * @return arr
   *    Array containing retrieval success, LinkedIn response.
   */
  public function updates($options = NULL, $id = NULL) {
    // check passed data
    if(!is_null($options) && !is_string($options)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->updates(): bad data passed, $options must be of type string.');
    }
    if(!is_null($id) && !is_string($id)) {
      // bad data passed
      throw new LinkedInException('LinkedIn->updates(): bad data passed, $id must be of type string.');
    }
    
    // construct and send the request
    if(!is_null($id) && self::isId($id)) {
      $query = self::_URL_API . '/v1/people/' . $id . '/network/updates' . trim($options);
    } else {
      $query = self::_URL_API . '/v1/people/~/network/updates' . trim($options);
    }
    $response = $this->fetch('GET', $query);
    
    /**
     * Check for successful request (a 200 response from LinkedIn server) 
     * per the documentation linked in method comments above.
     */
    return $this->checkResponse(200, $response);
  }
  
  /**
   * Converts passed XML data to an array.
   * 
   * @param str $xml 
   *    The XML to convert to an array.
   *               
   * @return arr 
   *    Array containing the XML data.     
   * @return bool 
   *    FALSE if passed data cannot be parsed to an array.       
   */
  public static function xmlToArray($xml) {
    // check passed data
    if(!is_string($xml)) {
      // bad data possed
      throw new LinkedInException('LinkedIn->xmlToArray(): bad data passed, $xml must be a non-zero length string.');
    }
    
    $parser = xml_parser_create();
    xml_parser_set_option($parser, XML_OPTION_CASE_FOLDING, 0);
    xml_parser_set_option($parser, XML_OPTION_SKIP_WHITE, 1);
    if(xml_parse_into_struct($parser, $xml, $tags)) {
      $elements = array();
      $stack    = array();
      foreach($tags as $tag) {
        $index = count($elements);
        if($tag['type'] == 'complete' || $tag['type'] == 'open') {
          $elements[$tag['tag']]               = array();
          $elements[$tag['tag']]['attributes'] = (array_key_exists('attributes', $tag)) ? $tag['attributes'] : NULL;
          $elements[$tag['tag']]['content']    = (array_key_exists('value', $tag)) ? $tag['value'] : NULL;
          if($tag['type'] == 'open') {
            $elements[$tag['tag']]['children'] = array();
            $stack[count($stack)] = &$elements;
            $elements = &$elements[$tag['tag']]['children'];
          }
        }
        if($tag['type'] == 'close') {
          $elements = &$stack[count($stack) - 1];
          unset($stack[count($stack) - 1]);
        }
      }
      $return_data = $elements;
    } else {
      // not valid xml data
      $return_data = FALSE;
    }
    xml_parser_free($parser);
    return $return_data;
  }
}

?>