/*
 * Copyright (C) 2021 Red Hat Inc.
 *
 * 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/>.
 */

/*
 * The image difference code is originally a reformatted and simplified
 * copy of weston-test-client-helper.c from the weston repository, with
 * the following copyright and license note:
 *
 * Copyright © 2012 Intel Corporation
 * Copyright © 2015 Samsung Electronics Co., Ltd
 * Copyright 2016, 2017 Collabora, Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/*
 * To update or initialize reference images for tests, set the
 * MUTTER_REF_TEST_UPDATE environment variable.
 *
 * The MUTTER_REF_TEST_UPDATE is interpreted as a comma seperated list of
 * regular expressions. If the test path matches any of the regular
 * expressions, the test reference image will be updated, unless the
 * existing reference image is pixel identical to the newly created one.
 *
 * Updating test reference images also requires using a software OpenGL
 * renderer, which can be achieved using LIBGL_ALWAYS_SOFTWARE=1
 *
 * For example, for the test case '/path/to/test/case', run the test
 * inside
 *
 * ```
 * env LIBGL_ALWAYS_SOFTWARE=1 MUTTER_REF_TEST_UPDATE='/path/to/test/case`
 * ```
 *
 */

#include "config.h"

#include "tests/meta-ref-test.h"

#include <cairo.h>
#include <glib.h>

#include "backends/meta-backend-private.h"
#include "backends/meta-stage-private.h"
#include "clutter/clutter/clutter-stage-view-private.h"

typedef struct _Range
{
  int a;
  int b;
} Range;

typedef struct _ImageIterator
{
  uint8_t *data;
  int stride;
} ImageIterator;

typedef struct _PixelDiffStat
{
  /* Pixel diff stat channel */
  struct {
    int min_diff;
    int max_diff;
  } ch[4];
} PixelDiffStat;

/**
 * range_get:
 * @range: Range to validate or NULL.
 *
 * Validate and get range.
 *
 * Returns the given range, or {0, 0} for NULL.
 *
 * Will abort if range is invalid, that is a > b.
 */
static Range
range_get (const Range *range)
{
  if (!range)
    return (Range) { 0, 0 };

  g_assert_cmpint (range->a, <=, range->b);
  return *range;
}

static void
image_iterator_init (ImageIterator   *it,
                     cairo_surface_t *image)
{
  it->stride = cairo_image_surface_get_stride (image);
  it->data = cairo_image_surface_get_data (image);

  g_assert_cmpint (cairo_image_surface_get_format (image), ==,
                   CAIRO_FORMAT_ARGB32);
}

static uint32_t *
image_iterator_get_row (ImageIterator *it,
                        int            y)
{
  return (uint32_t *) (it->data + y * it->stride);
}

static gboolean
fuzzy_match_pixels (uint32_t       pix_a,
                    uint32_t       pix_b,
                    const Range   *fuzz,
                    PixelDiffStat *diff_stat)
{
  gboolean ret = TRUE;
  int shift;
  int i;

  for (shift = 0, i = 0; i < 4; shift += 8, i++)
    {
      int val_a = (pix_a >> shift) & 0xffu;
      int val_b = (pix_b >> shift) & 0xffu;
      int d = val_b - val_a;

      if (diff_stat)
        {
          diff_stat->ch[i].min_diff = MIN (diff_stat->ch[i].min_diff, d);
          diff_stat->ch[i].max_diff = MAX (diff_stat->ch[i].max_diff, d);
        }

      if (d < fuzz->a || d > fuzz->b)
        ret = FALSE;
    }

  return ret;
}

static gboolean
compare_images (cairo_surface_t *ref_image,
                cairo_surface_t *result_image,
                const Range     *precision,
                PixelDiffStat   *diff_stat)
{
  Range fuzz = range_get (precision);
  ImageIterator it_ref;
  ImageIterator it_result;
  int x, y;
  uint32_t *pix_ref;
  uint32_t *pix_result;

  g_assert_cmpint (cairo_image_surface_get_width (ref_image), ==,
                   cairo_image_surface_get_width (result_image));
  g_assert_cmpint (cairo_image_surface_get_height (ref_image), ==,
                   cairo_image_surface_get_height (result_image));

  image_iterator_init (&it_ref, ref_image);
  image_iterator_init (&it_result, result_image);

  for (y = 0; y < cairo_image_surface_get_height (ref_image); y++)
    {
      pix_ref = image_iterator_get_row (&it_ref, y);
      pix_result = image_iterator_get_row (&it_result, y);

