envoy/src/main/java/envoy/client/ui/container/ChatWindow.java

package envoy.client.ui.container;

import java.awt.*;
import java.awt.datatransfer.StringSelection;
import java.awt.event.*;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;

import envoy.client.data.Chat;
import envoy.client.data.LocalDB;
import envoy.client.data.Settings;
import envoy.client.event.MessageCreationEvent;
import envoy.client.event.ThemeChangeEvent;
import envoy.client.net.Client;
import envoy.client.net.WriteProxy;
import envoy.client.ui.Theme;
import envoy.client.ui.list.ComponentList;
import envoy.client.ui.list.ComponentList.SelectionMode;
import envoy.client.ui.list.Model;
import envoy.client.ui.list_component.ContactSearchComponent;
import envoy.client.ui.list_component.MessageComponent;
import envoy.client.ui.primary.PrimaryButton;
import envoy.client.ui.primary.PrimaryScrollPane;
import envoy.client.ui.primary.PrimaryTextArea;
import envoy.client.ui.renderer.UserListRenderer;
import envoy.client.ui.settings.SettingsScreen;
import envoy.data.Message;
import envoy.data.Message.MessageStatus;
import envoy.data.MessageBuilder;
import envoy.data.User;
import envoy.event.*;
import envoy.util.EnvoyLog;

/**
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>ChatWindow.java</strong><br>
 * Created: <strong>28 Sep 2019</strong><br>
 *
 * @author Kai S. K. Engelbart
 * @author Maximilian K&auml;fer
 * @author Leon Hofmeister
 * @since Envoy Client v0.1-alpha
 */
public class ChatWindow extends JFrame {

	/**
	 * This integer defines the maximum amount of chars allowed per message.
	 *
	 * @since Envoy 0.1-beta
	 */
	public static final int MAX_MESSAGE_LENGTH = 200;

	// User specific objects
	private Client		client;
	private WriteProxy	writeProxy;
	private LocalDB		localDB;
	private Chat		currentChat;

	// GUI components
	private JPanel					contentPane				= new JPanel();
	private PrimaryTextArea			messageEnterTextArea	= new PrimaryTextArea(space);
	private JList<User>				userList				= new JList<>();
	private DefaultListModel<User>	userListModel			= new DefaultListModel<>();
	private ComponentList<Message>	messageList				= new ComponentList<>();
	private PrimaryScrollPane		scrollPane				= new PrimaryScrollPane();
	private JTextPane				textPane				= new JTextPane();
	private PrimaryButton			postButton				= new PrimaryButton("Post");
	private PrimaryButton			settingsButton			= new PrimaryButton("Settings");
	private JPopupMenu				contextMenu;

	// Contacts Header
	private JPanel			contactsHeader	= new JPanel();
	private JTextPane		contactsDisplay	= new JTextPane();
	private PrimaryButton	addContact		= new PrimaryButton("+");

	// Search Contacts
	private final JPanel				searchPane					= new JPanel();
	private final PrimaryButton			cancelButton				= new PrimaryButton("x");
	private final PrimaryTextArea		searchField					= new PrimaryTextArea(space);
	private final PrimaryScrollPane		scrollForPossibleContacts	= new PrimaryScrollPane();
	private final Model<User>			contactsModel				= new Model<>();
	private final ComponentList<User>	contactList					= new ComponentList<User>().setRenderer(ContactSearchComponent::new);

	private static final Logger logger = EnvoyLog.getLogger(ChatWindow.class);

	// GUI component spacing
	private final static int	space	= 4;
	private static final Insets	insets	= new Insets(space, space, space, space);

	private static final long serialVersionUID = 0L;

	/**
	 * Initializes a {@link JFrame} with UI elements used to send and read messages
	 * to different users.
	 *
	 * @since Envoy Client v0.1-alpha
	 */
	public ChatWindow() {
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 600, 800);
		setMinimumSize(new Dimension(400, 300));
		setTitle("Envoy");
		setLocationRelativeTo(null);
		setIconImage(Toolkit.getDefaultToolkit().createImage(getClass().getClassLoader().getResource("envoy_logo.png")));

