<?php

/*
 * Abraham Williams (abraham@abrah.am) http://abrah.am
 *
 * The first PHP Library to support OAuth for Twitter's REST API.
 */

/* Load OAuth lib. You can find it at http://oauth.net */

		/* Generic exception class
		 */
		class OAuthException extends Exception {
		  // pass
		}

		class OAuthConsumer {
		  public $key;
		  public $secret;

		  function __construct($key, $secret, $callback_url=NULL) {
			$this->key = $key;
			$this->secret = $secret;
			$this->callback_url = $callback_url;
		  }

		  function __toString() {
			return "OAuthConsumer[key=$this->key,secret=$this->secret]";
		  }
		}

		class OAuthToken {
		  // access tokens and request tokens
		  public $key;
		  public $secret;

		  /**
		   * key = the token
		   * secret = the token secret
		   */
		  function __construct($key, $secret) {
			$this->key = $key;
			$this->secret = $secret;
		  }

		  /**
		   * generates the basic string serialization of a token that a server
		   * would respond to request_token and access_token calls with
		   */
		  function to_string() {
			return "oauth_token=" .
				   OAuthUtil::urlencode_rfc3986($this->key) .
				   "&oauth_token_secret=" .
				   OAuthUtil::urlencode_rfc3986($this->secret);
		  }

		  function __toString() {
			return $this->to_string();
		  }
		}

		/**
		 * A class for implementing a Signature Method
		 * See section 9 ("Signing Requests") in the spec
		 */
		abstract class OAuthSignatureMethod {
		  /**
		   * Needs to return the name of the Signature Method (ie HMAC-SHA1)
		   * @return string
		   */
		  abstract public function get_name();

		  /**
		   * Build up the signature
		   * NOTE: The output of this function MUST NOT be urlencoded.
		   * the encoding is handled in OAuthRequest when the final
		   * request is serialized
		   * @param OAuthRequest $request
		   * @param OAuthConsumer $consumer
		   * @param OAuthToken $token
		   * @return string
		   */
		  abstract public function build_signature($request, $consumer, $token);

		  /**
		   * Verifies that a given signature is correct
		   * @param OAuthRequest $request
		   * @param OAuthConsumer $consumer
		   * @param OAuthToken $token
		   * @param string $signature
		   * @return bool
		   */
		  public function check_signature($request, $consumer, $token, $signature) {
			$built = $this->build_signature($request, $consumer, $token);
			return $built == $signature;
		  }
		}

		/**
		 * The HMAC-SHA1 signature method uses the HMAC-SHA1 signature algorithm as defined in [RFC2104] 
		 * where the Signature Base String is the text and the key is the concatenated values (each first 
		 * encoded per Parameter Encoding) of the Consumer Secret and Token Secret, separated by an '&' 
		 * character (ASCII code 38) even if empty.
		 *   - Chapter 9.2 ("HMAC-SHA1")
		 */
		class OAuthSignatureMethod_HMAC_SHA1 extends OAuthSignatureMethod {
		  function get_name() {
			return "HMAC-SHA1";
		  }

		  public function build_signature($request, $consumer, $token) {
			$base_string = $request->get_signature_base_string();
			$request->base_string = $base_string;

			$key_parts = array(
			  $consumer->secret,
			  ($token) ? $token->secret : ""
			);

			$key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
			$key = implode('&', $key_parts);

			return base64_encode(hash_hmac('sha1', $base_string, $key, true));
		  }
		}

		/**
		 * The PLAINTEXT method does not provide any security protection and SHOULD only be used 
		 * over a secure channel such as HTTPS. It does not use the Signature Base String.
		 *   - Chapter 9.4 ("PLAINTEXT")
		 */
		class OAuthSignatureMethod_PLAINTEXT extends OAuthSignatureMethod {
		  public function get_name() {
			return "PLAINTEXT";
		  }

		  /**
		   * oauth_signature is set to the concatenated encoded values of the Consumer Secret and 
		   * Token Secret, separated by a '&' character (ASCII code 38), even if either secret is 
		   * empty. The result MUST be encoded again.
		   *   - Chapter 9.4.1 ("Generating Signatures")
		   *
		   * Please note that the second encoding MUST NOT happen in the SignatureMethod, as
		   * OAuthRequest handles this!
		   */
		  public function build_signature($request, $consumer, $token) {
			$key_parts = array(
			  $consumer->secret,
			  ($token) ? $token->secret : ""
			);