      for (x = 0; x < cairo_image_surface_get_width (ref_image); x++)
        {
          if (!fuzzy_match_pixels (*pix_ref, *pix_result,
                                   &fuzz, diff_stat))
            return FALSE;

          pix_ref++;
          pix_result++;
        }
    }

  return TRUE;
}

static void
assert_software_rendered (void)
{
  MetaBackend *backend = meta_get_backend ();

  g_assert_false (meta_backend_is_rendering_hardware_accelerated (backend));
}

static void
capture_view_into (ClutterStageView *view,
                   MetaRectangle    *rect,
                   uint8_t          *buffer,
                   int               stride)
{
  CoglFramebuffer *framebuffer;
  ClutterBackend *backend;
  CoglContext *context;
  CoglBitmap *bitmap;
  cairo_rectangle_int_t view_layout;
  float view_scale;
  float texture_width;
  float texture_height;
  int x, y;

  framebuffer = clutter_stage_view_get_framebuffer (view);

  view_scale = clutter_stage_view_get_scale (view);
  texture_width = roundf (rect->width * view_scale);
  texture_height = roundf (rect->height * view_scale);

  backend = clutter_get_default_backend ();
  context = clutter_backend_get_cogl_context (backend);
  bitmap = cogl_bitmap_new_for_data (context,
                                     texture_width, texture_height,
                                     CLUTTER_CAIRO_FORMAT_ARGB32,
                                     stride,
                                     buffer);

  clutter_stage_view_get_layout (view, &view_layout);

  x = roundf ((rect->x - view_layout.x) * view_scale);
  y = roundf ((rect->y - view_layout.y) * view_scale);
  cogl_framebuffer_read_pixels_into_bitmap (framebuffer,
                                            x, y,
                                            COGL_READ_PIXELS_COLOR_BUFFER,
                                            bitmap);

  cogl_object_unref (bitmap);
}

typedef struct
{
  MetaStageWatch *watch;
  GMainLoop *loop;

  cairo_surface_t *out_image;
} CaptureViewData;

static void
on_after_paint (MetaStage           *stage,
                ClutterStageView    *view,
                ClutterPaintContext *paint_context,
                gpointer             user_data)
{
  CaptureViewData *data = user_data;
  MetaRectangle rect;
  float view_scale;
  int texture_width, texture_height;
  cairo_surface_t *image;
  uint8_t *buffer;
  int stride;

  meta_stage_remove_watch (stage, data->watch);
  data->watch = NULL;

  clutter_stage_view_get_layout (view, &rect);
  view_scale = clutter_stage_view_get_scale (view);
  texture_width = roundf (rect.width * view_scale);
  texture_height = roundf (rect.height * view_scale);
  image = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
                                      texture_width, texture_height);
  cairo_surface_set_device_scale (image, view_scale, view_scale);

  buffer = cairo_image_surface_get_data (image);
  stride = cairo_image_surface_get_stride (image);

  capture_view_into (view, &rect, buffer, stride);

  data->out_image = image;

  cairo_surface_mark_dirty (data->out_image);

  g_main_loop_quit (data->loop);
}

static cairo_surface_t *
capture_view (ClutterStageView *view)
{
  MetaBackend *backend = meta_get_backend ();
  MetaStage *stage = META_STAGE (meta_backend_get_stage (backend));
  CaptureViewData data = { 0 };

  data.loop = g_main_loop_new (NULL, FALSE);
  data.watch = meta_stage_watch_view (stage, view,
                                      META_STAGE_WATCH_AFTER_PAINT,
                                      on_after_paint,
                                      &data);
  clutter_stage_view_add_redraw_clip (view, NULL);
  clutter_stage_view_schedule_update (view);

  g_main_loop_run (data.loop);
  g_main_loop_unref (data.loop);

  g_assert_null (data.watch);
  g_assert_nonnull (data.out_image);

  return data.out_image;
}

static void
depathify (char *path)
{
  int len = strlen (path);
  int i;

  for (i = 0; i < len; i++)
    {
      if (path[i] == '/')
        path[i] = '_';
    }
}

static void
ensure_expected_format (cairo_surface_t **ref_image)
{
  int width, height;
  cairo_surface_t *target;
  cairo_t *cr;

  if (cairo_image_surface_get_format (*ref_image) ==
      CAIRO_FORMAT_ARGB32)
    return;

  width = cairo_image_surface_get_width (*ref_image);
  height = cairo_image_surface_get_height (*ref_image);
  target = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, width, height);