		contentPane.setBorder(new EmptyBorder(space, space, space, space));
		setContentPane(contentPane);
		GridBagLayout gbl_contentPane = new GridBagLayout();
		gbl_contentPane.columnWidths	= new int[] { 1, 1, 1 };
		gbl_contentPane.rowHeights		= new int[] { 1, 1, 1, 1 };
		gbl_contentPane.columnWeights	= new double[] { 0.03, 1.0, 0.1 };
		gbl_contentPane.rowWeights		= new double[] { 0.03, 0.001, 1.0, 0.001 };
		contentPane.setLayout(gbl_contentPane);

		messageList.setBorder(new EmptyBorder(space, space, space, space));
		messageList.setSelectionMode(SelectionMode.SINGLE);
		messageList.setSelectionHandler((message, comp, isSelected) -> {
			final var theme = Settings.getInstance().getCurrentTheme();
			comp.setBackground(isSelected ? theme.getSelectionColor() : theme.getCellColor());

			// ContextMenu
			Map<String, ActionListener> commands = Map.of("forward selected message", evt -> {
				final Message	selectedMessage	= messageList.getSingleSelectedElement();
				List<User>		chosenContacts	= ContactsChooserDialog
					.showForwardingDialog("Forward selected message to", null, selectedMessage, localDB.getUsers().values());
				if (chosenContacts != null && chosenContacts.size() > 0) forwardMessage(selectedMessage, chosenContacts.toArray(new User[0]));
			}, "copy", evt -> {
				// TODO should be enhanced to allow also copying of message attachments,
				// especially pictures
				StringSelection copy = new StringSelection(messageList.getSingleSelectedElement().getText());
				Toolkit.getDefaultToolkit().getSystemClipboard().setContents(copy, copy);
				// TODO insert implementation to edit and delete messages
			}, "delete", evt -> {}, "edit", evt -> {}, "quote", evt -> {});

			if (isSelected) {
				contextMenu = new ContextMenu(null, comp, commands, null, null).build();
				contextMenu.show(comp, 0, 0);
			}
		});

		scrollPane.setViewportView(messageList);
		scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
		scrollPane.addComponentListener(new ComponentAdapter() {

			// Update list elements when scroll pane (and thus list) is resized
			@Override
			public void componentResized(ComponentEvent e) {
				messageList.setMaximumSize(new Dimension(scrollPane.getWidth(), Integer.MAX_VALUE));
				messageList.synchronizeModel();
			}
		});

		GridBagConstraints gbc_scrollPane = new GridBagConstraints();
		gbc_scrollPane.fill			= GridBagConstraints.BOTH;
		gbc_scrollPane.gridwidth	= 2;
		gbc_scrollPane.gridheight	= 2;
		gbc_scrollPane.gridx		= 1;
		gbc_scrollPane.gridy		= 1;

		gbc_scrollPane.insets = insets;

		drawChatBox(gbc_scrollPane);

		// MessageEnterTextArea
		messageEnterTextArea.addInputMethodListener(new InputMethodListener() {

			@Override
			public void inputMethodTextChanged(InputMethodEvent event) {
				checkMessageTextLength();
				checkPostButton(messageEnterTextArea.getText());
			}

			@Override
			public void caretPositionChanged(InputMethodEvent event) {}
		});

		messageEnterTextArea.addKeyListener(new KeyAdapter() {

			@Override
			public void keyReleased(KeyEvent e) {
				if (e.getKeyCode() == KeyEvent.VK_ENTER
						&& (Settings.getInstance().isEnterToSend() && e.getModifiersEx() == 0 || e.getModifiersEx() == KeyEvent.CTRL_DOWN_MASK)
						&& postButton.isEnabled())
					postMessage();
				// Checking if text is too long
				checkMessageTextLength();
				checkPostButton(messageEnterTextArea.getText());
			}
		});

		GridBagConstraints gbc_messageEnterTextArea = new GridBagConstraints();
		gbc_messageEnterTextArea.fill	= GridBagConstraints.BOTH;
		gbc_messageEnterTextArea.gridx	= 1;
		gbc_messageEnterTextArea.gridy	= 3;
		gbc_messageEnterTextArea.insets	= insets;
		contentPane.add(messageEnterTextArea, gbc_messageEnterTextArea);

		// Post Button
		GridBagConstraints gbc_postButton = new GridBagConstraints();
		gbc_postButton.fill		= GridBagConstraints.BOTH;
		gbc_postButton.gridx	= 2;
		gbc_postButton.gridy	= 3;
		gbc_postButton.insets	= insets;
		postButton.addActionListener((evt) -> { postMessage(); });
		postButton.setEnabled(false);
		contentPane.add(postButton, gbc_postButton);

