package com.jotuntech.sketcher.server.command;

import java.nio.ByteBuffer;
import java.util.Deque;

import com.jotuntech.sketcher.common.UndoEntry;
import com.jotuntech.sketcher.common.User;
import com.jotuntech.sketcher.server.Command;
import com.jotuntech.sketcher.server.Connection;
import com.jotuntech.sketcher.server.Server;

public class UndoCommand implements Command {

	public int perform(Server server, Connection connection) {
		User user = connection.getUser();
		if(user == null) {
			return Connection.SEND_NONE;
		}
		if(user.isViewer()) {
			return Connection.SEND_NONE;
		}
		Deque<UndoEntry> undoDeque = connection.getUser().getUndoDeque();
		if(undoDeque.size() == 0) {
			return Connection.SEND_NONE;
		}
		UndoEntry undoEntry = undoDeque.removeFirst();
		undoEntry.getLayer().undo(undoEntry.getUndoData());
		return Connection.SEND_OTHERS;
	}

	public void decode(ByteBuffer in) {

	}

	public void encode(ByteBuffer out) {

	}
}