From 76c3088c3a930e5a09b158a5a0ee76cfd2cbe506 Mon Sep 17 00:00:00 2001
From: Roman Mager <roman.mager@outlook.com>
Date: Thu, 29 Aug 2024 10:27:25 +0300
Subject: [PATCH] Implement token caching

---
 .../java/com/ypm/service/TokenService.java    | 22 ++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/ypm/service/TokenService.java b/src/main/java/com/ypm/service/TokenService.java
index 2712deb..5e50cdb 100644
--- a/src/main/java/com/ypm/service/TokenService.java
+++ b/src/main/java/com/ypm/service/TokenService.java
@@ -6,11 +6,16 @@
 import org.springframework.security.oauth2.client.authentication.OAuth2AuthenticationToken;
 import org.springframework.stereotype.Service;
 
+import java.time.Instant;
+
 @Service
 public class TokenService {
 
     private final OAuth2AuthorizedClientService authorizedClientService;
 
+    private String cachedToken;
+    private Instant expiresAt;
+
     public TokenService(OAuth2AuthorizedClientService authorizedClientService) {
         this.authorizedClientService = authorizedClientService;
     }
@@ -20,12 +25,23 @@ public String getToken(OAuth2AuthorizedClient authClient) {
     }
 
     public String getToken() {
-        var authentication = SecurityContextHolder.getContext().getAuthentication();
-        var oauthToken = (OAuth2AuthenticationToken) authentication;
+        if (isTokenExpired()) refreshToken();
+
+        return cachedToken;
+    }
+
+    private boolean isTokenExpired() {
+        return cachedToken == null || Instant.now().isAfter(expiresAt);
+    }
+
+    private void refreshToken() {
+        var oauthToken = (OAuth2AuthenticationToken) SecurityContextHolder.getContext().getAuthentication();
         var clientRegistrationId = oauthToken.getAuthorizedClientRegistrationId();
         var principalName = oauthToken.getPrincipal().getName();
         var client = authorizedClientService.loadAuthorizedClient(clientRegistrationId, principalName);
 
-        return client.getAccessToken().getTokenValue();
+        var accessToken = client.getAccessToken();
+        cachedToken = accessToken.getTokenValue();
+        expiresAt = accessToken.getExpiresAt();
     }
 }