		// Settings Button
		GridBagConstraints gbc_moveSelectionSettingsButton = new GridBagConstraints();

		gbc_moveSelectionSettingsButton.fill	= GridBagConstraints.BOTH;
		gbc_moveSelectionSettingsButton.gridx	= 2;
		gbc_moveSelectionSettingsButton.gridy	= 0;

		gbc_moveSelectionSettingsButton.insets = insets;

		settingsButton.addActionListener(evt -> new SettingsScreen().setVisible(true));
		contentPane.add(settingsButton, gbc_moveSelectionSettingsButton);

		// Partner name display
		textPane.setFont(new Font("Arial", Font.PLAIN, 20));
		textPane.setEditable(false);

		GridBagConstraints gbc_partnerName = new GridBagConstraints();
		gbc_partnerName.fill	= GridBagConstraints.HORIZONTAL;
		gbc_partnerName.gridx	= 1;
		gbc_partnerName.gridy	= 0;

		gbc_partnerName.insets = insets;
		contentPane.add(textPane, gbc_partnerName);

		userList.setCellRenderer(new UserListRenderer());
		userList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
		userList.addListSelectionListener((listSelectionEvent) -> {
			if (client != null && localDB != null && !listSelectionEvent.getValueIsAdjusting()) {
				final JList<User>	selectedUserList	= (JList<User>) listSelectionEvent.getSource();
				final User			user				= selectedUserList.getSelectedValue();

				for (int i = 0; i < contentPane.getComponents().length; i++)
					if (contentPane.getComponent(i).equals(searchPane)) drawChatBox(gbc_scrollPane);
				if (user != null) {
					// Select current chat
					currentChat = localDB.getChats().stream().filter(chat -> chat.getRecipient().getID() == user.getID()).findFirst().get();

					// Read current chat
					readCurrentChat();

					// Set chat title
					textPane.setText(currentChat.getRecipient().getName());

					// Update model and scroll down
					// messageList.setModel(currentChat.getModel());
					scrollPane.setChatOpened(true);

					messageList.synchronizeModel();
					revalidate();
					repaint();
				}
			}
		});

		userList.setFont(new Font("Arial", Font.PLAIN, 17));
		userList.setBorder(new EmptyBorder(space, space, space, space));

		GridBagConstraints gbc_userList = new GridBagConstraints();
		gbc_userList.fill		= GridBagConstraints.VERTICAL;
		gbc_userList.gridx		= 0;
		gbc_userList.gridy		= 2;
		gbc_userList.gridheight	= 2;
		gbc_userList.anchor		= GridBagConstraints.PAGE_START;
		gbc_userList.insets		= insets;

		contentPane.add(userList, gbc_userList);
		contentPane.revalidate();

		// Contacts Search
		GridBagConstraints gbc_searchPane = new GridBagConstraints();
		gbc_searchPane.fill			= GridBagConstraints.BOTH;
		gbc_searchPane.gridwidth	= 2;
		gbc_searchPane.gridheight	= 2;
		gbc_searchPane.gridx		= 1;
		gbc_searchPane.gridy		= 1;

		gbc_searchPane.insets = insets;

		GridBagLayout gbl_contactsSearch = new GridBagLayout();
		gbl_contactsSearch.columnWidths		= new int[] { 1, 1 };
		gbl_contactsSearch.rowHeights		= new int[] { 1, 1 };
		gbl_contactsSearch.columnWeights	= new double[] { 1, 0.1 };
		gbl_contactsSearch.rowWeights		= new double[] { 0.001, 1 };
		searchPane.setLayout(gbl_contactsSearch);

		GridBagConstraints gbc_searchField = new GridBagConstraints();
		gbc_searchField.fill	= GridBagConstraints.BOTH;
		gbc_searchField.gridx	= 0;
		gbc_searchField.gridy	= 0;
		gbc_searchField.insets	= new Insets(7, 4, 4, 4);

		searchPane.add(searchField, gbc_searchField);

		// Sends event to server, if input has changed
		searchField.getDocument().addDocumentListener(new DocumentListener() {

			@Override
			public void removeUpdate(DocumentEvent evt) {
				if (client.isOnline()) if (searchField.getText().isEmpty()) {
					contactsModel.clear();
					revalidate();
					repaint();
				} else try {
					client.sendEvent(new ContactSearchRequest(searchField.getText()));
				} catch (IOException e) {
					e.printStackTrace();
				}
			}

