package envoy.client.ui.controller;

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.stream.Collectors;

import javafx.application.Platform;
import javafx.collections.FXCollections;
import javafx.fxml.FXML;
import javafx.scene.control.*;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;

import envoy.client.data.Chat;
import envoy.client.data.LocalDB;
import envoy.client.data.Settings;
import envoy.client.event.MessageCreationEvent;
import envoy.client.net.Client;
import envoy.client.net.WriteProxy;
import envoy.client.ui.ContactListCell;
import envoy.client.ui.MessageListCell;
import envoy.client.ui.SceneContext;
import envoy.data.*;
import envoy.event.EventBus;
import envoy.event.MessageStatusChangeEvent;
import envoy.event.UserStatusChangeEvent;
import envoy.event.contact.ContactOperationEvent;
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 {

	@FXML
	private Label contactLabel;

	@FXML
	private ListView<Message> messageList;

	@FXML
	private ListView<Contact> userList;

	@FXML
	private Button postButton;

	@FXML
	private Button settingsButton;

	@FXML
	private TextArea messageTextArea;

	@FXML
	private Label remainingChars;

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

	private Chat currentChat;

	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 int		MAX_MESSAGE_LENGTH	= 255;

	/**
	 * Initializes the appearance of certain visual components.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void initialize() {

		// Initialize message and user rendering
		messageList.setCellFactory(listView -> new MessageListCell());
		userList.setCellFactory(listView -> new ContactListCell());

		// Listen to received messages
		eventBus.register(MessageCreationEvent.class, e -> {
			final var message = e.get();
			localDB.getChat(message.getSenderID()).ifPresent(chat -> {
				chat.getMessages().add(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);
				}
			});
		});

		// Listen to message status changes
		eventBus.register(MessageStatusChangeEvent.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);
		}));

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

		// Listen to contacts changes
		eventBus.register(ContactOperationEvent.class, e -> {
			final var contact = e.get();
			switch (e.getOperationType()) {
				case ADD:
					localDB.getUsers().put(contact.getName(), contact);
					localDB.getChats().add(new Chat(contact));
					Platform.runLater(() -> userList.getItems().add(contact));
					break;
				case REMOVE:
					localDB.getUsers().remove(contact.getName());
					localDB.getChats().removeIf(c -> c.getRecipient().getID() == contact.getID());
					Platform.runLater(() -> userList.getItems().removeIf(c -> c.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;

		userList.setItems(FXCollections.observableList(localDB.getChats().stream().map(Chat::getRecipient).collect(Collectors.toList())));
	}

	/**
	 * Actions to perform when the list of contacts has been clicked.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void userListClicked() {
		final Contact user = userList.getSelectionModel().getSelectedItem();
		if (user != null && (currentChat == null || !user.equals(currentChat.getRecipient()))) {
			contactLabel.setText(user.getName());

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

			// Load the chat or create a new one and add it to the LocalDB
			currentChat = localDB.getChat(user.getID())
				.orElseGet(() -> { final var chat = new Chat(user); localDB.getChats().add(chat); return chat; });

			messageList.setItems(FXCollections.observableList(currentChat.getMessages()));

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

			remainingChars.setVisible(true);
			remainingChars
				.setText(String.format("remaining chars: %d/%d", MAX_MESSAGE_LENGTH - messageTextArea.getText().length(), MAX_MESSAGE_LENGTH));
		}
		messageTextArea.setDisable(currentChat == null);
	}

	/**
	 * 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);
	}

	/**
	 * 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) {
		if (!postButton.isDisabled() && (settings.isEnterToSend() && e.getCode() == KeyCode.ENTER
				|| !settings.isEnterToSend() && e.getCode() == KeyCode.ENTER && e.isControlDown()))
			postMessage();
		postButton.setDisable(messageTextArea.getText().isBlank() || currentChat == null);
	}

	/**
	 * 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 message to the server based on the text entered in the
	 * messageTextArea.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@FXML
	private void postMessage() {
		final var text = messageTextArea.getText().strip();
		if (text.isBlank()) throw new IllegalArgumentException("A message without visible text can not be sent.");
		try {
			// Create and send message
			final var message = new MessageBuilder(localDB.getUser().getID(), currentChat.getRecipient().getID(), localDB.getIDGenerator())
				.setText(text)
				.build();

			// Send message
			writeProxy.writeMessage(message);

			// Add message to LocalDB and update UI
			messageList.getItems().add(message);

			// 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();
	}
}