package envoy.client.ui.controller;

import java.awt.Toolkit;
import java.awt.datatransfer.StringSelection;
import java.io.*;
import java.nio.file.Files;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.logging.*;

import javafx.animation.RotateTransition;
import javafx.application.Platform;
import javafx.collections.ObservableList;
import javafx.collections.transformation.FilteredList;
import javafx.fxml.*;
import javafx.scene.control.*;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.image.*;
import javafx.scene.input.*;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.FileChooser;
import javafx.util.Duration;

import envoy.client.data.*;
import envoy.client.data.audio.AudioRecorder;
import envoy.client.event.*;
import envoy.client.net.*;
import envoy.client.ui.*;
import envoy.client.ui.chatscene.*;
import envoy.client.ui.control.ChatControl;
import envoy.client.ui.listcell.*;
import envoy.client.util.*;
import envoy.data.*;
import envoy.data.Attachment.AttachmentType;
import envoy.data.Message.MessageStatus;
import envoy.event.*;
import envoy.event.contact.ContactOperation;
import envoy.exception.EnvoyException;
import envoy.util.EnvoyLog;

import dev.kske.eventbus.*;
import dev.kske.eventbus.Event;

/**
 * Controller for the chat scene.
 *
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.1-beta
 */
public final class ChatScene implements EventListener, Restorable {

	@FXML
	private GridPane scene;

	@FXML
	private Label contactLabel;

	@FXML
	private ListView<Message> messageList;

	@FXML
	private ListView<Chat> chatList;

	@FXML
	private Button postButton;

	@FXML
	private Button voiceButton;

	@FXML
	private Button attachmentButton;

	@FXML
	private Button settingsButton;

	@FXML
	private Button messageSearchButton;

	@FXML
	private Button newGroupButton;

	@FXML
	private Button newContactButton;

	@FXML
	private TextArea messageTextArea;

	@FXML
	private Label remainingChars;

	@FXML
	private Label infoLabel;

	@FXML
	private MenuItem deleteContactMenuItem;

	@FXML
	private ImageView attachmentView;

	@FXML
	private Label topBarContactLabel;

	@FXML
	private Label topBarStatusLabel;

	@FXML
	private ImageView clientProfilePic;

	@FXML
	private ImageView recipientProfilePic;

	@FXML
	private TextArea contactSearch;

	@FXML
	private VBox contactOperations;

	@FXML
	private TabPane tabPane;

	@FXML
	private Tab contactSearchTab;

	@FXML
	private Tab groupCreationTab;

	@FXML
	private HBox contactSpecificOnlineOperations;

	private Chat				currentChat;
	private FilteredList<Chat>	chats;
	private boolean				recording;
	private Attachment			pendingAttachment;
	private boolean				postingPermanentlyDisabled;
	private boolean				isCustomAttachmentImage;
	private ChatSceneCommands	commands;

	private final LocalDB		localDB				= context.getLocalDB();
	private final Client		client				= context.getClient();
	private final WriteProxy	writeProxy			= context.getWriteProxy();
	private final SceneContext	sceneContext		= context.getSceneContext();
	private final AudioRecorder	recorder			= new AudioRecorder();
	private final Tooltip		onlyIfOnlineTooltip	= new Tooltip("You need to be online to do this");

	private static Image DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);

	private static final Settings	settings			= Settings.getInstance();
	private static final EventBus	eventBus			= EventBus.getInstance();
	private static final Logger		logger				= EnvoyLog.getLogger(ChatScene.class);
	private static final Context	context				= Context.getInstance();
	private static final int		MAX_MESSAGE_LENGTH	= 255;
	private static final int		DEFAULT_ICON_SIZE	= 16;

	/**
	 * Initializes the appearance of certain visual components.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void initialize() {
		eventBus.registerListener(this);
		commands = new ChatSceneCommands(messageList, this);

		// Initialize message and user rendering
		messageList.setCellFactory(MessageListCell::new);
		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));

		// JavaFX provides an internal way of populating the context menu of a text
		// area.
		// We, however, need additional functionality.
		messageTextArea.setContextMenu(new TextInputContextMenu(messageTextArea, e -> checkKeyCombination(null)));

