#!/usr/bin/gjs

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

const Gio = imports.gi.Gio;

const Gtk = imports.gi.Gtk;

class StatusbarExample {

    // Create the application itself

    constructor() {

        this.application = new Gtk.Application({

            application_id: 'org.example.jsstatusbar',

            flags: Gio.ApplicationFlags.FLAGS_NONE

        });

        // 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 window 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,

            default_height: 120,

            default_width: 300,

            title: "Button Clicker"});

        // Create a paned interface

        this._panes = new Gtk.Paned ({

            orientation: Gtk.Orientation.VERTICAL });

        // Create the main button

        this._clickMe = new Gtk.Button ({

            label: "Click Me!" });

        this._clickMe.connect ("clicked", this._clicked.bind(this));

        // Create the back button

        this._backButton = new Gtk.Button ({

            label: "gtk-go-back",

            use_stock: true });

        this._backButton.connect ("clicked", this._back.bind(this));

        // Create the clear button

        this._clearButton = new Gtk.Button ({

            label: "gtk-clear",

            use_stock: true });

        this._clearButton.connect ("clicked", this._clear.bind(this));

        // Put the buttons in a grid

        this._grid = new Gtk.Grid ({

            halign: Gtk.Align.CENTER,

            valign: Gtk.Align.CENTER });

        this._grid.attach (this._backButton, 0, 0, 1, 1);

        this._grid.attach_next_to (this._clickMe, this._backButton, Gtk.PositionType.RIGHT, 1, 1);

        this._grid.attach_next_to (this._clearButton, this._clickMe, Gtk.PositionType.RIGHT, 1, 1);

        // Put the grid in a large frame that fills most of the window

        this._topFrame = new Gtk.Frame ({

            border_width: 20,

            height_request: 90,

            width_request: 300});

        this._topFrame.add (this._grid);

        // Create the statusbar

        this._statusbar = new Gtk.Statusbar();

        // Keep track of the number of times the button has been clicked

        this.Clicks = 0;

        this.ContextID = this._statusbar.get_context_id ("Number of Clicks");

        // Give the statusbar an initial message

        this._statusbar.push (this.ContextID, "Number of clicks: " + this.Clicks);

        // Put the statusbar in its own frame at the bottom

        this._barFrame = new Gtk.Frame ({

            height_request: 30 });

        this._barFrame.add (this._statusbar);

        // Assemble the frames into the paned interface

        this._panes.pack1 (this._topFrame, true, false);

        this._panes.pack2 (this._barFrame, false, false);

        // Put the panes into the window

        this._window.add (this._panes);

        // Show the window and all child widgets

        this._window.show_all();

    }

    _clicked() {

        // Increment the number of clicks by 1

        this.Clicks++;

        // Update the statusbar with the new number of clicks

        this._statusbar.push (this.ContextID, "Number of clicks: " + this.Clicks);

    }

    _back() {

        // If there have been any clicks, decrement by 1 and remove last statusbar update

        if (this.Clicks > 0 ) {

            this.Clicks--;

            this._statusbar.pop (this.ContextID);

        };

    }

    _clear() {

        // Reset the number of clicks

        this.Clicks = 0;

        // Wipe out all the messages pushed to the statusbar

        this._statusbar.remove_all (this.ContextID);

        // Reset the statusbar's message

        this._statusbar.push (this.ContextID, "Number of clicks: " + this.Clicks);

    }

};

// Run the application

let app = new StatusbarExample ();

app.application.run (ARGV);