/* GIMP - The GNU Image Manipulation Program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * gimpoperationbuffersourcevalidate.c
 * Copyright (C) 2017 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 <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include <cairo.h>
#include <gegl-plugin.h>
#include <gdk-pixbuf/gdk-pixbuf.h>

#include "libgimpcolor/gimpcolor.h"
#include "libgimpconfig/gimpconfig.h"
#include "libgimpmath/gimpmath.h"

#include "operations-types.h"

#include "gegl/gimptilehandlervalidate.h"

#include "gimpoperationbuffersourcevalidate.h"


enum
{
  PROP_0,
  PROP_BUFFER
};


static void           gimp_operation_buffer_source_validate_dispose          (GObject                           *object);
static void           gimp_operation_buffer_source_validate_get_property     (GObject                           *object,
                                                                              guint                              property_id,
                                                                              GValue                            *value,
                                                                              GParamSpec                        *pspec);
static void           gimp_operation_buffer_source_validate_set_property     (GObject                           *object,
                                                                              guint                              property_id,
                                                                              const GValue                      *value,
                                                                              GParamSpec                        *pspec);

static GeglRectangle  gimp_operation_buffer_source_validate_get_bounding_box (GeglOperation                     *operation);
static void           gimp_operation_buffer_source_validate_prepare          (GeglOperation                     *operation);
static gboolean       gimp_operation_buffer_source_validate_process          (GeglOperation                     *operation,
                                                                              GeglOperationContext              *context,
                                                                              const gchar                       *output_pad,
                                                                              const GeglRectangle               *result,
                                                                              gint                               level);

static void           gimp_operation_buffer_source_validate_buffer_changed   (GeglBuffer                        *buffer,
                                                                              const GeglRectangle               *rect,
                                                                              gpointer                           data);


G_DEFINE_TYPE (GimpOperationBufferSourceValidate, gimp_operation_buffer_source_validate,
               GEGL_TYPE_OPERATION_SOURCE)

#define parent_class gimp_operation_buffer_source_validate_parent_class


static void
gimp_operation_buffer_source_validate_class_init (GimpOperationBufferSourceValidateClass *klass)
{
  GObjectClass       *object_class    = G_OBJECT_CLASS (klass);
  GeglOperationClass *operation_class = GEGL_OPERATION_CLASS (klass);

  object_class->dispose             = gimp_operation_buffer_source_validate_dispose;
  object_class->set_property        = gimp_operation_buffer_source_validate_set_property;
  object_class->get_property        = gimp_operation_buffer_source_validate_get_property;

  operation_class->get_bounding_box = gimp_operation_buffer_source_validate_get_bounding_box;
  operation_class->prepare          = gimp_operation_buffer_source_validate_prepare;
  operation_class->process          = gimp_operation_buffer_source_validate_process;

  operation_class->threaded         = FALSE;
  operation_class->no_cache         = TRUE;

  gegl_operation_class_set_keys (operation_class,
                                 "name",        "gimp:buffer-source-validate",
                                 "categories",  "gimp",
                                 "description", "GIMP Buffer-Source Validate operation",
                                 NULL);

  g_object_class_install_property (object_class, PROP_BUFFER,
                                   g_param_spec_object ("buffer",
                                                        "Buffer",
                                                        "Input buffer",
                                                        GEGL_TYPE_BUFFER,
                                                        G_PARAM_READWRITE));
}

static void
gimp_operation_buffer_source_validate_init (GimpOperationBufferSourceValidate *self)
{
}

static void
gimp_operation_buffer_source_validate_dispose (GObject *object)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (object);

  if (buffer_source_validate->buffer)
    {
      g_signal_handlers_disconnect_by_func (
        buffer_source_validate->buffer,
        gimp_operation_buffer_source_validate_buffer_changed,
        buffer_source_validate);

      g_clear_object (&buffer_source_validate->buffer);
    }

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

static void
gimp_operation_buffer_source_validate_get_property (GObject    *object,
                                                    guint       property_id,
                                                    GValue     *value,
                                                    GParamSpec *pspec)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (object);

  switch (property_id)
    {
    case PROP_BUFFER:
      g_value_set_object (value, buffer_source_validate->buffer);
      break;

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

static void
gimp_operation_buffer_source_validate_set_property (GObject      *object,
                                                    guint         property_id,
                                                    const GValue *value,
                                                    GParamSpec   *pspec)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (object);

  switch (property_id)
    {
    case PROP_BUFFER:
      {
        if (buffer_source_validate->buffer)
          {
            gimp_operation_buffer_source_validate_buffer_changed (
              buffer_source_validate->buffer,
              gegl_buffer_get_extent (buffer_source_validate->buffer),
              buffer_source_validate);

            g_signal_handlers_disconnect_by_func (
              buffer_source_validate->buffer,
              G_CALLBACK (gimp_operation_buffer_source_validate_buffer_changed),
              buffer_source_validate);

            g_clear_object (&buffer_source_validate->buffer);
          }

        buffer_source_validate->buffer = g_value_dup_object (value);

        if (buffer_source_validate->buffer)
          {
            gegl_buffer_signal_connect (
              buffer_source_validate->buffer,
              "changed",
              G_CALLBACK (gimp_operation_buffer_source_validate_buffer_changed),
              buffer_source_validate);

            gimp_operation_buffer_source_validate_buffer_changed (
              buffer_source_validate->buffer,
              gegl_buffer_get_extent (buffer_source_validate->buffer),
              buffer_source_validate);
          }
      }
      break;

