//Sakshi Lende
//Cryptography
//Spec: Shift alphabet forwards or backwards depending on inputted key

public class Cryptography
{
    public int key;
    public String ciphertext, plaintext = "";
    public char position;
    //public String message, encryptedMessage = "";
    public char ch;

    public Cryptography()
    {
        key = 0;
        plaintext = "";
                ciphertext = "";
    }

    public Cryptography(int k, String message)
    {
        key = k;
        plaintext = message;
    }

    public String getEncrypt()
    {
        if (key > 25)
        {
            return "Please enter a key between 1 and 25";
        }
        else
        {
            for(int i = 0; i < plaintext.length(); i++)
            {
                position = plaintext.charAt(i);

                if(position >= 'a' && position <= 'z')
                {
                    position = (char)(position + key);

                    if(position > 'z')
                    {
                        position = (char)(position - 'z' + 'a' - 1);
                    }
                    ciphertext += position;
                }

                else
                {
                    ciphertext += position;
                }
            }
            return ciphertext;
        }
    }

    public String getDecrypt()
    {
        if (key > 25)
        {
            return "Please enter a key between 1 and 25";
        }
        else
        {
            for(int i = 0; i < plaintext.length(); i++)
            {
                position = plaintext.charAt(i);

                if(position >= 'a' && position <= 'z')
                {
                    position = (char)(position - key);

                    if(position > 'z')
                    {
                        position = (char)(position + 'z' - 'a' + 1);
                    }
                    ciphertext += position;
                }

                else
                {
                    ciphertext += position;
                }
            }
                                return ciphertext.substring(4);

        }
    }

    public String test()
    {
        for(int i = 0; i < plaintext.length(); ++i)
                {
                    ch = plaintext.charAt(i);

                    if(ch >= 'a' && ch <= 'z')
                    {
                        ch = (char)(ch + key);

                        if(ch > 'z')
                        {
                            ch = (char)(ch - 'z' + 'a' - 1);
                        }
                        ciphertext += ch;
                    }

                    else if(ch >= 'A' && ch <= 'Z')
                    {
                        ch = (char)(ch + key);

                        if(ch > 'Z')
                        {
                            ch = (char)(ch - 'Z' + 'A' - 1);
                        }
                        ciphertext += ch;
                    }
                    else
                    {
                        ciphertext += ch;
                    }
                }
        return ciphertext;
    }

    public String pleaseWork()
    {
        for(int i = 0; i < plaintext.length(); i++){
            ch = plaintext.charAt(i);

            if(ch >= 'a' && ch <= 'z'){
                ch = (char)(ch + key);

                if(ch > 'z'){
                    ch = (char)(ch - 'z' + 'a' - 1);
                }

                    ciphertext += ch;
            }
            else {
                        ciphertext += ch;
            }
        }

        return ciphertext.substring(4);
    }
}