import java.io.*;

public class RotNInputStream extends InputStream {

    Decrypt decrypter;        // The decryption class used

    InputStream in;           // The stream to encrypt


    public  RotNInputStream(InputStream in, int rotate )
	throws IOException {

	this.decrypter = new Decrypt(rotate);

	if ( (this.in = in) == null)
	    throw new IOException ("InputStream is null");
    }


    public int available()
	throws IOException {

	return in.available();
    }

    
    public int read() 
	throws IOException {

	return decrypter.decrypt(in.read());
    }


    public int read(byte b[], int off, int len)
	throws IOException {

	int readlength = in.read(b, off, len);

	if (readlength == 0 || readlength == -1 )
	    return readlength;

	for (int i = 0; i < readlength; i++)
	    b[off + i] = (byte) decrypter.decrypt((int) b[off + i]);
    
	return readlength;
    }


    public int read(byte b[])
	throws IOException {

	return read(b, 0, b.length);
    }


    public void close() 
	throws IOException {

	in.close();
    }


    public void mark(int readlimit) {
	in.mark(readlimit);
    }


    public void reset()
	throws IOException {

	in.reset();
    }


    public boolean markSupported() {
	return in.markSupported();
    }

	
    ////////////////////////////////////////
    // Test function

    public static void main(String args[]) {

	FileInputStream fIn = null;
	RotNInputStream rIn = null;

	try {

	    fIn = new FileInputStream("test.txt");
	    rIn = new RotNInputStream(fIn, 10);

	    while ( rIn.available() > 0 )
		System.out.print("" + (char) rIn.read());
	    System.out.println("");

	    rIn.close();

	} catch (IOException e) { 

	}
    }
}