#!/usr/bin/gjs

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

const Gtk = imports.gi.Gtk;

class ComboBoxTextExample {

    // Create the application itself

    constructor() {

        this.application = new Gtk.Application ({

            application_id: 'org.example.jscomboboxtext'});

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

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

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

    }

    // Callback function for 'activate' signal presents windows when active

    _onActivate() {

        this._window.present ();

    }

    // Callback function for 'startup' signal builds the UI

    _onStartup() {

        this._buildUI();

    }

    // Build the application's UI

    _buildUI() {

        // Create the application window

        this._window = new Gtk.ApplicationWindow  ({

            application: this.application,

            window_position: Gtk.WindowPosition.CENTER,

            title: "Welcome to GNOME",

            default_width: 200,

            border_width: 10 });

        // Create the combobox

        this._comboBoxText = new Gtk.ComboBoxText();

        // Populate the combobox

        let distros = ["Select distribution", "Fedora", "Mint", "Suse"];

        for (let i = 0; i < distros.length; i++)

            this._comboBoxText.append_text (distros[i]);

        this._comboBoxText.set_active (0);

        // Connect the combobox's 'changed' signal to our callback function

        this._comboBoxText.connect ('changed', this._onComboChanged.bind(this));

        // Add the combobox to the window

        this._window.add (this._comboBoxText);

        // Show the window and all child widgets

        this._window.show_all();

    }

    _onComboChanged() {

        // The responses we'll use for our messagedialog

        let responses = ["",

            "Fedora is a community distro sponsored by Red Hat.",

            "Mint is a popular distro based on Ubuntu.",

            "SUSE is a name shared by two separate distros."];

        // Which combobox item is active?

        let activeItem = this._comboBoxText.get_active();

        // No messagedialog if you chose "Select distribution"

        if (activeItem != 0) {

            this._popUp = new Gtk.MessageDialog ({

                transient_for: this._window,

                modal: true,

                buttons: Gtk.ButtonsType.OK,

                message_type: Gtk.MessageType.INFO,

                text: responses[activeItem]});

            // Connect the OK button to a handler function

            this._popUp.connect ('response', this._onDialogResponse.bind(this));

            // Show the messagedialog

            this._popUp.show();

        }

    }

    _onDialogResponse() {

        this._popUp.destroy ();

    }

};

// Run the application

let app = new ComboBoxTextExample ();

app.application.run (ARGV);