Push Notifications Gmail API Google

Looking to set up a webhook that runs when i get a new email i have a script that gets latest email and pits in my database. but trying to figure out a way to run the script when i get a new email. i could run the script every min using a cron job hut dont wanna do this as it waists resources i used a pub sub with end point url in google console before which worked fine but for some reason it has stopped working im also looking to get a browser notification when i get a new email.