package seng302.Networking;

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

/**
 * Created by hba56 on 21/04/17.
 */
public class BinaryMessageDecoder {
    private byte[] fullMessage;
    private byte[] header;
    private byte[] message;
    private byte[] crc;

    private byte headerSync1;
    private byte headerSync2;
    private byte headerMessageType;
    private byte[] headerTimeStamp;
    private byte[] headerSourceID;
    private byte[] headerMessageLength;


    public BinaryMessageDecoder(byte[] fullMessage) {
        this.fullMessage = fullMessage;
    }

    public void decode() throws IndexOutOfBoundsException {
        //get the header
        this.header = Arrays.copyOfRange(this.fullMessage, 0, 15);

        this.headerSync1 = this.header[0];
        this.headerSync2 = this.header[1];
        this.headerMessageType = this.header[2];
        this.headerTimeStamp = Arrays.copyOfRange(this.header, 3, 9);
        this.headerSourceID = Arrays.copyOfRange(this.header, 9, 13);
        this.headerMessageLength = Arrays.copyOfRange(this.header, 13, 15);

        //get message
        this.message = Arrays.copyOfRange(this.fullMessage, 15, this.fullMessage.length - 4);

        //get crc
        this.crc = Arrays.copyOfRange(this.fullMessage, this.fullMessage.length - 4, fullMessage.length);

        //run through the checks
        if (this.message.length != bytesToShort(this.headerMessageLength)) {
            System.err.println("message length in header does not equal the message length");
            System.err.println("message length in header: " + bytesToInt(this.headerMessageLength));
            System.err.println("message length: " + this.message.length);
        } else if (this.headerSync1 != 0x47) {
            System.err.println("Sync byte 1 is wrong");
        } else if (this.headerSync2 != (byte) 0x83) {
            System.err.println("Sync byte 2 is wrong");
        } else if (false) {
            //todo check crc
        }
    }


    private short bytesToShort(byte[] bytesShort) {
        ByteBuffer wrapped = ByteBuffer.wrap(bytesShort);
        short num = wrapped.getShort();
        return num;
    }

    private int bytesToInt(byte[] bytesInt) {
        ByteBuffer wrapped = ByteBuffer.wrap(bytesInt);
        int num = wrapped.getInt();
        return num;
    }

    private long bytesToLong(byte[] bytesLong) {
        ByteBuffer byteBuffer = ByteBuffer.allocate(8);
        byteBuffer.order(ByteOrder.BIG_ENDIAN);
        byteBuffer.put((byte) 0);
        byteBuffer.put((byte) 0);
        byteBuffer.put(bytesLong[0]);
        byteBuffer.put(bytesLong[1]);
        byteBuffer.put(bytesLong[2]);
        byteBuffer.put(bytesLong[3]);
        byteBuffer.put(bytesLong[4]);
        byteBuffer.put(bytesLong[5]);
        long longVal = byteBuffer.getLong(0);
        return longVal;
    }

    public long getTimeStamp() {
        return bytesToLong(this.headerTimeStamp);
    }

    public int getSourceID() {
        return bytesToInt(this.headerSourceID);
    }

    public short getMessageLength() {
        return bytesToShort(this.headerMessageLength);
    }

    public int getMessageType() {
        return (int) this.headerMessageType;
    }

    public byte[] getMessage() {
        return message;
    }
}