class Chaocipher {
    private enum Mode {
        ENCRYPT,
        DECRYPT
    }

    private static final String L_ALPHABET = "HXUCZVAMDSLKPEFJRIGTWOBNYQ"
    private static final String R_ALPHABET = "PTLNBQDEOYSFAVZKGJRIHWXUMC"

    private static int indexOf(char[] a, char c) {
        for (int i = 0; i < a.length; ++i) {
            if (a[i] == c) {
                return i
            }
        }
        return -1
    }

    private static String exec(String text, Mode mode) {
        return exec(text, mode, false)
    }

    private static String exec(String text, Mode mode, Boolean showSteps) {
        char[] left = L_ALPHABET.toCharArray()
        char[] right = R_ALPHABET.toCharArray()
        char[] eText = new char[text.length()]
        char[] temp = new char[26]

        for (int i = 0; i < text.length(); ++i) {
            if (showSteps) {
                println("${new String(left)}  ${new String(right)}")
            }
            int index
            if (mode == Mode.ENCRYPT) {
                index = indexOf(right, text.charAt(i))
                eText[i] = left[index]
            } else {
                index = indexOf(left, text.charAt(i))
                eText[i] = right[index]
            }
            if (i == text.length() - 1) {
                break
            }

            // permute left

            if (26 - index >= 0) System.arraycopy(left, index, temp, 0, 26 - index)
            System.arraycopy(left, 0, temp, 26 - index, index)
            char store = temp[1]
            System.arraycopy(temp, 2, temp, 1, 12)
            temp[13] = store
            left = Arrays.copyOf(temp, temp.length)

            // permute right

            if (26 - index >= 0) System.arraycopy(right, index, temp, 0, 26 - index)
            System.arraycopy(right, 0, temp, 26 - index, index)
            store = temp[0]
            System.arraycopy(temp, 1, temp, 0, 25)
            temp[25] = store
            store = temp[2]
            System.arraycopy(temp, 3, temp, 2, 11)
            temp[13] = store
            right = Arrays.copyOf(temp, temp.length)
        }

        return new String(eText)
    }

    static void main(String[] args) {
        String plainText = "WELLDONEISBETTERTHANWELLSAID"
        println("The original plaintext is : $plainText")
        println("\nThe left and right alphabets after each permutation during encryption are:")
        String cipherText = exec(plainText, Mode.ENCRYPT, true)
        println("\nThe cipher text is : $cipherText")
        String plainText2 = exec(cipherText, Mode.DECRYPT)
        println("\nThe recovered plaintext is : $plainText2")
    }
}