package ciphers;

import java.util.Scanner;

/**
 * A Java implementation of Caesar Cipher. /It is a type of substitution cipher in which each letter
 * in the plaintext is replaced by a letter some fixed number of positions down the alphabet. /
 *
 * @author FAHRI YARDIMCI
 * @author khalil2535
 */
public class Caesar {

  /**
   * Encrypt text by shifting every Latin char by add number shift for ASCII Example : A + 1 -> B
   *
   * @param message
   * @param shift
   * @return Encrypted message
   */
  public static String encode(String message, int shift) {
    String encoded = "";

    shift %= 26;

    final int length = message.length();
    for (int i = 0; i < length; i++) {

      //            int current = message.charAt(i); //using char to shift characters because ascii
      // is in-order latin alphabet
      char current = message.charAt(i); // Java law : char + int = char

      if (IsCapitalLatinLetter(current)) {

        current += shift;
        encoded += (char) (current > 'Z' ? current - 26 : current); // 26 = number of latin letters

      } else if (IsSmallLatinLetter(current)) {

        current += shift;
        encoded += (char) (current > 'z' ? current - 26 : current); // 26 = number of latin letters

      } else {
        encoded += current;
      }
    }
    return encoded;
  }

  /**
   * Decrypt message by shifting back every Latin char to previous the ASCII Example : B - 1 -> A
   *
   * @param encryptedMessage
   * @param shift
   * @return message
   */
  public static String decode(String encryptedMessage, int shift) {
    String decoded = "";

    shift %= 26;

    final int length = encryptedMessage.length();
    for (int i = 0; i < length; i++) {
      char current = encryptedMessage.charAt(i);
      if (IsCapitalLatinLetter(current)) {

        current -= shift;
        decoded += (char) (current < 'A' ? current + 26 : current); // 26 = number of latin letters

      } else if (IsSmallLatinLetter(current)) {

        current -= shift;
        decoded += (char) (current < 'a' ? current + 26 : current); // 26 = number of latin letters

      } else {
        decoded += current;
      }
    }
    return decoded;
  }

  /**
   * @param c
   * @return true if character is capital Latin letter or false for others
   */
  private static boolean IsCapitalLatinLetter(char c) {
    return c >= 'A' && c = 'a' && c