import java.util.*;

public class BitStrings {

    static int commArray[];
    static String bitStringOne;
    static String bitStringTwo;
    static String operator = " ";
    static String command;
    static String promptOne = "\nPlease enter an 8-bit string: ";
    static String promptTwo = "\nPlease enter a command: ";
    static String[] tokens = new String[2];
    static Scanner in = new Scanner(System.in);


    public static void main(String[] args) {
        while (true)
        {
            System.out.println(promptOne);
            bitStringOne = in.next();

            // Place scanner on the next line. If we don't do this, the next time we call nextLine(), we will get null.
            in.nextLine();

            // If the bit string is 8 bits long, continue.
            if (bitStringOne.length() == 8)
            {
                while (promptUser())
                {
                }
            }
            // Otherwise, prompt the user again.
            else
            {
                System.out.println("The string is not 8 bits long!");
            }
        }
    }

    public static boolean promptUser()
    {
        System.out.println(promptTwo);
        command = in.nextLine();

        // If command contains a space character, split it into tokens.
        if (command.indexOf(' ') != -1)
        {
            tokens = command.split(" ");
            operator = tokens[0];
            bitStringTwo = tokens[1];

            // If the bit string is not 8 bits long, prompt user again.
            if (bitStringTwo.length() != 8)
            {
                System.out.println("The string is not 8 bits long!");
                return true;
            }

            // If the operator is 'and', perform AND operation.
            if (operator.equalsIgnoreCase("and"))
            {
                AND(bitStringOne, bitStringTwo);
            }
            // If the operator is 'or', perform OR operation.
            else if (operator.equalsIgnoreCase("or"))
            {
                OR(bitStringOne, bitStringTwo);
            }
            // If the user enters an invalid command, prompt again.
            else
            {
                System.out.println("Invalid command!");
                return true;
            }
        }
        else
        {
            // If user types 'q', exit the program.
            if (command.equalsIgnoreCase("q"))
            {
                System.exit(0);
            }
            // If user types 'n', prompt the user for a new first bitstring.
            else if (command.equalsIgnoreCase("n"))
            {
                return false;
            }
            // If user types 'not', perform NOT operation.
            else if (command.equalsIgnoreCase("not"))
            {
                NOT(bitStringOne);
            }
            // If user types an invalid command, prompt again.
            else
            {
                System.out.println("Invalid command!");
                return true;
            }
        }

        return true;
    }

    public static void AND(String str1, String str2)
    {
        int numArray1[] = new int[str1.length()];
        int numArray2[] = new int[str2.length()];
        int numArray3[] = new int[numArray1.length];
        String output = "";

        for (int k = 0; k < str1.length(); k++) {
            numArray1[k] = Character.digit(str1.charAt(k), 10);
        }

        for (int l = 0; l < str2.length(); l++) {
            numArray2[l] = Character.digit(str2.charAt(l), 10);
        }

        ///////////////////////////////////////////////////////////////////

        for(int i =0; i<numArray1.length; i++){
            if(numArray1[i] == 1 && numArray2[i]== 1){
                numArray3[i] = numArray1[i];
            }
            else
            {
                numArray3[i] = 0;
            }
        }

        for (int i = 0; i< numArray3.length; i++){
            output+= numArray3[i];
        }

        System.out.println("Result of operation AND: " + output);
    }

    public static void OR(String str1, String str2)
    {
        int numArray1[] = new int[str1.length()];
        int numArray2[] = new int[str2.length()];
        int numArray3[] = new int[numArray1.length];
        String output = "";

        for (int k = 0; k < str1.length(); k++) {
            numArray1[k] = Character.digit(str1.charAt(k), 10);
        }

        for (int l = 0; l < str2.length(); l++) {
            numArray2[l] = Character.digit(str2.charAt(l), 10);
        }


        ///////////////////////////////////////////////////////////////////

        for(int i =0; i<numArray1.length; i++){
            if(numArray1[i] == 1 || numArray2[i] == 1){
                numArray3[i] = 1;
            }
            else
            {
                numArray3[i] = 0;
            }
        }

        for (int i = 0; i< numArray3.length; i++){
            output+= numArray3[i];
        }

        System.out.println("Result of operation OR: " + output);
    }

    public static void NOT(String str1)
    {
        int numArray1[] = new int[str1.length()];
        int numArray2[] = new int[numArray1.length];
        String output = "";

        for (int k = 0; k < str1.length(); k++) {
            numArray1[k] = Character.digit(str1.charAt(k), 10);
        }

        // Swap the bits
        for(int i =0; i<numArray1.length; i++){
            if(numArray1[i] == 1){
                numArray2[i] = 0;
            }
            else
            {
                numArray2[i] = 1;
            }
        }

        for (int i = 0; i< numArray2.length; i++){
            output+= numArray2[i];
        }

        System.out.println("Result of operation NOT: " + output);

    }
}