		// Set the icons of buttons and image views
		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
		attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
		onlyIfOnlineTooltip.setShowDelay(Duration.millis(250));
		final var clip = new Rectangle();
		clip.setWidth(43);
		clip.setHeight(43);
		clip.setArcHeight(43);
		clip.setArcWidth(43);
		clientProfilePic.setClip(clip);

		chatList.setItems(chats = new FilteredList<>(localDB.getChats()));
		contactLabel.setText(localDB.getUser().getName());

		Platform.runLater(() -> {
			final var online = client.isOnline();
			// no check will be performed in case it has already been disabled - a negative
			// GroupCreationResult might have been returned
			if (!newGroupButton.isDisabled()) newGroupButton.setDisable(!online);
			newContactButton.setDisable(!online);
			if (online) try {
				Tooltip.uninstall(contactSpecificOnlineOperations, onlyIfOnlineTooltip);
				contactSearchTab.setContent(new FXMLLoader().load(getClass().getResourceAsStream("/fxml/ContactSearchTab.fxml")));
				groupCreationTab.setContent(new FXMLLoader().load(getClass().getResourceAsStream("/fxml/GroupCreationTab.fxml")));
			} catch (final IOException e) {
				logger.log(Level.SEVERE, "An error occurred when attempting to load tabs: ", e);
			}
			else {
				Tooltip.install(contactSpecificOnlineOperations, onlyIfOnlineTooltip);
				updateInfoLabel("You are offline", "info-label-warning");
			}
		});
	}

	@Event(eventType = BackEvent.class)
	private void onBackEvent() { tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal()); }

	@Event(includeSubtypes = true)
	private void onMessage(Message message) {

		// The sender of the message is the recipient of the chat
		// Exceptions: this user is the sender (sync) or group message (group is
		// recipient)
		final var	ownMessage	= message.getSenderID() == localDB.getUser().getID();
		final var	recipientID	= message instanceof GroupMessage || ownMessage ? message.getRecipientID() : message.getSenderID();

		localDB.getChat(recipientID).ifPresent(chat -> {
			chat.insert(message);

			// Read current chat or increment unread amount
			if (chat.equals(currentChat)) {
				currentChat.read(writeProxy);
				Platform.runLater(this::scrollToMessageListEnd);
			} else if (!ownMessage && message.getStatus() != MessageStatus.READ) chat.incrementUnreadAmount();

			// Move chat with most recent unread messages to the top
			Platform.runLater(() -> {
				chats.getSource().remove(chat);
				((ObservableList<Chat>) chats.getSource()).add(0, chat);

				if (chat.equals(currentChat)) chatList.getSelectionModel().select(0);
			});
		});
	}

	@Event
	private void onMessageStatusChange(MessageStatusChange evt) {

		// Update UI if in current chat and the current user was the sender of the
		// message
		if (currentChat != null) localDB.getMessage(evt.getID())
			.filter(msg -> msg.getSenderID() == client.getSender().getID())
			.ifPresent(msg -> Platform.runLater(messageList::refresh));
	}

	@Event(eventType = UserStatusChange.class)
	private void onUserStatusChange() { Platform.runLater(chatList::refresh); }

	@Event
	private void onContactOperation(ContactOperation operation) {
		final var contact = operation.get();
		switch (operation.getOperationType()) {
			case ADD:
				if (contact instanceof User) localDB.getUsers().put(contact.getName(), (User) contact);
				final var chat = contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact);
				Platform.runLater(() -> ((ObservableList<Chat>) chats.getSource()).add(0, chat));
				break;
			case REMOVE:
				Platform.runLater(() -> chats.getSource().removeIf(c -> c.getRecipient().equals(contact)));
				break;
		}
	}

	@Event(eventType = NoAttachments.class)
	private void onNoAttachments() {
		Platform.runLater(() -> {
			attachmentButton.setDisable(true);
			voiceButton.setDisable(true);
			final var alert = new Alert(AlertType.ERROR);
			alert.setTitle("No attachments possible");
			alert.setHeaderText("Your current server does not support attachments.");
			alert.setContentText("If this is unplanned, please contact your server administrator.");
			alert.showAndWait();
		});
	}

