Lost and Found Application

It is a GPS application to be implemented initially for only two users, features required:

1) show the real-time location of each user
2) place a marker at every point stopped at by each user and the path that was followed is shown
3) be able to send a request of a meeting point and the other user can either accept or decline and if accepted then follows the way to that point

The application should provide a login screen and after having logged in the user can view all the online users as well. The login could be an email and a password

– Google maps and GPS required
– maybe Firebase database for the login
– please include comments as much as possible to help understand the code