How do I return an auth token to the google assistant using a website?

Question

I want to implement an Actions for Google app that links to user account in a Firebase project and query's their data. I have a website that is set up using Firebase UI that logs them in and redirects them to a dummy page that basically just says "You have been logged in." I cannot see any documentation anywhere that shows how to return this auth token to google so the assistant can use it to query things on their account. Does anybody know how to accomplish this? I am using this documentation https://developers.google.com/actions/identity/google-sign-in-oauth?creation=no. This is the specific text I am not understanding. "Your service creates an access token and returns it to Google by redirecting the user's browser back to Google with the access token attached to the request."

Answer 1

This basically means that, instead of returning a new page, you issue an HTTP redirect to a URL that they have sent you as part of the request. You will need to add some parameters to this URL that include the auth info, and this is how Google will get the information - via the redirect handled by the user's browser.

They provide some details further down in step 4 on that page, which reads

Send an HTTP response that redirects the user's browser to the URL specified by the redirect_uri parameter. Include all of the following parameters in the URL fragment:

access_token: the access token you just generated

token_type: the string bearer

state: the unmodified state value from the original request

The following is an example of the resulting URL: https://oauth-redirect.googleusercontent.com/r/YOUR_PROJECT_ID#access_token=ACCESS_TOKEN&token_type=bearer&state=STATE_STRING