package example5_3javaiodecorator;


import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.LinkedList;
import java.util.Queue;

/**
 * @author hornick
 * This input stream decorator modifies a wrapped input stream
 */

public class EncryptedInputStream extends FilterInputStream {
	private String encryptionKey;	  // the "key" to use for encryption
	private Queue<Character> shifter; // Encryption "barrel". Note: Queue is abstract

	/**
	 * constructs the input stream encrypter
	 * @param key (ignored currently)
	 * @param wrappedStream
	 */
	public EncryptedInputStream(String key, InputStream wrappedStream) {
		super(wrappedStream);

        // TODO: This shifter is unused. Use it.
		// fill the barrel with the encryption key
		shifter = new LinkedList<Character>();
		encryptionKey = key;
		for( int c = 0; c<encryptionKey.length(); c++ )
			shifter.offer(encryptionKey.charAt(c));
	}

	/**
	 * decrypt the input stream
	 */
	@Override
	public int read( byte[] b ) throws IOException {
		int numRead = in.read(b);
		for( int index = 0; index<numRead; index++) {
			char k = (char)(b[index] - 5);
			b[index]=(byte)k;
		}
		return numRead;
	}


	/**
	 * decrypt the input stream
	 */
	@Override
	public int read( byte[] b, int offset, int len ) throws IOException {
		int numRead = in.read(b);

        return numRead;
	}
}