			$key_parts = OAuthUtil::urlencode_rfc3986($key_parts);
			$key = implode('&', $key_parts);
			$request->base_string = $key;

			return $key;
		  }
		}

		/**
		 * The RSA-SHA1 signature method uses the RSASSA-PKCS1-v1_5 signature algorithm as defined in 
		 * [RFC3447] section 8.2 (more simply known as PKCS#1), using SHA-1 as the hash function for 
		 * EMSA-PKCS1-v1_5. It is assumed that the Consumer has provided its RSA public key in a 
		 * verified way to the Service Provider, in a manner which is beyond the scope of this 
		 * specification.
		 *   - Chapter 9.3 ("RSA-SHA1")
		 */
		abstract class OAuthSignatureMethod_RSA_SHA1 extends OAuthSignatureMethod {
		  public function get_name() {
			return "RSA-SHA1";
		  }

		  // Up to the SP to implement this lookup of keys. Possible ideas are:
		  // (1) do a lookup in a table of trusted certs keyed off of consumer
		  // (2) fetch via http using a url provided by the requester
		  // (3) some sort of specific discovery code based on request
		  //
		  // Either way should return a string representation of the certificate
		  protected abstract function fetch_public_cert(&$request);

		  // Up to the SP to implement this lookup of keys. Possible ideas are:
		  // (1) do a lookup in a table of trusted certs keyed off of consumer
		  //
		  // Either way should return a string representation of the certificate
		  protected abstract function fetch_private_cert(&$request);

		  public function build_signature($request, $consumer, $token) {
			$base_string = $request->get_signature_base_string();
			$request->base_string = $base_string;

			// Fetch the private key cert based on the request
			$cert = $this->fetch_private_cert($request);

			// Pull the private key ID from the certificate
			$privatekeyid = openssl_get_privatekey($cert);

			// Sign using the key
			$ok = openssl_sign($base_string, $signature, $privatekeyid);

			// Release the key resource
			openssl_free_key($privatekeyid);

			return base64_encode($signature);
		  }

		  public function check_signature($request, $consumer, $token, $signature) {
			$decoded_sig = base64_decode($signature);

			$base_string = $request->get_signature_base_string();

			// Fetch the public key cert based on the request
			$cert = $this->fetch_public_cert($request);

			// Pull the public key ID from the certificate
			$publickeyid = openssl_get_publickey($cert);

			// Check the computed signature against the one passed in the query
			$ok = openssl_verify($base_string, $decoded_sig, $publickeyid);

			// Release the key resource
			openssl_free_key($publickeyid);

			return $ok == 1;
		  }
		}

		class OAuthRequest {
		  private $parameters;
		  private $http_method;
		  private $http_url;
		  // for debug purposes
		  public $base_string;
		  public static $version = '1.0';
		  public static $POST_INPUT = 'php://input';

		  function __construct($http_method, $http_url, $parameters=NULL) {
			@$parameters or $parameters = array();
			$parameters = array_merge( OAuthUtil::parse_parameters(parse_url($http_url, PHP_URL_QUERY)), $parameters);
			$this->parameters = $parameters;
			$this->http_method = $http_method;
			$this->http_url = $http_url;
		  }


		  /**
		   * attempt to build up a request from what was passed to the server
		   */
		  public static function from_request($http_method=NULL, $http_url=NULL, $parameters=NULL) {
			$scheme = (!isset($_SERVER['HTTPS']) || $_SERVER['HTTPS'] != "on")
					  ? 'http'
					  : 'https';
			@$http_url or $http_url = $scheme .
									  '://' . $_SERVER['HTTP_HOST'] .
									  ':' .
									  $_SERVER['SERVER_PORT'] .
									  $_SERVER['REQUEST_URI'];
			@$http_method or $http_method = $_SERVER['REQUEST_METHOD'];

			// We weren't handed any parameters, so let's find the ones relevant to
			// this request.
			// If you run XML-RPC or similar you should use this to provide your own
			// parsed parameter-list
			if (!$parameters) {
			  // Find request headers
			  $request_headers = OAuthUtil::get_headers();

			  // Parse the query-string to find GET parameters
			  $parameters = OAuthUtil::parse_parameters($_SERVER['QUERY_STRING']);

