/* Copyright  (C) 2010-2015 The RetroArch team
 *
 * ---------------------------------------------------------------------------------------
 * The following license statement only applies to this file (rpng.c).
 * ---------------------------------------------------------------------------------------
 *
 * 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 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.
 */

#include <formats/rpng.h>

#include <zlib.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "rpng_common.h"

#undef GOTO_END_ERROR
#define GOTO_END_ERROR() do { \
   fprintf(stderr, "[RPNG]: Error in line %d.\n", __LINE__); \
   ret = false; \
   goto end; \
} while(0)

#ifdef HAVE_ZLIB_DEFLATE

static void dword_write_be(uint8_t *buf, uint32_t val)
{
   *buf++ = (uint8_t)(val >> 24);
   *buf++ = (uint8_t)(val >> 16);
   *buf++ = (uint8_t)(val >>  8);
   *buf++ = (uint8_t)(val >>  0);
}

static bool png_write_crc(FILE *file, const uint8_t *data, size_t size)
{
   uint32_t crc = crc32(0, data, size);
   uint8_t crc_raw[4] = {0};
   dword_write_be(crc_raw, crc);
   return fwrite(crc_raw, 1, sizeof(crc_raw), file) == sizeof(crc_raw);
}

static bool png_write_ihdr(FILE *file, const struct png_ihdr *ihdr)
{
   uint8_t ihdr_raw[] = {
      '0', '0', '0', '0', /* Size */
      'I', 'H', 'D', 'R',

      0, 0, 0, 0, /* Width */
      0, 0, 0, 0, /* Height */
      ihdr->depth,
      ihdr->color_type,
      ihdr->compression,
      ihdr->filter,
      ihdr->interlace,
   };

   dword_write_be(ihdr_raw +  0, sizeof(ihdr_raw) - 8);
   dword_write_be(ihdr_raw +  8, ihdr->width);
   dword_write_be(ihdr_raw + 12, ihdr->height);
   if (fwrite(ihdr_raw, 1, sizeof(ihdr_raw), file) != sizeof(ihdr_raw))
      return false;

   if (!png_write_crc(file, ihdr_raw + sizeof(uint32_t),
            sizeof(ihdr_raw) - sizeof(uint32_t)))
      return false;

   return true;
}

static bool png_write_idat(FILE *file, const uint8_t *data, size_t size)
{
   if (fwrite(data, 1, size, file) != size)
      return false;

   if (!png_write_crc(file, data + sizeof(uint32_t), size - sizeof(uint32_t)))
      return false;

   return true;
}

static bool png_write_iend(FILE *file)
{
   const uint8_t data[] = {
      0, 0, 0, 0,
      'I', 'E', 'N', 'D',
   };

   if (fwrite(data, 1, sizeof(data), file) != sizeof(data))
      return false;

   if (!png_write_crc(file, data + sizeof(uint32_t),
            sizeof(data) - sizeof(uint32_t)))
      return false;

   return true;
}

static void copy_argb_line(uint8_t *dst, const uint32_t *src, unsigned width)
{
   unsigned i;
   for (i = 0; i < width; i++)
   {
      uint32_t col = src[i];
      *dst++ = (uint8_t)(col >> 16);
      *dst++ = (uint8_t)(col >>  8);
      *dst++ = (uint8_t)(col >>  0);
      *dst++ = (uint8_t)(col >> 24);
   }
}

static void copy_bgr24_line(uint8_t *dst, const uint8_t *src, unsigned width)
{
   unsigned i;
   for (i = 0; i < width; i++, dst += 3, src += 3)
   {
      dst[2] = src[0];
      dst[1] = src[1];
      dst[0] = src[2];
   }
}

static unsigned count_sad(const uint8_t *data, size_t size)
{
   size_t i;
   unsigned cnt = 0;
   for (i = 0; i < size; i++)
      cnt += abs((int8_t)data[i]);
   return cnt;
}

static unsigned filter_up(uint8_t *target, const uint8_t *line,
      const uint8_t *prev, unsigned width, unsigned bpp)
{
   unsigned i;
   width *= bpp;
   for (i = 0; i < width; i++)
      target[i] = line[i] - prev[i];

   return count_sad(target, width);
}

static unsigned filter_sub(uint8_t *target, const uint8_t *line,
      unsigned width, unsigned bpp)
{
   unsigned i;
   width *= bpp;
   for (i = 0; i < bpp; i++)
      target[i] = line[i];
   for (i = bpp; i < width; i++)
      target[i] = line[i] - line[i - bpp];

   return count_sad(target, width);
}

static unsigned filter_avg(uint8_t *target, const uint8_t *line,
      const uint8_t *prev, unsigned width, unsigned bpp)
{
   unsigned i;
   width *= bpp;
   for (i = 0; i < bpp; i++)
      target[i] = line[i] - (prev[i] >> 1);
   for (i = bpp; i < width; i++)
      target[i] = line[i] - ((line[i - bpp] + prev[i]) >> 1);

   return count_sad(target, width);
}

static unsigned filter_paeth(uint8_t *target,
      const uint8_t *line, const uint8_t *prev,
      unsigned width, unsigned bpp)
{
   unsigned i;
   width *= bpp;
   for (i = 0; i < bpp; i++)
      target[i] = line[i] - paeth(0, prev[i], 0);
   for (i = bpp; i < width; i++)
      target[i] = line[i] - paeth(line[i - bpp], prev[i], prev[i - bpp]);

   return count_sad(target, width);
}

static bool rpng_save_image(const char *path,
      const uint8_t *data,
      unsigned width, unsigned height, unsigned pitch, unsigned bpp)
{
   unsigned h;
   bool ret = true;
   struct png_ihdr ihdr = {0};

   size_t encode_buf_size  = 0;
   uint8_t *encode_buf     = NULL;
   uint8_t *deflate_buf    = NULL;
   uint8_t *rgba_line      = NULL;
   uint8_t *up_filtered    = NULL;
   uint8_t *sub_filtered   = NULL;
   uint8_t *avg_filtered   = NULL;
   uint8_t *paeth_filtered = NULL;
   uint8_t *prev_encoded   = NULL;
   uint8_t *encode_target  = NULL;

   z_stream stream = {0};

