package org.hyperion.rs2.net;

import java.security.SecureRandom;
import java.util.logging.Logger;

import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.CumulativeProtocolDecoder;
import org.apache.mina.filter.codec.ProtocolCodecFilter;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;
import org.hyperion.Server;
import org.hyperion.rs2.model.PlayerDetails;
import org.hyperion.rs2.model.World;
import org.hyperion.rs2.Constants;
import org.hyperion.rs2.net.ondemand.OnDemandPool;
import org.hyperion.rs2.net.ondemand.OnDemandRequest;
import org.hyperion.rs2.util.IoBufferUtils;
import org.hyperion.rs2.util.NameUtils;
import org.hyperion.rs2.util.TextUtils;

/**
 * Login protocol decoding class.
 * @author Graham Edgecombe
 *
 */
public class RS2LoginDecoder extends CumulativeProtocolDecoder {

	/**
	 * Logger instance.
	 */
	private static final Logger logger = Logger.getLogger(RS2LoginDecoder.class.getName());

	/**
	 * The world list opcode.
	 */
	public static final int OPCODE_WORLD_LIST = 131;

	/**
	 * Update opcode.
	 */
	public static final int OPCODE_UPDATE = 15;

	/**
	 * Game opcode.
	 */
	public static final int OPCODE_GAME = 14;

	/**
	 * The JS5 stage.
	 */
	private static final int STATE_JS5 = -1;

	/**
	 * Update stage.
	 */
	public static final int STATE_UPDATE = -2;

	/**
	 * World stage.
	 */
	public static final int STATE_WORLD = -3;

	/**
	 * Opcode stage.
	 */
	public static final int STATE_OPCODE = 0;

	/**
	 * Precrypted stage.
	 */
	public static final int STATE_PRECRYPTED = 1;

	/**
	 * Crypted stage.
	 */
	public static final int STATE_CRYPTED = 2;

	/**
	 * Login stage.
	 */
	public static final int STATE_LOGIN = 3;

	/**
	 * Secure random number generator.
	 */
	private static final SecureRandom RANDOM = new SecureRandom();

	/**
	 * Initial login response.
	 */
	private static final byte[] INITIAL_RESPONSE = new byte[] {
		0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0
	};

	@Override
	protected boolean doDecode(IoSession session, IoBuffer in, ProtocolDecoderOutput out) throws Exception {
		synchronized(session) {
			int state = (Integer) session.getAttribute("state", STATE_OPCODE);
			switch(state) {
			case STATE_WORLD:
				if(in.remaining() >= 2) {
					int worldOpcode = in.getShort();
					PacketBuilder worldList = new PacketBuilder();
					for(int data : Constants.WORLD_LIST_DATA) {
						worldList.put((byte) data);
					}
					session.write(worldList.toPacket());
					session.close(false);
				}
				return true;
			case STATE_UPDATE:
				if(in.remaining() >= 4) {
					for(int i = 0; i < 4; i++) {
						in.get();
					}
					PacketBuilder uKeys = new PacketBuilder();
					for(int key : Constants.UPDATE_KEYS) {
						uKeys.put((byte) key);
						System.out.println("uKey sent");
					}
					session.write(uKeys.toPacket());
					session.close(false);
					return true;
				} else {
					in.rewind();
					return false;
				}
			case STATE_JS5:
				if(in.remaining() >= 4) {
					in.get();
					int clientVersion = in.getShort();
					if(clientVersion == 525) {
						PacketBuilder u1Response = new PacketBuilder();
						u1Response.put((byte) 0);
						session.write(u1Response.toPacket());
						session.setAttribute("state", STATE_UPDATE);
					}
				}
				in.rewind();
				return false;
			case STATE_OPCODE:
				int opcode = in.get() & 0xFF;
				switch(opcode) {
				case OPCODE_GAME:
					session.setAttribute("state", STATE_LOGIN);
					return true;
				case OPCODE_UPDATE:
					session.setAttribute("state", STATE_JS5);
					return true;
				case OPCODE_WORLD_LIST:
					session.setAttribute("state", STATE_WORLD);
					return true;
				default:
					logger.info("Invalid opcode : " + opcode);
					session.close(false);
					break;
				}
				break;
			case STATE_LOGIN:
				if(in.remaining() >= 1) {
					/*
					 * The name hash is a simple hash of the name which is
					 * suspected to be used to select the appropriate login
					 * server.
					 */
					@SuppressWarnings("unused")
					int nameHash = in.get() & 0xFF;

					/*
					 * We generated the server session key using a SecureRandom
					 * class for security.
					 */
					long serverKey = RANDOM.nextLong();