			  // It's a POST request of the proper content-type, so parse POST
			  // parameters and add those overriding any duplicates from GET
			  if ($http_method == "POST"
				  && @strstr($request_headers["Content-Type"],
							 "application/x-www-form-urlencoded")
				  ) {
				$post_data = OAuthUtil::parse_parameters(
				  file_get_contents(self::$POST_INPUT)
				);
				$parameters = array_merge($parameters, $post_data);
			  }

			  // We have a Authorization-header with OAuth data. Parse the header
			  // and add those overriding any duplicates from GET or POST
			  if (@substr($request_headers['Authorization'], 0, 6) == "OAuth ") {
				$header_parameters = OAuthUtil::split_header(
				  $request_headers['Authorization']
				);
				$parameters = array_merge($parameters, $header_parameters);
			  }

			}

			return new OAuthRequest($http_method, $http_url, $parameters);
		  }

		  /**
		   * pretty much a helper function to set up the request
		   */
		  public static function from_consumer_and_token($consumer, $token, $http_method, $http_url, $parameters=NULL) {
			@$parameters or $parameters = array();
			$defaults = array("oauth_version" => OAuthRequest::$version,
							  "oauth_nonce" => OAuthRequest::generate_nonce(),
							  "oauth_timestamp" => OAuthRequest::generate_timestamp(),
							  "oauth_consumer_key" => $consumer->key);
			if ($token)
			  $defaults['oauth_token'] = $token->key;

			$parameters = array_merge($defaults, $parameters);

			return new OAuthRequest($http_method, $http_url, $parameters);
		  }

		  public function set_parameter($name, $value, $allow_duplicates = true) {
			if ($allow_duplicates && isset($this->parameters[$name])) {
			  // We have already added parameter(s) with this name, so add to the list
			  if (is_scalar($this->parameters[$name])) {
				// This is the first duplicate, so transform scalar (string)
				// into an array so we can add the duplicates
				$this->parameters[$name] = array($this->parameters[$name]);
			  }

			  $this->parameters[$name][] = $value;
			} else {
			  $this->parameters[$name] = $value;
			}
		  }

		  public function get_parameter($name) {
			return isset($this->parameters[$name]) ? $this->parameters[$name] : null;
		  }

		  public function get_parameters() {
			return $this->parameters;
		  }

		  public function unset_parameter($name) {
			unset($this->parameters[$name]);
		  }

		  /**
		   * The request parameters, sorted and concatenated into a normalized string.
		   * @return string
		   */
		  public function get_signable_parameters() {
			// Grab all parameters
			$params = $this->parameters;

			// Remove oauth_signature if present
			// Ref: Spec: 9.1.1 ("The oauth_signature parameter MUST be excluded.")
			if (isset($params['oauth_signature'])) {
			  unset($params['oauth_signature']);
			}

			return OAuthUtil::build_http_query($params);
		  }

		  /**
		   * Returns the base string of this request
		   *
		   * The base string defined as the method, the url
		   * and the parameters (normalized), each urlencoded
		   * and the concated with &.
		   */
		  public function get_signature_base_string() {
			$parts = array(
			  $this->get_normalized_http_method(),
			  $this->get_normalized_http_url(),
			  $this->get_signable_parameters()
			);

			$parts = OAuthUtil::urlencode_rfc3986($parts);

			return implode('&', $parts);
		  }

		  /**
		   * just uppercases the http method
		   */
		  public function get_normalized_http_method() {
			return strtoupper($this->http_method);
		  }

		  /**
		   * parses the url and rebuilds it to be
		   * scheme://host/path
		   */
		  public function get_normalized_http_url() {
			$parts = parse_url($this->http_url);

			$port = @$parts['port'];
			$scheme = $parts['scheme'];
			$host = $parts['host'];
			$path = @$parts['path'];

			$port or $port = ($scheme == 'https') ? '443' : '80';

			if (($scheme == 'https' && $port != '443')
				|| ($scheme == 'http' && $port != '80')) {
			  $host = "$host:$port";
			}
			return "$scheme://$host$path";
		  }

		  /**
		   * builds a url usable for a GET request
		   */
		  public function to_url() {
			$post_data = $this->to_postdata();
			$out = $this->get_normalized_http_url();
			if ($post_data) {
			  $out .= '?'.$post_data;
			}
			return $out;
		  }

