envoy/src/main/java/envoy/server/processors/LoginCredentialProcessor.java

package envoy.server.processors;

import static envoy.data.User.UserStatus.ONLINE;
import static envoy.event.HandshakeRejection.*;

import java.io.IOException;
import java.time.LocalDateTime;
import java.util.Arrays;
import java.util.HashSet;
import java.util.logging.Logger;
import java.util.regex.Pattern;

import javax.persistence.NoResultException;

import envoy.data.LoginCredentials;
import envoy.data.Message.MessageStatus;
import envoy.event.HandshakeRejection;
import envoy.event.MessageStatusChange;
import envoy.server.Startup;
import envoy.server.data.PersistenceManager;
import envoy.server.data.User;
import envoy.server.net.ConnectionManager;
import envoy.server.net.ObjectWriteProxy;
import envoy.util.EnvoyLog;

/**
 * This {@link ObjectProcessor} handles {@link LoginCredentials}.<br>
 * <br>
 * Project: <strong>envoy-server-standalone</strong><br>
 * File: <strong>LoginCredentialProcessor.java</strong><br>
 * Created: <strong>30.12.2019</strong><br>
 *
 * @author Kai S. K. Engelbart
 * @author Maximilian K&auml;fer
 * @since Envoy Server Standalone v0.1-alpha
 */
public final class LoginCredentialProcessor implements ObjectProcessor<LoginCredentials> {

	private final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
	private final ConnectionManager		connectionManager	= ConnectionManager.getInstance();

	private static final Logger		logger			= EnvoyLog.getLogger(LoginCredentialProcessor.class);
	private static final Pattern	versionPattern	= Pattern.compile("(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");

	@Override
	public void process(LoginCredentials credentials, long socketID, ObjectWriteProxy writeProxy) throws IOException {

		// Cache this write proxy for user-independant notifications
		UserStatusChangeProcessor.setWriteProxy(writeProxy);

		// TODO: Verify compatibility
		if (!verifyCompatibility(credentials.getClientVersion())) {
			logger.info("The client has the wrong version.");
			writeProxy.write(socketID, new HandshakeRejection("Wrong version"));
			return;
		}

		// Acquire a user object (or reject the handshake if that's impossible)
		User user = null;
		if (!credentials.isRegistration()) {
			try {
				user = persistenceManager.getUserByName(credentials.getIdentifier());

				// Checking if user is already online
				if (connectionManager.isOnline(user.getID())) {
					logger.warning(user + " is already online!");
					writeProxy.write(socketID, new HandshakeRejection(INTERNAL_ERROR));
					return;
				}
				// Evaluating the correctness of the password hash
				if (!Arrays.equals(credentials.getPasswordHash(), user.getPasswordHash())) {
					logger.info(user + " has entered the wrong password.");
					writeProxy.write(socketID, new HandshakeRejection(WRONG_PASSWORD_OR_USER));
					return;
				}
			} catch (NoResultException e) {
				logger.info("The requested user does not exist.");
				writeProxy.write(socketID, new HandshakeRejection(WRONG_PASSWORD_OR_USER));
				return;
			}
		} else {
			try {
				// Checking that no user already has this identifier
				PersistenceManager.getInstance().getUserByName(credentials.getIdentifier());

				// This code only gets executed if this user already exists
				logger.info("The requested user already exists.");
				writeProxy.write(socketID, new HandshakeRejection(INTERNAL_ERROR));
				return;
			} catch (NoResultException e) {
				// Creation of a new user
				user = new User();
				user.setName(credentials.getIdentifier());
				user.setLastSeen(LocalDateTime.now());
				user.setStatus(ONLINE);
				user.setPasswordHash(credentials.getPasswordHash());
				user.setContacts(new HashSet<>());
				persistenceManager.addContact(user);
				logger.info("Registered new " + user);
			}
		}

		logger.info(user + " successfully authenticated.");

		connectionManager.registerUser(user.getID(), socketID);

		// Change status and notify contacts about it
		user.setStatus(ONLINE);
		UserStatusChangeProcessor.updateUserStatus(user);

		// Complete the handshake
		writeProxy.write(socketID, user.toCommon());

		final var pendingMessages = PersistenceManager.getInstance().getPendingMessages(user);
		logger.fine("Sending " + pendingMessages.size() + " pending messages to " + user + "...");
		for (var msg : pendingMessages) {
			final var msgCommon = msg.toCommon();
			if (msg.getStatus() == MessageStatus.SENT) {
				writeProxy.write(socketID, msgCommon);
				msg.received();
				if (connectionManager.isOnline(msg.getSender().getID()))
					writeProxy.write(connectionManager.getSocketID(msg.getSender().getID()), new MessageStatusChange(msgCommon));
				PersistenceManager.getInstance().updateMessage(msg);
			} else writeProxy.write(socketID, new MessageStatusChange(msgCommon));
		}
	}

	private boolean verifyCompatibility(String version) {
		final var currentMatcher = versionPattern.matcher(version);

		if (!currentMatcher.matches()) return false;

		final var	minMatcher	= versionPattern.matcher(Startup.MIN_CLIENT_VERSION);
		final var	maxMatcher	= versionPattern.matcher(Startup.MAX_CLIENT_VERSION);

		if (!minMatcher.matches() || !maxMatcher.matches()) throw new RuntimeException("Invalid min or max client version configured!");

		// Compare suffixes
		{
			final var	currentSuffix	= convertSuffix(currentMatcher.group("suffix"));
			final var	minSuffix		= convertSuffix(minMatcher.group("suffix"));
			final var	maxSuffix		= convertSuffix(maxMatcher.group("suffix"));

			if (currentSuffix < minSuffix || currentSuffix > maxSuffix) return false;
		}

		// Compare major
		{
			final var	currentMajor	= Integer.parseInt(currentMatcher.group("major"));
			final var	minMajor		= Integer.parseInt(minMatcher.group("major"));
			final var	maxMajor		= Integer.parseInt(maxMatcher.group("major"));

			if (currentMajor < minMajor || currentMajor > maxMajor) return false;
		}

		// Compare minor
		{
			final var	currentMinor	= Integer.parseInt(currentMatcher.group("minor"));
			final var	minMinor		= Integer.parseInt(minMatcher.group("minor"));
			final var	maxMinor		= Integer.parseInt(maxMatcher.group("minor"));

			if (currentMinor < minMinor || currentMinor > maxMinor) return false;
		}

		return true;
	}

	private int convertSuffix(String suffix) {
		switch (suffix == null ? "" : suffix) {
			case "alpha":
				return 0;
			case "beta":
				return 1;
			default:
				return 2;
		}
	}

	@Override
	public Class<LoginCredentials> getInputClass() { return LoginCredentials.class; }
}