i want to add login to my chatbot with webhook.I want to take username and password from user and send it to the webhook.
I know you didn't get much search results for that
there are following approaches
If you use only Google Assistant for chatbot then use built in "Sign-in" required option and then open link https://console.actions.google.com/project/your-project-name/accountlinking/ and in that provide your required settings like
"Do you want signup ?" or "Login Only"
select type of Oauth and Implicit
Enter the endpoint url
and bingo you will get button in Google Assistant for login
If you wanna add login for web-demo use Detect Intent API
then go for Account linking OAuth2 using either code flow or implicit flow but I would suggest to go for implicit flow first.
there are various resourses out here for each language.
Integrating API you need a service account keys add that to your enviornment for Authentication to google apis
then use detectIntent function to get response and IMPORTANT use Unique session id
hope you got it ;-)