Use Case:
User accesses login page
1a. If user has an active session, user is redirected to main page
User inputs user name and password
- 2a. User is redirected to login page if user has invalid username,
password
User does not have an active session
Check for validity of input (valid username, password)
- Valid input
User has an active login session
- Redirect to last visited page during session, or to main page if none.
Authentication is done on the main controller, checkmark_controller.