			@Override
			public void insertUpdate(DocumentEvent evt) {
				if (client.isOnline()) try {
					client.sendEvent(new ContactSearchRequest(searchField.getText()));
				} catch (IOException e) {
					e.printStackTrace();
				}
			}

			@Override
			public void changedUpdate(DocumentEvent evt) {}
		});

		GridBagConstraints gbc_cancelButton = new GridBagConstraints();
		gbc_cancelButton.fill	= GridBagConstraints.BOTH;
		gbc_cancelButton.gridx	= 1;
		gbc_cancelButton.gridy	= 0;
		gbc_cancelButton.insets	= new Insets(7, 4, 4, 4);

		cancelButton.addActionListener((evt) -> { drawChatBox(gbc_scrollPane); });

		searchPane.add(cancelButton, gbc_cancelButton);

		contactList.setModel(contactsModel);
		scrollForPossibleContacts.setBorder(new EmptyBorder(space, space, space, space));
		scrollForPossibleContacts.setViewportView(contactList);

		GridBagConstraints gbc_possibleContacts = new GridBagConstraints();
		gbc_possibleContacts.fill		= GridBagConstraints.BOTH;
		gbc_possibleContacts.gridwidth	= 2;
		gbc_possibleContacts.gridx		= 0;
		gbc_possibleContacts.gridy		= 1;

		gbc_possibleContacts.insets = insets;

		searchPane.add(scrollForPossibleContacts, gbc_possibleContacts);

		// Contacts Header
		GridBagConstraints gbc_contactsHeader = new GridBagConstraints();
		gbc_contactsHeader.fill		= GridBagConstraints.BOTH;
		gbc_contactsHeader.gridx	= 0;
		gbc_contactsHeader.gridy	= 1;
		gbc_contactsHeader.insets	= insets;

		GridBagLayout gbl_contactHeader = new GridBagLayout();
		gbl_contactHeader.columnWidths	= new int[] { 1, 1 };
		gbl_contactHeader.rowHeights	= new int[] { 1 };
		gbl_contactHeader.columnWeights	= new double[] { 1, 1 };
		gbl_contactHeader.rowWeights	= new double[] { 1 };
		contactsHeader.setLayout(gbl_contactHeader);

		contactsDisplay.setEditable(false);
		contactsDisplay.setFont(new Font("Arial", Font.PLAIN, 12));
		contactsDisplay.setText("Contacts");

		GridBagConstraints gbc_contactsDisplay = new GridBagConstraints();
		gbc_contactsDisplay.fill	= GridBagConstraints.BOTH;
		gbc_contactsDisplay.gridx	= 0;
		gbc_contactsDisplay.gridy	= 0;

		contactsHeader.add(contactsDisplay, gbc_contactsDisplay);

		addContact.setFont(new Font("Arial", Font.PLAIN, 15));

		GridBagConstraints gbc_addContact = new GridBagConstraints();
		gbc_addContact.fill		= GridBagConstraints.BOTH;
		gbc_addContact.gridx	= 1;
		gbc_addContact.gridy	= 0;
		gbc_addContact.insets	= insets;

		addContact.addActionListener(evt -> drawContactSearch(gbc_searchPane));

		contactsHeader.add(addContact, gbc_addContact);

		applyTheme(Settings.getInstance().getCurrentTheme());

		contentPane.add(contactsHeader, gbc_contactsHeader);
		contentPane.revalidate();

		// Listen to theme changes
		EventBus.getInstance().register(ThemeChangeEvent.class, evt -> applyTheme(evt.get()));

		// Listen to user status changes
		EventBus.getInstance().register(UserStatusChangeEvent.class, evt -> { userList.revalidate(); userList.repaint(); });

		// Listen to received messages
		EventBus.getInstance().register(MessageCreationEvent.class, evt -> {
			Message	message	= evt.get();
			Chat	chat	= localDB.getChats().stream().filter(c -> c.getRecipient().getID() == message.getSenderID()).findFirst().get();
			// chat.appendMessage(message);

			// Read message and update UI if in current chat
			if (chat == currentChat) readCurrentChat();

			revalidate();
			repaint();
		});

