app.py

@@ -9,6 +9,8 @@ from google.oauth2.credentials import Credentials
 from google_auth_oauthlib.flow import Flow
 from google.auth.transport.requests import Request
 import json
+import logging
+from oauthlib.oauth2.rfc6749.errors import InvalidGrantError
 
 # Load environment variables from .env file
 load_dotenv()
@@ -58,10 +60,12 @@ SCOPES = ['https://www.googleapis.com/auth/userinfo.email', 'https://www.googlea
 
 # Function to create OAuth flow
 def create_flow():
+    redirect_uri = "https://meng21-gradeview.hf.space/"  # Update this with your Streamlit app's URL
+    logging.debug(f"Creating flow with redirect URI: {redirect_uri}")
     flow = Flow.from_client_config(
         client_config=CLIENT_CONFIG,
         scopes=SCOPES,
-        redirect_uri="https://meng21-gradeview.hf.space/"  # Update this with your Streamlit app's URL
+        redirect_uri=redirect_uri
     )
     return flow
 
@@ -179,15 +183,32 @@ def handle_callback():
     flow = create_flow()
     code = st.query_params.get("code")
     if code:
-        flow.fetch_token(code=code)
-        credentials = flow.credentials
-        st.session_state['credentials'] = credentials.to_json()
-        return credentials
+        try:
+            logging.debug(f"Attempting to fetch token with code: {code}")
+            flow.fetch_token(code=code)
+            credentials = flow.credentials
+            st.session_state['credentials'] = credentials.to_json()
+            logging.debug("Token fetch successful")
+            return credentials
+        except InvalidGrantError as e:
+            logging.error(f"InvalidGrantError: {str(e)}")
+            st.error("The authorization code has expired or is invalid. Please try logging in again.")
+            if 'credentials' in st.session_state:
+                del st.session_state['credentials']
+        except Exception as e:
+            logging.error(f"Unexpected error during token fetch: {str(e)}")
+            st.error(f"An unexpected error occurred: {str(e)}")
     else:
+        logging.warning("No authorization code found in the URL parameters.")
         st.error("No authorization code found in the URL parameters.")
 
+# Set up logging
+logging.basicConfig(level=logging.DEBUG)
+
 if __name__ == '__main__':
+    logging.debug("Starting the application")
     if 'code' in st.query_params:
+        logging.debug("Authorization code found in query parameters")
         handle_callback()
         st.rerun()
     main()