/*
 * Copyright 2021 dorkbox, llc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package dorkbox.systemTray.ui.gtk;

import static dorkbox.jna.linux.Gtk.Gtk2;

import java.io.File;
import java.util.concurrent.atomic.AtomicBoolean;

import com.sun.jna.Pointer;

import dorkbox.javaFx.JavaFx;
import dorkbox.jna.linux.GEventCallback;
import dorkbox.jna.linux.GObject;
import dorkbox.jna.linux.GtkEventDispatch;
import dorkbox.jna.linux.structs.GdkEventButton;
import dorkbox.systemTray.MenuItem;
import dorkbox.systemTray.Tray;
import dorkbox.systemTray.util.ImageResizeUtil;

/**
 * Class for handling all system tray interactions via GTK.
 * <p/>
 * This is the "old" way to do it, and does not work with some newer desktop environments.
 */
@SuppressWarnings("Duplicates")
public final
class _GtkStatusIconNativeTray extends Tray {
    private volatile Pointer trayIcon;

    // http://code.metager.de/source/xref/gnome/Platform/gtk%2B/gtk/deprecated/gtkstatusicon.c
    // https://github.com/djdeath/glib/blob/master/gobject/gobject.c

    // have to save these in a field to prevent GC on the objects (since they go out-of-scope from java)
    // see: https://github.com/java-native-access/jna/blob/master/www/CallbacksAndClosures.md
    private GEventCallback gtkCallback = null;

    // This is required if we have JavaFX or SWT shutdown hooks (to prevent us from shutting down twice...)
    private final AtomicBoolean shuttingDown = new AtomicBoolean();

    private volatile boolean isActive = false;

    // is the system tray visible or not.
    private volatile boolean visible = true;
    private volatile File imageFile;
    private volatile String tooltipText = "";

    private final GtkMenu gtkMenu;

    // called on the EDT
    public
    _GtkStatusIconNativeTray(final String trayName, final ImageResizeUtil imageResizeUtil, final Runnable onRemoveEvent) {
        super(onRemoveEvent);

        // setup some GTK menu bits...
        GtkBaseMenuItem.transparentIcon = imageResizeUtil.getTransparentImage();
        GtkMenuItemCheckbox.uncheckedFile = imageResizeUtil.getTransparentImage().getAbsolutePath();

        // we override various methods, because each tray implementation is SLIGHTLY different. This allows us customization.
        gtkMenu = new GtkMenu() {
            @Override
            public
            void setEnabled(final MenuItem menuItem) {
                GtkEventDispatch.dispatch(()->{
                    boolean enabled = menuItem.getEnabled();

                    if (visible && !enabled) {
                        Gtk2.gtk_status_icon_set_visible(trayIcon, false);
                        visible = false;
                    }
                    else if (!visible && enabled) {
                        Gtk2.gtk_status_icon_set_visible(trayIcon, true);
                        visible = true;
                    }
                });
            }

            @Override
            public
            void setImage(final MenuItem menuItem) {
                imageFile = menuItem.getImage();
                if (imageFile == null) {
                    return;
                }

                GtkEventDispatch.dispatch(()->{
                    Gtk2.gtk_status_icon_set_from_file(trayIcon, imageFile.getAbsolutePath());

                    if (!isActive) {
                        isActive = true;
                        Gtk2.gtk_status_icon_set_visible(trayIcon, true);
                    }
                });
            }

            @Override
            public
            void setText(final MenuItem menuItem) {
                // no op
            }

            @Override
            public
            void setShortcut(final MenuItem menuItem) {
                // no op
            }

            @Override
            public
            void setTooltip(final MenuItem menuItem) {
                final String text = menuItem.getTooltip();

                if (tooltipText != null && tooltipText.equals(text) ||
                    tooltipText == null && text != null) {
                    return;
                }

                tooltipText = text;

                GtkEventDispatch.dispatch(()->Gtk2.gtk_status_icon_set_tooltip_text(trayIcon, text));
            }

            @Override
            public
            void remove() {
                // This is required if we have JavaFX or SWT shutdown hooks (to prevent us from shutting down twice...)
                if (!shuttingDown.getAndSet(true)) {
                    GtkEventDispatch.dispatch(()->{
                        // this hides the indicator
                        Gtk2.gtk_status_icon_set_visible(trayIcon, false);
                        GObject.g_object_unref(trayIcon);

                        // mark for GC
                        trayIcon = null;
                        gtkCallback = null;
                    });

                    super.remove();

                    // does not need to be called on the dispatch (it does that)
                    GtkEventDispatch.shutdownGui();
                }
            }
        };

        GtkEventDispatch.dispatch(()->{
            trayIcon = Gtk2.gtk_status_icon_new();

            gtkCallback = new GEventCallback() {
                @Override
                public
                void callback(Pointer notUsed, final GdkEventButton event) {
                    // show the swing menu on the EDT
                    // BUTTON_PRESS only (any mouse click)
                    if (event.type == 4) {
                        Gtk2.gtk_menu_popup(gtkMenu._nativeMenu, null, null, Gtk2.gtk_status_icon_position_menu,
                                            trayIcon, 0, event.time);
                    }
                }
            };
            GObject.g_signal_connect_object(trayIcon, "button_press_event", gtkCallback, null, 0);
        });

        GtkEventDispatch.waitForEventsToComplete();

        // we have to be able to set our title, otherwise the gnome-shell extension WILL NOT work
        GtkEventDispatch.dispatchAndWait(()->{
            // in GNOME by default, the title/name of the tray icon is "java". We are the only java-based tray icon, so we just use that.
            // If you change "SystemTray" to something else, make sure to change it in extension.js as well

            // necessary for gnome icon detection/placement because we move tray icons around by title. This is hardcoded
            //  in extension.js, so don't change it
            Gtk2.gtk_status_icon_set_title(trayIcon, trayName);

            // can cause
            // Gdk-CRITICAL **: gdk_window_thaw_toplevel_updates: assertion 'window->update_and_descendants_freeze_count > 0' failed
            // Gdk-CRITICAL **: IA__gdk_window_thaw_toplevel_updates_libgtk_only: assertion 'private->update_and_descendants_freeze_count > 0' failed

            // ... so, bizzaro things going on here. These errors DO NOT happen if JavaFX or Gnome is dispatching the events.
            //     BUT   this is REQUIRED when running JavaFX or Gnome For unknown reasons, the title isn't pushed to GTK, so our
            //           gnome-shell extension cannot see our tray icon -- so naturally, it won't move it to the "top" area and
            //           we appear broken.
            if (JavaFx.isLoaded || Tray.gtkGnomeWorkaround) {
                Gtk2.gtk_status_icon_set_name(trayIcon, trayName);
            }
        });

        bind(gtkMenu, null, imageResizeUtil);
    }

    @Override
    public
    boolean hasImage() {
        return imageFile != null;
    }
}