envoy/src/main/java/envoy/client/ui/LoginDialog.java

package envoy.client.ui;

import java.io.IOException;
import java.util.logging.Logger;

import javax.naming.TimeLimitExceededException;

import envoy.client.data.Cache;
import envoy.client.data.ClientConfig;
import envoy.client.data.LocalDB;
import envoy.client.net.Client;
import envoy.data.LoginCredentials;
import envoy.data.Message;
import envoy.data.User;
import envoy.event.EventBus;
import envoy.event.HandshakeRejectionEvent;
import envoy.exception.EnvoyException;
import envoy.util.EnvoyLog;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.*;
import javafx.scene.control.Alert.AlertType;

/**
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>LoginDialog.java</strong><br>
 * Created: <strong>03.04.2020</strong><br>
 * 
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.1-beta
 */
public final class LoginDialog extends Dialog<Void> {

	@FXML
	private TextField userTextField;

	@FXML
	private PasswordField passwordField;

	@FXML
	private PasswordField repeatPasswordField;

	@FXML
	private Label repeatPasswordLabel;

	@FXML
	private CheckBox registerCheckBox;

	private final Client			client;
	private final LocalDB			localDB;
	private final Cache<Message>	receivedMessageCache;

	private static final Logger			logger		= EnvoyLog.getLogger(LoginDialog.class);
	private static final EventBus		eventBus	= EventBus.getInstance();
	private static final ClientConfig	config		= ClientConfig.getInstance();

	/**
	 * Loads the login dialog using the FXML file {@code LoginDialog.fxml}.
	 * 
	 * @param client               the client used to perform the handshake
	 * @param localDB              the local database used for offline login
	 * @param receivedMessageCache the cache storing messages received during the
	 *                             handshake
	 * @throws IOException if an exception occurs during loading
	 * @since Envoy Client v0.1-beta
	 */
	public LoginDialog(Client client, LocalDB localDB, Cache<Message> receivedMessageCache) throws IOException {
		this.client					= client;
		this.localDB				= localDB;
		this.receivedMessageCache	= receivedMessageCache;

		final var loader = new FXMLLoader(getClass().getResource("LoginDialog.fxml"));
		loader.setController(this);
		final var dialogPane = loader.<DialogPane>load();

		// Configure dialog buttons
		dialogPane.getButtonTypes().addAll(ButtonType.CLOSE, ButtonType.OK);

		// Close button
		dialogPane.lookupButton(ButtonType.CLOSE).addEventHandler(ActionEvent.ACTION, e -> abortLogin());

		// Login button
		final var loginButton = (Button) dialogPane.lookupButton(ButtonType.OK);
		loginButton.setText("Login");
		loginButton.addEventFilter(ActionEvent.ACTION, e -> {
			e.consume();

			// Prevent registration with unequal passwords
			if (registerCheckBox.isSelected() && !passwordField.getText().equals(repeatPasswordField.getText())) {
				clearPasswordFields();
				new Alert(AlertType.ERROR, "The entered password is unequal to the repeated one").showAndWait();
			} else
				performHandshake(new LoginCredentials(userTextField.getText(), passwordField.getText().toCharArray(), registerCheckBox.isSelected()));
		});

		// Perform automatic login if configured
		setOnShown(e -> { if (config.hasLoginCredentials()) performHandshake(config.getLoginCredentials()); });

		setDialogPane(dialogPane);
	}

	@FXML
	private void initialize() {

		// Show an alert after an unsuccessful handshake
		eventBus.register(HandshakeRejectionEvent.class,
				e -> Platform.runLater(() -> { clearPasswordFields(); new Alert(AlertType.ERROR, e.get()).showAndWait(); }));

		// Set initial cursor
		userTextField.requestFocus();
	}

	@FXML
	private void registerCheckboxChanged() {

		// Make repeat password field and label visible / invisible
		repeatPasswordField.setVisible(registerCheckBox.isSelected());
		repeatPasswordLabel.setVisible(registerCheckBox.isSelected());

		clearPasswordFields();
	}

	private void abortLogin() {
		logger.info("The login process has been cancelled. Exiting...");
		System.exit(0);
	}

	private void performHandshake(LoginCredentials credentials) {
		try {
			client.performHandshake(credentials, receivedMessageCache);
			if (client.isOnline()) {
				client.initReceiver(localDB, receivedMessageCache);
				Platform.runLater(this::hide);
			}
		} catch (IOException | InterruptedException | TimeLimitExceededException e) {
			logger.warning("Could not connect to server. Trying offline mode...");
			e.printStackTrace();
			try {
				// Try entering offline mode
				localDB.loadUsers();
				User clientUser = (User) localDB.getUsers().get(credentials.getIdentifier());
				if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
				client.setSender(clientUser);
				Platform.runLater(() -> {
					new Alert(AlertType.WARNING, "A connection to the server could not be established. Starting in offline mode.\n" + e)
						.showAndWait();
					hide();
				});
			} catch (Exception e1) {
				Platform.runLater(() -> new Alert(AlertType.ERROR, "Client error: " + e.toString()).showAndWait());
				System.exit(1);
			}
		}
	}

	private void clearPasswordFields() {
		passwordField.clear();
		repeatPasswordField.clear();
	}
}