	@Event
	private void onGroupCreationResult(GroupCreationResult result) { Platform.runLater(() -> newGroupButton.setDisable(!result.get())); }

	@Event(eventType = ThemeChangeEvent.class)
	private void onThemeChange() {
		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
		DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
		attachmentView.setImage(isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
		messageList.setCellFactory(MessageListCell::new);
		// TODO: cache image
		if (currentChat.getRecipient() instanceof User) recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
		else recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
	}

	@Event(eventType = Logout.class, priority = 200)
	private void onLogout() { eventBus.removeListener(this); }

	@Override
	public void onRestore() { updateRemainingCharsLabel(); }

	/**
	 * Actions to perform when the list of contacts has been clicked.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void chatListClicked() {
		if (chatList.getSelectionModel().isEmpty()) return;

		final var user = chatList.getSelectionModel().getSelectedItem().getRecipient();
		if (user != null && (currentChat == null || !user.equals(currentChat.getRecipient()))) {

			// LEON: JFC <===> JAVA FRIED CHICKEN <=/=> Java Foundation Classes

			// Load the chat
			currentChat = localDB.getChat(user.getID()).get();

			messageList.setItems(currentChat.getMessages());
			final var scrollIndex = messageList.getItems().size() - currentChat.getUnreadAmount();
			messageList.scrollTo(scrollIndex);
			logger.log(Level.FINEST, "Loading chat with " + user + " at index " + scrollIndex);
			deleteContactMenuItem.setText("Delete " + user.getName());

			// Read the current chat
			currentChat.read(writeProxy);

			// Discard the pending attachment
			if (recorder.isRecording()) {
				recorder.cancel();
				recording = false;
			}
			pendingAttachment = null;
			updateAttachmentView(false);

			remainingChars.setVisible(true);
			remainingChars
				.setText(String.format("remaining chars: %d/%d", MAX_MESSAGE_LENGTH - messageTextArea.getText().length(), MAX_MESSAGE_LENGTH));
		}
		messageTextArea.setDisable(currentChat == null || postingPermanentlyDisabled);
		voiceButton.setDisable(!recorder.isSupported());
		attachmentButton.setDisable(false);
		chatList.refresh();

		if (currentChat != null) {
			topBarContactLabel.setText(currentChat.getRecipient().getName());
			if (currentChat.getRecipient() instanceof User) {
				final var status = ((User) currentChat.getRecipient()).getStatus().toString();
				topBarStatusLabel.setText(status);
				topBarStatusLabel.getStyleClass().add(status.toLowerCase());
				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
			} else {
				topBarStatusLabel.setText(currentChat.getRecipient().getContacts().size() + " members");
				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
			}
			final var clip = new Rectangle();
			clip.setWidth(43);
			clip.setHeight(43);
			clip.setArcHeight(43);
			clip.setArcWidth(43);
			recipientProfilePic.setClip(clip);

			messageSearchButton.setVisible(true);
		}
	}

	/**
	 * Actions to perform when the Settings Button has been clicked.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void settingsButtonClicked() { sceneContext.load(SceneContext.SceneInfo.SETTINGS_SCENE); }

	/**
	 * Actions to perform when the "Add Contact" - Button has been clicked.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void addContactButtonClicked() { tabPane.getSelectionModel().select(Tabs.CONTACT_SEARCH.ordinal()); }

	@FXML
	private void groupCreationButtonClicked() { tabPane.getSelectionModel().select(Tabs.GROUP_CREATION.ordinal()); }

