/* GIMP - The GNU Image Manipulation Program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * gimphighlightablebutton.c
 * Copyright (C) 2018 Ell
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <string.h>

#include <gegl.h>
#include <gtk/gtk.h>

#include "libgimpcolor/gimpcolor.h"
#include "libgimpwidgets/gimpwidgets.h"

#include "widgets-types.h"

#include "core/gimp-cairo.h"

#include "gimphighlightablebutton.h"


#define DEFAULT_HIGHLIGHT_COLOR {0.20, 0.70, 0.20, 0.65}

#define PADDING       1
#define BORDER_WIDTH  1
#define CORNER_RADIUS 2

#define REV (2.0 * G_PI)


enum
{
  PROP_0,
  PROP_HIGHLIGHT,
  PROP_HIGHLIGHT_COLOR
};


struct _GimpHighlightableButtonPrivate
{
  gboolean highlight;
  GimpRGB  highlight_color;
};


static void       gimp_highlightable_button_set_property (GObject        *object,
                                                          guint           property_id,
                                                          const GValue   *value,
                                                          GParamSpec     *pspec);
static void       gimp_highlightable_button_get_property (GObject        *object,
                                                          guint           property_id,
                                                          GValue         *value,
                                                          GParamSpec     *pspec);

static gboolean   gimp_highlightable_button_expose_event (GtkWidget      *widget,
                                                          GdkEventExpose *event);


G_DEFINE_TYPE_WITH_PRIVATE (GimpHighlightableButton, gimp_highlightable_button,
                            GIMP_TYPE_BUTTON)

#define parent_class gimp_highlightable_button_parent_class


static void
gimp_highlightable_button_class_init (GimpHighlightableButtonClass *klass)
{
  GObjectClass   *object_class = G_OBJECT_CLASS (klass);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

  object_class->get_property = gimp_highlightable_button_get_property;
  object_class->set_property = gimp_highlightable_button_set_property;

  widget_class->expose_event = gimp_highlightable_button_expose_event;

  g_object_class_install_property (object_class, PROP_HIGHLIGHT,
                                   g_param_spec_boolean ("highlight",
                                                         NULL, NULL,
                                                         FALSE,
                                                         GIMP_PARAM_READWRITE |
                                                         G_PARAM_CONSTRUCT));

  g_object_class_install_property (object_class, PROP_HIGHLIGHT_COLOR,
                                   gimp_param_spec_rgb ("highlight-color",
                                                        NULL, NULL,
                                                        TRUE,
                                                        &(GimpRGB) DEFAULT_HIGHLIGHT_COLOR,
                                                        GIMP_PARAM_READWRITE |
                                                        G_PARAM_CONSTRUCT));
}

static void
gimp_highlightable_button_init (GimpHighlightableButton *button)
{
  button->priv = gimp_highlightable_button_get_instance_private (button);
}

static void
gimp_highlightable_button_set_property (GObject      *object,
                                        guint         property_id,
                                        const GValue *value,
                                        GParamSpec   *pspec)
{
  GimpHighlightableButton *button = GIMP_HIGHLIGHTABLE_BUTTON (object);

  switch (property_id)
    {
    case PROP_HIGHLIGHT:
      gimp_highlightable_button_set_highlight (button,
                                               g_value_get_boolean (value));
      break;

    case PROP_HIGHLIGHT_COLOR:
      gimp_highlightable_button_set_highlight_color (button,
                                                     g_value_get_boxed (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
      break;
    }
}

static void
gimp_highlightable_button_get_property (GObject    *object,
                                        guint       property_id,
                                        GValue     *value,
                                        GParamSpec *pspec)
{
  GimpHighlightableButton *button = GIMP_HIGHLIGHTABLE_BUTTON (object);

  switch (property_id)
    {
    case PROP_HIGHLIGHT:
      g_value_set_boolean (value, button->priv->highlight);
      break;

    case PROP_HIGHLIGHT_COLOR:
      g_value_set_boxed (value, &button->priv->highlight_color);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
      break;
    }
}

static gboolean
gimp_highlightable_button_expose_event (GtkWidget      *widget,
                                        GdkEventExpose *event)
{
  GimpHighlightableButton *button = GIMP_HIGHLIGHTABLE_BUTTON (widget);

  if (button->priv->highlight)
    {
      if (gtk_widget_is_drawable (widget))
        {
          GtkStyle      *style = gtk_widget_get_style (widget);
          GtkStateType   state = gtk_widget_get_state (widget);
          GtkAllocation  allocation;
          gboolean       border;
          gdouble        lightness;
          gdouble        opacity;
          gdouble        x;
          gdouble        y;
          gdouble        width;
          gdouble        height;
          cairo_t       *cr;

          gtk_widget_get_allocation (widget, &allocation);

          border =
            (state                                       == GTK_STATE_ACTIVE   ||
             state                                       == GTK_STATE_PRELIGHT ||
             gtk_button_get_relief (GTK_BUTTON (button)) == GTK_RELIEF_NORMAL);

          lightness = 1.00;
          opacity   = 1.00;

