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

#include "testcases.h"

int buffer[MAX_SIZE];
unsigned long comparisons;

void assert_sorted(size_t size, cmpfun cmp)
{
	for (size_t i = 1; i < size; i++) {
		if (cmp(buffer + i-1, buffer + i) > 0) abort();
	}
}

static int compare(const void *a, const void *b)
{
	const int *aa = a;
	const int *bb = b;

	comparisons++;
	if (*aa < *bb)
		return -1;
	else if (*aa > *bb)
		return 1;
	else
		return 0;
}

static void init_random(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 init_sorted(size_t size)
{
	for (size_t i = 0; i < size; i++) buffer[i] = i;
}

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

static void init_constant(size_t size)
{
	for (size_t i = 0; i < size; i++) buffer[i] = 42;
}

static void add_noise(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 init_sorted_noise(size_t size)
{
	init_sorted(size);
	add_noise(size);
}

static void init_reverse_noise(size_t size)
{
	init_reverse(size);
	add_noise(size);
}

/* quicksort-killer testcase from http://www.cs.dartmouth.edu/~doug/mdmspe.pdf */
static int    qsk_buffer[MAX_SIZE];
static size_t qsk_nsolid;
static size_t qsk_candidate;

static void init_qsk(size_t size)
{
	qsk_nsolid = qsk_candidate = 0;
	for (size_t i = 0; i < size; i++) {
		qsk_buffer[i] = INT_MAX;
		buffer[i]     = i;
	}
}

static int qsk_compare(const void *a, const void *b)
{
	const int x = *(const int*)a;
	const int y = *(const int*)b;

	if (qsk_buffer[x] == INT_MAX && qsk_buffer[y] == INT_MAX) {
		if (qsk_buffer[x] == INT_MAX) qsk_buffer[x] = qsk_nsolid++;
		else                          qsk_buffer[y] = qsk_nsolid++;
	}

	if (qsk_buffer[x] == INT_MAX) qsk_candidate = x;
	else if (qsk_buffer[y] == INT_MAX) qsk_candidate = y;

	return compare(qsk_buffer + x, qsk_buffer + y);
}

const struct testcase testcases[] = {
	{ .name = "random",        .init = init_random,        .cmp = compare },
	{ .name = "sorted",        .init = init_sorted,        .cmp = compare },
	{ .name = "reverse",       .init = init_reverse,       .cmp = compare },
	{ .name = "constant",      .init = init_constant,      .cmp = compare },
	{ .name = "sorted+noise",  .init = init_sorted_noise,  .cmp = compare },
	{ .name = "reverse+noise", .init = init_reverse_noise, .cmp = compare },
	{ .name = "qsort-killer",  .init = init_qsk,           .cmp = qsk_compare },
	{ 0 }
};