	@FXML
	private void voiceButtonClicked() {
		new Thread(() -> {
			try {
				if (!recording) {
					recording = true;
					Platform.runLater(() -> {
						voiceButton.setText("Recording");
						voiceButton.setGraphic(new ImageView(IconUtil.loadIcon("microphone_recording", DEFAULT_ICON_SIZE)));
					});
					recorder.start();
				} else {
					pendingAttachment	= new Attachment(recorder.finish(), "Voice_recording_"
							+ DateTimeFormatter.ofPattern("yyyy_MM_dd-HH_mm_ss").format(LocalDateTime.now()) + "." + AudioRecorder.FILE_FORMAT,
							AttachmentType.VOICE);
					recording			= false;
					Platform.runLater(() -> {
						voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
						voiceButton.setText(null);
						checkPostConditions(false);
						updateAttachmentView(true);
					});
				}
			} catch (final EnvoyException e) {
				logger.log(Level.SEVERE, "Could not record audio: ", e);
				Platform.runLater(new Alert(AlertType.ERROR, "Could not record audio")::showAndWait);
			}
		}).start();
	}

	@FXML
	private void attachmentButtonClicked() {

		// Display file chooser
		final var fileChooser = new FileChooser();
		fileChooser.setTitle("Add Attachment");
		fileChooser.setInitialDirectory(new File(System.getProperty("user.home")));
		fileChooser.getExtensionFilters()
			.addAll(new FileChooser.ExtensionFilter("Pictures", "*.png", "*.jpg", "*.bmp", "*.gif"),
					new FileChooser.ExtensionFilter("Videos", "*.mp4"),
					new FileChooser.ExtensionFilter("All Files", "*.*"));
		final var file = fileChooser.showOpenDialog(sceneContext.getStage());

		if (file != null) {

			// Check max file size
			if (file.length() > 16E6) {
				new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 16MB!").showAndWait();
				return;
			}

			// Get attachment type (default is document)
			var type = AttachmentType.DOCUMENT;
			switch (fileChooser.getSelectedExtensionFilter().getDescription()) {
				case "Pictures":
					type = AttachmentType.PICTURE;
					break;
				case "Videos":
					type = AttachmentType.VIDEO;
					break;
			}

			// Create the pending attachment
			try {
				final var fileBytes = Files.readAllBytes(file.toPath());
				pendingAttachment = new Attachment(fileBytes, file.getName(), type);
				checkPostConditions(false);
				// Setting the preview image as image of the attachmentView
				if (type == AttachmentType.PICTURE) {
					attachmentView.setImage(new Image(new ByteArrayInputStream(fileBytes), DEFAULT_ICON_SIZE, DEFAULT_ICON_SIZE, true, true));
					isCustomAttachmentImage = true;
				}
				attachmentView.setVisible(true);
			} catch (final IOException e) {
				new Alert(AlertType.ERROR, "The selected file could not be loaded!").showAndWait();
			}
		}
	}

	/**
	 * Rotates every element in our application by {@code rotations}*360° in
	 * {@code an}.
	 *
	 * @param rotations     the amount of times the scene is rotated by 360°
	 * @param animationTime the time in seconds that this animation lasts
	 * @since Envoy Client v0.1-beta
	 */
	public void doABarrelRoll(int rotations, double animationTime) {
		// Limiting the rotations and duration
		rotations		= Math.min(rotations, 100000);
		rotations		= Math.max(rotations, 1);
		animationTime	= Math.min(animationTime, 150);
		animationTime	= Math.max(animationTime, 0.25);

		// contains all Node objects in ChatScene
		final var rotatableNodes = ReflectionUtil.getAllDeclaredNodeVariables(this);
		for (final var node : rotatableNodes) {
			// Sets the animation duration to {animationTime}
			final var rotateTransition = new RotateTransition(Duration.seconds(animationTime), node);
			// rotates every element {rotations} times
			rotateTransition.setByAngle(rotations * 360);
			rotateTransition.play();
			// This is needed as for some strange reason objects could stop before being
			// rotated back to 0°
			rotateTransition.setOnFinished(e -> node.setRotate(0));
		}
	}

	/**
	 * Checks the text length of the {@code messageTextArea}, adjusts the
	 * {@code remainingChars} label and checks whether to send the message
	 * automatically.
	 *
	 * @param e the key event that will be analyzed for a post request
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void checkKeyCombination(KeyEvent e) {

		// Checks whether the text is too long
		messageTextUpdated();