          switch (state)
            {
            case GTK_STATE_ACTIVE:      lightness = 0.80; break;
            case GTK_STATE_PRELIGHT:    lightness = 1.25; break;
            case GTK_STATE_INSENSITIVE: opacity   = 0.50; break;
            default:                                      break;
            }

          x      = allocation.x      +       PADDING;
          y      = allocation.y      +       PADDING;
          width  = allocation.width  - 2.0 * PADDING;
          height = allocation.height - 2.0 * PADDING;

          if (border)
            {
              x      += BORDER_WIDTH / 2.0;
              y      += BORDER_WIDTH / 2.0;
              width  -= BORDER_WIDTH;
              height -= BORDER_WIDTH;
            }

          cr = gdk_cairo_create (event->window);
          gdk_cairo_region (cr, event->region);
          cairo_clip (cr);

          cairo_set_source_rgba (cr,
                                 button->priv->highlight_color.r * lightness,
                                 button->priv->highlight_color.g * lightness,
                                 button->priv->highlight_color.b * lightness,
                                 button->priv->highlight_color.a * opacity);

          gimp_cairo_rounded_rectangle (cr,
                                        x, y, width, height, CORNER_RADIUS);

          cairo_fill_preserve (cr);

          if (border)
            {
              gdk_cairo_set_source_color (cr, &style->fg[state]);

              cairo_set_line_width (cr, BORDER_WIDTH);

              cairo_stroke (cr);
            }

          cairo_destroy (cr);

          if (gtk_widget_has_focus (widget))
            {
              gboolean interior_focus;
              gint     focus_width;
              gint     focus_pad;
              gint     child_displacement_x;
              gint     child_displacement_y;
              gboolean displace_focus;
              gint     x;
              gint     y;
              gint     width;
              gint     height;

              gtk_widget_style_get (widget,
                                    "interior-focus",       &interior_focus,
                                    "focus-line-width",     &focus_width,
                                    "focus-padding",        &focus_pad,
                                    "child-displacement-y", &child_displacement_y,
                                    "child-displacement-x", &child_displacement_x,
                                    "displace-focus",       &displace_focus,
                                    NULL);

              x      = allocation.x      +     PADDING;
              y      = allocation.y      +     PADDING;
              width  = allocation.width  - 2 * PADDING;
              height = allocation.height - 2 * PADDING;

              if (interior_focus)
                {
                  x      += style->xthickness + focus_pad;
                  y      += style->ythickness + focus_pad;
                  width  -= 2 * (style->xthickness + focus_pad);
                  height -= 2 * (style->ythickness + focus_pad);
                }
              else
                {
                  x      -= focus_width + focus_pad;
                  y      -= focus_width + focus_pad;
                  width  += 2 * (focus_width + focus_pad);
                  height += 2 * (focus_width + focus_pad);
                }

              if (state == GTK_STATE_ACTIVE && displace_focus)
                {
                  x += child_displacement_x;
                  y += child_displacement_y;
                }

              gtk_paint_focus (style, gtk_widget_get_window (widget), state,
                               &event->area, widget, "button",
                               x, y, width, height);
            }

          gtk_container_propagate_expose (GTK_CONTAINER (button),
                                          gtk_bin_get_child (GTK_BIN (button)),
                                          event);
        }

      return FALSE;
    }
  else
    {
      return GTK_WIDGET_CLASS (parent_class)->expose_event (widget, event);
    }
}


/*  public functions  */


GtkWidget *
gimp_highlightable_button_new (void)
{
  return g_object_new (GIMP_TYPE_HIGHLIGHTABLE_BUTTON, NULL);
}

void
gimp_highlightable_button_set_highlight (GimpHighlightableButton *button,
                                         gboolean                 highlight)
{
  g_return_if_fail (GIMP_IS_HIGHLIGHTABLE_BUTTON (button));

  if (button->priv->highlight != highlight)
    {
      button->priv->highlight = highlight;

      gtk_widget_queue_draw (GTK_WIDGET (button));

      g_object_notify (G_OBJECT (button), "highlight");
    }
}

gboolean
gimp_highlightable_button_get_highlight (GimpHighlightableButton *button)
{
  g_return_val_if_fail (GIMP_IS_HIGHLIGHTABLE_BUTTON (button), FALSE);

  return button->priv->highlight;
}

void
gimp_highlightable_button_set_highlight_color (GimpHighlightableButton *button,
                                               const GimpRGB           *color)
{
  g_return_if_fail (GIMP_IS_HIGHLIGHTABLE_BUTTON (button));
  g_return_if_fail (color != NULL);

  if (memcmp (&button->priv->highlight_color, color, sizeof (GimpRGB)))
    {
      button->priv->highlight_color = *color;

      if (button->priv->highlight)
        gtk_widget_queue_draw (GTK_WIDGET (button));

      g_object_notify (G_OBJECT (button), "highlight-color");
    }
}

void
gimp_highlightable_button_get_highlight_color (GimpHighlightableButton *button,
                                               GimpRGB                 *color)
{
  g_return_if_fail (GIMP_IS_HIGHLIGHTABLE_BUTTON (button));
  g_return_if_fail (color != NULL);

  *color = button->priv->highlight_color;
}