import java.util.Scanner;

/**
 * Program 2 driver program.
 * 
 * @author John Paxton 
 * @version October 2, 2008
 */

public class Driver
{
    public static void main (String [] args)
    {
        Scanner in = new Scanner(System.in);    // read input from terminal window
        CaesarCipher code;                      // an instance of a cipher
        String text;                            // user input to convert
        String result;                          // result of conversion
        int key;                                // key for Caesar cipher
        int menuSelection;                      // user's menu selection
        
        System.out.println("CS 160, Program 2: Caesar Cipher");
        System.out.println("--------------------------------\n");
        
        System.out.print("Enter the cipher key [0..25]: ");
        key = in.nextInt();
        code = new CaesarCipher(key);
        
        displayMenu();
        menuSelection = getMenuChoice(in);

        while (menuSelection != QUIT)
        {
            if (menuSelection == ENCODE)
            {
                System.out.print("Enter a sentence to encode: ");
                text = in.nextLine();
                result = code.encode(text);
                System.out.println("Plain:  " + text);
                System.out.println("Cipher: " + result);
            }
            else if (menuSelection == DECODE)
            {
                System.out.print("Enter numbers to decode: ");
                text = in.nextLine();
                result = code.decode(text);
                System.out.println("Cipher: " + text);
                System.out.println("Plain:  " + result);
            }
            else
            {
                System.out.println("Invalid option, please try again.");
            }
            
            displayMenu();
            menuSelection = getMenuChoice(in);
        }
        
        System.out.println("\nGoodbye.");
        
    }
    
    private static void displayMenu()
    {
        System.out.println();
        System.out.println("1. Encode a message.");
        System.out.println("2. Decode a message.");
        System.out.println("3. Quit.");
    }
    
    private static int getMenuChoice(Scanner in)
    {
        int menuChoice;     // user's menu selection     
        
        System.out.print("Please enter your menu choice: ");
        menuChoice = in.nextInt();
        in.nextLine();      // clear the user input line
        return menuChoice;
    }
    
    public static final int ENCODE = 1;     // user wants to encode text
    public static final int DECODE = 2;     // user wants to decode numbers
    public static final int QUIT = 3;       // user wants to quit
}