Checking sudo in Bash (script with if statements)

I've been working with bash for not more than 6 hours, and now I'm trying to create a menu that allows you to do some "fun" stuff :D.

My problem is with the if statement that check if you're in sudo mode. I want to have 3 conditions:

1. If I execute the script with sudo mode, I'll be able to enter the path of the folder to be copied.
2. If I execute the script without sudo mode, it'll ask me to insert the password, if I do that correctly the script will show me the echo and read op that allows me to write the path of the folder to be copied.
3. The same as the point 2, but if I fail the authentication the application will be closed automatically.