Gmail Oauth with Zend

function newmail()
    {
        /**
         * Copyright 2010 Google Inc.
         *
         * Licensed under the Apache License, Version 2.0 (the "License");
         * you may not use this file except in compliance with the License.
         * You may obtain a copy of the License at
         *
              * http://www.apache.org/licenses/LICENSE-2.0
         *
         * Unless required by applicable law or agreed to in writing, software
         * distributed under the License is distributed on an "AS IS" BASIS,
         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
         * See the License for the specific language governing permissions and
         * limitations under the License.
         */

        session_start();

        // these need to be grabbed from database
        $THREE_LEGGED_CONSUMER_KEY = 'www.mysite.com';
        $THREE_LEGGED_SIGNATURE_METHOD = 'HMAC-SHA1';
        $THREE_LEGGED_CONSUMER_SECRET_HMAC = 'mysecret';

        $THREE_LEGGED_SCOPES = array('https://mail.google.com/');

        ini_set('include_path', ini_get('include_path') . PATH_SEPARATOR . APPPATH . 'libraries');

        require_once 'Zend/Oauth/Consumer.php';
        require_once 'Zend/Crypt/Rsa/Key/Private.php';
        require_once 'Zend/Mail/Protocol/Imap.php';
        require_once 'Zend/Mail/Storage/Imap.php';

        /**
         * If the e-mail address was just submitted via a
         * form POST, set it in the session.  Else if we
         * don't yet have an email address, prompt the user
         * for their address.
         */

        /**
         * Setup OAuth
         */
        $options = array(
            'requestScheme' => Zend_Oauth::REQUEST_SCHEME_HEADER,
            'version' => '1.0',
            'consumerKey' => $THREE_LEGGED_CONSUMER_KEY,
            'callbackUrl' => current_url(),
            'requestTokenUrl' => 'https://www.google.com/accounts/OAuthGetRequestToken',
            'userAuthorizationUrl' => 'https://www.google.com/accounts/OAuthAuthorizeToken',
            'accessTokenUrl' => 'https://www.google.com/accounts/OAuthGetAccessToken'
        );

        if ($THREE_LEGGED_SIGNATURE_METHOD == 'RSA-SHA1') {
            $options['signatureMethod'] = 'RSA-SHA1';
            $options['consumerSecret'] = new Zend_Crypt_Rsa_Key_Private(
                file_get_contents(realpath($THREE_LEGGED_RSA_PRIVATE_KEY)));
        } else {
            $options['signatureMethod'] = 'HMAC-SHA1';
            $options['consumerSecret'] = $THREE_LEGGED_CONSUMER_SECRET_HMAC;
        }

        $consumer = new Zend_Oauth_Consumer($options);

        /**
         * When using HMAC-SHA1, you need to persist the request token in some way.
         * This is because you'll need the request token's token secret when upgrading
         * to an access token later on. The example below saves the token object
         * as a session variable.
         */
        if (!isset($_SESSION['ACCESS_TOKEN'])) {
          if (!isset($_SESSION['REQUEST_TOKEN'])) {
            // Get Request Token and redirect to Google
            $_SESSION['REQUEST_TOKEN'] = serialize($consumer->getRequestToken(array('scope' => implode(' ', $THREE_LEGGED_SCOPES))));
            $consumer->redirect();
          } else {
            echo 'have access token';
            // Have Request Token already, Get Access Token
            $_SESSION['ACCESS_TOKEN'] = serialize($consumer->getAccessToken($_GET, unserialize($_SESSION['REQUEST_TOKEN'])));
            header('Location: ' . getCurrentUrl(false));
            exit;
          }
        } else {
          // Retrieve mail using Access Token
          $accessToken = unserialize($_SESSION['ACCESS_TOKEN']);
          $config = new Zend_Oauth_Config();
          $config->setOptions($options);
          $config->setToken($accessToken);
          $config->setRequestMethod('GET');
          $url = 'https://mail.google.com/mail/b/' .
               $email_address .
               '/imap/';

          $httpUtility = new Zend_Oauth_Http_Utility();

          /**
           * Get an unsorted array of oauth params,
           * including the signature based off those params.
           */
          $params = $httpUtility->assembleParams(
              $url,
              $config);

          /**
           * Sort parameters based on their names, as required
           * by OAuth.
           */
          ksort($params);

          /**
           * Construct a comma-deliminated,ordered,quoted list of
           * OAuth params as required by XOAUTH.
           *
           * Example: oauth_param1="foo",oauth_param2="bar"
           */
          $first = true;
          $oauthParams = '';
          foreach ($params as $key => $value) {
            // only include standard oauth params
            if (strpos($key, 'oauth_') === 0) {
              if (!$first) {
                $oauthParams .= ',';
              }
              $oauthParams .= $key . '="' . urlencode($value) . '"';
              $first = false;
            }
          }

          /**
           * Generate SASL client request, using base64 encoded
           * OAuth params
           */
          $initClientRequest = 'GET ' . $url . ' ' . $oauthParams;
          $initClientRequestEncoded = base64_encode($initClientRequest);

          /**
           * Make the IMAP connection and send the auth request
           */
          $imap = new Zend_Mail_Protocol_Imap('imap.gmail.com', '993', true);
          $authenticateParams = array('XOAUTH', $initClientRequestEncoded);
          $imap->requestAndResponse('AUTHENTICATE', $authenticateParams);

          /**
           * Print the INBOX message count and the subject of all messages
           * in the INBOX
           */
          $storage = new Zend_Mail_Storage_Imap($imap);

          $data = array(
                'imap'  => $storage
            );

            $this->load->view('main',$data);
        }
    }