<?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 
 */
 
/**
 * Source: http://code.google.com/p/oauth/
 * 
 * Rename and move as needed, changing the require_once() call to the correct 
 * name and path.
 */    
if(!extension_loaded('oauth')) {
  // the PECL OAuth extension is not present, load our third-party OAuth library
  require_once('OAuth.php');
} else {
  // the PECL extension is present, which is not compatible with this library
  throw new LinkedInException('Simple-LinkedIn: library not compatible with installed PECL OAuth extension.  Please disable this extension to use the Simple-LinkedIn library.');
}

/**
 * '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);
   }


	/**
	 * 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)) {
		  array_walk($http_code_required, function($value, $key) {
        if(!is_int($value)) {
    			throw new LinkedInException('LinkedIn->checkResponse(): $http_code_required must be an integer or an array of integer values');
    		}
      });
		} else {
		  if(!is_int($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;
	}
	
	/**
	 * 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());
    }
	}
	
	/**
	 * 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();
	}	
	
	/**
	 * 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;
	}

	/**
	 * 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);
	}
	
  /**
	 * 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);
	}
	
	/**
	 * 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;
	}
	
	/**
	 * 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);
	}
		
	/**
	 * 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;
  }
}
?>