Enabled Caching of Access Tokens

- Updated AuthTokenCredential to store access token in file storage
- Updated samples to include the configuration to disable/enable caching

lib/PayPal/Auth/OAuthTokenCredential.php

@@ -2,6 +2,8 @@
 
 namespace PayPal\Auth;
 
+use PayPal\Cache\AuthorizationCache;
+use PayPal\Common\PPModel;
 use PayPal\Common\PPUserAgent;
 use PayPal\Common\ResourceModel;
 use PayPal\Core\PPConstants;
@@ -10,12 +12,15 @@ use PayPal\Core\PPHttpConnection;
 use PayPal\Core\PPLoggingManager;
 use PayPal\Exception\PPConfigurationException;
 use PayPal\Rest\RestHandler;
+use PayPal\Validation\JsonValidator;
 
 /**
  * Class OAuthTokenCredential
  */
 class OAuthTokenCredential extends ResourceModel
 {
+
+    public static $CACHE_PATH = '/../../../var/auth.cache';
     /**
      * Private Variable
      *
@@ -107,6 +112,15 @@ class OAuthTokenCredential extends ResourceModel
      */
     public function getAccessToken($config)
     {
+        // Check for persisted data first
+        $token = AuthorizationCache::pull($config, $this->clientId);
+        if ($token) {
+            // We found it
+            $this->accessToken = $token['accessToken'];
+            $this->tokenCreateTime = $token['tokenCreateTime'];
+            $this->tokenExpiresIn = $token['tokenExpiresIn'];
+        }
+
         // Check if Access Token is not null and has not expired.
         // The API returns expiry time as a relative time unit
         // We use a buffer time when checking for token expiry to account
@@ -121,12 +135,15 @@ class OAuthTokenCredential extends ResourceModel
 
         // If accessToken is Null, obtain a new token
         if ($this->accessToken == null) {
+            // Get a new one by making calls to API
             $this->updateAccessToken($config);
+            AuthorizationCache::push($config, $this->clientId, $this->accessToken, $this->tokenCreateTime, $this->tokenExpiresIn);
         }
 
         return $this->accessToken;
     }
 
+
     /**
      * Get a Refresh Token from Authorization Code
      *

lib/PayPal/Cache/AuthorizationCache.php

@@ -0,0 +1,94 @@
+<?php
+
+namespace PayPal\Cache;
+
+use PayPal\Core\PPConfigManager;
+use PayPal\Validation\JsonValidator;
+
+abstract class AuthorizationCache
+{
+    public static $CACHE_PATH = '/../../../var/auth.cache';
+
+    /**
+     * A pull method which would read the persisted data based on clientId.
+     * If clientId is not provided, an array with all the tokens would be passed.
+     *
+     * @param array|null $config
+     * @param string $clientId
+     * @return mixed|null
+     */
+    public static function pull($config = null, $clientId = null)
+    {
+        // Return if not enabled
+        if (!self::isEnabled($config)) { return null; }
+
+        $tokens = null;
+        if (file_exists(__DIR__ . self::$CACHE_PATH)) {
+            // Read from the file
+            $cachedToken = file_get_contents(__DIR__ . self::$CACHE_PATH);
+            if ($cachedToken && JsonValidator::validate($cachedToken, true)) {
+                $tokens = json_decode($cachedToken, true);
+                if ($clientId && is_array($tokens) && array_key_exists($clientId, $tokens)) {
+                    // If client Id is found, just send in that data only
+                    return $tokens[$clientId];
+                } else if ($clientId) {
+                    // If client Id is provided, but no key in persisted data found matching it.
+                    return null;
+                }
+            }
+        }
+        return $tokens;
+    }
+
+    /**
+     * Persists the data into a cache file provided in $CACHE_PATH
+     *
+     * @param array|null $config
+     * @param      $clientId
+     * @param      $accessToken
+     * @param      $tokenCreateTime
+     * @param      $tokenExpiresIn
+     */
+    public static function push($config = null, $clientId, $accessToken, $tokenCreateTime, $tokenExpiresIn)
+    {
+        // Return if not enabled
+        if (!self::isEnabled($config)) { return; }
+
+        if (!is_dir(dirname(__DIR__ . self::$CACHE_PATH))) {
+            if (mkdir(dirname(__DIR__ . self::$CACHE_PATH), 0755, true) == false) {
+                return;
+            }
+        }
+
+        // Reads all the existing persisted data
+        $tokens = self::pull();
+        $tokens = $tokens ? $tokens : array();
+        if (is_array($tokens)) {
+            $tokens[$clientId] = array(
+                'clientId' => $clientId,
+                'accessToken' => $accessToken,
+                'tokenCreateTime' => $tokenCreateTime,
+                'tokenExpiresIn' => $tokenExpiresIn
+            );
+        }
+        file_put_contents(__DIR__ . self::$CACHE_PATH, json_encode($tokens));
+    }
+
+    /**
+     * Determines from the Configuration if caching is currently enabled/disabled
+     *
+     * @param $config
+     * @return bool
+     */
+    public static function isEnabled($config)
+    {
+        $config = ($config && is_array($config)) ? $config : PPConfigManager::getInstance()->getConfigHashmap();
+        if (array_key_exists("cache.enabled", $config)) {
+            $value = $config['cache.enabled'];
+            return (trim($value) == 'true') ?  true : false;
+        }
+        return false;
+    }
+
+
+}

lib/PayPal/Core/PPConstants.php

@@ -12,7 +12,7 @@ class PPConstants
 {
 
     const SDK_NAME = 'PayPal-PHP-SDK';
-    const SDK_VERSION = '0.15.1';
+    const SDK_VERSION = '0.16.0';
 
     const REST_SANDBOX_ENDPOINT = "https://api.sandbox.paypal.com/";
     const OPENID_REDIRECT_SANDBOX_URL = "https://www.sandbox.paypal.com/webapps/auth/protocol/openidconnect";