import java.util.*;

public class AccesscControl1 {

	public static Scanner console;
	public static String username = "";
	public static String password = "";

	public static void main(String[] args) {

		console = new Scanner(System.in);
		userCreationUsername();
		userCreationPassword();
		System.out.println("*** User " + username + " is registered.");
		login();
		mainMenu();
	}

	//Method for creating and verifying username
	public static void userCreationUsername(){
		while ( true ) {
			System.out.println("Please enter a non-empty username:");
			username = console.nextLine();
			if ( checkUserName (username)) {
				break;
			}
		}
	}

	//Method for creating and verifying password
	public static void userCreationPassword() {

		while ( true ) {
			System.out.println("Please enter a password    :");
			password = console.nextLine();
			if ( checkPWD(password) ) {
				System.out.println("Please repeat the password : ");
				String password2 = console.nextLine();

				if ( password.equals(password2) ) {
					break;
				}
			}
		}
	}

	//Method for login section
	public static void login() {
		System.out.println("To logon enter username:");
		System.out.println("To logon enter password:");
		int tries = 0;

		while ( true ) {
			String usernameTemp = console.nextLine();
			if ( usernameTemp.equals(username) ) {
				break;
			} else {
				System.out.println("To logon enter username:");
			}
		}

		while ( true ) {
			String passwordTemp = console.nextLine();

			if (passwordTemp.equals(password) ) {
				System.out.println("*** User " + username + " is Logged on.");
				break;
			}
			tries++;

			if ( tries == 3) {
				System.exit(0);
			} else {
				System.out.println("To logon enter password:");
			}
		}
	}

	//Main menu - 1 for log off, 2 for change password and 3 for shut down
	public static void mainMenu() {
		while ( true ) {
			System.out.println("You now have the following choices:");
			System.out.println("  1 - Change Password");
			System.out.println("  2 - Log off");
			System.out.println("  3 - Shut down");
			System.out.println("Please select:");

			//Takes valid user input
			int select = 0;
			while ( true ) {
				if ( console.hasNextInt() ) {
					select = console.nextInt();
					break;
				} else {
					console.next();
				}
			}

			if ( select == 1 ) {
				userCreationPassword();
				System.out.println("*** Password changed for user " + username);
			} else if ( select == 2 ) {
				System.out.println("*** User " + username + " is logged off");
				login();
			} else if ( select == 3 ) {
				System.out.println("*** User " + username + " is logged off");
				System.out.println("*** System shutting down.");
				System.exit(0);
			}
		}
	}

	public static boolean checkPWD(String password) {
		int digitCount = 0;
		int letterCount = 0;
		int alphaCount = 0;

		for ( int i = 0; i < password.length(); i++) {
			if( Character.isDigit(password.charAt(i)) ) {
				digitCount++;
				alphaCount++;
			}
			if ( Character.isLetter(password.charAt(i)) ) {
				letterCount++;
				alphaCount++;
			}
		}

		if ( digitCount >= 2 && letterCount >= 2 && alphaCount == password.length() ) {
			if( password.length() < 8 ) {
				return false;
			} else if( password.equals(password.toLowerCase()) ) {
				return false;
			} else if( password.equals(password.toUpperCase()) ) {
				return false;
			}
			return true;

		} else {
			return false;
		}
	}


	//Username checker
	public static boolean checkUserName(String username) {
		if ( Character.isLetter(username.charAt(0)) && username.contains(" ") == false  ) {
			return true;
		} else {
			return false;
		}
	}
}