package envoy.client.ui.container;

import java.awt.*;
import java.awt.event.ItemEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.logging.Logger;

import javax.naming.TimeLimitExceededException;
import javax.swing.*;
import javax.swing.border.EmptyBorder;

import envoy.client.data.*;
import envoy.client.event.HandshakeSuccessfulEvent;
import envoy.client.net.Client;
import envoy.client.ui.Theme;
import envoy.client.ui.primary.PrimaryButton;
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;

/**
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>LoginDialog.java</strong><br>
 * Created: <strong>01.01.2020</strong><br>
 *
 * @author Kai S. K. Engelbart
 * @author Maximilian K&auml;fer
 * @since Envoy Client v0.3-alpha
 */
public class LoginDialog extends JDialog {

	private JPanel			contentPanel;
	private JTextField		textField;
	private JPasswordField	passwordField;
	private JPasswordField	repeatPasswordField;

	private JLabel	lblUserName;
	private JLabel	lblPassword;
	private JLabel	lblRepeatPassword;
	private JLabel	errorMessage;

	private GridBagConstraints	gbc_lblRepeatPassword;
	private GridBagConstraints	gbc_repeatPasswordField;
	private GridBagConstraints	gbc_errorMessage;

	private JPanel			buttonPane;
	private JTextPane		registerText;
	private JCheckBox		registerCheckBox;
	private PrimaryButton	okButton;
	private PrimaryButton	cancelButton;

	private LoginCredentials credentials;

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

	private static final ClientConfig	config				= ClientConfig.getInstance();
	private static final Logger			logger				= EnvoyLog.getLogger(LoginDialog.class);
	private static final long			serialVersionUID = 0L;

	/**
	 * Displays a dialog enabling the user to enter their user name and password.
	 *
	 * @param client               the client used to perform the handshake
	 * @param localDB              the local database in which data is persisted
	 * @param receivedMessageCache the cache that stored messages received during
	 *                             the handshake
	 * @since Envoy Client v0.3-alpha
	 */
	public LoginDialog(Client client, LocalDB localDB, Cache<Message> receivedMessageCache) {
		this.client					= client;
		this.localDB				= localDB;
		this.receivedMessageCache	= receivedMessageCache;

		// Prepare handshake
		localDB.loadIDGenerator();

		addWindowListener(new WindowAdapter() {

			@Override
			public void windowClosing(WindowEvent e) { abortLogin(); }
		});

		initUi();

		okButton.addActionListener((evt) -> {
			try {
				if (registerCheckBox.isSelected()) {
					// Check password equality
					if (Arrays.equals(passwordField.getPassword(), repeatPasswordField.getPassword())) {
						credentials = new LoginCredentials(textField.getText(), passwordField.getPassword(), true);
						performHandshake();
					} else {
						JOptionPane.showMessageDialog(this, "The repeated password is not the original password!");
						clearPasswordFields();
					}
				} else {
					credentials = new LoginCredentials(textField.getText(), passwordField.getPassword(), false);
					performHandshake();
				}
			} catch (NoSuchAlgorithmException e) {
				e.printStackTrace();
			}
		});

		// Listen to handshake rejections
		EventBus.getInstance()
			.register(HandshakeRejectionEvent.class,
					evt -> { clearPasswordFields(); errorMessage.setVisible(true); errorMessage.setText(evt.get()); });

		// Exit the application when the dialog is cancelled
		cancelButton.addActionListener(evt -> abortLogin());

