logical　error

<?php
/*
 * Copyright 2011 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.
 */
include_once "templates/base.php";
session_start();

header( "Content-Type: text/html; Charset=utf-8" );
header( "pragma: no-cache" );
header( "Expires: Wed, 31 May 2000 14:59:58 GMT" );
header( "Cache-control: no-cache" );

require_once realpath(dirname(__FILE__) . '/../autoload.php');

/************************************************
  $redirect_uri はこのスクリプトの URL
 ************************************************/
$client_id = '';
$client_secret = '';
$redirect_uri = 'http://localhost/gapi/examples/gmail-send.php';

/************************************************
  クライアントの作成
 ************************************************/
$client = new Google_Client();
$client->setClientId($client_id);
$client->setClientSecret($client_secret);
$client->setRedirectUri($redirect_uri);

/************************************************
  サービスの作成
 ************************************************/
// https://developers.google.com/gmail/api/auth/scopes
// https://developers.google.com/gmail/api/v1/reference/users/messages/send
$client->addScope("https://mail.google.com/");
$service = new Google_Service_Gmail($client);

/************************************************
  アクセストークンの取得プロセス
 ************************************************/
if (isset($_REQUEST['logout'])) {
  unset($_SESSION['access_token']);
}

if (isset($_GET['code'])) {
  $client->authenticate($_GET['code']);
  $_SESSION['access_token'] = $client->getAccessToken();
  $redirect = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
  header('Location: ' . filter_var($redirect, FILTER_SANITIZE_URL));
}

if (isset($_SESSION['access_token']) && $_SESSION['access_token']) {
  $client->setAccessToken($_SESSION['access_token']);
  if ($client->isAccessTokenExpired()) {
    unset($_SESSION['access_token']);
  }
} else {
  $authUrl = $client->createAuthUrl();
}

/************************************************
  アクセストークンが取得できた時の処理
 ************************************************/
if ($client->getAccessToken() && $_POST['send'] != '' && $_POST['body'] != '') {

  // メール送信
  $subject = mb_convert_encoding( $_POST['subject'], "JIS", "UTF-8" );
  $subject = "Subject: =?ISO-2022-JP?B?" . base64_encode($subject) . "?=";
  $to = "To: {$_POST['to']}";
  $body = $_POST['body'];

  $send_data = "$subject¥n$to¥n¥n$body";
  // Base64URL
  $send_data = rtrim(strtr(base64_encode($send_data), '+/', '-_'), '=');
  $msg = new Google_Service_Gmail_Message();
  $msg->setRaw($send_data);
  $result = $service->users_messages->send("me", $msg);

}

echo pageHeader("Gmail メール送信");
if ($client->getAccessToken()) {
?>
<div style='width:300px;margin:auto'>
<form method="post" >
<input type="text" name="to"><br>
<input type="text" name="subject"><br>
<textarea name="body" style='height:100px;'></textarea><br>
<input type="submit" name="send" value="送信">
</form>
</div>
<?php
}
?>
<div class="box">
  <div class="request">
<?php 
if (isset($authUrl)) {
  echo "<a class='login' href='" . $authUrl . "'>Connect Me!</a>";
}
?>
  </div>

  <pre class="shortened" style='width:100%;height:500px;'>
<?php 
if (isset($result) && $result) {
  print_r($result);
}
?>
  </pre>
</div>