/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Authored By: Emmanuele Bassi <ebassi@linux.intel.com>
 *
 * Copyright (C) 2009  Intel Corporation.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * SECTION:clutter-master-clock
 * @short_description: The master clock for all animations
 *
 * The #ClutterMasterClock class is responsible for advancing all
 * #ClutterTimelines when a stage is being redrawn. The master clock
 * makes sure that the scenegraph is always integrally updated before
 * painting it.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "clutter-master-clock.h"
#include "clutter-debug.h"
#include "clutter-private.h"

#define CLUTTER_MASTER_CLOCK_CLASS(klass)       (G_TYPE_CHECK_CLASS_CAST ((klass), CLUTTER_TYPE_MASTER_CLOCK, ClutterMasterClockClass))
#define CLUTTER_IS_MASTER_CLOCK_CLASS(klass)    (G_TYPE_CHECK_CLASS_TYPE ((klass), CLUTTER_TYPE_MASTER_CLOCK))
#define CLUTTER_MASTER_CLASS_GET_CLASS(obj)     (G_TYPE_INSTANCE_GET_CLASS ((obj), CLUTTER_TYPE_MASTER_CLOCK, ClutterMasterClockClass))

typedef struct _ClutterClockSource              ClutterClockSource;
typedef struct _ClutterMasterClockClass         ClutterMasterClockClass;

struct _ClutterMasterClock
{
  GObject parent_instance;

  /* the list of timelines handled by the clock */
  GSList *timelines;

  /* the previous state of the clock, used to compute
   * the delta
   */
  GTimeVal prev_tick;
  gulong msecs_delta;

  /* an idle source, used by the Master Clock to queue
   * a redraw on the stage and drive the animations
   */
  GSource *source;

  /* a guard, so that we dispatch the last redraw even
   * after the last timeline has been completed
   */
  guint last_advance : 1;
};

struct _ClutterMasterClockClass
{
  GObjectClass parent_class;
};

struct _ClutterClockSource
{
  GSource source;

  ClutterMasterClock *master_clock;
};

static void on_timeline_started   (ClutterTimeline    *timeline,
                                   ClutterMasterClock *master_clock);
static void on_timeline_completed (ClutterTimeline    *timeline,
                                   ClutterMasterClock *master_clock);
static void on_timeline_paused    (ClutterTimeline    *timeline,
                                   ClutterMasterClock *master_clock);

static gboolean clutter_clock_prepare  (GSource     *source,
                                        gint        *timeout);
static gboolean clutter_clock_check    (GSource     *source);
static gboolean clutter_clock_dispatch (GSource     *source,
                                        GSourceFunc  callback,
                                        gpointer     user_data);

static ClutterMasterClock *default_clock = NULL;

static GSourceFuncs clock_funcs = {
  clutter_clock_prepare,
  clutter_clock_check,
  clutter_clock_dispatch,
  NULL
};

G_DEFINE_TYPE (ClutterMasterClock, clutter_master_clock, G_TYPE_OBJECT);

/*
 * has_running_timeline:
 * @master_clock: a #ClutterMasterClock
 * @filter: a #ClutterTimeline or %NULL
 *
 * Checks if @master_clock has any running timeline; if @filter
 * is not %NULL then the timeline will be filtered from the
 * list of timelines held by @master_clock
 *
 * Return value: %TRUE if the #ClutterMasterClock has at least
 *   one running timeline
 */
static gboolean
has_running_timeline (ClutterMasterClock *master_clock,
                      ClutterTimeline    *filter)
{
  GSList *l;

  if (master_clock->last_advance)
    return TRUE;

  if (master_clock->timelines == NULL)
    return FALSE;

  for (l = master_clock->timelines; l != NULL; l = l->next)
    {
      /* if we get a timeline then we should filter it
       * from the list of timelines we want to check
       */
      if (filter != NULL && filter == l->data)
        continue;

      if (clutter_timeline_is_playing (l->data))
        return TRUE;
    }

  return FALSE;
}

/*
 * clutter_clock_source_new:
 * @master_clock: a #ClutterMasterClock for the source
 *
 * The #ClutterClockSource is an idle GSource that will queue a redraw
 * if @master_clock has at least a running #ClutterTimeline. The redraw
 * will cause @master_clock to advance all timelines, thus advancing all
 * animations as well.
 *
 * Return value: the newly created #GSource
 */
static GSource *
clutter_clock_source_new (ClutterMasterClock *master_clock)
{
  GSource *source = g_source_new (&clock_funcs, sizeof (ClutterClockSource));
  ClutterClockSource *clock_source = (ClutterClockSource *) source;

  clock_source->master_clock = master_clock;

  return source;
}

static gboolean
clutter_clock_prepare (GSource *source,
                       gint    *timeout)
{
  ClutterClockSource *clock_source = (ClutterClockSource *) source;
  ClutterMasterClock *master_clock = clock_source->master_clock;
  gboolean retval;

