/*
 * Copyright (c) 2013 Hugh Bailey <obs.jim@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <unistd.h>
#include <glob.h>
#include <time.h>

#if !defined(__APPLE__)
#include <sys/times.h>
#endif

#include "darray.h"
#include "dstr.h"
#include "platform.h"

void *os_dlopen(const char *path)
{
	struct dstr dylib_name;

	if (!path)
		return NULL;

	dstr_init_copy(&dylib_name, path);
	if (!dstr_find(&dylib_name, ".so"))
		dstr_cat(&dylib_name, ".so");

	void *res = dlopen(dylib_name.array, RTLD_LAZY);
	if (!res)
		blog(LOG_ERROR, "os_dlopen(%s->%s): %s\n",
				path, dylib_name.array, dlerror());

	dstr_free(&dylib_name);
	return res;
}

void *os_dlsym(void *module, const char *func)
{
	return dlsym(module, func);
}

void os_dlclose(void *module)
{
	dlclose(module);
}

#if !defined(__APPLE__)

struct os_cpu_usage_info {
	clock_t last_cpu_time, last_sys_time, last_user_time;
	int core_count;
};

os_cpu_usage_info_t *os_cpu_usage_info_start(void)
{
	struct os_cpu_usage_info *info = bmalloc(sizeof(*info));
	struct tms               time_sample;

	info->last_cpu_time  = times(&time_sample);
	info->last_sys_time  = time_sample.tms_stime;
	info->last_user_time = time_sample.tms_utime;
	info->core_count     = sysconf(_SC_NPROCESSORS_ONLN);
	return info;
}

double os_cpu_usage_info_query(os_cpu_usage_info_t *info)
{
	struct tms time_sample;
	clock_t    cur_cpu_time;
	double     percent;

	if (!info)
		return 0.0;

	cur_cpu_time = times(&time_sample);
	if (cur_cpu_time <= info->last_cpu_time ||
	    time_sample.tms_stime < info->last_sys_time ||
	    time_sample.tms_utime < info->last_user_time)
		return 0.0;

	percent = (double)(time_sample.tms_stime - info->last_sys_time +
			(time_sample.tms_utime - info->last_user_time));
	percent /= (double)(cur_cpu_time - info->last_cpu_time);
	percent /= (double)info->core_count;

	info->last_cpu_time  = cur_cpu_time;
	info->last_sys_time  = time_sample.tms_stime;
	info->last_user_time = time_sample.tms_utime;

	return percent * 100.0;
}

void os_cpu_usage_info_destroy(os_cpu_usage_info_t *info)
{
	if (info)
		bfree(info);
}

#endif

bool os_sleepto_ns(uint64_t time_target)
{
	uint64_t current = os_gettime_ns();
	if (time_target < current)
		return false;

	time_target -= current;

	struct timespec req, remain;
	memset(&req, 0, sizeof(req));
	memset(&remain, 0, sizeof(remain));
	req.tv_sec = time_target/1000000000;
	req.tv_nsec = time_target%1000000000;

	while (nanosleep(&req, &remain)) {
		req = remain;
		memset(&remain, 0, sizeof(remain));
	}

	return true;
}

void os_sleep_ms(uint32_t duration)
{
	usleep(duration*1000);
}

#if !defined(__APPLE__)

uint64_t os_gettime_ns(void)
{
	struct timespec ts;
	clock_gettime(CLOCK_MONOTONIC, &ts);
	return ((uint64_t) ts.tv_sec * 1000000000ULL + (uint64_t) ts.tv_nsec);
}

/* should return $HOME/.[name], or when using XDG,
 * should return $HOME/.config/[name] as default */
int os_get_config_path(char *dst, size_t size, const char *name)
{
#ifdef USE_XDG
	char *xdg_ptr = getenv("XDG_CONFIG_HOME");

	// If XDG_CONFIG_HOME is unset,
	// we use the default $HOME/.config/[name] instead
	if (xdg_ptr == NULL) {
		char *home_ptr = getenv("HOME");
		if (home_ptr == NULL)
			bcrash("Could not get $HOME\n");

		if (!name || !*name) {
			return snprintf(dst, size, "%s/.config", home_ptr);
		} else {
			return snprintf(dst, size, "%s/.config/%s", home_ptr,
					name);
		}
	} else {
		if (!name || !*name)
			return snprintf(dst, size, "%s", xdg_ptr);
		else
			return snprintf(dst, size, "%s/%s", xdg_ptr, name);
	}
#else
	char *path_ptr = getenv("HOME");
	if (path_ptr == NULL)
		bcrash("Could not get $HOME\n");

	if (!name || !*name)
		return snprintf(dst, size, "%s", path_ptr);
	else
		return snprintf(dst, size, "%s/.%s", path_ptr, name);
#endif
}

/* should return $HOME/.[name], or when using XDG,
 * should return $HOME/.config/[name] as default */
char *os_get_config_path_ptr(const char *name)
{
#ifdef USE_XDG
	struct dstr path;
	char *xdg_ptr = getenv("XDG_CONFIG_HOME");

