/* mks-display.c
 *
 * Copyright 2023 Christian Hergert <chergert@redhat.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

#include "config.h"

#include "mks-display.h"
#include "mks-screen.h"

typedef struct
{
  GdkPaintable *paintable;
  MksScreen    *screen;
} MksDisplayPrivate;

enum {
  PROP_0,
  PROP_SCREEN,
  N_PROPS
};

G_DEFINE_TYPE_WITH_PRIVATE (MksDisplay, mks_display, GTK_TYPE_WIDGET)

static GParamSpec *properties [N_PROPS];

static void
mks_display_snapshot (GtkWidget   *widget,
                      GtkSnapshot *snapshot)
{
  MksDisplay *self = (MksDisplay *)widget;
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);
  GtkAllocation alloc;
  double width;
  double height;

  g_assert (MKS_IS_DISPLAY (self));
  g_assert (GTK_IS_SNAPSHOT (snapshot));

  if (priv->paintable == NULL)
    return;

  gtk_widget_get_allocation (widget, &alloc);

  width = gdk_paintable_get_intrinsic_width (priv->paintable);
  height = gdk_paintable_get_intrinsic_height (priv->paintable);

  gtk_snapshot_scale (snapshot,
                      alloc.width / width,
                      alloc.height / height);

  gdk_paintable_snapshot (priv->paintable, snapshot, width, height);
}

static void
mks_display_attach_cb (GObject      *object,
                       GAsyncResult *result,
                       gpointer      user_data)
{
  g_autoptr(MksDisplay) self = user_data;
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);
  MksScreen *screen = (MksScreen *)object;
  g_autoptr(GdkPaintable) paintable = NULL;
  g_autoptr(GError) error = NULL;

  g_assert (MKS_IS_SCREEN (screen));
  g_assert (G_IS_ASYNC_RESULT (result));
  g_assert (MKS_IS_DISPLAY (self));

  paintable = mks_screen_attach_finish (screen, result, &error);

  if (priv->screen != screen)
    return;

  if (g_set_object (&priv->paintable, paintable))
    {
      g_signal_connect_object (priv->paintable,
                               "invalidate-size",
                               G_CALLBACK (gtk_widget_queue_resize),
                               self,
                               G_CONNECT_SWAPPED);
      g_signal_connect_object (priv->paintable,
                               "invalidate-contents",
                               G_CALLBACK (gtk_widget_queue_draw),
                               self,
                               G_CONNECT_SWAPPED);
    }

  gtk_widget_queue_resize (GTK_WIDGET (self));
}

static void
mks_display_connect (MksDisplay *self,
                     MksScreen  *screen)
{
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);

  g_assert (MKS_IS_DISPLAY (self));
  g_assert (priv->screen == NULL);

  g_set_object (&priv->screen, screen);

  mks_screen_attach (screen,
                     NULL,
                     mks_display_attach_cb,
                     g_object_ref (self));
}

static void
mks_display_disconnect (MksDisplay *self)
{
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);

  g_assert (MKS_IS_DISPLAY (self));
  g_assert (priv->screen != NULL);

  g_clear_object (&priv->screen);
  g_clear_object (&priv->paintable);
}

static void
mks_display_measure (GtkWidget      *widget,
                     GtkOrientation  orientation,
                     int             for_size,
                     int            *minimum,
                     int            *natural,
                     int            *minimum_baseline,
                     int            *natural_baseline)
{
  MksDisplay *self = (MksDisplay *)widget;
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);

  g_assert (MKS_IS_DISPLAY (self));

  *minimum_baseline = -1;
  *natural_baseline = -1;
  *minimum = 0;

  if (orientation == GTK_ORIENTATION_HORIZONTAL)
    {
      if (priv->paintable != NULL)
        *natural = gdk_paintable_get_intrinsic_width (priv->paintable);
      else
        *natural = 0;
    }
  else
    {
      if (priv->paintable != NULL)
        *natural = gdk_paintable_get_intrinsic_width (priv->paintable)
                 * gdk_paintable_get_intrinsic_aspect_ratio (priv->paintable);
      else
        *natural = 0;
    }
}

static GtkSizeRequestMode
mks_display_get_request_mode (GtkWidget *widget)
{
  return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
}

static void
mks_display_dispose (GObject *object)
{
  MksDisplay *self = (MksDisplay *)object;
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);

  if (priv->screen != NULL)
    mks_display_disconnect (self);

  g_clear_object (&priv->paintable);
  g_clear_object (&priv->screen);

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

static void
mks_display_get_property (GObject    *object,
                          guint       prop_id,
                          GValue     *value,
                          GParamSpec *pspec)
{
  MksDisplay *self = MKS_DISPLAY (object);

  switch (prop_id)
    {
    case PROP_SCREEN:
      g_value_set_object (value, mks_display_get_screen (self));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
mks_display_set_property (GObject      *object,
                          guint         prop_id,
                          const GValue *value,
                          GParamSpec   *pspec)
{
  MksDisplay *self = MKS_DISPLAY (object);

  switch (prop_id)
    {
    case PROP_SCREEN:
      mks_display_set_screen (self, g_value_get_object (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
mks_display_class_init (MksDisplayClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

  object_class->dispose = mks_display_dispose;
  object_class->get_property = mks_display_get_property;
  object_class->set_property = mks_display_set_property;

  widget_class->snapshot = mks_display_snapshot;
  widget_class->measure = mks_display_measure;
  widget_class->get_request_mode = mks_display_get_request_mode;

  properties[PROP_SCREEN] =
    g_param_spec_object ("screen", NULL, NULL,
                         MKS_TYPE_SCREEN,
                         (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));

  g_object_class_install_properties (object_class, N_PROPS, properties);
}

static void
mks_display_init (MksDisplay *self)
{
}

GtkWidget *
mks_display_new (void)
{
  return g_object_new (MKS_TYPE_DISPLAY, NULL);
}

/**
 * mks_display_get_screen:
 * @self: a #MksDisplay
 *
 * Gets the screen connected to the display.
 *
 * Returns: (transfer none): a #MksScreen
 */
MksScreen *
mks_display_get_screen (MksDisplay *self)
{
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);

  g_return_val_if_fail (MKS_IS_DISPLAY (self), NULL);

  return priv->screen;
}

void
mks_display_set_screen (MksDisplay *self,
                        MksScreen  *screen)
{
  MksDisplayPrivate *priv = mks_display_get_instance_private (self);

  g_return_if_fail (MKS_IS_DISPLAY (self));

  if (priv->screen == screen)
    return;

  if (priv->screen != NULL)
    mks_display_disconnect (self);

  if (screen != NULL)
    mks_display_connect (self, screen);

  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SCREEN]);
}