package envoy.client.ui;

import java.io.*;
import java.time.Instant;
import java.util.concurrent.TimeoutException;
import java.util.logging.*;

import javafx.application.Application;
import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;
import javafx.stage.Stage;

import envoy.client.data.*;
import envoy.client.event.EnvoyCloseEvent;
import envoy.client.net.Client;
import envoy.client.ui.SceneContext.SceneInfo;
import envoy.client.ui.controller.LoginScene;
import envoy.data.*;
import envoy.data.User.UserStatus;
import envoy.event.*;
import envoy.exception.EnvoyException;
import envoy.util.EnvoyLog;

import dev.kske.eventbus.EventBus;

/**
 * Handles application startup and shutdown.
 * <p>
 * Project: <strong>envoy-client</strong><br>
 * File: <strong>Startup.java</strong><br>
 * Created: <strong>26.03.2020</strong><br>
 *
 * @author Kai S. K. Engelbart
 * @author Maximilian K&auml;fer
 * @since Envoy Client v0.1-beta
 */
public final class Startup extends Application {

	/**
	 * The version of this client. Used to verify compatibility with the server.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	public static final String VERSION = "0.1-beta";

	private static LocalDB localDB;

	private static final Context		context	= Context.getInstance();
	private static final Client			client	= context.getClient();
	private static final ClientConfig	config	= ClientConfig.getInstance();
	private static final Logger			logger	= EnvoyLog.getLogger(Startup.class);

	/**
	 * Loads the configuration, initializes the client and the local database and
	 * delegates the rest of the startup process to {@link LoginScene}.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	@Override
	public void start(Stage stage) throws Exception {
		try {
			config.loadAll(Startup.class, "client.properties", getParameters().getRaw().toArray(new String[0]));
			EnvoyLog.initialize(config);
		} catch (final IllegalStateException e) {
			new Alert(AlertType.ERROR, "Error loading configuration values:\n" + e);
			logger.log(Level.SEVERE, "Error loading configuration values: ", e);
			System.exit(1);
		}
		logger.log(Level.INFO, "Envoy starting...");

		// Initialize the local database
		try {
			final var localDBDir = new File(config.getHomeDirectory(), config.getLocalDB().getPath());
			logger.info("Initializing LocalDB at " + localDBDir);
			localDB = new LocalDB(localDBDir);
		} catch (IOException | EnvoyException e) {
			logger.log(Level.SEVERE, "Could not initialize local database: ", e);
			new Alert(AlertType.ERROR, "Could not initialize local database!\n" + e).showAndWait();
			System.exit(1);
			return;
		}

		// Prepare handshake
		context.setLocalDB(localDB);

		// Configure stage
		stage.setTitle("Envoy");
		stage.getIcons().add(IconUtil.loadIcon("envoy_logo"));

		// Create scene context
		final var sceneContext = new SceneContext(stage);
		context.setSceneContext(sceneContext);

		// Authenticate with token if present
		if (localDB.getAuthToken() != null) {
			logger.info("Attempting authentication with token...");
			localDB.loadUserData();
			if (!performHandshake(
					LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(), VERSION, localDB.getLastSync())))
				sceneContext.load(SceneInfo.LOGIN_SCENE);
		} else
			// Load login scene
			sceneContext.load(SceneInfo.LOGIN_SCENE);
	}

	/**
	 * Tries to perform a Handshake with the server.
	 *
	 * @param credentials the credentials to use for the handshake
	 * @return whether the handshake was successful or offline mode could be entered
	 * @since Envoy Client v0.2-beta
	 */
	public static boolean performHandshake(LoginCredentials credentials) {
		final var cacheMap = new CacheMap();
		cacheMap.put(Message.class, new Cache<Message>());
		cacheMap.put(GroupMessage.class, new Cache<GroupMessage>());
		cacheMap.put(MessageStatusChange.class, new Cache<MessageStatusChange>());
		cacheMap.put(GroupMessageStatusChange.class, new Cache<GroupMessageStatusChange>());
		try {
			final var client = context.getClient();
			client.performHandshake(credentials, cacheMap);
			if (client.isOnline()) {
				loadChatScene();
				client.initReceiver(localDB, cacheMap);
				return true;
			} else return false;
		} catch (IOException | InterruptedException | TimeoutException e) {
			logger.log(Level.INFO, "Could not connect to server. Entering offline mode...");
			return attemptOfflineMode(credentials.getIdentifier());
		}
	}

	/**
	 * Attempts to load {@link envoy.client.ui.controller.ChatScene} in offline mode
	 * for a given user.
	 *
	 * @param identifier the identifier of the user - currently his username
	 * @return whether the offline mode could be entered
	 * @since Envoy Client v0.2-beta
	 */
	public static boolean attemptOfflineMode(String identifier) {
		try {
			// Try entering offline mode
			final User clientUser = localDB.getUsers().get(identifier);
			if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
			client.setSender(clientUser);
			loadChatScene();
			return true;
		} catch (final Exception e) {
			new Alert(AlertType.ERROR, "Client error: " + e).showAndWait();
			logger.log(Level.SEVERE, "Offline mode could not be loaded: ", e);
			System.exit(1);
			return false;
		}
	}

	/**
	 * Loads the last known time a user has been online.
	 *
	 * @param identifier the identifier of this user - currently his name
	 * @return the last {@code Instant} at which he has been online
	 * @since Envoy Client v0.2-beta
	 */
	public static Instant loadLastSync(String identifier) {
		try {
			localDB.setUser(localDB.getUsers().get(identifier));
			localDB.loadUserData();
		} catch (final Exception e) {
			// User storage empty, wrong user name etc. -> default lastSync
		}
		return localDB.getLastSync();
	}

	private static void loadChatScene() {

		// Set client user in local database
		localDB.setUser(client.getSender());

		// Initialize chats in local database
		try {
			localDB.loadUserData();
		} catch (final FileNotFoundException e) {
			// The local database file has not yet been created, probably first login
		} catch (final Exception e) {
			new Alert(AlertType.ERROR, "Error while loading local database: " + e + "\nChats will not be stored locally.").showAndWait();
			logger.log(Level.WARNING, "Could not load local database: ", e);
		}

		context.initWriteProxy();

		if (client.isOnline()) context.getWriteProxy().flushCache();
		else
			// Set all contacts to offline mode
			localDB.getChats()
				.stream()
				.map(Chat::getRecipient)
				.filter(User.class::isInstance)
				.map(User.class::cast)
				.forEach(u -> u.setStatus(UserStatus.OFFLINE));

		final var stage = context.getStage();

		// Pop LoginScene if present
		if (!context.getSceneContext().isEmpty()) context.getSceneContext().pop();

		// Load ChatScene
		stage.setMinHeight(400);
		stage.setMinWidth(843);
		context.getSceneContext().load(SceneContext.SceneInfo.CHAT_SCENE);
		stage.centerOnScreen();

		if (StatusTrayIcon.isSupported()) {

			// Configure hide on close
			stage.setOnCloseRequest(e -> {
				if (Settings.getInstance().isHideOnClose()) {
					stage.setIconified(true);
					e.consume();
				} else EventBus.getInstance().dispatch(new EnvoyCloseEvent());
			});

			// Initialize status tray icon
			final var trayIcon = new StatusTrayIcon(stage);
			Settings.getInstance().getItems().get("hideOnClose").setChangeHandler(c -> {
				if ((Boolean) c) trayIcon.show();
				else trayIcon.hide();
			});
		}
	}
}