/*
 * Copyright 2008-2013 Various Authors
 * Copyright 2004-2005 Timo Hirvonen
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "misc.h"
#include "prog.h"
#include "xmalloc.h"
#include "xstrjoin.h"

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <stdarg.h>
#include <pwd.h>

const char *cmus_config_dir = NULL;
const char *cmus_socket_path = NULL;
const char *home_dir = NULL;
const char *user_name = NULL;

char **get_words(const char *text)
{
	char **words;
	int i, j, count;

	while (*text == ' ')
		text++;

	count = 0;
	i = 0;
	while (text[i]) {
		count++;
		while (text[i] && text[i] != ' ')
			i++;
		while (text[i] == ' ')
			i++;
	}
	words = xnew(char *, count + 1);

	i = 0;
	j = 0;
	while (text[i]) {
		int start = i;

		while (text[i] && text[i] != ' ')
			i++;
		words[j++] = xstrndup(text + start, i - start);
		while (text[i] == ' ')
			i++;
	}
	words[j] = NULL;
	return words;
}

int strptrcmp(const void *a, const void *b)
{
	const char *as = *(char **)a;
	const char *bs = *(char **)b;

	return strcmp(as, bs);
}

int strptrcoll(const void *a, const void *b)
{
	const char *as = *(char **)a;
	const char *bs = *(char **)b;

	return strcoll(as, bs);
}

const char *escape(const char *str)
{
	static char *buf = NULL;
	static size_t alloc = 0;
	size_t len = strlen(str);
	size_t need = len * 2 + 1;
	int s, d;

	if (need > alloc) {
		alloc = (need + 16) & ~(16 - 1);
		buf = xrealloc(buf, alloc);
	}

	d = 0;
	for (s = 0; str[s]; s++) {
		if (str[s] == '\\') {
			buf[d++] = '\\';
			buf[d++] = '\\';
			continue;
		}
		if (str[s] == '\n') {
			buf[d++] = '\\';
			buf[d++] = 'n';
			continue;
		}
		buf[d++] = str[s];
	}
	buf[d] = 0;
	return buf;
}

const char *unescape(const char *str)
{
	static char *buf = NULL;
	static size_t alloc = 0;
	size_t need = strlen(str) + 1;
	int do_escape = 0;
	int s, d;

	if (need > alloc) {
		alloc = (need + 16) & ~(16 - 1);
		buf = xrealloc(buf, alloc);
	}

	d = 0;
	for (s = 0; str[s]; s++) {
		if (!do_escape && str[s] == '\\')
			do_escape = 1;
		else {
			buf[d++] = (do_escape && str[s] == 'n') ? '\n' : str[s];
			do_escape = 0;
		}
	}
	buf[d] = 0;
	return buf;
}

static int dir_exists(const char *dirname)
{
	DIR *dir;

	dir = opendir(dirname);
	if (dir == NULL) {
		if (errno == ENOENT)
			return 0;
		return -1;
	}
	closedir(dir);
	return 1;
}

static void make_dir(const char *dirname)
{
	int rc;

	rc = dir_exists(dirname);
	if (rc == 1)
		return;
	if (rc == -1)
		die_errno("error: opening `%s'", dirname);
	rc = mkdir(dirname, 0700);
	if (rc == -1)
		die_errno("error: creating directory `%s'", dirname);
}

static char *get_non_empty_env(const char *name)
{
	const char *val;

	val = getenv(name);
	if (val == NULL || val[0] == 0)
		return NULL;
	return xstrdup(val);
}

int misc_init(void)
{
	char *xdg_runtime_dir = get_non_empty_env("XDG_RUNTIME_DIR");

	home_dir = get_non_empty_env("HOME");
	if (home_dir == NULL)
		die("error: environment variable HOME not set\n");

	user_name = get_non_empty_env("USER");
	if (user_name == NULL) {
		user_name = get_non_empty_env("USERNAME");
		if (user_name == NULL)
			die("error: neither USER or USERNAME environment variable set\n");
	}

	cmus_config_dir = get_non_empty_env("CMUS_HOME");
	if (cmus_config_dir == NULL) {
		char *cmus_home = xstrjoin(home_dir, "/.cmus");
		int cmus_home_exists = dir_exists(cmus_home);

		if (cmus_home_exists == 1) {
			cmus_config_dir = xstrdup(cmus_home);
		} else if (cmus_home_exists == -1) {
			die_errno("error: opening `%s'", cmus_home);
		} else {
			char *xdg_config_home = get_non_empty_env("XDG_CONFIG_HOME");
			if (xdg_config_home == NULL) {
				xdg_config_home = xstrjoin(home_dir, "/.config");
			}

			make_dir(xdg_config_home);
			cmus_config_dir = xstrjoin(xdg_config_home, "/cmus");

			free(xdg_config_home);
		}

		free(cmus_home);
	}
	make_dir(cmus_config_dir);

	cmus_socket_path = get_non_empty_env("CMUS_SOCKET");
	if (cmus_socket_path == NULL) {
		if (xdg_runtime_dir == NULL) {
			cmus_socket_path = xstrjoin(cmus_config_dir, "/socket");
		} else {
			cmus_socket_path = xstrjoin(xdg_runtime_dir, "/cmus-socket");
		}
	}

	free(xdg_runtime_dir);
	return 0;
}

int replaygain_decode(unsigned int field, int *gain)
{
	unsigned int name_code, originator_code, sign_bit, val;

	name_code = (field >> 13) & 0x7;
	if (!name_code || name_code > 2)
		return 0;
	originator_code = (field >> 10) & 0x7;
	if (!originator_code)
		return 0;
	sign_bit = (field >> 9) & 0x1;
	val = field & 0x1ff;
	if (sign_bit && !val)
		return 0;
	*gain = (sign_bit ? -1 : 1) * val;
	return name_code;
}

static char *get_home_dir(const char *username)
{
	struct passwd *passwd;

	if (username == NULL)
		return xstrdup(home_dir);
	passwd = getpwnam(username);
	if (passwd == NULL)
		return NULL;
	/* don't free passwd */
	return xstrdup(passwd->pw_dir);
}

char *expand_filename(const char *name)
{
	if (name[0] == '~') {
		char *slash;

		slash = strchr(name, '/');
		if (slash) {
			char *username, *home;

			if (slash - name - 1 > 0) {
				/* ~user/... */
				username = xstrndup(name + 1, slash - name - 1);
			} else {
				/* ~/... */
				username = NULL;
			}
			home = get_home_dir(username);
			free(username);
			if (home) {
				char *expanded;

				expanded = xstrjoin(home, slash);
				free(home);
				return expanded;
			} else {
				return xstrdup(name);
			}
		} else {
			if (name[1] == 0) {
				return xstrdup(home_dir);
			} else {
				char *home;

				home = get_home_dir(name + 1);
				if (home)
					return home;
				return xstrdup(name);
			}
		}
	} else {
		return xstrdup(name);
	}
}

void shuffle_array(void *array, size_t n, size_t size) 
{
	char tmp[size];
	char *arr = array;
	for (ssize_t i = 0; i < (ssize_t)n - 1; ++i) {
		size_t rnd = (size_t) rand();
		size_t j = i + rnd / (RAND_MAX / (n - i) + 1);
		memcpy(tmp, arr + j * size, size);
		memcpy(arr + j * size, arr + i * size, size);
		memcpy(arr + i * size, tmp, size);
	}
}