#include <limits.h>
#include <stddef.h>
#include <stdlib.h>

#include "generators.h"

static void generate_random(int *buffer, size_t size)
{
	srandom(1);
	for (size_t i = 0; i < size; i++) buffer[i] = random();

	/* compress the values to nice small numbers to make debugging nicer */
#if 0
	int maxcompressed = -1;
	for (size_t compressed = 0; compressed < size; compressed++) {
		size_t minidx = -1;
		for (size_t i = 0; i < size; i++) {
			if (maxcompressed < buffer[i] && (minidx >= size || buffer[i] < buffer[minidx]))
				minidx = i;
		}
		buffer[minidx] = ++maxcompressed;
	}
#endif
}

static void generate_sorted(int *buffer, size_t size)
{
	for (size_t i = 0; i < size; i++) buffer[i] = i;
}

static void generate_reverse(int *buffer, size_t size)
{
	for (size_t i = 0; i < size; i++) buffer[i] = size - i - 1;
}

static void generate_constant(int *buffer, size_t size)
{
	for (size_t i = 0; i < size; i++) buffer[i] = 42;
}

static void add_noise(int *buffer, size_t size)
{
	int noisemax = size / 4;
	int noiseoff = size / 8;

	srandom(1);
	for (size_t i = 0; i < size; i++) {
		if (random() < 0.2 * RAND_MAX) {
			buffer[i] += random() % noisemax - noiseoff;
		}
	}
}

static void generate_sorted_noise(int *buffer, size_t size)
{
	generate_sorted(buffer, size);
	add_noise(buffer, size);
}

static void generate_reverse_noise(int *buffer, size_t size)
{
	generate_reverse(buffer, size);
	add_noise(buffer, size);
}

const struct generator generators[] = {
	{ .name = "random",        .func = generate_random        },
	{ .name = "sorted",        .func = generate_sorted        },
	{ .name = "reverse",       .func = generate_reverse       },
	{ .name = "constant",      .func = generate_constant      },
	{ .name = "sorted+noise",  .func = generate_sorted_noise  },
	{ .name = "reverse+noise", .func = generate_reverse_noise },
	{ 0 }
};