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#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

struct hypercube_entry
{
	uint32_t value;
};

struct hypercube
{
	size_t z_len, y_len, x_len, w_len;
	struct hypercube_entry entries[];
};

struct hypercube *
hypercube_alloc(size_t z_len,
                size_t y_len,
                size_t x_len,
                size_t w_len);

inline static struct hypercube_entry *
hypercube_entry(struct hypercube *hypercube,
                size_t z_len,
                size_t y_len,
                size_t x_len,
                size_t w_len);

size_t
hypercube_sizeof(size_t z_len,
                 size_t y_len,
                 size_t x_len,
                 size_t w_len);

struct hypercube *
hypercube_alloc(size_t z_len,
                size_t y_len,
                size_t x_len,
                size_t w_len)
{
	struct hypercube *hypercube_mem;
	size_t hypercube_sz;

	hypercube_sz = hypercube_sizeof(z_len, y_len, x_len, w_len);
	hypercube_mem = malloc(hypercube_sz);
	if (hypercube_mem == NULL) {
		fprintf(stderr,
                "Cannot allocate %lu bytes for hypercube. Aborting.\n",
		        hypercube_sz);
	}
	hypercube_mem->z_len = z_len;
	hypercube_mem->y_len = y_len;
	hypercube_mem->x_len = x_len;
	hypercube_mem->w_len = w_len;
}

size_t
hypercube_sizeof(size_t z_len,
                 size_t y_len,
                 size_t x_len,
                 size_t w_len)
{
	return sizeof(struct hypercube)
	       + sizeof(struct hypercube_entry) * z_len * y_len * x_len * w_len;
}

inline static struct hypercube_entry *
hypercube_entry(struct hypercube *hypercube,
                size_t z,
                size_t y,
                size_t x,
                size_t w)
{
	struct hypercube_entry *entry = hypercube->entries;
	entry += z * hypercube->y_len * hypercube->x_len * hypercube->w_len;
	entry += y * hypercube->x_len * hypercube->w_len;
	entry += x * hypercube->w_len;
	entry += w;
	return entry;
}

int
main(void)
{
	size_t z_len = 100;
	size_t y_len = 99;
	size_t x_len = 98;
	size_t w_len = 97;
	struct hypercube *hypercube;

	hypercube = hypercube_alloc(z_len, w_len, y_len, x_len);
	printf("Allocated %lu bytes\n.",
	       hypercube_sizeof(z_len, w_len, y_len, x_len));

	/* Draw 4-dimensional super-ellipsoid.
	 * Quite inefficient algorithm. */
	for (int x = 0; x < hypercube->x_len; x++)
	for (int y = 0; y < hypercube->y_len; y++)
	for (int z = 0; z < hypercube->z_len; z++)
	for (int w = 0; w < hypercube->w_len; w++) {
		bool is_inside = .5f >= (
			powf(((float) x - 50.f) * .02, 4.f)
			+ powf(((float) y - 50.f) * .02, 4.f)
			+ powf(((float) z - 50.f) * .02, 4.f)
			+ powf(((float) w - 50.f) * .02, 4.f));
		hypercube_entry(hypercube, z, y, x, w)->value
			= is_inside ? 1 : 0;
	}

	/* Draw slices of it. */
	for (int w = 10; w < hypercube->w_len - 10; w += 10) {
		printf("w = %i\n", w);
		for (int y = 1; y < hypercube->y_len; y += 2) {
			for (int x = 1; x < hypercube->x_len; x++) {
				int z = 0;
				for (;
				     z < hypercube->z_len
					 && !hypercube_entry(hypercube, z, y, x, w)->value;
				     z++);
				if (z < 80) {
					if (hypercube_entry(hypercube, z, y - 1, x - 1, w)
					    ->value) {
						putchar('*');
					} else {
						putchar('#');
					}
				} else {
					putchar('_');
				}
			}
			putchar('\n');
		}
		putchar('\n');
	}
}