#!/usr/bin/gjs

imports.gi.versions.Gtk = '3.0';

const Gio = imports.gi.Gio;

const GLib = imports.gi.GLib;

const Gtk = imports.gi.Gtk;

class Application {

    //create the application

    constructor() {

        this.application = new Gtk.Application ({

            application_id: 'org.example.myapp',

            flags: Gio.ApplicationFlags.FLAGS_NONE

        });

       //connect to 'activate' and 'startup' signals to the callback functions

       this.application.connect('activate', this._onActivate.bind(this));

       this.application.connect('startup', this._onStartup.bind(this));

    }

    //create the UI (in this case it's just the ApplicationWindow

    _buildUI() {

        this._window = new Gtk.ApplicationWindow  ({ application: this.application,

                                                   window_position: Gtk.WindowPosition.CENTER,

                                                   title: "Welcome to GNOME" });

        //uncommenting the line below will change the window size

        //this._window.set_default_size(600, 400);

        //show the window and all child widgets (none in this case)

        this._window.show_all();

    }

    _showNew() {

        print("This doesn't do anything. It is only a demonstration.");

    }

    _showAbout() {

        print("No AboutDialog here.  This is only a demonstration.");

    }

    //create the menu items and connect the signals to the callback functions.

    _initMenus() {

        let menu = new Gio.Menu();

        menu.append("New",'app.new');

        menu.append("About", 'app.about');

        menu.append("Quit",'app.quit');

        this.application.set_app_menu(menu);

        let newAction = new Gio.SimpleAction ({ name: 'new' });

        newAction.connect('activate', () => { this._showNew(); });

        this.application.add_action(newAction);

        let aboutAction = new Gio.SimpleAction ({ name: 'about' });

        aboutAction.connect('activate', () => { this._showAbout(); });

        this.application.add_action(aboutAction);

        let quitAction = new Gio.SimpleAction ({ name: 'quit' });

        quitAction.connect('activate', () => { this._window.destroy(); });

         this.application.add_action(quitAction);

    }

    //callback function for 'activate' signal

    _onActivate() {

        this._window.present();

    }

    //callback function for 'startup' signal

    _onStartup() {

        //You must call _initMenus() before calling _buildUI().

        this._initMenus();

        this._buildUI();

    }

};

//run the application

let app = new Application ();

app.application.run (ARGV);