		// Log in directly if configured
		if (config.hasLoginCredentials()) {
			credentials = config.getLoginCredentials();
			performHandshake();
			return;
		}

		setVisible(true);
	}

	private void performHandshake() {
		try {
			client.performHandshake(credentials, receivedMessageCache);
			if (client.isOnline()) {
				client.initReceiver(localDB, receivedMessageCache);
				dispose();
			}
		} 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 = localDB.getUsers().get(credentials.getIdentifier());
				if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
				client.setSender(clientUser);
				JOptionPane.showMessageDialog(null,
						"A connection to the server could not be established. Starting in offline mode.\n" + e,
						"Connection error",
						JOptionPane.WARNING_MESSAGE);
				dispose();
			} catch (Exception e1) {
				JOptionPane.showMessageDialog(null, e1, "Client error", JOptionPane.ERROR_MESSAGE);
				System.exit(1);
				return;
			}
		}
	}

	private void initUi() {
		setSize(338, 123);
		setLocationRelativeTo(null);
		setResizable(false);
		getContentPane().setLayout(new BorderLayout());
		contentPanel = new JPanel();
		contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
		getContentPane().add(contentPanel, BorderLayout.CENTER);
		GridBagLayout gbl_contentPanel = new GridBagLayout();
		gbl_contentPanel.columnWidths	= new int[] { 0, 0, 0 };
		gbl_contentPanel.rowHeights		= new int[] { 0, 0, 0 };
		gbl_contentPanel.columnWeights	= new double[] { 0.0, 1.0, Double.MIN_VALUE };
		gbl_contentPanel.rowWeights		= new double[] { 0.0, 0.0, Double.MIN_VALUE };
		contentPanel.setLayout(gbl_contentPanel);

		lblUserName = new JLabel("Username:");
		GridBagConstraints gbc_lblUserName = new GridBagConstraints();
		gbc_lblUserName.anchor	= GridBagConstraints.EAST;
		gbc_lblUserName.insets	= new Insets(0, 0, 5, 5);
		gbc_lblUserName.gridx	= 0;
		gbc_lblUserName.gridy	= 0;
		contentPanel.add(lblUserName, gbc_lblUserName);

		textField = new JTextField();
		textField.setBorder(null);
		GridBagConstraints gbc_textField = new GridBagConstraints();
		gbc_textField.insets	= new Insets(0, 0, 5, 0);
		gbc_textField.fill		= GridBagConstraints.HORIZONTAL;
		gbc_textField.gridx		= 1;
		gbc_textField.gridy		= 0;
		contentPanel.add(textField, gbc_textField);
		textField.setColumns(10);

		lblPassword = new JLabel("Password:");
		GridBagConstraints gbc_lblPassword = new GridBagConstraints();
		gbc_lblPassword.anchor	= GridBagConstraints.EAST;
		gbc_lblPassword.insets	= new Insets(0, 0, 0, 5);
		gbc_lblPassword.gridx	= 0;
		gbc_lblPassword.gridy	= 1;
		contentPanel.add(lblPassword, gbc_lblPassword);

		passwordField = new JPasswordField();
		passwordField.setBorder(null);
		GridBagConstraints gbc_passwordField = new GridBagConstraints();
		gbc_passwordField.fill	= GridBagConstraints.HORIZONTAL;
		gbc_passwordField.gridx	= 1;
		gbc_passwordField.gridy	= 1;
		contentPanel.add(passwordField, gbc_passwordField);

		lblRepeatPassword				= new JLabel("Repeat Password:");
		gbc_lblRepeatPassword			= new GridBagConstraints();
		gbc_lblRepeatPassword.anchor	= GridBagConstraints.EAST;
		gbc_lblRepeatPassword.insets	= new Insets(0, 0, 0, 5);
		gbc_lblRepeatPassword.gridx		= 0;
		gbc_lblRepeatPassword.gridy		= 2;

		repeatPasswordField				= new JPasswordField();
		gbc_repeatPasswordField			= new GridBagConstraints();
		gbc_repeatPasswordField.fill	= GridBagConstraints.HORIZONTAL;
		gbc_repeatPasswordField.gridx	= 1;
		gbc_repeatPasswordField.gridy	= 2;

		errorMessage			= new JLabel();
		gbc_errorMessage		= new GridBagConstraints();
		gbc_errorMessage.gridx	= 1;
		gbc_errorMessage.gridy	= 3;
		gbc_errorMessage.fill	= GridBagConstraints.HORIZONTAL;
		gbc_errorMessage.insets	= new Insets(5, 5, 5, 5);
		errorMessage.setForeground(Color.RED);
		errorMessage.setVisible(false);
		contentPanel.add(errorMessage, gbc_errorMessage);