		// Sending an IsTyping event if none has been sent for
		// IsTyping#millisecondsActive
		if (client.isOnline() && currentChat.getLastWritingEvent() + IsTyping.millisecondsActive <= System.currentTimeMillis()) {
			client.send(new IsTyping(getChatID(), currentChat.getRecipient().getID()));
			currentChat.lastWritingEventWasNow();
		}

		// KeyPressed will be called before the char has been added to the text, hence
		// this is needed for the first char
		if (messageTextArea.getText().length() == 1 && e != null) checkPostConditions(e);

		// This is needed for the messageTA context menu
		else if (e == null) checkPostConditions(false);
	}

	/**
	 * Returns the id that should be used to send things to the server: the id of
	 * 'our' {@link User} if the recipient of that object is another User, else the
	 * id of the {@link Group} 'our' user is sending to.
	 *
	 * @return an id that can be sent to the server
	 * @since Envoy Client v0.2-beta
	 */
	private long getChatID() {
		return currentChat.getRecipient() instanceof User ? client.getSender().getID() : currentChat.getRecipient().getID();
	}

	/**
	 * @param e the keys that have been pressed
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void checkPostConditions(KeyEvent e) {
		final var	enterPressed	= e.getCode() == KeyCode.ENTER;
		final var	messagePosted	= enterPressed ? settings.isEnterToSend() ? !e.isControlDown() : e.isControlDown() : false;
		if (messagePosted) {

			// Removing an inserted line break if added by pressing enter
			final var	text			= messageTextArea.getText();
			final var	textPosition	= messageTextArea.getCaretPosition() - 1;
			if (!e.isControlDown() && !text.isEmpty() && text.charAt(textPosition) == '\n')
				messageTextArea.setText(new StringBuilder(text).deleteCharAt(textPosition).toString());
		}

		// if control is pressed, the enter press is originally invalidated. Here it'll
		// be inserted again
		else if (enterPressed && e.isControlDown()) {
			var caretPosition = messageTextArea.getCaretPosition();
			messageTextArea.setText(new StringBuilder(messageTextArea.getText()).insert(caretPosition, '\n').toString());
			messageTextArea.positionCaret(++caretPosition);
		}
		checkPostConditions(messagePosted);
	}

	private void checkPostConditions(boolean postMessage) {
		if (!postingPermanentlyDisabled) {
			if (!postButton.isDisabled() && postMessage) postMessage();
			postButton.setDisable(messageTextArea.getText().isBlank() && pendingAttachment == null || currentChat == null);
		} else {
			final var noMoreMessaging = "Go online to send messages";
			if (!infoLabel.getText().equals(noMoreMessaging))
				// Informing the user that he is a f*cking moron and should use Envoy online
				// because he ran out of messageIDs to use
				updateInfoLabel(noMoreMessaging, "info-label-error");
		}
	}

	/**
	 * Actions to perform when the text was updated in the messageTextArea.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void messageTextUpdated() {
		// Truncating messages that are too long and staying at the same position
		if (messageTextArea.getText().length() >= MAX_MESSAGE_LENGTH) {
			messageTextArea.setText(messageTextArea.getText().substring(0, MAX_MESSAGE_LENGTH));
			messageTextArea.positionCaret(MAX_MESSAGE_LENGTH);
			messageTextArea.setScrollTop(Double.MAX_VALUE);
		}
		updateRemainingCharsLabel();
	}

	/**
	 * Sets the text and text color of the {@code remainingChars} label.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	private void updateRemainingCharsLabel() {
		final var	currentLength	= messageTextArea.getText().length();
		final var	remainingLength	= MAX_MESSAGE_LENGTH - currentLength;
		remainingChars.setText(String.format("remaining chars: %d/%d", remainingLength, MAX_MESSAGE_LENGTH));
		remainingChars.setTextFill(Color.rgb(currentLength, remainingLength, 0, 1));
	}

