SENG302/src/main/java/seng302/Networking/MessageEncoders/XMLMessageEncoder.java

package seng302.Networking.MessageEncoders;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Arrays;

/**
 * Encodes a XML file into a message of AC35 format
 */
public class XMLMessageEncoder {
    private byte messageVersionNumber;
    private short ackNumber;
    private long timeStamp;
    private byte xmlMsgSubType;
    private short sequenceNumber;
    private short xmlMsgLength;
    private String xmlMessage;

    public XMLMessageEncoder(byte messageVersionNumber, short ackNumber, long timeStamp, byte xmlMsgSubType, short sequenceNumber, short xmlMsgLenght, String xmlMessage) {
        this.messageVersionNumber = messageVersionNumber;
        this.ackNumber = ackNumber;
        this.timeStamp = timeStamp;
        this.xmlMsgSubType = xmlMsgSubType;
        this.sequenceNumber = sequenceNumber;
        this.xmlMsgLength = xmlMsgLenght;
        this.xmlMessage = xmlMessage;
    }

    public byte[] encode() {
        byte[] messageBytes = xmlMessage.getBytes();
        if (messageBytes.length > this.xmlMsgLength) {
            //System.err.println("Xml message is to big");
            return null;
        }
        ByteBuffer tempOutputByteBuffer = ByteBuffer.allocate(14 + messageBytes.length);

        //ackNumber converted to bytes
        byte[] ackNumberBytes = new byte[2];
        ackNumberBytes[0] = (byte) (ackNumber & 0xff);
        ackNumberBytes[1] = (byte) ((ackNumber >> 8) & 0xff);

        //sequenceNumber converted to bytes
        byte[] sequenceNumberBytes = new byte[2];
        sequenceNumberBytes[0] = (byte) (sequenceNumber & 0xff);
        sequenceNumberBytes[1] = (byte) ((sequenceNumber >> 8) & 0xff);

        //xmlMsgLength converted to bytes
        byte[] xmlMsgLengthBytes = new byte[2];
        xmlMsgLengthBytes[0] = (byte) (xmlMsgLength & 0xff);
        xmlMsgLengthBytes[1] = (byte) ((xmlMsgLength >> 8) & 0xff);


        tempOutputByteBuffer.put(messageVersionNumber);
        tempOutputByteBuffer.put(ackNumberBytes);
        tempOutputByteBuffer.put(longToSixBytes(timeStamp));
        tempOutputByteBuffer.put(xmlMsgSubType);
        tempOutputByteBuffer.put(sequenceNumberBytes);
        tempOutputByteBuffer.put(xmlMsgLengthBytes);
        tempOutputByteBuffer.put(messageBytes);

        return tempOutputByteBuffer.array();
    }

    private byte[] longToSixBytes(long x) {
        ByteBuffer buffer = ByteBuffer.allocate(Long.BYTES);
        buffer.putLong(x);

//        System.out.println("====encode====");
//        for (byte i:buffer.array()
//                ) {
//            System.out.println(i);
//        }
//        System.out.println("====encode====");

        return Arrays.copyOfRange(buffer.array(), 2, 8);
    }
}