#include "config.h"

#include <assert.h>
#include <ccan/err/err.h>
#include <ccan/isaac/isaac64.h>
#include <ccan/short_types/short_types.h>
#include <ccan/tal/grab_file/grab_file.h>
#include <ccan/tal/path/path.h>
#include <ccan/tal/tal.h>
#include <common/pseudorand.h>
#include <common/setup.h>
#include <dirent.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <tests/fuzz/libfuzz.h>
#include <unistd.h>

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
int LLVMFuzzerInitialize(int *argc, char ***argv);

/* Provide a non-random pseudo-random function to speed fuzzing. */
static isaac64_ctx isaac64;

/* Most tests should not be calling this */
bool fuzz_allow_siphash_seed = false;

/* Define this so we don't try to link against common/pseudorand.o! */
const struct siphash_seed *siphash_seed(void)
{
	if (!fuzz_allow_siphash_seed)
		abort();

	struct siphash_seed *siphashseed = tal(tmpctx, struct siphash_seed);
	memset(siphashseed, 1, sizeof(*siphashseed));
	return siphashseed;
}

uint64_t pseudorand_(uint64_t max, uint64_t *offset)
{
	assert(max);
	return isaac64_next_uint(&isaac64, max);
}

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
	isaac64_init(&isaac64, NULL, 0);

	run(data, size);
	return 0;
}

int LLVMFuzzerInitialize(int *argc, char ***argv) {
	init(argc, argv);

	return 0;
}

const uint8_t **get_chunks(const void *ctx, const uint8_t *data,
			  size_t data_size, size_t chunk_size)
{
	size_t n_chunks = data_size / chunk_size;
	const uint8_t **chunks = tal_arr(ctx, const uint8_t *, n_chunks);

	for (size_t i = 0; i < n_chunks; i++)
		chunks[i] = tal_dup_arr(chunks, const uint8_t,
					data + i * chunk_size, chunk_size, 0);

	return chunks;
}

char *to_string(const tal_t *ctx, const u8 *data, size_t data_size)
{
	char *string = tal_arr(ctx, char, data_size + 1);

	for (size_t i = 0; i < data_size; i++)
		string[i] = (char) data[i] % (CHAR_MAX + 1);
	string[data_size] = '\0';

	return string;
}

static size_t insert_part(const u8 *in1, size_t in1_size, const u8 *in2,
			  size_t in2_size, u8 *out, size_t max_out_size)
{
	size_t max_insert_size;
	size_t insert_begin;
	size_t insert_size;
	size_t in2_begin;

	if (in1_size >= max_out_size)
		return 0;
	if (in1_size == 0 || in2_size == 0)
		return 0;

	max_insert_size = max_out_size - in1_size;
	if (max_insert_size > in2_size)
		max_insert_size = in2_size;
	insert_begin = rand() % in1_size;
	insert_size = (rand() % max_insert_size) + 1;

	in2_begin = rand() % (in2_size - insert_size + 1);

	memcpy(out, in1, insert_begin);
	memcpy(out + insert_begin, in2 + in2_begin, insert_size);
	memcpy(out + insert_begin + insert_size, in1 + insert_begin,
	       in1_size - insert_begin);

	return in1_size + insert_size;
}

static size_t overwrite_part(const u8 *in1, size_t in1_size, const u8 *in2,
			     size_t in2_size, u8 *out, size_t max_out_size)
{
	size_t overwrite_begin;
	size_t overwrite_size;
	size_t in2_begin;

	if (in1_size > max_out_size)
		return 0;
	if (in1_size == 0)
		return 0;

	overwrite_begin = rand() % in1_size;
	overwrite_size = (rand() % (in1_size - overwrite_begin)) + 1;
	if (overwrite_size > in2_size)
		overwrite_size = in2_size;
	in2_begin = rand() % (in2_size - overwrite_size + 1);

	memcpy(out, in1, in1_size);
	memcpy(out + overwrite_begin, in2 + in2_begin, overwrite_size);

	return in1_size;
}

size_t cross_over(const u8 *in1, size_t in1_size, const u8 *in2,
		  size_t in2_size, u8 *out, size_t max_out_size, unsigned seed)
{
	srand(seed);
	if (rand() % 2)
		return insert_part(in1, in1_size, in2, in2_size, out,
				   max_out_size);
	return overwrite_part(in1, in1_size, in2, in2_size, out, max_out_size);
}

/* In non-fuzzing builds, these become unit tests which just run the corpora:
 * this is also good for attaching a debugger to! */
#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
static size_t find_opt(char *argv[], const char *opt)
{
	for (size_t i = 1; argv[i]; i++) {
		if (streq(argv[i], opt))
			return i;
	}
	return 0;
}

int main(int argc, char *argv[])
{
	DIR *d;
	struct dirent *di;
	int verbose_flag;

	common_setup(argv[0]);
	assert(chdir("tests/fuzz/corpora") == 0);
	assert(chdir(path_basename(tmpctx, argv[0])) == 0);

	init(&argc, &argv);
	verbose_flag = find_opt(argv, "-v");
	d = opendir(".");
	while ((di = readdir(d)) != NULL) {
		u8 *contents;
		if (streq(di->d_name, ".") || streq(di->d_name, ".."))
			continue;
		/* If you specify options other than -v, they're test names */
		if (argv[verbose_flag + 1] && !find_opt(argv, di->d_name))
			continue;
		if (verbose_flag)
			printf("%s\n", di->d_name);
		contents = grab_file_raw(tmpctx, di->d_name);
		if (!contents)
			err(1, "Could not read %s", di->d_name);
		run(contents, tal_bytelen(contents));
	}
	closedir(d);
	common_shutdown();
}

/* We never call any functions which might call these */
size_t LLVMFuzzerMutate(uint8_t *data, size_t size, size_t max_size);
size_t LLVMFuzzerMutate(uint8_t *data, size_t size, size_t max_size)
{
	abort();
}
#endif /* !FUZZING */