package envoy.client.ui;

import static java.awt.Image.SCALE_SMOOTH;

import java.awt.*;
import java.awt.TrayIcon.MessageType;
import java.awt.image.BufferedImage;

import javafx.application.Platform;
import javafx.stage.Stage;

import dev.kske.eventbus.core.Event;
import dev.kske.eventbus.core.EventBus;

import envoy.data.Message;
import envoy.data.User.UserStatus;

import envoy.client.data.*;
import envoy.client.event.*;
import envoy.client.helper.ShutdownHelper;
import envoy.client.util.*;

/**
 * A tray icon with the Envoy logo, an "Envoy" tool tip and a pop-up menu with menu items for
 * <ul>
 * <li>Changing the user status</li>
 * <li>Logging out</li>
 * <li>Quitting Envoy</li>
 * </ul>
 *
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.2-alpha
 */
public final class StatusTrayIcon {

	/**
	 * The {@link TrayIcon} provided by the System Tray API for controlling the system tray. This
	 * includes displaying the icon, but also creating notifications when new messages are received.
	 */
	private final TrayIcon trayIcon;

	/**
	 * A received {@link Message} is only displayed as a system tray notification if this variable
	 * is set to {@code true}.
	 */
	private boolean displayMessageNotification;

	/**
	 * The size of the tray icon's image.
	 */
	private final Dimension size;

	/**
	 * The Envoy logo on which the current user status and unread message count will be drawn to
	 * compose the tray icon.
	 */
	private final Image logo;

	private static final Font unreadMessageFont = new Font("sans-serif", Font.PLAIN, 8);

	/**
	 * @return {@code true} if the status tray icon is supported on this platform
	 * @since Envoy Client v0.2-beta
	 */
	public static boolean isSupported() { return SystemTray.isSupported(); }

	/**
	 * Creates a {@link StatusTrayIcon} with the Envoy logo, a tool tip and a pop-up menu.
	 *
	 * @param stage the stage whose focus determines if message notifications are displayed
	 * @since Envoy Client v0.2-beta
	 */
	public StatusTrayIcon(Stage stage) {
		size	= SystemTray.getSystemTray().getTrayIconSize();
		logo	= IconUtil.loadAWTCompatible("/icons/envoy_logo.png").getScaledInstance(size.width,
			size.height, SCALE_SMOOTH);

		final var popup = new PopupMenu();

		// Adding the exit menu item
		final var exitMenuItem = new MenuItem("Exit");
		exitMenuItem.addActionListener(evt -> ShutdownHelper.exit(true));
		popup.add(exitMenuItem);

		// Adding the logout menu item
		final var logoutMenuItem = new MenuItem("Logout");
		logoutMenuItem.addActionListener(evt -> Platform.runLater(UserUtil::logout));
		popup.add(logoutMenuItem);

		// Adding the status change items
		final var statusSubMenu = new Menu("Change status");
		for (final var status : UserStatus.values()) {
			final var statusMenuItem = new MenuItem(status.toString().toLowerCase());
			statusMenuItem
				.addActionListener(evt -> Platform.runLater(() -> UserUtil.changeStatus(status)));
			statusSubMenu.add(statusMenuItem);
		}
		popup.add(statusSubMenu);

		// Initialize the icon
		trayIcon = new TrayIcon(createImage(), "Envoy", popup);

		// Only display messages if the stage is not focused and the current user status
		// is not BUSY (if BUSY, displayMessageNotification will be false)
		stage.focusedProperty()
			.addListener((ov, wasFocused, isFocused) -> displayMessageNotification =
				!displayMessageNotification && wasFocused ? false : !isFocused);

		// Listen to changes in the total unread message amount
		Chat.getTotalUnreadAmount().addListener((ov, oldValue, newValue) -> updateImage());

		// Show the window if the user clicks on the icon
		trayIcon.addActionListener(evt -> Platform.runLater(() -> {
			stage.setIconified(false);
			stage.toFront();
			stage.requestFocus();
		}));

		// Start processing message events
		EventBus.getInstance().registerListener(this);
	}

	/**
	 * Makes the icon appear in the system tray.
	 *
	 * @since Envoy Client v0.2-alpha
	 */
	public void show() {
		try {
			SystemTray.getSystemTray().add(trayIcon);
		} catch (AWTException e) {}
	}

	/**
	 * Removes the icon from the system tray.
	 *
	 * @since Envoy Client v0.2-beta
	 */
	@Event(Logout.class)
	public void hide() {
		SystemTray.getSystemTray().remove(trayIcon);
	}

	@Event
	private void onOwnStatusChange(OwnStatusChange statusChange) {
		displayMessageNotification = !statusChange.get().equals(UserStatus.BUSY);
		trayIcon.getImage().flush();
		trayIcon.setImage(createImage());
	}

	@Event
	private void onMessage(Message message) {
		if (displayMessageNotification)
			trayIcon
				.displayMessage(message.hasAttachment()
					? "New " + message.getAttachment().getType().toString().toLowerCase()
						+ " message received"
					: "New message received", message.getText(), MessageType.INFO);
	}

	/**
	 * Updates the tray icon's image by first releasing the resources held by the current image and
	 * then setting a new one generated by the {@link StatusTrayIcon#createImage()} method.
	 *
	 * @since Envoy Client v0.3-beta
	 */
	private void updateImage() {
		trayIcon.getImage().flush();
		trayIcon.setImage(createImage());
	}

	/**
	 * Composes an icon that displays the current user status and the amount of unread messages, if
	 * any are present.
	 *
	 * @since Envoy Client v0.3-beta
	 */
	private BufferedImage createImage() {

		// Create a new image with the dimensions of the logo
		var img = new BufferedImage(size.width, size.height, BufferedImage.TYPE_INT_ARGB);

		// Obtain the draw graphics of the image and copy the logo
		var g = img.createGraphics();
		g.drawImage(logo, 0, 0, null);

		// Draw the current user status
		switch (Context.getInstance().getLocalDB().getUser().getStatus()) {
			case ONLINE:
				g.setColor(Color.GREEN);
				break;
			case AWAY:
				g.setColor(Color.ORANGE);
				break;
			case BUSY:
				g.setColor(Color.RED);
				break;
			case OFFLINE:
				g.setColor(Color.GRAY);
		}
		g.fillOval(size.width / 2, size.height / 2, size.width / 2, size.height / 2);

		// Draw total amount of unread messages, if any are present
		if (Chat.getTotalUnreadAmount().get() > 0) {

			// Draw black background circle
			g.setColor(Color.BLACK);
			g.fillOval(size.width / 2, 0, size.width / 2, size.height / 2);

			// Unread amount in white
			String unreadAmount = Chat.getTotalUnreadAmount().get() > 9 ? "9+"
				: String.valueOf(Chat.getTotalUnreadAmount().get());
			g.setColor(Color.WHITE);
			g.setFont(unreadMessageFont);
			g.drawString(unreadAmount,
				3 * size.width / 4 - g.getFontMetrics().stringWidth(unreadAmount) / 2,
				size.height / 2);
		}

		// Finish drawing
		g.dispose();
		return img;
	}
}