#!/usr/bin/ruby
# encoding: UTF-8
#
# xscreensaver sample by Ruby + ruby-gtk2
#
# * Ubuntu Linux 20.04 LTS
# * Ruby 2.7.0 p0
# * ruby-gtk2 3.4.1-2build1
# * xscreensaver 6.04

require "gtk2"
require "logger"

# for gtk2
SIGNAL_DRAW = "expose_event"

# for gtk3
# SIGNAL_DRAW = "draw"

TMOUT = 16

$drawing_area = nil
$logger = Logger.new("/tmp/rubysaver-#{ENV["USER"]}.log", "monthly")

class RubyXscrApp < Gtk::Window
  def initialize
    super

    set_title "xscreensaver module"

    signal_connect "destroy" do
      $logger.warn "EXIT by destroy"
      Gtk.main_quit
    end

    signal_connect "delete-event" do
      $logger.warn "EXIT by delete-event"
      Gtk.main_quit
      false
    end

    signal_connect "delete_event" do
      $logger.warn "EXIT by delete_event"
      Gtk.main_quit
      false
    end

    realize

    ident = ENV["XSCREENSAVER_WINDOW"]
    if not ident.nil?
      $logger.warn "XSCREENSAVER_WINDOW = #{ident}"
      self.window = Gdk::Window.foreign_new(ident.to_i(16))
      self.window.set_events(Gdk::Event::EXPOSURE_MASK | Gdk::Event::STRUCTURE_MASK)

      x, y, width, height, depth = self.window.geometry
      # puts "window = #{self.window}, (x,y,w,h) = #{x}, #{y}, #{width}, #{height}"
      $logger.warn "window = #{self.window}, (x,y,w,h) = #{x}, #{y}, #{width}, #{height}"

      set_default_size width, height
      move(x, y)
      # set_window_position :center
    else
      x, y, width, height, depth = self.window.geometry
      width, height = 640, 360
      set_default_size width, height
      set_window_position :center
      puts "window = #{self.window}, (w,h) = #{width}, #{height}"
    end

    @x = width / 2
    @y = height / 2
    @dx = width.to_f / (60 * 1)
    @dy = height.to_f / (60 * 1.5)

    $drawing_area = @darea = Gtk::DrawingArea.new
    @bgcol = Gdk::Color.new(0x2000, 0x4000, 0xa000)
    @darea.modify_bg(:normal, @bgcol)
    @darea.set_size_request(width, height)

    @darea.signal_connect SIGNAL_DRAW do |widget, event|
      on_draw widget
    end

    @fixed = Gtk::Fixed.new
    @fixed.put(@darea, 0, 0)
    add(@fixed)

    show_all
  end

  def on_draw(widget)
    cr = widget.window.create_cairo_context
    x, y, width, height, depth = widget.window.geometry

    # update position
    r = 24
    @x += @dx
    @y += @dy
    @dx *= -1 if (@x <= r or @x >= width - r)
    @dy *= -1 if (@y <= r or @y >= height - r)

    # clear bg
    cr.set_source_rgb(0.1, 0.3, 0.5)
    cr.paint

    # draw circle
    cr.set_source_rgb(1.0, 0.0, 0.0)
    cr.arc(@x, @y, r, 0, 2 * Math::PI)
    cr.fill

    cr.destroy
  end
end

Gtk.init
window = RubyXscrApp.new

# animation
GLib::Timeout.add(TMOUT) do
  $drawing_area.queue_draw if (not $drawing_area.nil?)
  true
end

Gtk.main