/*
 * Copyright © 2018 Benjamin Otte
 *
 * 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 2.1 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/>.
 *
 * Authors: Benjamin Otte <otte@gnome.org>
 */

#include "config.h"

#include "fpsoverlay.h"

#include "gtkwidget.h"
#include "gtkwindow.h"
#include "gtknative.h"
#include "gtkmain.h"

/* duration before we start fading in us */
#define GDK_FPS_OVERLAY_LINGER_DURATION (1000 * 1000)
/* duration when fade is finished in us */
#define GDK_FPS_OVERLAY_FADE_DURATION (500 * 1000)

typedef struct _GtkFpsInfo GtkFpsInfo;

struct _GtkFpsInfo
{
  PangoFont *font;
  PangoGlyphString *glyphs;
  PangoGlyphString *digits;
  int width, height, baseline;

  gint64 last_frame;
  GskRenderNode *last_node;
};

struct _GtkFpsOverlay
{
  GtkInspectorOverlay parent_instance;

  GHashTable *infos; /* GtkWidget => GtkFpsInfo */
};

struct _GtkFpsOverlayClass
{
  GtkInspectorOverlayClass parent_class;
};

G_DEFINE_TYPE (GtkFpsOverlay, gtk_fps_overlay, GTK_TYPE_INSPECTOR_OVERLAY)

static void
gtk_fps_info_free (gpointer data)
{
  GtkFpsInfo *info = data;

  g_clear_pointer (&info->glyphs, pango_glyph_string_free);
  g_clear_pointer (&info->digits, pango_glyph_string_free);
  g_clear_object (&info->font);

  gsk_render_node_unref (info->last_node);

  g_free (info);
}

static GtkFpsInfo *
gtk_fps_info_new (GtkWidget *widget)
{
  PangoLayout *layout;
  PangoLayoutIter *iter;
  PangoLayoutRun *run;
  PangoAttrList *attrs;
  GtkFpsInfo *info;

  info = g_new0 (GtkFpsInfo, 1);

  layout = gtk_widget_create_pango_layout (widget, "0000.00 fps");
  attrs = pango_attr_list_new ();
  pango_attr_list_insert (attrs, pango_attr_font_features_new ("tnum=1"));
  pango_layout_set_attributes (layout, attrs);
  pango_attr_list_unref (attrs);
  pango_layout_get_pixel_size (layout, &info->width, &info->height);

  iter = pango_layout_get_iter (layout);
  info->baseline = pango_layout_iter_get_baseline (iter) / (double) PANGO_SCALE;
  run = pango_layout_iter_get_run_readonly (iter);

  info->glyphs = pango_glyph_string_copy (run->glyphs);
  info->font = g_object_ref (run->item->analysis.font);

  pango_layout_iter_free (iter);

  pango_layout_set_text (layout, "0123456789 ", -1);

  iter = pango_layout_get_iter (layout);
  run = pango_layout_iter_get_run_readonly (iter);

  g_assert (run->glyphs->num_glyphs == 11);

  info->digits = pango_glyph_string_copy (run->glyphs);

  pango_layout_iter_free (iter);
  g_object_unref (layout);

  return info;
}

static double
gtk_fps_overlay_get_fps (GtkWidget *widget)
{
  GdkFrameClock *frame_clock;

  frame_clock = gtk_widget_get_frame_clock (widget);
  if (frame_clock == NULL)
    return 0.0;

  return gdk_frame_clock_get_fps (frame_clock);
}

static gboolean
gtk_fps_overlay_force_redraw (GtkWidget     *widget,
                              GdkFrameClock *clock,
                              gpointer       unused)
{
  gdk_surface_queue_render (gtk_native_get_surface (gtk_widget_get_native (widget)));

  return G_SOURCE_REMOVE;
}

static void
gtk_fps_overlay_snapshot (GtkInspectorOverlay *overlay,
                          GtkSnapshot         *snapshot,
                          GskRenderNode       *node,
                          GtkWidget           *widget)
{
  GtkFpsOverlay *self = GTK_FPS_OVERLAY (overlay);
  GtkFpsInfo *info;
  gint64 now;
  double fps;
  graphene_rect_t bounds;
  gboolean has_bounds;
  double overlay_opacity;

