#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <png.h>

#include "newton.h"

static const int width = 10240, height=7680;

void
solid_image(struct pngdata *pp) {
	unsigned int x, y;

	for (x = 0; x < pp->height; x++)
		for (y = 0; y < pp->width; y++) {
			png_byte *bp = pp->rows[x] + 3 * y;
			// bp[3] = 0;
			bp[0] = 0;
			bp[1] = 0;
			bp[2] = 100;
		}
}

void
simple_image(struct pngdata *pp) {
	unsigned int x, y;

	for (x = 0; x < pp->height; x++)
		for (y = 0; y < pp->width; y++) {
			png_byte *bp = pp->rows[x] + 3 * y;
			// bp[3] = 0;
			bp[0] = (x * y) % 256;
			bp[1] = y % 256;
			bp[2] = sin(x * x + y * y) * 256;
		}
}

void
usage(const char *argv0)
{
	printf("Usage: %s filename\n", argv0);
}

int
png_write(const char *filename, struct pngdata *data)
{
	int retval = 1;
	FILE *fp = NULL;
	png_structp png_p = NULL;
	png_infop info_p = NULL;

	fp = fopen(filename, "wb");
	if (fp == NULL)
		goto _bailout;

	png_p = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (png_p == NULL)
		goto _bailout;

	info_p = png_create_info_struct(png_p);
	if (!info_p)
		goto _bailout;

	png_init_io(png_p, fp);

	png_set_IHDR(png_p, info_p, data->width, data->height, 8,
	  PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
	  PNG_FILTER_TYPE_BASE);

	png_write_info(png_p, info_p);
	png_write_image(png_p, data->rows);

	png_write_end(png_p, NULL);

	retval = 0;
_bailout:
	if (png_p)
		png_destroy_write_struct(&png_p, &info_p);
	if (fp)
		fclose(fp);
	return retval;
}

int
main(int argc, char *argv[])
{
	struct pngdata pd;
	unsigned int i;
	void (*i_create)(struct pngdata *) = simple_image;

	// i_create = solid_image;
	i_create = newton;

	if (argc < 2) {
		usage(argv[0]);
		return 1;
	}

	pd.width = width;
	pd.height = height;

	pd.rows = (png_bytep *)calloc(pd.height, sizeof(pd.rows[0]));
	if (pd.rows == NULL) {
		printf("Not enough memory for row data.\n");
		return 1;
	}
	for (i = 0; i < pd.height; i++) {
		pd.rows[i] = (png_byte *)calloc(4 * pd.width, sizeof(*(pd.rows[i])));
		if (pd.rows[i] == NULL) {
			printf("Not enough memory for column %d.\n", i);
			return 1;
		}
	}

	i_create(&pd);
	if (png_write(argv[1], &pd) != 0)
		printf("Failed to write PNG data to '%s'.\n", argv[1]);

	for (i = 0; i < pd.height; i++)
		free((void *)pd.rows[i]);
	free((void *)pd.rows);

	return 0;
}