	/**
	 * Sends a new {@link Message} or {@link GroupMessage} to the server based on
	 * the text entered in the {@code messageTextArea} and the given attachment.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void postMessage() {
		postingPermanentlyDisabled = !(client.isOnline() || localDB.getIDGenerator().hasNext());
		if (postingPermanentlyDisabled) {
			postButton.setDisable(true);
			messageTextArea.setDisable(true);
			messageTextArea.clear();
			updateInfoLabel("You need to go online to send more messages", "info-label-error");
			return;
		}
		final var text = messageTextArea.getText().strip();
		if (!commands.getChatSceneCommands().executeIfAnyPresent(text)) {
			// Creating the message and its metadata
			final var builder = new MessageBuilder(localDB.getUser().getID(), currentChat.getRecipient().getID(), localDB.getIDGenerator())
				.setText(text);
			// Setting an attachment, if present
			if (pendingAttachment != null) {
				builder.setAttachment(pendingAttachment);
				pendingAttachment = null;
				updateAttachmentView(false);
			}
			// Building the final message
			final var message = currentChat.getRecipient() instanceof Group ? builder.buildGroupMessage((Group) currentChat.getRecipient())
					: builder.build();

			// Send message
			writeProxy.writeMessage(message);

			// Add message to LocalDB and update UI
			currentChat.insert(message);
			// Moving currentChat to the top
			Platform.runLater(() -> {
				chats.getSource().remove(currentChat);
				((ObservableList<Chat>) chats.getSource()).add(0, currentChat);
				chatList.getSelectionModel().select(0);
				localDB.getChats().remove(currentChat);
				localDB.getChats().add(0, currentChat);
			});
			scrollToMessageListEnd();

			// Request a new ID generator if all IDs were used
			if (!localDB.getIDGenerator().hasNext() && client.isOnline()) client.requestIDGenerator();
		}

		// Clear text field and disable post button
		messageTextArea.setText("");
		postButton.setDisable(true);
		updateRemainingCharsLabel();
		isCustomAttachmentImage = false;
	}

	/**
	 * Scrolls to the bottom of the {@code messageList}.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	private void scrollToMessageListEnd() { messageList.scrollTo(messageList.getItems().size() - 1); }

	/**
	 * Updates the {@code infoLabel}.
	 *
	 * @param text        the text to use
	 * @param infoLabelID the id the the {@code infoLabel} should have so that it
	 *                    can be styled accordingly in CSS
	 * @since Envoy Client v0.1-beta
	 */
	private void updateInfoLabel(String text, String infoLabelID) {
		infoLabel.setText(text);
		infoLabel.setId(infoLabelID);
		infoLabel.setVisible(true);
	}

	/**
	 * Updates the {@code attachmentView} in terms of visibility.<br>
	 * Additionally resets the shown image to {@code DEFAULT_ATTACHMENT_VIEW_IMAGE}
	 * if another image is currently present.
	 *
	 * @param visible whether the {@code attachmentView} should be displayed
	 * @since Envoy Client v0.1-beta
	 */
	private void updateAttachmentView(boolean visible) {
		if (!attachmentView.getImage().equals(DEFAULT_ATTACHMENT_VIEW_IMAGE)) attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
		attachmentView.setVisible(visible);
	}

	// Context menu actions

	@FXML
	private void deleteContact() { try {} catch (final NullPointerException e) {} }

	@FXML
	private void copyAndPostMessage() {
		final var messageText = messageTextArea.getText();
		Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(messageText), null);
		final var	image				= attachmentView.getImage();
		final var	messageAttachment	= pendingAttachment;
		postMessage();
		messageTextArea.setText(messageText);
		updateRemainingCharsLabel();
		postButton.setDisable(messageText.isBlank());
		attachmentView.setImage(image);
		if (attachmentView.getImage() != null) attachmentView.setVisible(true);
		pendingAttachment = messageAttachment;
	}

	/**
	 * Clears the current message selection.
	 *
	 * @since Envoy Client v0.3-beta
	 */
	public void clearMessageSelection() { messageList.getSelectionModel().clearSelection(); }

	@FXML
	private void searchContacts() {
		chats.setPredicate(contactSearch.getText().isBlank() ? c -> true
				: c -> c.getRecipient().getName().toLowerCase().contains(contactSearch.getText().toLowerCase()));
	}
}