		  /**
		   * builds the data one would send in a POST request
		   */
		  public function to_postdata() {
			return OAuthUtil::build_http_query($this->parameters);
		  }

		  /**
		   * builds the Authorization: header
		   */
		  public function to_header($realm=null) {
			$first = true;
			if($realm) {
			  $out = 'Authorization: OAuth realm="' . OAuthUtil::urlencode_rfc3986($realm) . '"';
			  $first = false;
			} else
			  $out = 'Authorization: OAuth';

			$total = array();
			foreach ($this->parameters as $k => $v) {
			  if (substr($k, 0, 5) != "oauth") continue;
			  if (is_array($v)) {
				throw new OAuthException('Arrays not supported in headers');
			  }
			  $out .= ($first) ? ' ' : ',';
			  $out .= OAuthUtil::urlencode_rfc3986($k) .
					  '="' .
					  OAuthUtil::urlencode_rfc3986($v) .
					  '"';
			  $first = false;
			}
			return $out;
		  }

		  public function __toString() {
			return $this->to_url();
		  }


		  public function sign_request($signature_method, $consumer, $token) {
			$this->set_parameter(
			  "oauth_signature_method",
			  $signature_method->get_name(),
			  false
			);
			$signature = $this->build_signature($signature_method, $consumer, $token);
			$this->set_parameter("oauth_signature", $signature, false);
		  }

		  public function build_signature($signature_method, $consumer, $token) {
			$signature = $signature_method->build_signature($this, $consumer, $token);
			return $signature;
		  }

		  /**
		   * util function: current timestamp
		   */
		  private static function generate_timestamp() {
			return time();
		  }

		  /**
		   * util function: current nonce
		   */
		  private static function generate_nonce() {
			$mt = microtime();
			$rand = mt_rand();

			return md5($mt . $rand); // md5s look nicer than numbers
		  }
		}

		class OAuthServer {
		  protected $timestamp_threshold = 300; // in seconds, five minutes
		  protected $version = '1.0';             // hi blaine
		  protected $signature_methods = array();

		  protected $data_store;

		  function __construct($data_store) {
			$this->data_store = $data_store;
		  }

		  public function add_signature_method($signature_method) {
			$this->signature_methods[$signature_method->get_name()] =
			  $signature_method;
		  }

		  // high level functions

		  /**
		   * process a request_token request
		   * returns the request token on success
		   */
		  public function fetch_request_token(&$request) {
			$this->get_version($request);

			$consumer = $this->get_consumer($request);

			// no token required for the initial token request
			$token = NULL;

			$this->check_signature($request, $consumer, $token);

			// Rev A change
			$callback = $request->get_parameter('oauth_callback');
			$new_token = $this->data_store->new_request_token($consumer, $callback);

			return $new_token;
		  }

		  /**
		   * process an access_token request
		   * returns the access token on success
		   */
		  public function fetch_access_token(&$request) {
			$this->get_version($request);

			$consumer = $this->get_consumer($request);

			// requires authorized request token
			$token = $this->get_token($request, $consumer, "request");

			$this->check_signature($request, $consumer, $token);

			// Rev A change
			$verifier = $request->get_parameter('oauth_verifier');
			$new_token = $this->data_store->new_access_token($token, $consumer, $verifier);

			return $new_token;
		  }

		  /**
		   * verify an api call, checks all the parameters
		   */
		  public function verify_request(&$request) {
			$this->get_version($request);
			$consumer = $this->get_consumer($request);
			$token = $this->get_token($request, $consumer, "access");
			$this->check_signature($request, $consumer, $token);
			return array($consumer, $token);
		  }

		  // Internals from here
		  /**
		   * version 1
		   */
		  private function get_version(&$request) {
			$version = $request->get_parameter("oauth_version");
			if (!$version) {
			  // Service Providers MUST assume the protocol version to be 1.0 if this parameter is not present. 
			  // Chapter 7.0 ("Accessing Protected Ressources")
			  $version = '1.0';
			}
			if ($version !== $this->version) {
			  throw new OAuthException("OAuth version '$version' not supported");
			}
			return $version;
		  }