  /* just like an idle source, we are ready if nothing else is */
  *timeout = -1;

  retval = has_running_timeline (master_clock, NULL);

  return retval;
}

static gboolean
clutter_clock_check (GSource *source)
{
  ClutterClockSource *clock_source = (ClutterClockSource *) source;
  ClutterMasterClock *master_clock = clock_source->master_clock;
  gboolean retval;

  retval = has_running_timeline (master_clock, NULL);

  return retval;
}

static gboolean
clutter_clock_dispatch (GSource     *source,
                        GSourceFunc  callback,
                        gpointer     user_data)
{
  ClutterClockSource *clock_source = (ClutterClockSource *) source;
  ClutterMasterClock *master_clock = clock_source->master_clock;
  ClutterStageManager *stage_manager = clutter_stage_manager_get_default ();
  const GSList *stages, *l;

  CLUTTER_NOTE (SCHEDULER, "Master clock [tick]");

  stages = clutter_stage_manager_peek_stages (stage_manager);

  /* queue a redraw for each stage; this will advance each timeline
   * held by the master clock of the amount of milliseconds elapsed
   * since the last redraw
   */
  for (l = stages; l != NULL; l = l->next)
    clutter_actor_queue_redraw (l->data);

  /* if this is the remainder of an advancement, needed for the last
   * timeline to finish its run, then we need to reset the prev_tick
   */
  if (master_clock->last_advance)
    {
      master_clock->prev_tick.tv_sec = 0;
      master_clock->last_advance = FALSE;
    }

  return TRUE;
}

static void
timeline_weak_ref (gpointer  data,
                   GObject  *object_pointer)
{
  ClutterMasterClock *master_clock = data;

  master_clock->timelines =
    g_slist_remove (master_clock->timelines, object_pointer);

  if (master_clock->timelines == NULL)
    master_clock->prev_tick.tv_sec = 0;
}

static void
clutter_master_clock_finalize (GObject *gobject)
{
  ClutterMasterClock *master_clock = CLUTTER_MASTER_CLOCK (gobject);
  GSList *l;

  for (l = master_clock->timelines; l != NULL; l = l->next)
    {
      ClutterTimeline *timeline = l->data;

      g_object_weak_unref (G_OBJECT (timeline),
                           timeline_weak_ref,
                           master_clock);

      g_signal_handlers_disconnect_by_func (timeline,
                                            G_CALLBACK (on_timeline_started),
                                            master_clock);
      g_signal_handlers_disconnect_by_func (timeline,
                                            G_CALLBACK (on_timeline_completed),
                                            master_clock);
      g_signal_handlers_disconnect_by_func (timeline,
                                            G_CALLBACK (on_timeline_paused),
                                            master_clock);
    }

  g_slist_free (master_clock->timelines);

  G_OBJECT_CLASS (clutter_master_clock_parent_class)->finalize (gobject);
}

static void
clutter_master_clock_class_init (ClutterMasterClockClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);

  gobject_class->finalize = clutter_master_clock_finalize;
}

static void
clutter_master_clock_init (ClutterMasterClock *self)
{
  GSource *source;

  source = clutter_clock_source_new (self);
  self->source = source;

  g_source_set_priority (source, CLUTTER_PRIORITY_REDRAW);
  g_source_set_can_recurse (source, FALSE);
  g_source_attach (source, NULL);
}

/*
 * _clutter_master_clock_get_default:
 *
 * Retrieves the default master clock. If this function has never
 * been called before, the default master clock is created.
 *
 * Return value: the default master clock. The returned object is
 *   owned by Clutter and should not be modified or freed
 */
ClutterMasterClock *
_clutter_master_clock_get_default (void)
{
  if (G_LIKELY (default_clock != NULL))
    return default_clock;

  default_clock = g_object_new (CLUTTER_TYPE_MASTER_CLOCK, NULL);

  return default_clock;
}

static void
on_timeline_started (ClutterTimeline    *timeline,
                     ClutterMasterClock *master_clock)
{
  /* we want to reset the prev_tick if this is the first
   * timeline; since timeline is playing we need to filter
   * it out, otherwise has_running_timeline() will return
   * TRUE and prev_tick will not be unset
   */
  if (!has_running_timeline (master_clock, timeline))
    master_clock->prev_tick.tv_sec = 0;
}

static void
on_timeline_completed (ClutterTimeline *timeline,
                       ClutterMasterClock *master_clock)
{
  /* if this is the last timeline we need to turn :last-advance
   * on in order to queue the redraw of the scene for the last
   * frame; otherwise the ClockSource will fail the prepare and
   * check phases and the last frame will not be painted
   */
  if (!has_running_timeline (master_clock, NULL))
    master_clock->last_advance = TRUE;
}

static void
on_timeline_paused (ClutterTimeline *timeline,
                    ClutterMasterClock *master_clock)
{
  /* see the comment in on_timeline_completed */
  if (!has_running_timeline (master_clock, NULL))
    master_clock->last_advance = TRUE;
}

