#include <stdlib.h>
#include <math.h>
#include <cairo.h>
#include <clutter/clutter.h>

static gboolean
draw_clock (ClutterCairoTexture *canvas,
            cairo_t             *cr)
{
  guint width, height;
  GDateTime *now;
  float hours, minutes, seconds;

  /* get the current time and compute the angles */
  now = g_date_time_new_now_local ();
  seconds = g_date_time_get_second (now) * G_PI / 30;
  minutes = g_date_time_get_minute (now) * G_PI / 30;
  hours = g_date_time_get_hour (now) * G_PI / 6;

  /* clear the contents of the canvas, to avoid painting
   * over the previous frame
   */
  clutter_cairo_texture_clear (canvas);

  /* scale the modelview to the size of the surface */
  clutter_cairo_texture_get_surface_size (canvas, &width, &height);
  cairo_scale (cr, width, height);

  cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
  cairo_set_line_width (cr, 0.1);

  /* the black rail that holds the seconds indicator */
  clutter_cairo_set_source_color (cr, CLUTTER_COLOR_Black);
  cairo_translate (cr, 0.5, 0.5);
  cairo_arc (cr, 0, 0, 0.4, 0, G_PI * 2);
  cairo_stroke (cr);

  /* the seconds indicator */
  clutter_cairo_set_source_color (cr, CLUTTER_COLOR_White);
  cairo_move_to (cr, 0, 0);
  cairo_arc (cr, sinf (seconds) * 0.4, - cosf (seconds) * 0.4, 0.05, 0, G_PI * 2);
  cairo_fill (cr);

  /* the minutes hand */
  clutter_cairo_set_source_color (cr, CLUTTER_COLOR_DarkChameleon);
  cairo_set_source_rgba (cr, 0.2, 0.2, 1, 0.6);
  cairo_move_to (cr, 0, 0);
  cairo_line_to (cr, sinf (minutes) * 0.4, -cosf (minutes) * 0.4);
  cairo_stroke (cr);

  /* the hours hand */
  cairo_move_to (cr, 0, 0);
  cairo_line_to (cr, sinf (hours) * 0.2, -cosf (hours) * 0.2);
  cairo_stroke (cr);

  g_date_time_unref (now);

  /* we're done drawing */
  return TRUE;
}

static gboolean
invalidate_clock (gpointer data_)
{
  /* invalidate the contents of the canvas */
  clutter_cairo_texture_invalidate (data_);

  /* keep the timeout source */
  return TRUE;
}

G_MODULE_EXPORT int
test_cairo_clock_main (int argc, char *argv[])
{
  ClutterActor *stage, *canvas;

  /* initialize Clutter */
  if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
    return EXIT_FAILURE;

  /* create a fixed size stage */
  stage = clutter_stage_new ();
  clutter_stage_set_title (CLUTTER_STAGE (stage), "2D Clock");
  clutter_stage_set_color (CLUTTER_STAGE (stage), CLUTTER_COLOR_LightSkyBlue);
  clutter_actor_set_size (stage, 300, 300);
  clutter_actor_show (stage);

  /* our 2D canvas, courtesy of Cairo */
  canvas = clutter_cairo_texture_new (300, 300);
  clutter_container_add_actor (CLUTTER_CONTAINER (stage), canvas);

  /* quit on destroy */
  g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);

  /* connect our drawing code */
  g_signal_connect (canvas, "draw", G_CALLBACK (draw_clock), NULL);

  /* invalidate the canvas, so that we can draw before the main loop starts */
  clutter_cairo_texture_invalidate (CLUTTER_CAIRO_TEXTURE (canvas));

  /* set up a timer that invalidates the canvas every second */
  clutter_threads_add_timeout (1000, invalidate_clock, canvas);

  clutter_main ();

  return EXIT_SUCCESS;
}