		  /**
		   * figure out the signature with some defaults
		   */
		  private function get_signature_method(&$request) {
			$signature_method =
				@$request->get_parameter("oauth_signature_method");

			if (!$signature_method) {
			  // According to chapter 7 ("Accessing Protected Ressources") the signature-method
			  // parameter is required, and we can't just fallback to PLAINTEXT
			  throw new OAuthException('No signature method parameter. This parameter is required');
			}

			if (!in_array($signature_method,
						  array_keys($this->signature_methods))) {
			  throw new OAuthException(
				"Signature method '$signature_method' not supported " .
				"try one of the following: " .
				implode(", ", array_keys($this->signature_methods))
			  );
			}
			return $this->signature_methods[$signature_method];
		  }

		  /**
		   * try to find the consumer for the provided request's consumer key
		   */
		  private function get_consumer(&$request) {
			$consumer_key = @$request->get_parameter("oauth_consumer_key");
			if (!$consumer_key) {
			  throw new OAuthException("Invalid consumer key");
			}

			$consumer = $this->data_store->lookup_consumer($consumer_key);
			if (!$consumer) {
			  throw new OAuthException("Invalid consumer");
			}

			return $consumer;
		  }

		  /**
		   * try to find the token for the provided request's token key
		   */
		  private function get_token(&$request, $consumer, $token_type="access") {
			$token_field = @$request->get_parameter('oauth_token');
			$token = $this->data_store->lookup_token(
			  $consumer, $token_type, $token_field
			);
			if (!$token) {
			  throw new OAuthException("Invalid $token_type token: $token_field");
			}
			return $token;
		  }

		  /**
		   * all-in-one function to check the signature on a request
		   * should guess the signature method appropriately
		   */
		  private function check_signature(&$request, $consumer, $token) {
			// this should probably be in a different method
			$timestamp = @$request->get_parameter('oauth_timestamp');
			$nonce = @$request->get_parameter('oauth_nonce');

			$this->check_timestamp($timestamp);
			$this->check_nonce($consumer, $token, $nonce, $timestamp);

			$signature_method = $this->get_signature_method($request);

			$signature = $request->get_parameter('oauth_signature');
			$valid_sig = $signature_method->check_signature(
			  $request,
			  $consumer,
			  $token,
			  $signature
			);

			if (!$valid_sig) {
			  throw new OAuthException("Invalid signature");
			}
		  }

		  /**
		   * check that the timestamp is new enough
		   */
		  private function check_timestamp($timestamp) {
			if( ! $timestamp )
			  throw new OAuthException(
				'Missing timestamp parameter. The parameter is required'
			  );
			
			// verify that timestamp is recentish
			$now = time();
			if (abs($now - $timestamp) > $this->timestamp_threshold) {
			  throw new OAuthException(
				"Expired timestamp, yours $timestamp, ours $now"
			  );
			}
		  }

		  /**
		   * check that the nonce is not repeated
		   */
		  private function check_nonce($consumer, $token, $nonce, $timestamp) {
			if( ! $nonce )
			  throw new OAuthException(
				'Missing nonce parameter. The parameter is required'
			  );

			// verify that the nonce is uniqueish
			$found = $this->data_store->lookup_nonce(
			  $consumer,
			  $token,
			  $nonce,
			  $timestamp
			);
			if ($found) {
			  throw new OAuthException("Nonce already used: $nonce");
			}
		  }

		}

		class OAuthDataStore {
		  function lookup_consumer($consumer_key) {
			// implement me
		  }

		  function lookup_token($consumer, $token_type, $token) {
			// implement me
		  }

		  function lookup_nonce($consumer, $token, $nonce, $timestamp) {
			// implement me
		  }

		  function new_request_token($consumer, $callback = null) {
			// return a new token attached to this consumer
		  }

		  function new_access_token($token, $consumer, $verifier = null) {
			// return a new access token attached to this consumer
			// for the user associated with this token if the request token
			// is authorized
			// should also invalidate the request token
		  }

		}

		class OAuthUtil {
		  public static function urlencode_rfc3986($input) {
		  if (is_array($input)) {
			return array_map(array('OAuthUtil', 'urlencode_rfc3986'), $input);
		  } else if (is_scalar($input)) {
			return str_replace(
			  '+',
			  ' ',
			  str_replace('%7E', '~', rawurlencode($input))
			);
		  } else {
			return '';
		  }
		}


		  // This decode function isn't taking into consideration the above
		  // modifications to the encoding process. However, this method doesn't
		  // seem to be used anywhere so leaving it as is.
		  public static function urldecode_rfc3986($string) {
			return urldecode($string);
		  }