  now = gdk_frame_clock_get_frame_time (gtk_widget_get_frame_clock (widget));
  info = g_hash_table_lookup (self->infos, widget);
  if (info == NULL)
    {
      info = gtk_fps_info_new (widget);
      g_hash_table_insert (self->infos, widget, info);
    }
  if (info->last_node != node)
    {
      g_clear_pointer (&info->last_node, gsk_render_node_unref);
      info->last_node = gsk_render_node_ref (node);
      info->last_frame = now;
      overlay_opacity = 1.0;
    }
  else
    {
      if (now - info->last_frame > GDK_FPS_OVERLAY_LINGER_DURATION + GDK_FPS_OVERLAY_FADE_DURATION)
        {
          g_hash_table_remove (self->infos, widget);
          return;
        }
      else if (now - info->last_frame > GDK_FPS_OVERLAY_LINGER_DURATION)
        {
          overlay_opacity = 1.0 - (double) (now - info->last_frame - GDK_FPS_OVERLAY_LINGER_DURATION)
                                  / GDK_FPS_OVERLAY_FADE_DURATION;
        }
      else
        {
          overlay_opacity = 1.0;
        }
    }

  if (GTK_IS_WINDOW (widget))
    {
      GtkWidget *child = gtk_window_get_child (GTK_WINDOW (widget));
      if (!child ||
          !gtk_widget_compute_bounds (child, widget, &bounds))
        has_bounds = gtk_widget_compute_bounds (widget, widget, &bounds);
      else
        has_bounds = gtk_widget_compute_bounds (child, widget, &bounds);
    }
   else
    {
      has_bounds = gtk_widget_compute_bounds (widget, widget, &bounds);
    }

  gtk_snapshot_save (snapshot);
  if (has_bounds)
    gtk_snapshot_translate (snapshot, &GRAPHENE_POINT_INIT (bounds.origin.x + bounds.size.width - info->width, bounds.origin.y));

  if (overlay_opacity < 1.0)
    gtk_snapshot_push_opacity (snapshot, overlay_opacity);
  gtk_snapshot_append_color (snapshot,
                             &(GdkRGBA) { 0, 0, 0, 0.5 },
                             &GRAPHENE_RECT_INIT (-1, -1, info->width + 2, info->height + 2));

  fps = gtk_fps_overlay_get_fps (widget);
  if (fps != 0.0)
    {
      GskRenderNode *fps_node;
      char fps_string[40];

      g_snprintf (fps_string, sizeof (fps_string), "%7.2f fps", fps);
      for (int i = 0; i < 7; i++)
        {
          if (g_ascii_isdigit (fps_string[i]))
            info->glyphs->glyphs[i].glyph = info->digits->glyphs[fps_string[i] - '0'].glyph;
          else if (fps_string[i] == ' ')
            info->glyphs->glyphs[i].glyph = info->digits->glyphs[10].glyph;
        }

      fps_node = gsk_text_node_new (info->font,
                                    info->glyphs,
                                    &(GdkRGBA) { 1, 1, 1, 1 },
                                    &GRAPHENE_POINT_INIT (0, info->baseline));
      gtk_snapshot_append_node (snapshot, fps_node);
      gsk_render_node_unref (fps_node);
    }

  if (overlay_opacity < 1.0)
    gtk_snapshot_pop (snapshot);
  gtk_snapshot_restore (snapshot);

  gtk_widget_add_tick_callback (widget, gtk_fps_overlay_force_redraw, NULL, NULL);
}

static void
gtk_fps_overlay_queue_draw (GtkInspectorOverlay *overlay)
{
  GtkFpsOverlay *self = GTK_FPS_OVERLAY (overlay);
  GHashTableIter iter;
  gpointer widget;

  g_hash_table_iter_init (&iter, self->infos);
  while (g_hash_table_iter_next (&iter, &widget, NULL))
    gdk_surface_queue_render (gtk_native_get_surface (gtk_widget_get_native (widget)));
}

static void
gtk_fps_overlay_dispose (GObject *object)
{
  GtkFpsOverlay *self = GTK_FPS_OVERLAY (object);

  g_hash_table_unref (self->infos);

  G_OBJECT_CLASS (gtk_fps_overlay_parent_class)->dispose (object);
}

static void
gtk_fps_overlay_class_init (GtkFpsOverlayClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  GtkInspectorOverlayClass *overlay_class = GTK_INSPECTOR_OVERLAY_CLASS (klass);

  overlay_class->snapshot = gtk_fps_overlay_snapshot;
  overlay_class->queue_draw = gtk_fps_overlay_queue_draw;

  gobject_class->dispose = gtk_fps_overlay_dispose;
}

static void
gtk_fps_overlay_init (GtkFpsOverlay *self)
{
  self->infos = g_hash_table_new_full (g_direct_hash, g_direct_equal, NULL, gtk_fps_info_free);
}

GtkInspectorOverlay *
gtk_fps_overlay_new (void)
{
  GtkFpsOverlay *self;

  self = g_object_new (GTK_TYPE_FPS_OVERLAY, NULL);

  return GTK_INSPECTOR_OVERLAY (self);
}