/*
 * _clutter_master_clock_add_timeline:
 * @master_clock: a #ClutterMasterClock
 * @timeline: a #ClutterTimeline
 *
 * Adds @timeline to the list of timelines held by the master
 * clock. This function should be called during the instance
 * creation phase of the timeline.
 */
void
_clutter_master_clock_add_timeline (ClutterMasterClock *master_clock,
                                    ClutterTimeline    *timeline)
{
  gboolean is_first = FALSE;

  if (g_slist_find (master_clock->timelines, timeline))
    return;

  is_first = (master_clock->timelines == NULL) ? TRUE : FALSE;

  master_clock->timelines = g_slist_prepend (master_clock->timelines,
                                             timeline);

  g_object_weak_ref (G_OBJECT (timeline),
                     timeline_weak_ref,
                     master_clock);

  g_signal_connect (timeline, "started",
                    G_CALLBACK (on_timeline_started),
                    master_clock);
  g_signal_connect (timeline, "completed",
                    G_CALLBACK (on_timeline_completed),
                    master_clock);
  g_signal_connect (timeline, "paused",
                    G_CALLBACK (on_timeline_paused),
                    master_clock);
}

/*
 * _clutter_master_clock_remove_timeline:
 * @master_clock: a #ClutterMasterClock
 * @timeline: a #ClutterTimeline
 *
 * Removes @timeline from the list of timelines held by the
 * master clock. This function should be called during the
 * #ClutterTimeline finalization.
 */
void
_clutter_master_clock_remove_timeline (ClutterMasterClock *master_clock,
                                       ClutterTimeline    *timeline)
{
  if (!g_slist_find (master_clock->timelines, timeline))
    return;

  master_clock->timelines = g_slist_remove (master_clock->timelines,
                                            timeline);

  g_object_weak_unref (G_OBJECT (timeline),
                       timeline_weak_ref,
                       master_clock);

  g_signal_handlers_disconnect_by_func (timeline,
                                        G_CALLBACK (on_timeline_started),
                                        master_clock);
  g_signal_handlers_disconnect_by_func (timeline,
                                        G_CALLBACK (on_timeline_completed),
                                        master_clock);
  g_signal_handlers_disconnect_by_func (timeline,
                                        G_CALLBACK (on_timeline_paused),
                                        master_clock);

  /* last timeline: unset the prev_tick so that we can start
   * from scratch when we add a new timeline
   */
  if (master_clock->timelines == NULL)
    master_clock->prev_tick.tv_sec = 0;
}

/*
 * _clutter_master_clock_advance:
 * @master_clock: a #ClutterMasterClock
 *
 * Advances all the timelines held by the master clock. This function
 * should be called before calling clutter_redraw() to make sure that
 * all the timelines are advanced and the scene is updated.
 */
void
_clutter_master_clock_advance (ClutterMasterClock *master_clock)
{
  GTimeVal cur_tick = { 0, };
  gulong msecs;
  GSList *l;

  g_return_if_fail (CLUTTER_IS_MASTER_CLOCK (master_clock));

  if (master_clock->timelines == NULL)
    return;

  g_get_current_time (&cur_tick);

  if (master_clock->prev_tick.tv_sec == 0)
    master_clock->prev_tick = cur_tick;

  msecs = (cur_tick.tv_sec - master_clock->prev_tick.tv_sec) * 1000
        + (cur_tick.tv_usec - master_clock->prev_tick.tv_usec) / 1000;

  if (msecs == 0)
    return;

  CLUTTER_NOTE (SCHEDULER, "Advancing %d timelines by %lu milliseconds",
                g_slist_length (master_clock->timelines),
                msecs);

  for (l = master_clock->timelines; l != NULL; l = l->next)
    {
      ClutterTimeline *timeline = l->data;

      if (clutter_timeline_is_playing (timeline))
        clutter_timeline_advance_delta (timeline, msecs);
    }

  /* store the previous state so that we can use
   * it for the next advancement
   */
  master_clock->msecs_delta = msecs;
  master_clock->prev_tick = cur_tick;
}