		  // Utility function for turning the Authorization: header into
		  // parameters, has to do some unescaping
		  // Can filter out any non-oauth parameters if needed (default behaviour)
		  public static function split_header($header, $only_allow_oauth_parameters = true) {
			$pattern = '/(([-_a-z]*)=("([^"]*)"|([^,]*)),?)/';
			$offset = 0;
			$params = array();
			while (preg_match($pattern, $header, $matches, PREG_OFFSET_CAPTURE, $offset) > 0) {
			  $match = $matches[0];
			  $header_name = $matches[2][0];
			  $header_content = (isset($matches[5])) ? $matches[5][0] : $matches[4][0];
			  if (preg_match('/^oauth_/', $header_name) || !$only_allow_oauth_parameters) {
				$params[$header_name] = OAuthUtil::urldecode_rfc3986($header_content);
			  }
			  $offset = $match[1] + strlen($match[0]);
			}

			if (isset($params['realm'])) {
			  unset($params['realm']);
			}

			return $params;
		  }

		  // helper to try to sort out headers for people who aren't running apache
		  public static function get_headers() {
			if (function_exists('apache_request_headers')) {
			  // we need this to get the actual Authorization: header
			  // because apache tends to tell us it doesn't exist
			  $headers = apache_request_headers();

			  // sanitize the output of apache_request_headers because
			  // we always want the keys to be Cased-Like-This and arh()
			  // returns the headers in the same case as they are in the
			  // request
			  $out = array();
			  foreach( $headers AS $key => $value ) {
				$key = str_replace(
					" ",
					"-",
					ucwords(strtolower(str_replace("-", " ", $key)))
				  );
				$out[$key] = $value;
			  }
			} else {
			  // otherwise we don't have apache and are just going to have to hope
			  // that $_SERVER actually contains what we need
			  $out = array();
			  if( isset($_SERVER['CONTENT_TYPE']) )
				$out['Content-Type'] = $_SERVER['CONTENT_TYPE'];
			  if( isset($_ENV['CONTENT_TYPE']) )
				$out['Content-Type'] = $_ENV['CONTENT_TYPE'];

			  foreach ($_SERVER as $key => $value) {
				if (substr($key, 0, 5) == "HTTP_") {
				  // this is chaos, basically it is just there to capitalize the first
				  // letter of every word that is not an initial HTTP and strip HTTP
				  // code from przemek
				  $key = str_replace(
					" ",
					"-",
					ucwords(strtolower(str_replace("_", " ", substr($key, 5))))
				  );
				  $out[$key] = $value;
				}
			  }
			}
			return $out;
		  }

		  // This function takes a input like a=b&a=c&d=e and returns the parsed
		  // parameters like this
		  // array('a' => array('b','c'), 'd' => 'e')
		  public static function parse_parameters( $input ) {
			if (!isset($input) || !$input) return array();

			$pairs = explode('&', $input);

			$parsed_parameters = array();
			foreach ($pairs as $pair) {
			  $split = explode('=', $pair, 2);
			  $parameter = OAuthUtil::urldecode_rfc3986($split[0]);
			  $value = isset($split[1]) ? OAuthUtil::urldecode_rfc3986($split[1]) : '';

			  if (isset($parsed_parameters[$parameter])) {
				// We have already recieved parameter(s) with this name, so add to the list
				// of parameters with this name

				if (is_scalar($parsed_parameters[$parameter])) {
				  // This is the first duplicate, so transform scalar (string) into an array
				  // so we can add the duplicates
				  $parsed_parameters[$parameter] = array($parsed_parameters[$parameter]);
				}

				$parsed_parameters[$parameter][] = $value;
			  } else {
				$parsed_parameters[$parameter] = $value;
			  }
			}
			return $parsed_parameters;
		  }

		  public static function build_http_query($params) {
			if (!$params) return '';

			// Urlencode both keys and values
			$keys = OAuthUtil::urlencode_rfc3986(array_keys($params));
			$values = OAuthUtil::urlencode_rfc3986(array_values($params));
			$params = array_combine($keys, $values);

			// Parameters are sorted by name, using lexicographical byte value ordering.
			// Ref: Spec: 9.1.1 (1)
			uksort($params, 'strcmp');