   FILE *file = fopen(path, "wb");
   if (!file)
      GOTO_END_ERROR();

   if (fwrite(png_magic, 1, sizeof(png_magic), file) != sizeof(png_magic))
      GOTO_END_ERROR();

   ihdr.width = width;
   ihdr.height = height;
   ihdr.depth = 8;
   ihdr.color_type = bpp == sizeof(uint32_t) ? 6 : 2; /* RGBA or RGB */
   if (!png_write_ihdr(file, &ihdr))
      GOTO_END_ERROR();

   encode_buf_size = (width * bpp + 1) * height;
   encode_buf = (uint8_t*)malloc(encode_buf_size);
   if (!encode_buf)
      GOTO_END_ERROR();

   prev_encoded = (uint8_t*)calloc(1, width * bpp);
   if (!prev_encoded)
      GOTO_END_ERROR();

   rgba_line      = (uint8_t*)malloc(width * bpp);
   up_filtered    = (uint8_t*)malloc(width * bpp);
   sub_filtered   = (uint8_t*)malloc(width * bpp);
   avg_filtered   = (uint8_t*)malloc(width * bpp);
   paeth_filtered = (uint8_t*)malloc(width * bpp);
   if (!rgba_line || !up_filtered || !sub_filtered || !avg_filtered || !paeth_filtered)
      GOTO_END_ERROR();

   encode_target = encode_buf;
   for (h = 0; h < height;
         h++, encode_target += width * bpp, data += pitch)
   {
      if (bpp == sizeof(uint32_t))
         copy_argb_line(rgba_line, (const uint32_t*)data, width);
      else
         copy_bgr24_line(rgba_line, data, width);

      /* Try every filtering method, and choose the method
       * which has most entries as zero.
       *
       * This is probably not very optimal, but it's very 
       * simple to implement.
       */
      unsigned none_score  = count_sad(rgba_line, width * bpp);
      unsigned up_score    = filter_up(up_filtered, rgba_line, prev_encoded, width, bpp);
      unsigned sub_score   = filter_sub(sub_filtered, rgba_line, width, bpp);
      unsigned avg_score   = filter_avg(avg_filtered, rgba_line, prev_encoded, width, bpp);
      unsigned paeth_score = filter_paeth(paeth_filtered, rgba_line, prev_encoded, width, bpp);

      uint8_t filter = 0;
      unsigned min_sad = none_score;
      const uint8_t *chosen_filtered = rgba_line;

      if (sub_score < min_sad)
      {
         filter = 1;
         chosen_filtered = sub_filtered;
         min_sad = sub_score;
      }

      if (up_score < min_sad)
      {
         filter = 2;
         chosen_filtered = up_filtered;
         min_sad = up_score;
      }

      if (avg_score < min_sad)
      {
         filter = 3;
         chosen_filtered = avg_filtered;
         min_sad = avg_score;
      }

      if (paeth_score < min_sad)
      {
         filter = 4;
         chosen_filtered = paeth_filtered;
         min_sad = paeth_score;
      }

      *encode_target++ = filter;
      memcpy(encode_target, chosen_filtered, width * bpp);

      memcpy(prev_encoded, rgba_line, width * bpp);
   }

   deflate_buf = (uint8_t*)malloc(encode_buf_size * 2); /* Just to be sure. */
   if (!deflate_buf)
      GOTO_END_ERROR();

   stream.next_in   = encode_buf;
   stream.avail_in  = encode_buf_size;
   stream.next_out  = deflate_buf + 8;
   stream.avail_out = encode_buf_size * 2;

   deflateInit(&stream, 9);
   if (deflate(&stream, Z_FINISH) != Z_STREAM_END)
   {
      deflateEnd(&stream);
      GOTO_END_ERROR();
   }
   deflateEnd(&stream);

   memcpy(deflate_buf + 4, "IDAT", 4);
   dword_write_be(deflate_buf + 0, stream.total_out);
   if (!png_write_idat(file, deflate_buf, stream.total_out + 8))
      GOTO_END_ERROR();

   if (!png_write_iend(file))
      GOTO_END_ERROR();

end:
   if (file)
      fclose(file);
   free(encode_buf);
   free(deflate_buf);
   free(rgba_line);
   free(prev_encoded);
   free(up_filtered);
   free(sub_filtered);
   free(avg_filtered);
   free(paeth_filtered);
   return ret;
}

bool rpng_save_image_argb(const char *path, const uint32_t *data,
      unsigned width, unsigned height, unsigned pitch)
{
   return rpng_save_image(path, (const uint8_t*)data,
         width, height, pitch, sizeof(uint32_t));
}

bool rpng_save_image_bgr24(const char *path, const uint8_t *data,
      unsigned width, unsigned height, unsigned pitch)
{
   return rpng_save_image(path, (const uint8_t*)data,
         width, height, pitch, 3);
}

#endif