Write script for Squid proxy deploy & config on ubuntu pcs

I need a script that I can execute on a ubuntu server. The script should get Squid proxy, install it and let the user configure Squid by asking him simple questions, like what port he wants to use. Then the user needs to be able to add username + passwords of people that are allowed to use the proxy to a simple text file. So: User downloads .sh script and makes it executable. User executes script. Script downloads lates Squid proxy. Script installs Squid proxy. Script asks user for proxy settings, changes Squid config accordingly and starts Squid. User goes to a text file and adds several username:password combinations. External users can now use the Squid proxy to browse the web with http/https. External users have to use username:password set in the text file too be allowed to use the proxy. Doesnt have to be super complicated.