			$pairs = array();
			foreach ($params as $parameter => $value) {
			  if (is_array($value)) {
				// If two or more parameters share the same name, they are sorted by their value
				// Ref: Spec: 9.1.1 (1)
				natsort($value);
				foreach ($value as $duplicate_value) {
				  $pairs[] = $parameter . '=' . $duplicate_value;
				}
			  } else {
				$pairs[] = $parameter . '=' . $value;
			  }
			}
			// For each parameter, the name is separated from the corresponding value by an '=' character (ASCII code 61)
			// Each name-value pair is separated by an '&' character (ASCII code 38)
			return implode('&', $pairs);
		  }
		}


/**
 * Twitter OAuth class
 */
class TwitterOAuth {
  /* Contains the last HTTP status code returned. */
  public $http_code;
  /* Contains the last API call. */
  public $url;
  /* Set up the API root URL. */
  public $host = "https://api.twitter.com/1/";
  /* Set timeout default. */
  public $timeout = 30;
  /* Set connect timeout. */
  public $connecttimeout = 30; 
  /* Verify SSL Cert. */
  public $ssl_verifypeer = FALSE;
  /* Respons format. */
  public $format = 'json';
  /* Decode returned json data. */
  public $decode_json = TRUE;
  /* Contains the last HTTP headers returned. */
  public $http_info;
  /* Set the useragnet. */
  public $useragent = 'TwitterOAuth v0.2.0-beta2';
  /* Immediately retry the API call if the response was not successful. */
  //public $retry = TRUE;


  /**
   * Set API URLS
   */
  function accessTokenURL()  { return 'https://api.twitter.com/oauth/access_token'; }
  function authenticateURL() { return 'https://api.twitter.com/oauth/authenticate'; }
  function authorizeURL()    { return 'https://api.twitter.com/oauth/authorize'; }
  function requestTokenURL() { return 'https://api.twitter.com/oauth/request_token'; }

  /**
   * Debug helpers
   */
  function lastStatusCode() { return $this->http_status; }
  function lastAPICall() { return $this->last_api_call; }

  /**
   * construct TwitterOAuth object
   */
  function __construct($consumer_key, $consumer_secret, $oauth_token = NULL, $oauth_token_secret = NULL) {
    $this->sha1_method = new OAuthSignatureMethod_HMAC_SHA1();
    $this->consumer = new OAuthConsumer($consumer_key, $consumer_secret);
    if (!empty($oauth_token) && !empty($oauth_token_secret)) {
      $this->token = new OAuthConsumer($oauth_token, $oauth_token_secret);
    } else {
      $this->token = NULL;
    }
  }


  /**
   * Get a request_token from Twitter
   *
   * @returns a key/value array containing oauth_token and oauth_token_secret
   */
  function getRequestToken($oauth_callback = NULL) {
    $parameters = array();
    if (!empty($oauth_callback)) {
      $parameters['oauth_callback'] = $oauth_callback;
    } 
    $request = $this->oAuthRequest($this->requestTokenURL(), 'GET', $parameters);
    $token = OAuthUtil::parse_parameters($request);
    $this->token = new OAuthConsumer($token['oauth_token'], $token['oauth_token_secret']);
    return $token;
  }

  /**
   * Get the authorize URL
   *
   * @returns a string
   */
  function getAuthorizeURL($token, $sign_in_with_twitter = TRUE) {
    if (is_array($token)) {
      $token = $token['oauth_token'];
    }
    if (empty($sign_in_with_twitter)) {
      return $this->authorizeURL() . "?oauth_token={$token}";
    } else {
       return $this->authenticateURL() . "?oauth_token={$token}";
    }
  }

  /**
   * Exchange request token and secret for an access token and
   * secret, to sign API calls.
   *
   * @returns array("oauth_token" => "the-access-token",
   *                "oauth_token_secret" => "the-access-secret",
   *                "user_id" => "9436992",
   *                "screen_name" => "abraham")
   */
  function getAccessToken($oauth_verifier = FALSE) {
    $parameters = array();
    if (!empty($oauth_verifier)) {
      $parameters['oauth_verifier'] = $oauth_verifier;
    }
    $request = $this->oAuthRequest($this->accessTokenURL(), 'GET', $parameters);
    $token = OAuthUtil::parse_parameters($request);
    $this->token = new OAuthConsumer($token['oauth_token'], $token['oauth_token_secret']);
    return $token;
  }