					/*
					 * The initial response is just 0s which the client is set
					 * to ignore (probably some sort of modification).
					 */
					session.write(new PacketBuilder().put((byte) 0).putLong(serverKey).toPacket());
					session.setAttribute("state", STATE_PRECRYPTED);
					session.setAttribute("serverKey", serverKey);
					return true;
				}
				break;
			case STATE_PRECRYPTED:
				if(in.remaining() >= 2) {
					/*
					 * We read the type of login.
					 *
					 * 16 = normal
					 * 18 = reconnection
					 */
					int loginOpcode = in.get() & 0xFF;
					if(loginOpcode != 16 && loginOpcode != 18) {
						logger.info("Invalid login opcode : " + loginOpcode);
						session.close(false);
						in.rewind();
						return false;
					}

					/*
					 * We read the size of the login packet.
					 */
					int loginSize = in.get() & 0xFF;

					/*
					 * And calculated how long the encrypted block will be.
					 */
					int loginEncryptSize = loginSize - (36 + 1 + 1 + 2);

					session.setAttribute("state", STATE_CRYPTED);
					session.setAttribute("size", loginSize);
					session.setAttribute("encryptSize", loginEncryptSize);
					return true;
				}
				break;
			case STATE_CRYPTED:
				int size = (Integer) session.getAttribute("size");
				int encryptSize = (Integer) session.getAttribute("encryptSize");
				if(in.remaining() >= size) {

					/*
					 * We now read a short which is the client version and
					 * check if it equals 317.
					 */
					int version = in.getInt();
					if(version != Server.VERSION) {
						logger.info("Incorrect version : " + version);
						session.close(false);
						in.rewind();
						return false;
					}

		            for (int byteIdx = 0;byteIdx < 4;byteIdx++) {
		            	in.get();
		            }
		            in.getShort();

		            in.getShort();

		            in.get();

		            for (int byteIdx = 0;byteIdx < 24;byteIdx++)
		            	in.get();

		            IoBufferUtils.getRS2String(in);

		            for (int byteIdx = 0;byteIdx < 3;byteIdx++)
		            	in.get();

		            for (int it = 0;it < 2;it++)
		                in.getInt();

		            in.getShort();

		            for (int i = 0; i < 26; i++) {
		                in.getInt();
		            }

		            int junk29 = in.getShort();
		            int junk30 = in.get();
		            int junk31 = in.getShort();
		            int junk32 = in.get();

					/*
					 * The encrypted size includes the size byte which we don't
					 * need.
					 */
					encryptSize--;

					/*
					 * We check if there is a mismatch in the sizing.
					 */
					int reportedSize = in.get() & 0xFF;
					if(reportedSize != 10) {
						in.get();
					}

					/*
					 * We read the client's session key.
					 */
					long clientKey = in.getLong();

					/*
					 * And verify it has the correct server session key.
					 */
					long serverKey = (Long) session.getAttribute("serverKey");
					long reportedServerKey = in.getLong();
					if(reportedServerKey != serverKey) {
						//logger.info("Server key mismatch (expected : " + serverKey + ", reported : " + reportedServerKey + ")");
						//session.close(false);
						//in.rewind();
						//return false;
					}

					/*
					 * We read and format the name and passwords.
					 */
					String name = NameUtils.formatName(TextUtils.longToPlayerName(in.getLong()));
					String pass = IoBufferUtils.getRS2String(in);
					logger.info("Login request : username=" + name + " password=" + pass);

					/*
					 * And setup the ISAAC cipher which is used to encrypt and
					 * decrypt opcodes.
					 *
					 * However, without RSA, this is rendered useless anyway.
					 */
					int[] sessionKey = new int[4];
					sessionKey[0] = (int) (clientKey >> 32);
					sessionKey[1] = (int) clientKey;
					sessionKey[2] = (int) (serverKey >> 32);
					sessionKey[3] = (int) serverKey;

					session.removeAttribute("state");
					session.removeAttribute("serverKey");
					session.removeAttribute("size");
					session.removeAttribute("encryptSize");

					ISAACCipher inCipher = null;// new ISAACCipher(sessionKey);
					for(int i = 0; i < 4; i++) {
						sessionKey[i] += 50;
					}
					ISAACCipher outCipher = null;// new ISAACCipher(sessionKey);

					/*
					 * Now, the login has completed, and we do the appropriate
					 * things to fire off the chain of events which will load
					 * and check the saved games etc.
					 */
					session.getFilterChain().remove("protocol");
					session.getFilterChain().addFirst("protocol", new ProtocolCodecFilter(RS2CodecFactory.GAME));

					PlayerDetails pd = new PlayerDetails(session, name, pass, 0, inCipher, outCipher);
					World.getWorld().load(pd);
				}
				break;
			}
			in.rewind();
			return false;
		}
	}

}