How can I authenticate and upload files to Google Cloud Storage in Ballerina without manually generating access tokens?

I'm trying to upload files to a Google Cloud Storage bucket from a Ballerina application. Right now, the only way I’ve found to authenticate is by manually generating an access token using a service-account.json file from the Google Cloud Console.

My question: Is there a way in Ballerina to:

• Load a service account JSON key
• Request a Google OAuth 2.0 access token
• Use that token to interact with GCS APIs

If so, what’s the right way to do this using Ballerina’s built-in modules?

What I tried:

• I used Ballerina’s http to send a POST request to GCS.
• I passed an access token (manually generated via gcloud auth application-default print-access-token) in the Authorization header.
• It works, but the access token expires quickly and must be regenerated manually.

What I want: I’d like to programmatically authenticate using a service account key or some supported method in Ballerina, so the token can be generated or refreshed within the app.