package rep;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.util.LinkedList;
import java.util.StringTokenizer;

import rep.channel.ChannelSimulator;
import rep.channel.REPSocketChannel;

public class REPPacketReceive {
	
	REPSocketChannel<REPCommand> socketchannel;
	private final int HEADER_SIZE = 24;
	SelectionKey key;
	
	public REPPacketReceive(REPSocketChannel<REPCommand> sc){
		socketchannel = sc;
	}
	
	public void setkey(SelectionKey key) {
		this.key = key;
	}
	

	public REPCommand unpackUConv() {
		ByteBuffer header = ByteBuffer.allocateDirect(HEADER_SIZE);
		long len = 0;
		header.clear();
		try {
			len = socketchannel.read(header);
			if(len == -1){
				if(key != null){
					key.cancel();
				}					
				socketchannel.close();
				return null;
			}else if(len == 0){
				return null;
			}
		} catch (IOException e1) {
			e1.printStackTrace();
		}  // limit = read length
		if (len !=HEADER_SIZE) {
			System.out.println("error.");
			// this can't happen
		}
		header.rewind();  // position = 0

		int cmd = header.getInt();
		int sid = header.getInt();
		int eid = header.getInt();
		int seqid = header.getInt();
		int lineno = header.getInt();
		int textsiz = header.getInt();
		
		ByteBuffer textBuffer = ByteBuffer.allocateDirect(textsiz);
		
		try {
			len = socketchannel.read(textBuffer);
			if(len == -1){
				if(key != null){
					key.cancel();
				}					
				socketchannel.close();
				return null;
			}
		} catch (IOException e1) {
			e1.printStackTrace();
		}  // limit = read length
		if (len != textsiz) {
			// this can't happen
			System.out.println("error.");
		}
		textBuffer.rewind();

		//Decode UTF-8 to System Encoding(UTF-16) 
		Charset charset = Charset.forName("UTF-8");
		CharsetDecoder decoder = charset.newDecoder();
		CharBuffer cb = null;
		try {
			cb = decoder.decode(textBuffer);
		} catch (CharacterCodingException e) {
			e.printStackTrace();
		}
		cb.rewind();
		
		String string = cb.toString();
		
		textsiz = string.length();

		REPCommand repcommand = new REPCommand(cmd, sid, eid, seqid, lineno, textsiz, string);
		System.out.println("UnPack Packet: => cmd:"+cmd+" sid:"+sid+" eid:"+eid+"seqid:"+seqid+" lineno:"+lineno+" textsiz:" +textsiz+" text: "+string);
		System.out.println("received command: " + repcommand.toString());
		
		return repcommand;		
	}
}