		// Listen to message status changes
		EventBus.getInstance().register(MessageStatusChangeEvent.class, evt -> {
			final long			id		= evt.getID();
			final MessageStatus	status	= evt.get();

			for (Chat c : localDB.getChats())
				// for (Message m : c.getModel())
				// if (m.getID() == id) {
				//
				// // Update message status
				// m.setStatus(status);
				//
				// // Update model and scroll down if current chat
				// if (c == currentChat) {
				// messageList.setModel(currentChat.getModel());
				// scrollPane.setChatOpened(true);
				// } else messageList.synchronizeModel();
				// }

			revalidate();
			repaint();
		});

		// Listen to contact search results
		EventBus.getInstance()
			.register(ContactSearchResult.class,
					evt -> {
						contactsModel.clear();
						final java.util.List<User> contacts = evt.get();
						contacts.forEach(contactsModel::add);
						revalidate();
						repaint();
					});

		// Add new contacts to the contact list
		EventBus.getInstance().register(ContactOperationEvent.class, evt -> {
			User contact = evt.get();

			// Clearing the search field and the searchResultList
			searchField.setText("");
			contactsModel.clear();

			// Update LocalDB
			userListModel.addElement(contact);
			localDB.getUsers().put(contact.getName(), contact);
			localDB.getChats().add(new Chat(contact));

			revalidate();
			repaint();
		});

		revalidate();
		repaint();
	}

	/**
	 * Used to immediately reload the {@link ChatWindow} when settings were changed.
	 *
	 * @param theme the theme to change colors into
	 * @since Envoy Client v0.2-alpha
	 */
	private void applyTheme(Theme theme) {
		// contentPane
		contentPane.setBackground(theme.getBackgroundColor());
		contentPane.setForeground(theme.getUserNameColor());
		// messageList
		messageList.setForeground(theme.getTextColor());
		messageList.setBackground(theme.getCellColor());
		messageList.synchronizeModel();
		// scrollPane
		scrollPane.applyTheme(theme);
		scrollPane.autoscroll();
		// messageEnterTextArea
		messageEnterTextArea.setCaretColor(theme.getTypingMessageColor());
		messageEnterTextArea.setForeground(theme.getTypingMessageColor());
		messageEnterTextArea.setBackground(theme.getCellColor());
		// postButton
		postButton.setForeground(theme.getInteractableForegroundColor());
		postButton.setBackground(theme.getInteractableBackgroundColor());
		// settingsButton
		settingsButton.setForeground(theme.getInteractableForegroundColor());
		settingsButton.setBackground(theme.getInteractableBackgroundColor());
		// textPane
		textPane.setBackground(theme.getBackgroundColor());
		textPane.setForeground(theme.getUserNameColor());
		// userList
		userList.setSelectionForeground(theme.getUserNameColor());
		userList.setSelectionBackground(theme.getSelectionColor());
		userList.setForeground(theme.getUserNameColor());
		userList.setBackground(theme.getCellColor());
		// contacts header
		contactsHeader.setBackground(theme.getCellColor());
		contactsDisplay.setBackground(theme.getCellColor());
		contactsDisplay.setForeground(theme.getUserNameColor());
		addContact.setBackground(theme.getInteractableBackgroundColor());
		addContact.setForeground(theme.getInteractableForegroundColor());
		// SearchPane
		searchPane.setBackground(theme.getCellColor());
		searchField.setBackground(theme.getBackgroundColor());
		searchField.setForeground(theme.getUserNameColor());
		cancelButton.setBackground(theme.getInteractableBackgroundColor());
		cancelButton.setForeground(theme.getInteractableForegroundColor());
		contactList.setForeground(theme.getTextColor());
		contactList.setBackground(theme.getCellColor());
		scrollForPossibleContacts.applyTheme(theme);
	}

	/**
	 * Sends a new message to the server based on the text entered in the textArea.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	private void postMessage() {
		if (userList.isSelectionEmpty()) {
			JOptionPane.showMessageDialog(this, "Please select a recipient!", "Cannot send message", JOptionPane.INFORMATION_MESSAGE);
			return;
		}
		String text = messageEnterTextArea.getText().trim();
		if (!text.isEmpty()) checkMessageTextLength();

		// Create message
		final Message message = new MessageBuilder(localDB.getUser().getID(), currentChat.getRecipient().getID(), localDB.getIDGenerator())
			.setText(text)
			.build();
		sendMessage(message);
		// Clear text field
		messageEnterTextArea.setText("");
		postButton.setEnabled(false);
	}

