// Gmsh - Copyright (C) 1997-2025 C. Geuzaine, J.-F. Remacle
//
// See the LICENSE.txt file in the Gmsh root directory for license information.
// Please report all issues on https://gitlab.onelab.info/gmsh/gmsh/issues.

/*
 * This code is based on the rgbtoycc.c code from the MPEG-1 Video
 * Software Encoder (Version 1.5; February 1, 1995), by Lawrence
 * A. Rowe, Kevin Gong, Eugene Hung, Ketan Patel, Steve Smoot and Dan
 * Wallach Computer Science Division-EECS, Univ. of Calif. at Berkeley
 *
 * Copyright (c) 1995 The Regents of the University of California.
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 *
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#include "MallocUtils.h"
#include "gl2yuv.h"

void create_yuv(FILE *outfile, PixelBuffer *buffer)
{
  if(buffer->getFormat() != GL_RGB || buffer->getType() != GL_UNSIGNED_BYTE) {
    Msg::Error("YUV only implemented for GL_RGB and GL_UNSIGNED_BYTE");
    return;
  }

  int x, y;
  unsigned char *dy0, *dy1;
  unsigned char *dcr, *dcb;
  unsigned char *src0, *src1;
  int cdivisor;

  static int first = 1;
  static float mult299[1024], mult587[1024], mult114[1024];
  static float mult16874[1024], mult33126[1024], mult5[1024];
  static float mult41869[1024], mult08131[1024];

  unsigned char **orig_y, **orig_cr, **orig_cb;

  if(first) {
    int index;
    int maxValue;

    maxValue = 255;

    for(index = 0; index <= maxValue; index++) {
      mult299[index] = index * 0.29900F;
      mult587[index] = index * 0.58700F;
      mult114[index] = index * 0.11400F;
      mult16874[index] = -0.16874F * index;
      mult33126[index] = -0.33126F * index;
      mult5[index] = index * 0.50000F;
      mult41869[index] = -0.41869F * index;
      mult08131[index] = -0.08131F * index;
    }

    first = 0;
  }

  int width = buffer->getWidth();
  int height = buffer->getHeight();
  unsigned char *pixels = (unsigned char *)buffer->getPixels();

  // yuv format assumes even number of rows and columns
  height -= height % 2;
  width -= width % 2;

  int row_stride = width * 3;

  orig_y = (unsigned char **)Malloc(sizeof(unsigned char *) * height);
  for(y = 0; y < height; y++) {
    orig_y[y] = (unsigned char *)Malloc(sizeof(unsigned char) * width);
  }

  orig_cr = (unsigned char **)Malloc(sizeof(char *) * height / 2);
  for(y = 0; y < height / 2; y++) {
    orig_cr[y] = (unsigned char *)Malloc(sizeof(char) * width / 2);
  }

  orig_cb = (unsigned char **)Malloc(sizeof(char *) * height / 2);
  for(y = 0; y < height / 2; y++) {
    orig_cb[y] = (unsigned char *)Malloc(sizeof(char) * width / 2);
  }

  // assume ydivisor = 1, so cdivisor = 4
  cdivisor = 4;

  for(y = 0; y < height; y += 2) {
    src0 = &(pixels[y * row_stride]);
    src1 = &(pixels[(y + 1) * row_stride]);
    dy0 = orig_y[y];
    dy1 = orig_y[y + 1];
    dcr = orig_cr[y / 2];
    dcb = orig_cb[y / 2];

    for(x = 0; x < width;
        x += 2, dy0 += 2, dy1 += 2, dcr++, dcb++, src0 += 6, src1 += 6) {
      *dy0 =
        (unsigned char)(mult299[*src0] + mult587[src0[1]] + mult114[src0[2]]);

      *dy1 =
        (unsigned char)(mult299[*src1] + mult587[src1[1]] + mult114[src1[2]]);

      dy0[1] =
        (unsigned char)(mult299[src0[3]] + mult587[src0[4]] + mult114[src0[5]]);

      dy1[1] =
        (unsigned char)(mult299[src1[3]] + mult587[src1[4]] + mult114[src1[5]]);

      *dcb = (unsigned char)((mult16874[*src0] + mult33126[src0[1]] +
                              mult5[src0[2]] + mult16874[*src1] +
                              mult33126[src1[1]] + mult5[src1[2]] +
                              mult16874[src0[3]] + mult33126[src0[4]] +
                              mult5[src0[5]] + mult16874[src1[3]] +
                              mult33126[src1[4]] + mult5[src1[5]]) /
                             cdivisor) +
             128;

      *dcr = (unsigned char)((mult5[*src0] + mult41869[src0[1]] +
                              mult08131[src0[2]] + mult5[*src1] +
                              mult41869[src1[1]] + mult08131[src1[2]] +
                              mult5[src0[3]] + mult41869[src0[4]] +
                              mult08131[src0[5]] + mult5[src1[3]] +
                              mult41869[src1[4]] + mult08131[src1[5]]) /
                             cdivisor) +
             128;
    }
  }

  // Y
  for(y = height - 1; y >= 0; y--) fwrite(orig_y[y], 1, width, outfile);

  // U
  for(y = height / 2 - 1; y >= 0; y--)
    fwrite(orig_cb[y], 1, width / 2, outfile);

  // V
  for(y = height / 2 - 1; y >= 0; y--)
    fwrite(orig_cr[y], 1, width / 2, outfile);

  for(y = 0; y < height; y++) Free(orig_y[y]);
  Free(orig_y);

  for(y = 0; y < height / 2; y++) Free(orig_cr[y]);
  Free(orig_cr);

  for(y = 0; y < height / 2; y++) Free(orig_cb[y]);
  Free(orig_cb);
}
