#define _GNU_SOURCE

#if __APPLE__ && __MACH__

#define _DARWIN_C_SOURCE

#include <fcntl.h>	/* For function fcntl.	*/

#endif	/* Apple Macintosh */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <limits.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>
#include <err.h>

#include "version.h"
#include "utils.h"

const char *adjust_unit(double *ptr_bytes)
{
	const char *units[] = { "Byte", "KB", "MB", "GB", "TB", "PB", "EB" };
	int i = 0;
	double final = *ptr_bytes;

	while (i < 7 && final >= 1024) {
		final /= 1024;
		i++;
	}
	*ptr_bytes = final;
	return units[i];
}

int is_my_file(const char *filename)
{
	const char *p = filename;

	if (!p || !isdigit(*p))
		return 0;

	/* Skip digits. */
	do {
		p++;
	} while (isdigit(*p));

	return	(p[0] == '.') && (p[1] == 'h') && (p[2] == '2') &&
		(p[3] == 'w') && (p[4] == '\0');
}

char *full_fn_from_number(const char **filename, const char *path, long num)
{
	char *str;
	assert(asprintf(&str, "%s/%li.h2w", path, num + 1) > 0);
	*filename = str + strlen(path) + 1;
	return str;
}

/* Parse @param and return the start-at parameter.
 * The string must be of the format "--start-at=NUM"; otherwise it returns -1.
 */
#define START_AT_TEXT "--start-at="
#define   END_AT_TEXT   "--end-at="

static inline int is_param(const char *text, const char *param)
{
	return !strncmp(param, text, strlen(text));
}

static long parse_long_param(const char *param)
{
	char *endptr;
	long value;

	/* Skip text. */
	while (*param != '=') {
		if (*param == '\0')
			return -1;
		param++;
	}
	param++; /* Skip '='. */

	value = strtol(param, &endptr, 10);
	if (*endptr != '\0')
		return -1;

	return (value <= 0 || value == LONG_MAX) ? -1 : value - 1;
}

static int parse_param(const char *param, long *pstart_at, long *pend_at)
{
	if (is_param(START_AT_TEXT, param))
		*pstart_at = parse_long_param(param);
	else if (is_param(END_AT_TEXT, param))
		*pend_at = parse_long_param(param);
	else
		return 1;
	return 0;
}

int parse_args(const char *name, int argc, char **argv,
	long *pstart_at, long *pend_at, const char **ppath)
{
	*pstart_at = 0;
	*pend_at = LONG_MAX - 1;

	switch (argc) {
	case 2:
		*ppath = argv[1];
		break;

	case 3:
		if (parse_param(argv[1], pstart_at, pend_at))
			goto error;
		*ppath = argv[2];
		break;

	case 4:
		if (parse_param(argv[1], pstart_at, pend_at))
			goto error;
		if (parse_param(argv[2], pstart_at, pend_at))
			goto error;
		*ppath = argv[3];
		break;

	default:
		goto error;
	}

	if (*pstart_at >= 0 && *pend_at >= 0 && *pstart_at <= *pend_at)
		return 0;

error:
	print_header(stderr, name);
	fprintf(stderr, "Usage: f3%s [%sNUM] [%sNUM] <PATH>\n",
		name, START_AT_TEXT, END_AT_TEXT);
	return 1;
}

static long number_from_filename(const char *filename)
{
	const char *p;
	long num;

	assert(is_my_file(filename));

	p = filename;
	num = 0;
	do {
		num = num * 10 + (*p - '0');
		p++;
	} while (isdigit(*p));

	return num - 1;
}

/* Don't call this function directly, use ls_my_files() instead. */
static long *__ls_my_files(DIR *dir, long start_at, long end_at,
	int *pcount, int *pindex)
{
	struct dirent *entry;
	const char *filename;
	long number, *ret;
	int my_index;

	entry = readdir(dir);
	if (!entry) {
		ret = malloc(sizeof(long) * (*pcount + 1));
		assert(ret);
		*pindex = *pcount - 1;
		ret[*pcount] = -1;
		closedir(dir);
		return ret;
	}

	filename = entry->d_name;
	if (!is_my_file(filename))
		return __ls_my_files(dir, start_at, end_at, pcount, pindex);

	/* Cache @number because @entry may go away. */
	number = number_from_filename(filename);

	/* Ignore files before @start_at and after @end_at. */
	if (number < start_at || end_at < number)
		return __ls_my_files(dir, start_at, end_at, pcount, pindex);

	(*pcount)++;
	ret = __ls_my_files(dir, start_at, end_at, pcount, &my_index);
	ret[my_index] = number;
	*pindex = my_index - 1;
	return ret;
}

/* To be used with qsort(3). */
static int cmpintp(const void *p1, const void *p2)
{
	return *(const long *)p1 - *(const long *)p2;
}

const long *ls_my_files(const char *path, long start_at, long end_at)
{
	DIR *dir = opendir(path);
	int my_count;
	int my_index;
	long *ret;

	if (!dir)
		err(errno, "Can't open path %s", path);

	my_count = 0;
	ret = __ls_my_files(dir, start_at, end_at, &my_count, &my_index);
	assert(my_index == -1);
	qsort(ret, my_count, sizeof(*ret), cmpintp);
	return ret;
}

void print_header(FILE *f, const char *name)
{
	fprintf(f,
	"F3 %s " F3_STR_VERSION "\n"
	"Copyright (C) 2010 Digirati Internet LTDA.\n"
	"This is free software; see the source for copying conditions.\n"
	"\n", name);
}

#if __APPLE__ && __MACH__

/* This function is a _rough_ approximation of fdatasync(2). */
static inline int fdatasync(int fd)
{
	return fcntl(fd, F_FULLFSYNC);
}

/* This function is a _rough_ approximation of posix_fadvise(2). */
int posix_fadvise(int fd, off_t offset, off_t len, int advice)
{
	switch (advice) {
	case POSIX_FADV_SEQUENTIAL:
		return fcntl(fd, F_RDAHEAD, 1);
	case POSIX_FADV_DONTNEED:
		return fcntl(fd, F_NOCACHE, 1);
	default:
		assert(0);
	}
}

#endif	/* Apple Macintosh */