	/* If XDG_CONFIG_HOME is unset,
	 * we use the default $HOME/.config/[name] instead */
	if (xdg_ptr == NULL) {
		char *home_ptr = getenv("HOME");
		if (home_ptr == NULL)
			bcrash("Could not get $HOME\n");

		dstr_init_copy(&path, home_ptr);
		dstr_cat(&path, "/.config/");
		dstr_cat(&path, name);
	} else {
		dstr_init_copy(&path, xdg_ptr);
		dstr_cat(&path, "/");
		dstr_cat(&path, name);
	}
	return path.array;
#else
	char *path_ptr = getenv("HOME");
	if (path_ptr == NULL)
		bcrash("Could not get $HOME\n");

	struct dstr path;
	dstr_init_copy(&path, path_ptr);
	dstr_cat(&path, "/.");
	dstr_cat(&path, name);
	return path.array;
#endif
}

#endif

bool os_file_exists(const char *path)
{
	return access(path, F_OK) == 0;
}

struct os_dir {
	const char       *path;
	DIR              *dir;
	struct dirent    *cur_dirent;
	struct os_dirent out;
};

os_dir_t *os_opendir(const char *path)
{
	struct os_dir *dir;
	DIR           *dir_val;

	dir_val = opendir(path);
	if (!dir_val)
		return NULL;

	dir = bzalloc(sizeof(struct os_dir));
	dir->dir  = dir_val;
	dir->path = path;
	return dir;
}

static inline bool is_dir(const char *path)
{
	struct stat stat_info;
	if (stat(path, &stat_info) == 0)
		return !!S_ISDIR(stat_info.st_mode);

	blog(LOG_DEBUG, "is_dir: stat for %s failed, errno: %d", path, errno);
	return false;
}

struct os_dirent *os_readdir(os_dir_t *dir)
{
	struct dstr file_path = {0};

	if (!dir) return NULL;

	dir->cur_dirent = readdir(dir->dir);
	if (!dir->cur_dirent)
		return NULL;

	strncpy(dir->out.d_name, dir->cur_dirent->d_name, 255);

	dstr_copy(&file_path, dir->path);
	dstr_cat(&file_path, "/");
	dstr_cat(&file_path, dir->out.d_name);

	dir->out.directory = is_dir(file_path.array);

	dstr_free(&file_path);

	return &dir->out;
}

void os_closedir(os_dir_t *dir)
{
	if (dir) {
		closedir(dir->dir);
		bfree(dir);
	}
}

struct posix_glob_info {
	struct os_glob_info base;
	glob_t gl;
};

int os_glob(const char *pattern, int flags, os_glob_t **pglob)
{
	struct posix_glob_info pgi;
	int ret = glob(pattern, 0, NULL, &pgi.gl);

	if (ret == 0) {
		DARRAY(struct os_globent) list;
		da_init(list);

		for (size_t i = 0; i < pgi.gl.gl_pathc; i++) {
			struct os_globent ent = {0};

			ent.path = pgi.gl.gl_pathv[i];
			ent.directory = is_dir(ent.path);
			da_push_back(list, &ent);
		}

		pgi.base.gl_pathc = list.num;
		pgi.base.gl_pathv = list.array;

		*pglob = bmemdup(&pgi, sizeof(pgi));
	} else {
		*pglob = NULL;
	}

	UNUSED_PARAMETER(flags);
	return ret;
}

void os_globfree(os_glob_t *pglob)
{
	if (pglob) {
		struct posix_glob_info *pgi = (struct posix_glob_info*)pglob;
		globfree(&pgi->gl);

		bfree(pgi->base.gl_pathv);
		bfree(pgi);
	}
}

int os_unlink(const char *path)
{
	return unlink(path);
}

int os_rmdir(const char *path)
{
	return rmdir(path);
}

int os_mkdir(const char *path)
{
	if (mkdir(path, 0755) == 0)
		return MKDIR_SUCCESS;

	return (errno == EEXIST) ? MKDIR_EXISTS : MKDIR_ERROR;
}

int os_rename(const char *old_path, const char *new_path)
{
	return rename(old_path, new_path);
}

#if !defined(__APPLE__)
os_performance_token_t *os_request_high_performance(const char *reason)
{
	UNUSED_PARAMETER(reason);
	return NULL;
}

void os_end_high_performance(os_performance_token_t *token)
{
	UNUSED_PARAMETER(token);
}
#endif

int os_copyfile(const char *file_path_in, const char *file_path_out)
{
	FILE *file_out = NULL;
	FILE *file_in = NULL;
	uint8_t data[4096];
	int ret = -1;
	size_t size;

	if (os_file_exists(file_path_out))
		return -1;

	file_in = fopen(file_path_in, "rb");
	if (!file_in)
		return -1;

	file_out = fopen(file_path_out, "ab+");
	if (!file_out)
		goto error;

	do {
		size = fread(data, 1, sizeof(data), file_in);
		if (size)
			size = fwrite(data, 1, size, file_out);
	} while (size == sizeof(data));

	ret = feof(file_in) ? 0 : -1;

error:
	if (file_out)
		fclose(file_out);
	fclose(file_in);
	return ret;
}