  cr = cairo_create (target);
  cairo_set_source_surface (cr, *ref_image, 0.0, 0.0);
  cairo_paint (cr);
  cairo_destroy (cr);

  cairo_surface_destroy (*ref_image);
  *ref_image = target;
}

/**
 * Tint a color:
 * @src Source pixel as x8r8g8b8.
 * @add The tint as x8r8g8b8, x8 must be zero; r8, g8 and b8 must be
 * no greater than 0xc0 to avoid overflow to another channel.
 * Returns: The tinted pixel color as x8r8g8b8, x8 guaranteed to be 0xff.
 *
 * The source pixel RGB values are divided by 4, and then the tint is added.
 * To achieve colors outside of the range of src, a tint color channel must be
 * at least 0x40. (0xff / 4 = 0x3f, 0xff - 0x3f = 0xc0)
 */
static uint32_t
tint (uint32_t src,
      uint32_t add)
{
  uint32_t v;

  v = ((src & 0xfcfcfcfc) >> 2) | 0xff000000;

  return v + add;
}

static cairo_surface_t *
visualize_difference (cairo_surface_t *ref_image,
                      cairo_surface_t *result_image,
                      const Range     *precision)
{
  Range fuzz = range_get (precision);
  int width, height;
  cairo_surface_t *diff_image;
  cairo_t *cr;
  ImageIterator it_ref;
  ImageIterator it_result;
  ImageIterator it_diff;
  int y;

  width = cairo_image_surface_get_width (ref_image);
  height = cairo_image_surface_get_height (ref_image);

  diff_image = cairo_surface_create_similar_image (ref_image,
                                                   CAIRO_FORMAT_ARGB32,
                                                   width,
                                                   height);
  cr = cairo_create (diff_image);
  cairo_set_source_rgba (cr, 1.0, 1.0, 1.0, 1.0);
  cairo_paint (cr);
  cairo_set_source_surface (cr, ref_image, 0.0, 0.0);
  cairo_set_operator (cr, CAIRO_OPERATOR_HSL_LUMINOSITY);
  cairo_paint (cr);
  cairo_destroy (cr);

  image_iterator_init (&it_ref, ref_image);
  image_iterator_init (&it_result, result_image);
  image_iterator_init (&it_diff, diff_image);

  for (y = 0; y < cairo_image_surface_get_height (ref_image); y++)
    {
      uint32_t *ref_pixel;
      uint32_t *result_pixel;
      uint32_t *diff_pixel;
      int x;

      ref_pixel = image_iterator_get_row (&it_ref, y);
      result_pixel = image_iterator_get_row (&it_result, y);
      diff_pixel = image_iterator_get_row (&it_diff, y);

      for (x = 0; x < cairo_image_surface_get_width (ref_image); x++)
        {
          if (fuzzy_match_pixels (*ref_pixel, *result_pixel,
                                  &fuzz, NULL))
            *diff_pixel = tint (*diff_pixel, 0x00008000); /* green */
          else
            *diff_pixel = tint (*diff_pixel, 0x00c00000); /* red */

          ref_pixel++;
          result_pixel++;
          diff_pixel++;
        }
    }

  return diff_image;
}

void
meta_ref_test_verify_view (ClutterStageView *view,
                           const char       *test_name_unescaped,
                           int               test_seq_no,
                           MetaReftestFlag   flags)
{
  cairo_surface_t *view_image;
  const char *dist_dir;
  g_autofree char *test_name = NULL;
  g_autofree char *ref_image_path = NULL;
  cairo_surface_t *ref_image;
  cairo_status_t ref_status;

  if (flags & META_REFTEST_FLAG_UPDATE_REF)
    assert_software_rendered ();

  view_image = capture_view (view);

  test_name = g_strdup (test_name_unescaped + 1);
  depathify (test_name);

  dist_dir = g_test_get_dir (G_TEST_DIST);
  ref_image_path = g_strdup_printf ("%s/tests/ref-tests/%s_%d.ref.png",
                                    dist_dir,
                                    test_name, test_seq_no);

  ref_image = cairo_image_surface_create_from_png (ref_image_path);
  g_assert_nonnull (ref_image);
  ref_status = cairo_surface_status (ref_image);

  if (flags & META_REFTEST_FLAG_UPDATE_REF)
    {
      g_assert (ref_status == CAIRO_STATUS_FILE_NOT_FOUND ||
                ref_status == CAIRO_STATUS_SUCCESS);

      if (ref_status == CAIRO_STATUS_SUCCESS)
        ensure_expected_format (&ref_image);

