Update app.js

app.js

@@ -30,7 +30,43 @@ function logRequest(req, status, message) {
 }
 
 async function getAccessToken() {
-  // ... (保持不变)
+  const now = Date.now() / 1000;
+
+  if (tokenCache.accessToken && now < tokenCache.expiry - 120) {
+    return tokenCache.accessToken;
+  }
+
+  if (tokenCache.refreshPromise) {
+    await tokenCache.refreshPromise;
+    return tokenCache.accessToken;
+  }
+
+  tokenCache.refreshPromise = (async () => {
+    try {
+      const response = await fetch(TOKEN_URL, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json'
+        },
+        body: JSON.stringify({
+          client_id: CLIENT_ID,
+          client_secret: CLIENT_SECRET,
+          refresh_token: REFRESH_TOKEN,
+          grant_type: 'refresh_token'
+        })
+      });
+
+      const data = await response.json();
+      
+      tokenCache.accessToken = data.access_token;
+      tokenCache.expiry = now + data.expires_in;
+    } finally {
+      tokenCache.refreshPromise = null;
+    }
+  })();
+
+  await tokenCache.refreshPromise;
+  return tokenCache.accessToken;
 }
 
 function getLocation() {