		buttonPane = new JPanel();

		registerText = new JTextPane();
		registerText.setEditable(false);
		registerText.setText("Register?");
		registerText.setFont(new Font("Arial", Font.BOLD, 12));
		registerText.setAlignmentX(LEFT_ALIGNMENT);
		buttonPane.add(registerText);

		registerCheckBox = new JCheckBox();
		registerCheckBox.setAlignmentX(LEFT_ALIGNMENT);
		registerCheckBox.addItemListener(e -> {
			switch (e.getStateChange()) {
				case ItemEvent.SELECTED:
					contentPanel.add(lblRepeatPassword, gbc_lblRepeatPassword);
					contentPanel.add(repeatPasswordField, gbc_repeatPasswordField);
					setSize(338, 173);
					break;

				case ItemEvent.DESELECTED:
					if (repeatPasswordField.getParent() == contentPanel) {
						contentPanel.remove(lblRepeatPassword);
						contentPanel.remove(repeatPasswordField);
						setSize(338, 148);
					}
					break;
			}
			contentPanel.revalidate();
			contentPanel.repaint();
		});
		buttonPane.add(registerCheckBox);

		buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
		getContentPane().add(buttonPane, BorderLayout.SOUTH);
		okButton = new PrimaryButton("OK");
		okButton.setActionCommand("OK");
		buttonPane.add(okButton);
		getRootPane().setDefaultButton(okButton);

		cancelButton = new PrimaryButton("Cancel");
		cancelButton.setActionCommand("Cancel");
		buttonPane.add(cancelButton);
		setTheme();

		setModalityType(Dialog.DEFAULT_MODALITY_TYPE);

		EventBus.getInstance().register(HandshakeSuccessfulEvent.class, evt -> dispose());
	}

	/**
	 * Resets the text stored in the password fields.
	 *
	 * @since Envoy Client v0.3-alpha
	 */
	private void clearPasswordFields() {
		passwordField.setText(null);
		repeatPasswordField.setText(null);
	}

	private void setTheme() {
		Theme theme = Settings.getInstance().getCurrentTheme();

		// Panels
		contentPanel.setBackground(theme.getBackgroundColor());
		contentPanel.setForeground(theme.getBackgroundColor());

		buttonPane.setBackground(theme.getBackgroundColor());
		buttonPane.setForeground(theme.getBackgroundColor());

		// Input Fields
		textField.setBackground(theme.getCellColor());
		textField.setForeground(theme.getUserNameColor());

		passwordField.setBackground(theme.getCellColor());
		passwordField.setForeground(theme.getUserNameColor());

		repeatPasswordField.setBackground(theme.getCellColor());
		repeatPasswordField.setForeground(theme.getUserNameColor());

		// JLabels
		lblUserName.setBackground(theme.getCellColor());
		lblUserName.setForeground(theme.getUserNameColor());

		lblPassword.setBackground(theme.getCellColor());
		lblPassword.setForeground(theme.getUserNameColor());

		lblRepeatPassword.setBackground(theme.getCellColor());
		lblRepeatPassword.setForeground(theme.getUserNameColor());

		// Register
		registerText.setBackground(theme.getCellColor());
		registerText.setForeground(theme.getUserNameColor());

		registerCheckBox.setBackground(theme.getCellColor());

		// Buttons
		okButton.setBackground(theme.getInteractableBackgroundColor());
		okButton.setForeground(theme.getInteractableForegroundColor());

		cancelButton.setBackground(theme.getInteractableBackgroundColor());
		cancelButton.setForeground(theme.getInteractableForegroundColor());
	}

	/**
	 * Shuts the system down properly if the login was aborted.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	private void abortLogin() {
		logger.info("The login process has been cancelled. Exiting...");
		System.exit(0);
	}
}