  /**
   * One time exchange of username and password for access token and secret.
   *
   * @returns array("oauth_token" => "the-access-token",
   *                "oauth_token_secret" => "the-access-secret",
   *                "user_id" => "9436992",
   *                "screen_name" => "abraham",
   *                "x_auth_expires" => "0")
   */  
  function getXAuthToken($username, $password) {
    $parameters = array();
    $parameters['x_auth_username'] = $username;
    $parameters['x_auth_password'] = $password;
    $parameters['x_auth_mode'] = 'client_auth';
    $request = $this->oAuthRequest($this->accessTokenURL(), 'POST', $parameters);
    $token = OAuthUtil::parse_parameters($request);
    $this->token = new OAuthConsumer($token['oauth_token'], $token['oauth_token_secret']);
    return $token;
  }

  /**
   * GET wrapper for oAuthRequest.
   */
  function get($url, $parameters = array()) {
    $response = $this->oAuthRequest($url, 'GET', $parameters);
    if ($this->format === 'json' && $this->decode_json) {
      return json_decode($response);
    }
    return $response;
  }
  
  /**
   * POST wrapper for oAuthRequest.
   */
  function post($url, $parameters = array()) {
    $response = $this->oAuthRequest($url, 'POST', $parameters);
    if ($this->format === 'json' && $this->decode_json) {
      return json_decode($response);
    }
    return $response;
  }

  /**
   * DELETE wrapper for oAuthReqeust.
   */
  function delete($url, $parameters = array()) {
    $response = $this->oAuthRequest($url, 'DELETE', $parameters);
    if ($this->format === 'json' && $this->decode_json) {
      return json_decode($response);
    }
    return $response;
  }

  /**
   * Format and sign an OAuth / API request
   */
  function oAuthRequest($url, $method, $parameters) {
    if (strrpos($url, 'https://') !== 0 && strrpos($url, 'http://') !== 0) {
      $url = "{$this->host}{$url}.{$this->format}";
    }
    $request = OAuthRequest::from_consumer_and_token($this->consumer, $this->token, $method, $url, $parameters);
    $request->sign_request($this->sha1_method, $this->consumer, $this->token);
    switch ($method) {
    case 'GET':
      return $this->http($request->to_url(), 'GET');
    default:
      return $this->http($request->get_normalized_http_url(), $method, $request->to_postdata());
    }
  }

  /**
   * Make an HTTP request
   *
   * @return API results
   */
  function http($url, $method, $postfields = NULL) {
    $this->http_info = array();
    $ci = curl_init();
    /* Curl settings */
    curl_setopt($ci, CURLOPT_USERAGENT, $this->useragent);
    curl_setopt($ci, CURLOPT_CONNECTTIMEOUT, $this->connecttimeout);
    curl_setopt($ci, CURLOPT_TIMEOUT, $this->timeout);
    curl_setopt($ci, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($ci, CURLOPT_HTTPHEADER, array('Expect:'));
    curl_setopt($ci, CURLOPT_SSL_VERIFYPEER, $this->ssl_verifypeer);
    curl_setopt($ci, CURLOPT_HEADERFUNCTION, array($this, 'getHeader'));
    curl_setopt($ci, CURLOPT_HEADER, FALSE);

    switch ($method) {
      case 'POST':
        curl_setopt($ci, CURLOPT_POST, TRUE);
        if (!empty($postfields)) {
          curl_setopt($ci, CURLOPT_POSTFIELDS, $postfields);
        }
        break;
      case 'DELETE':
        curl_setopt($ci, CURLOPT_CUSTOMREQUEST, 'DELETE');
        if (!empty($postfields)) {
          $url = "{$url}?{$postfields}";
        }
    }

    curl_setopt($ci, CURLOPT_URL, $url);
    $response = curl_exec($ci);
    $this->http_code = curl_getinfo($ci, CURLINFO_HTTP_CODE);
    $this->http_info = array_merge($this->http_info, curl_getinfo($ci));
    $this->url = $url;
    curl_close ($ci);
    return $response;
  }

  /**
   * Get the header info to store.
   */
  function getHeader($ch, $header) {
    $i = strpos($header, ':');
    if (!empty($i)) {
      $key = str_replace('-', '_', strtolower(substr($header, 0, $i)));
      $value = trim(substr($header, $i + 2));
      $this->http_header[$key] = $value;
    }
    return strlen($header);
  }
}