SongEncryption

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class SongEncryption {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String line = scanner.nextLine();
        String regex = "^([A-Z][a-z\' ]+):([A-Z\\\\s]+)$";
        Pattern pattern = Pattern.compile(regex);

        while (!line.equals("end")) {
            StringBuilder encrypted = new StringBuilder();
            Matcher matcher = pattern.matcher(line);
            if (matcher.find()){
                String artist = matcher.group(1);
                String song = matcher.group(2);

                for (int i = 0; i <line.length() ; i++) {
                  if (line.charAt(i) == ':'){
                      encrypted.append("@");
                  }else if (Character.isWhitespace(line.charAt(i))){
                      encrypted.append(" ");
                  }else if (line.charAt(i) == '\''){
                      encrypted.append('\'');
                  }else if (Character.isLetter(line.charAt(i))){
                      int key = artist.length();
                      char encryptedChar = (char)(line.charAt(i)+key);

                      if (Character.isLowerCase(encryptedChar) && encryptedChar > 'z'){
                     encryptedChar = (char) ('a' + (encryptedChar - 'z' -1));
                          encrypted.append((char)encryptedChar);
                      }else if (Character.isUpperCase(encryptedChar) && encryptedChar > 90){
                          encryptedChar =(char) ('A' + (encryptedChar - 'Z' -1));
                          encrypted.append((char) encryptedChar);
                      }else {

                          encrypted.append((char) encryptedChar);
                      }
                  }

                }
                System.out.println("Successful encryption: "+ encrypted.toString());
            }else {
                System.out.println("Invalid input!");
            }



                    line = scanner.nextLine();
        }
    }
}