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

static GeglRectangle
gimp_operation_buffer_source_validate_get_bounding_box (GeglOperation *operation)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (operation);

  GeglRectangle result = {};

  if (buffer_source_validate->buffer)
    result = *gegl_buffer_get_extent (buffer_source_validate->buffer);

  return result;
}

static void
gimp_operation_buffer_source_validate_prepare (GeglOperation *operation)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (operation);
  const Babl                        *format                 = NULL;

  if (buffer_source_validate->buffer)
    format = gegl_buffer_get_format (buffer_source_validate->buffer);

  gegl_operation_set_format (operation, "output", format);
}

static gboolean
gimp_operation_buffer_source_validate_process (GeglOperation        *operation,
                                               GeglOperationContext *context,
                                               const gchar          *output_pad,
                                               const GeglRectangle  *result,
                                               gint                  level)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (operation);
  GeglBuffer                        *buffer                 = buffer_source_validate->buffer;

  if (buffer)
    {
      GimpTileHandlerValidate *validate_handler;

      validate_handler = gimp_tile_handler_validate_get_assigned (buffer);

      if (validate_handler)
        {
          gint n_threads;

          g_object_get (gegl_config (),
                        "threads", &n_threads,
                        NULL);

          /* the main reason to validate the buffer during processing is to
           * avoid threading issues.  skip validation if not using
           * multithreading.
           */
          if (n_threads > 1)
            {
              gint                   shift_x;
              gint                   shift_y;
              gint                   tile_width;
              gint                   tile_height;
              cairo_rectangle_int_t  rect;
              cairo_region_overlap_t overlap;

              g_object_get (buffer_source_validate->buffer,
                            "shift-x",     &shift_x,
                            "shift-y",     &shift_y,
                            "tile-width",  &tile_width,
                            "tile-height", &tile_height,
                            NULL);

              /* align the rectangle to the tile grid */
              rect.x      = (gint) floor ((gdouble) (result->x                  + shift_x) / tile_width)  * tile_width;
              rect.y      = (gint) floor ((gdouble) (result->y                  + shift_y) / tile_height) * tile_height;
              rect.width  = (gint) ceil  ((gdouble) (result->x + result->width  + shift_x) / tile_width)  * tile_width  - rect.x;
              rect.height = (gint) ceil  ((gdouble) (result->y + result->height + shift_y) / tile_height) * tile_height - rect.y;

              /* check if the rectangle interescts with the dirty region */
              overlap = cairo_region_contains_rectangle (validate_handler->dirty_region,
                                                         &rect);

              if (overlap != CAIRO_REGION_OVERLAP_OUT)
                {
                  GeglBufferIterator *iter;

                  /* if the rectangle is not entirely within the dirty
                   * region ...
                   */
                  if (overlap == CAIRO_REGION_OVERLAP_PART)
                    {
                      cairo_region_t        *region;
                      cairo_rectangle_int_t  intersection;

                      /* ... intersect it with region and use the result's
                       * bounds
                       */
                      region = cairo_region_copy (validate_handler->dirty_region);

                      cairo_region_intersect_rectangle (region, &rect);
                      cairo_region_get_extents (region, &intersection);

                      cairo_region_destroy (region);

                      /* realign the rectangle to the tile grid */
                      rect.x      = (gint) floor ((gdouble) (intersection.x                      ) / tile_width)  * tile_width;
                      rect.y      = (gint) floor ((gdouble) (intersection.y                      ) / tile_height) * tile_height;
                      rect.width  = (gint) ceil  ((gdouble) (intersection.x + intersection.width ) / tile_width)  * tile_width  - rect.x;
                      rect.height = (gint) ceil  ((gdouble) (intersection.y + intersection.height) / tile_height) * tile_height - rect.y;
                    }

                  rect.x -= shift_x;
                  rect.y -= shift_y;

                  /* iterate over the rectangle -- this implicitly causes
                   * validation
                   */
                  iter = gegl_buffer_iterator_new (buffer,
                                                   GEGL_RECTANGLE (rect.x,
                                                                   rect.y,
                                                                   rect.width,
                                                                   rect.height),
                                                   level, NULL,
                                                   GEGL_BUFFER_READ,
                                                   GEGL_ABYSS_NONE);

                  while (gegl_buffer_iterator_next (iter));
                }
            }
        }

      gegl_operation_context_set_object (context, "output", G_OBJECT (buffer));

      gegl_object_set_has_forked (G_OBJECT (buffer));
    }

  return TRUE;
}

static void
gimp_operation_buffer_source_validate_buffer_changed (GeglBuffer          *buffer,
                                                      const GeglRectangle *rect,
                                                      gpointer             data)
{
  GimpOperationBufferSourceValidate *buffer_source_validate = GIMP_OPERATION_BUFFER_SOURCE_VALIDATE (data);

  gegl_operation_invalidate (GEGL_OPERATION (buffer_source_validate),
                             rect, FALSE);
}