/* clang -o mkwmicon -lpng mkwmicon.c */

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

static int CountBits(uint32_t n) {
  int ret = 0;
  for (int i = 0; i < 32; ++i)
    if (((n >> i) & 1) != 0)
      ++ret;
  return ret;
}

static const int DIMS[] = {16, 32, 48, 64, 128, 0};

int main(int argc, char* argv[]) {
  if (argc < 2) {
    fprintf(stderr, "Usage: makewmicon <out.bin>\n");
    return 1;
  }

  FILE* ofp = fopen(argv[1], "wb");
  if (!ofp) {
    fprintf(stderr, "'%s' is not able to be opened for writing as a regular file\n", argv[1]);
    return 1;
  }

  png_bytep row = malloc(4 * 128);

  char command[2048];

  for (const int* d = DIMS; *d != 0; ++d) {
    printf("Rendering main icon @%dx%d\n", *d, *d);
    fflush(stdout);

    snprintf(command, 2048, "%dx%d/apps/metaforce.png", *d, *d);
    FILE* fp = fopen(command, "rb");
    if (!fp) {
      fprintf(stderr, "unable to open '%s' for reading\n", command);
      fclose(ofp);
      return 1;
    }

    char header[8];
    fread(header, 1, 8, fp);
    if (png_sig_cmp((png_const_bytep)header, 0, 8)) {
      fprintf(stderr, "invalid PNG signature in '%s'\n", command);
      fclose(fp);
      fclose(ofp);
      return 1;
    }

    png_structp pngRead = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!pngRead) {
      fprintf(stderr, "unable to initialize libpng\n");
      fclose(fp);
      fclose(ofp);
      return 1;
    }
    png_infop info = png_create_info_struct(pngRead);
    if (!info) {
      fprintf(stderr, "unable to initialize libpng info\n");
      fclose(fp);
      fclose(ofp);
      return 1;
    }

    if (setjmp(png_jmpbuf(pngRead))) {
      fprintf(stderr, "unable to initialize libpng I/O for '%s'\n", command);
      fclose(fp);
      fclose(ofp);
      return 1;
    }

    png_init_io(pngRead, fp);
    png_set_sig_bytes(pngRead, 8);

    png_read_info(pngRead, info);

    png_uint_32 width = png_get_image_width(pngRead, info);
    png_uint_32 height = png_get_image_height(pngRead, info);
    png_byte colorType = png_get_color_type(pngRead, info);
    png_byte bitDepth = png_get_bit_depth(pngRead, info);

    if (colorType != PNG_COLOR_TYPE_RGB_ALPHA) {
      fprintf(stderr, "'%s' is not in RGBA color mode\n", command);
      fclose(fp);
      fclose(ofp);
      return 1;
    }

    if (bitDepth != 8) {
      fprintf(stderr, "'%s' is not 8 bits-per-channel\n", command);
      fclose(fp);
      fclose(ofp);
      return 1;
    }

    if (setjmp(png_jmpbuf(pngRead))) {
      fprintf(stderr, "unable to read image in '%s'\n", command);
      fclose(fp);
      fclose(ofp);
      return 1;
    }

    unsigned long lWidth = width;
    unsigned long lHeight = height;
    fwrite(&lWidth, 1, sizeof(lWidth), ofp);
    fwrite(&lHeight, 1, sizeof(lHeight), ofp);
    for (png_uint_32 r = 0; r < height; ++r) {
      png_read_row(pngRead, row, NULL);
      for (int i = 0; i < width; ++i) {
        unsigned long px;
        px = row[i * 4 + 2];
        px |= row[i * 4 + 1] << 8;
        px |= row[i * 4] << 16;
        px |= row[i * 4 + 3] << 24;
        fwrite(&px, 1, sizeof(unsigned long), ofp);
      }
    }

    png_destroy_read_struct(&pngRead, &info, NULL);
    fclose(fp);
  }

  free(row);
  fclose(ofp);
  return 0;
}