#include <stdint.h>
#include <stdio.h>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

int
main(int argc, char **argv) {
	if (argc != 2) {
		fprintf(stderr, "usage: %s palette.png\n",
		        argv[0]);
		return 1;
	}

	int pal_w, pal_h, pal_col_chans;
	uint8_t *const pal_data =
	    stbi_load(argv[1], &pal_w, &pal_h, &pal_col_chans, 3);

	if (pal_data == NULL) {
		fprintf(stderr, "error: failed to load palette\n");
		return 1;
	}
	if (pal_col_chans != 3) {
		fprintf(stderr, "error: palette isn't RGB\n");
		stbi_image_free(pal_data);
		return 1;
	}
	if (pal_w * pal_h == 0) {
		fprintf(stderr, "error: palette size is 0\n");
		stbi_image_free(pal_data);
		return 1;
	}
	if (pal_w * pal_h >= 256) {
		fprintf(stderr, "error: palette size is greater than 255\n");
		stbi_image_free(pal_data);
		return 1;
	}

	printf("#include \"px.h\"\n\n"
	       "__attribute__((constructor))\n"
	       "static void set_pxpal(void)\n"
	       "{\n");
	for (int i = 0; i < pal_w * pal_h; i++) {
		printf("\tpxpal[%d].r = %u; "
		       "pxpal[%d].g = %u; "
		       "pxpal[%d].b = %u;\n",
		       i, (unsigned)pal_data[i * 3],
		       i, (unsigned)pal_data[i * 3 + 1],
		       i, (unsigned)pal_data[i * 3 + 2]);
	}
	printf("}\n");
}