#include "pngwriter.h"
#include <stdlib.h>

png_data *png_create(int nWidth, int nHeight) {
  int i;

  png_data *pData = (png_data *)malloc(sizeof(png_data));

  pData->nWidth = nWidth;
  pData->nHeight = nHeight;
  pData->pPixels = (png_bytepp)malloc(nHeight * sizeof(png_bytep));
  for (i = 0; i < nHeight; i++)
    pData->pPixels[i] = (png_bytep)malloc(3 * nWidth * sizeof(png_byte));

  return pData;
}

#define CHECK_RGB_BOUNDS(x)                                                    \
  if (x > 255)                                                                 \
    x = 255;                                                                   \
  if (x < 0)                                                                   \
    x = 0;

void png_plot(png_data *pData, int x, int y, int r, int g, int b) {
  if (x >= pData->nWidth)
    return;
  if (y >= pData->nHeight)
    return;

  CHECK_RGB_BOUNDS(r)
  CHECK_RGB_BOUNDS(g)
  CHECK_RGB_BOUNDS(b)

  pData->pPixels[pData->nHeight - y - 1][3 * x - 3] = (char)r;
  pData->pPixels[pData->nHeight - y - 1][3 * x - 2] = (char)g;
  pData->pPixels[pData->nHeight - y - 1][3 * x - 1] = (char)b;
}

void png_write(png_data *pData, char *szFileName) {
  FILE *fp;
  png_structp png_ptr;
  png_infop info_ptr;

  fp = fopen(szFileName, "wb");
  if (fp == NULL)
    return;

  png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  info_ptr = png_create_info_struct(png_ptr);
  png_init_io(png_ptr, fp);
  png_set_compression_level(png_ptr, PNGWRITER_DEFAULT_COMPRESSION);

  png_set_IHDR(png_ptr, info_ptr, pData->nWidth, pData->nHeight, 8,
               PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
               PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

  png_set_gAMA(png_ptr, info_ptr, 0.7);

  png_write_info(png_ptr, info_ptr);
  png_write_image(png_ptr, pData->pPixels);
  png_write_end(png_ptr, info_ptr);
  png_destroy_write_struct(&png_ptr, &info_ptr);
  fclose(fp);

  free(pData);
}