      if (ref_status == CAIRO_STATUS_SUCCESS &&
          cairo_image_surface_get_width (ref_image) ==
          cairo_image_surface_get_width (view_image) &&
          cairo_image_surface_get_height (ref_image) ==
          cairo_image_surface_get_height (view_image) &&
          compare_images (ref_image, view_image, NULL, NULL))
        {
          g_message ("Not updating '%s', it didn't change.", ref_image_path);
        }
      else
        {
          g_message ("Updating '%s'.", ref_image_path);
          g_assert_cmpint (cairo_surface_write_to_png (view_image, ref_image_path),
                           ==,
                           CAIRO_STATUS_SUCCESS);
        }
    }
  else
    {
      const Range gl_fuzz = { -3, 4 };
      PixelDiffStat diff_stat = {};

      g_assert_cmpint (ref_status, ==, CAIRO_STATUS_SUCCESS);
      ensure_expected_format (&ref_image);

      if (!compare_images (ref_image, view_image, &gl_fuzz,
                           &diff_stat))
        {
          cairo_surface_t *diff_image;
          const char *build_dir;
          g_autofree char *ref_image_copy_path = NULL;
          g_autofree char *result_image_path = NULL;
          g_autofree char *diff_image_path = NULL;

          diff_image = visualize_difference (ref_image, view_image,
                                             &gl_fuzz);

          build_dir = g_test_get_dir (G_TEST_BUILT);
          ref_image_copy_path =
            g_strdup_printf ("%s/meson-logs/tests/ref-tests/%s_%d.ref.png",
                             build_dir,
                             test_name, test_seq_no);
          result_image_path =
            g_strdup_printf ("%s/meson-logs/tests/ref-tests/%s_%d.result.png",
                             build_dir,
                             test_name, test_seq_no);
          diff_image_path =
            g_strdup_printf ("%s/meson-logs/tests/ref-tests/%s_%d.diff.png",
                             build_dir,
                             test_name, test_seq_no);

          g_mkdir_with_parents (g_path_get_dirname (ref_image_copy_path),
                                0755);

          g_assert_cmpint (cairo_surface_write_to_png (ref_image,
                                                       ref_image_copy_path),
                           ==,
                           CAIRO_STATUS_SUCCESS);
          g_assert_cmpint (cairo_surface_write_to_png (view_image,
                                                       result_image_path),
                           ==,
                           CAIRO_STATUS_SUCCESS);
          g_assert_cmpint (cairo_surface_write_to_png (diff_image,
                                                       diff_image_path),
                           ==,
                           CAIRO_STATUS_SUCCESS);

          g_critical ("Pixel difference exceeds limits "
                      "(min: [%d, %d, %d, %d], "
                      "max: [%d, %d, %d, %d])\n"
                      "See %s, %s, and %s for details.",
                      diff_stat.ch[0].min_diff,
                      diff_stat.ch[1].min_diff,
                      diff_stat.ch[2].min_diff,
                      diff_stat.ch[3].min_diff,
                      diff_stat.ch[0].max_diff,
                      diff_stat.ch[1].max_diff,
                      diff_stat.ch[2].max_diff,
                      diff_stat.ch[3].max_diff,
                      ref_image_copy_path,
                      result_image_path,
                      diff_image_path);
        }
    }

  cairo_surface_destroy (view_image);
  cairo_surface_destroy (ref_image);
}

MetaReftestFlag
meta_ref_test_determine_ref_test_flag (void)
{
  const char *update_tests;
  char **update_test_rules;
  int n_update_test_rules;
  MetaReftestFlag flags;
  int i;

  update_tests = g_getenv ("MUTTER_REF_TEST_UPDATE");
  if (!update_tests)
    return META_REFTEST_FLAG_NONE;

  if (strcmp (update_tests, "all") == 0)
    return META_REFTEST_FLAG_UPDATE_REF;

  update_test_rules = g_strsplit (update_tests, ",", -1);
  n_update_test_rules = g_strv_length (update_test_rules);
  g_assert_cmpint (n_update_test_rules, >, 0);

  flags = META_REFTEST_FLAG_NONE;
  for (i = 0; i < n_update_test_rules; i++)
    {
      char *rule = update_test_rules[i];

      if (g_regex_match_simple (rule, g_test_get_path (), 0, 0))
        {
          flags |= META_REFTEST_FLAG_UPDATE_REF;
          break;
        }
    }

  g_strfreev (update_test_rules);

  return flags;
}