import java.util.Scanner;
import java.util.Random;

public class Cipher {

	public static final int TOTAL_CHAR = 27;
	public static final char[] ALPHABET = {' ','a','b','c','d',
											'e','f','g','h','i','j','k',
											'l','m','n','o','p','q','r',
											's','t','u','v','w','x','y','z'};
	public static void main(String[] args) {
		boolean finished = true;
		do {
			System.out.print("Please select the following action('decrpyt'/'encrpyt') or enter 'quit' to exit:");
			Scanner myScanner = new Scanner(System.in);
			String selectedAction = myScanner.next();
			char[] cipher = createCipher(ALPHABET);
			if(selectedAction.equals("encrpyt"))
			{
				System.out.print("Enter the word you need to encrpyt:");
				myScanner = new Scanner(System.in);
				String enteredString = myScanner.nextLine().toLowerCase();
				String encrpytedString = encrpyt(enteredString,cipher);
				System.out.println(encrpytedString);
			}
			else if(selectedAction.equals("decrpyt"))
			{
				System.out.print("Enter the word you need to decrpyt:");
				myScanner = new Scanner(System.in);
				String enteredString = myScanner.nextLine();
				String encrpytedString = decrpyt(enteredString,cipher);
				System.out.println(encrpytedString);
			}
			else if(selectedAction.equals("quit"))
			{
				finished = false;
			}
			else
			{
				System.out.print("Please enter 'decrpyt' or 'encrpyt' to select your action.");
			}
			}while(finished);

		}

	public static char[] createCipher(char[] alphabet)
	{
		Random generator = new Random(TOTAL_CHAR-1);
		int[] indexList = new int[TOTAL_CHAR];
		char[] cipher = new char[TOTAL_CHAR];
		int cipherIndex,count = 0;
		while(count<TOTAL_CHAR)
		{
			cipherIndex = generator.nextInt(TOTAL_CHAR);
			if(indexList[cipherIndex]==0)
			{
				indexList[cipherIndex] = 1;
				cipher[count] = alphabet[cipherIndex];
				count++;
			}
		}
		return cipher;
	}

	public static String encrpyt(String word,char[] cipher)
	{
		char[] characterArray1 = word.toCharArray();
		char[] encrpytedCharacter = new char[characterArray1.length];
		int tempIndex,index = 0;
		while(index<characterArray1.length)
		{
			boolean done = true;
			for(int count = 0; ((count<ALPHABET.length)&&(done));count++)
			{
				if(characterArray1[index] == ALPHABET[count])
				{
					tempIndex = count;
					done = false;
					encrpytedCharacter[index] = cipher[count];
				}
			}
		index++;
		}
		String encrpytedString = new String(encrpytedCharacter);
		return encrpytedString;
	}

	public static String decrpyt(String encrpytWord,char[] cipher)
	{
		char[] characterArray2 = encrpytWord.toCharArray();
		char[] decrpytedCharacter = new char[characterArray2.length];
		int tempIndex,index = 0;
		while(index<characterArray2.length)
		{
			boolean done = true;
			for(int count = 0; ((count<cipher.length)&&(done));count++)
			{
				if(characterArray2[index] == cipher[count])
				{
					tempIndex = count;
					done = false;
					decrpytedCharacter[index] = ALPHABET[count];
				}
			}
			index++;
		}
		String decrpytedString = new String(decrpytedCharacter);
		return decrpytedString;
	}


}