package envoy.client.ui.controller;

import java.awt.Toolkit;
import java.awt.datatransfer.StringSelection;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;

import javafx.animation.RotateTransition;
import javafx.application.Platform;
import javafx.collections.FXCollections;
import javafx.fxml.FXML;
import javafx.scene.Node;
import javafx.scene.control.*;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.GridPane;
import javafx.scene.paint.Color;
import javafx.stage.FileChooser;
import javafx.util.Duration;

import envoy.client.data.*;
import envoy.client.data.audio.AudioRecorder;
import envoy.client.event.MessageCreationEvent;
import envoy.client.net.Client;
import envoy.client.net.WriteProxy;
import envoy.client.ui.IconUtil;
import envoy.client.ui.Restorable;
import envoy.client.ui.SceneContext;
import envoy.client.ui.listcell.ContactListCellFactory;
import envoy.client.ui.listcell.MessageControl;
import envoy.client.ui.listcell.MessageListCellFactory;
import envoy.data.*;
import envoy.data.Attachment.AttachmentType;
import envoy.event.*;
import envoy.event.contact.ContactOperation;
import envoy.exception.EnvoyException;
import envoy.util.EnvoyLog;

/**
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>ChatSceneController.java</strong><br>
 * Created: <strong>26.03.2020</strong><br>
 *
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.1-beta
 */
public final class ChatScene implements 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 rotateButton;

	@FXML
	private TextArea messageTextArea;

	@FXML
	private Label remainingChars;

	@FXML
	private Label infoLabel;

	@FXML
	private MenuItem deleteContactMenuItem;

	@FXML
	private ImageView attachmentView;

	private LocalDB			localDB;
	private Client			client;
	private WriteProxy		writeProxy;
	private SceneContext	sceneContext;

	private Chat			currentChat;
	private AudioRecorder	recorder;
	private boolean			recording;
	private Attachment		pendingAttachment;
	private boolean			postingPermanentlyDisabled;

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

		// Initialize message and user rendering
		messageList.setCellFactory(MessageListCellFactory::new);
		chatList.setCellFactory(ContactListCellFactory::new);

		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);
		rotateButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("rotate", (int) (DEFAULT_ICON_SIZE * 1.5))));

		// Listen to received messages
		eventBus.register(MessageCreationEvent.class, e -> {
			final var message = e.get();
			localDB.getChat(message instanceof GroupMessage ? message.getRecipientID() : message.getSenderID()).ifPresent(chat -> {
				chat.insert(message);
				if (chat.equals(currentChat)) {
					try {
						currentChat.read(writeProxy);
					} catch (final IOException e1) {
						logger.log(Level.WARNING, "Could not read current chat: ", e1);
					}
					Platform.runLater(() -> { messageList.refresh(); scrollToMessageListEnd(); });
				} else chat.incrementUnreadAmount();
				// Moving chat with most recent unreadMessages to the top
				Platform.runLater(() -> {
					chatList.getItems().remove(chat);
					chatList.getItems().add(0, chat);
					if (chat.equals(currentChat)) chatList.getSelectionModel().select(0);
					localDB.getChats().remove(chat);
					localDB.getChats().add(0, chat);
				});
			});
		});

		// Listen to message status changes
		eventBus.register(MessageStatusChange.class, e -> localDB.getMessage(e.getID()).ifPresent(message -> {
			message.setStatus(e.get());
			// Update UI if in current chat
			if (currentChat != null && message.getSenderID() == currentChat.getRecipient().getID()) Platform.runLater(messageList::refresh);
		}));

		eventBus.register(GroupMessageStatusChange.class, e -> localDB.getMessage(e.getID()).ifPresent(groupMessage -> {
			((GroupMessage) groupMessage).getMemberStatuses().replace(e.getMemberID(), e.get());

			// Update UI if in current chat
			if (currentChat != null && groupMessage.getRecipientID() == currentChat.getRecipient().getID()) Platform.runLater(messageList::refresh);
		}));

		// Listen to user status changes
		eventBus.register(UserStatusChange.class,
				e -> chatList.getItems()
					.stream()
					.filter(c -> c.getRecipient().getID() == e.getID())
					.findAny()
					.map(Chat::getRecipient)
					.ifPresent(u -> { ((User) u).setStatus(e.get()); Platform.runLater(chatList::refresh); }));

