Resolve "Add "logout" button"

Closes #3 (closed)

public/index.php

@@ -4,17 +4,57 @@ session_start();
 require '../vendor/autoload.php';
 require '../config.php';
 
+if (isset($_GET['logout'])) {
+    $_SESSION['accessToken'] = '';
+    $_SESSION['refreshToken'] = '';
+}
+
 $accessToken = '';
 if (isset($_SESSION['accessToken'])) {
     $accessToken = $_SESSION['accessToken'];
 }
+$refreshToken = '';
+if (isset($_SESSION['refreshToken'])) {
+    $refreshToken = $_SESSION['refreshToken'];
+}
+
 if (!$accessToken) {
     header('Location: auth.php');
     die();
 }
 
-$api = new SpotifyWebAPI\SpotifyWebAPI();
-$api->setAccessToken($accessToken);
+$session = new SpotifyWebAPI\Session(
+    $CLIENT_ID,
+    $CLIENT_SECRET
+);
+
+// Use previously requested tokens fetched from session
+if ($accessToken) {
+    $session->setAccessToken($accessToken);
+    $session->setRefreshToken($refreshToken);
+} else {
+    // Or request a new access token
+    $session->refreshAccessToken($refreshToken);
+}
+
+$scopes = $session->getScope();
+
+$options = [
+  'scope' => [
+      'playlist-read-private',
+      'playlist-modify-private',
+      'user-read-private',
+  ],
+'auto_refresh' => true,
+];
+
+$api = new SpotifyWebAPI\SpotifyWebAPI($options, $session);
+
+// Save new tokens, they might have been updated
+$_SESSION['accessToken'] = $session->getAccessToken();
+$_SESSION['refreshToken'] = $session->getRefreshToken();
+
+// ################################################################
 
 $user = $api->me();