	/**
	 * Forwards a message.
	 *
	 * @param message   the message to forward
	 * @param recipient the new recipient of the message
	 * @since Envoy Client v0.1-beta
	 */
	private void forwardMessage(Message message, User... recipients) {
		Arrays.stream(recipients).forEach(recipient -> {
			if (message != null && recipients != null) sendMessage(new MessageBuilder(message, recipient.getID(), localDB.getIDGenerator()).build());
			else throw new NullPointerException("No recipient or no message selected");
		});

	}

	@SuppressWarnings("unused")
	private void forwardMessages(Collection<Message> messages, User... recipients) {
		messages.forEach(message -> { forwardMessage(message, recipients); });
	}

	/**
	 * Sends a {@link Message} to the server.
	 *
	 * @param message the message to send
	 * @since Envoy Client v0.1-beta
	 */
	private void sendMessage(final Message message) {
		try {
			// Send message
			writeProxy.writeMessage(message);

			// Add message to PersistentLocalDB and update UI
			// currentChat.appendMessage(message);

			// Update UI
			revalidate();
			repaint();

			// Request a new id generator if all IDs were used
			if (!localDB.getIDGenerator().hasNext()) client.requestIdGenerator();

		} catch (Exception e) {
			JOptionPane.showMessageDialog(this, "Error sending message:\n" + e.toString(), "Message sending error", JOptionPane.ERROR_MESSAGE);
			e.printStackTrace();
		}
	}

	private void readCurrentChat() {
		try {
			currentChat.read(writeProxy);
			if (messageList.getRenderer() != null) messageList.synchronizeModel();
		} catch (IOException e) {
			e.printStackTrace();
			logger.log(Level.WARNING, "Couldn't notify server about message status change", e);
		}
	}

	private void drawChatBox(GridBagConstraints gbc_scrollPane) {
		contentPane.remove(searchPane);
		contentPane.add(scrollPane, gbc_scrollPane);
		contentPane.revalidate();
		contentPane.repaint();
	}

	private void drawContactSearch(GridBagConstraints gbc_searchPane) {
		currentChat = null;
		userList.removeSelectionInterval(0, userList.getModel().getSize() - 1);
		messageList.setModel(null);
		textPane.setText("");
		contentPane.remove(scrollPane);
		contentPane.add(searchPane, gbc_searchPane);
		contentPane.revalidate();
		contentPane.repaint();
	}

	/**
	 * Initializes the components responsible server communication and
	 * persistence.<br>
	 * <br>
	 * This will trigger the display of the contact list.
	 *
	 * @param client     the client used to send and receive messages
	 * @param localDB    the local database used to manage stored messages
	 *                   and users
	 * @param writeProxy the write proxy used to send messages and status change
	 *                   events to the server or cache them inside the local
	 *                   database
	 * @since Envoy Client v0.3-alpha
	 */
	public void initContent(Client client, LocalDB localDB, WriteProxy writeProxy) {
		this.client		= client;
		this.localDB	= localDB;
		this.writeProxy	= writeProxy;

		messageList.setRenderer((list, message) -> new MessageComponent(list, message, client.getSender().getID()));

		// Load users and chats
		new Thread(() -> {
			localDB.getUsers().values().forEach(user -> {
				userListModel.addElement(user);

				// Check if user exists in local DB
				if (localDB.getChats().stream().noneMatch(c -> c.getRecipient().getID() == user.getID())) localDB.getChats().add(new Chat(user));
			});
			SwingUtilities.invokeLater(() -> userList.setModel(userListModel));

			revalidate();
			repaint();
		}).start();
	}

	/**
	 * Checks whether the length of the text inside messageEnterTextArea >=
	 * {@link ChatWindow#MAX_MESSAGE_LENGTH}
	 * and splits the text into the allowed part, if that is the case.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	private void checkMessageTextLength() {
		String input = messageEnterTextArea.getText();
		if (input.length() >= MAX_MESSAGE_LENGTH) {
			messageEnterTextArea.setText(input.substring(0, MAX_MESSAGE_LENGTH - 1));
			// TODO: current notification is like being hit with a hammer, maybe it should
			// be replaced with a more subtle notification
			JOptionPane.showMessageDialog(messageEnterTextArea,
					"the maximum length for a message has been reached",
					"maximum message length reached",
					JOptionPane.WARNING_MESSAGE);
		}
	}

	private void checkPostButton(String text) { postButton.setEnabled(!text.trim().isBlank()); }
}