		// Listen to contacts changes
		eventBus.register(ContactOperation.class, e -> {
			final var contact = e.get();
			switch (e.getOperationType()) {
				case ADD:
					localDB.getUsers().put(contact.getName(), contact);
					Chat chat = contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact);
					localDB.getChats().add(chat);
					Platform.runLater(() -> chatList.getItems().add(chat));
					break;
				case REMOVE:
					localDB.getUsers().remove(contact.getName());
					localDB.getChats().removeIf(c -> c.getRecipient().getID() == contact.getID());
					Platform.runLater(() -> chatList.getItems().removeIf(c -> c.getRecipient().getID() == contact.getID()));
					break;
			}
		});
	}

	/**
	 * Initializes all necessary data via dependency injection-
	 *
	 * @param sceneContext the scene context used to load other scenes
	 * @param localDB      the local database form which chats and users are loaded
	 * @param client       the client used to request ID generators
	 * @param writeProxy   the write proxy used to send messages and other data to
	 *                     the server
	 * @since Envoy Client v0.1-beta
	 */
	public void initializeData(SceneContext sceneContext, LocalDB localDB, Client client, WriteProxy writeProxy) {
		this.sceneContext	= sceneContext;
		this.localDB		= localDB;
		this.client			= client;
		this.writeProxy		= writeProxy;

		chatList.setItems(FXCollections.observableList(localDB.getChats()));
		contactLabel.setText(localDB.getUser().getName());
		MessageControl.setUser(localDB.getUser());
		if (!client.isOnline()) updateInfoLabel("You are offline", "infoLabel-info");

		recorder = new AudioRecorder();
	}

	@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() {
		final Contact 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(FXCollections.observableList(currentChat.getMessages()));
			final var scrollIndex = messageList.getItems().size() - currentChat.getUnreadAmount() - 1;
			messageList.scrollTo(scrollIndex);
			logger.log(Level.FINEST, "Loading chat with " + user + " at index " + scrollIndex);
			deleteContactMenuItem.setText("Delete " + user.getName());

			// Read the current chat
			try {
				currentChat.read(writeProxy);
			} catch (final IOException e) {
				logger.log(Level.WARNING, "Could not read current chat.", e);
			}

			// 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();
	}

	/**
	 * 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);
		sceneContext.<SettingsScene>getController().initializeData(sceneContext);
	}

	/**
	 * Actions to perform when the "Add Contact" - Button has been clicked.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void addContactButtonClicked() {
		sceneContext.load(SceneContext.SceneInfo.CONTACT_SEARCH_SCENE);
		sceneContext.<ContactSearchScene>getController().initializeData(sceneContext, localDB);
	}

	@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(), 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)
			AttachmentType 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, type);
				// 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));
				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 360° in at most 2.75s.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void doABarrelRoll() {
		// contains all Node objects in ChatScene in alphabetical order
		final var	rotatableNodes	= new Node[] { attachmentButton, attachmentView, contactLabel, infoLabel, messageList, messageTextArea,
				postButton, remainingChars, rotateButton, scene, settingsButton, chatList, voiceButton };
		final var	random			= new Random();
		for (final var node : rotatableNodes) {
			// Defines at most four whole rotation in at most 4s
			final var rotateTransition = new RotateTransition(Duration.seconds(random.nextDouble() * 3 + 1), node);
			rotateTransition.setByAngle((random.nextInt(3) + 1) * 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();
		// Automatic sending of messages via (ctrl +) enter
		checkPostConditions(e);
	}

	/**
	 * @param e the keys that have been pressed
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void checkPostConditions(KeyEvent e) {
		checkPostConditions(settings.isEnterToSend() && e.getCode() == KeyCode.ENTER
				|| !settings.isEnterToSend() && e.getCode() == KeyCode.ENTER && e.isControlDown());
	}

	private void checkPostConditions(boolean sendKeyPressed) {
		if (!postingPermanentlyDisabled) {
			if (!postButton.isDisabled() && sendKeyPressed) 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, "infoLabel-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 int	currentLength	= messageTextArea.getText().length();
		final int	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", "infoLabel-error");
			return;
		}
		final var text = messageTextArea.getText().strip();
		try {
			// 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(() -> {
				chatList.getItems().remove(currentChat);
				chatList.getItems().add(0, currentChat);
				chatList.getSelectionModel().select(0);
				localDB.getChats().remove(currentChat);
				localDB.getChats().add(0, currentChat);
			});
			messageList.refresh();
			scrollToMessageListEnd();

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

		} catch (final IOException e) {
			logger.log(Level.SEVERE, "Error while sending message: ", e);
			new Alert(AlertType.ERROR, "An error occured while sending the message!").showAndWait();
		}

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

	/**
	 * 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);
		postMessage();
		messageTextArea.setText(messageText);
		updateRemainingCharsLabel();
		postButton.setDisable(messageText.isBlank());
	}
}