#ifdef WIN32
# ifndef DONT_USE_SETDLLDIRECTORY
#  define _WIN32_WINNT 0x0502
# endif
#endif

#include "quakedef.h"
#include "taskqueue.h"
#include "thread.h"

#define SUPPORTDLL

#ifdef WIN32
# include <windows.h>
# include <mmsystem.h> // timeGetTime
# include <time.h> // localtime
#ifdef _MSC_VER
#pragma comment(lib, "winmm.lib")
#endif
#else
# ifdef __FreeBSD__
#  include <sys/sysctl.h>
# endif
# include <unistd.h>
# include <fcntl.h>
# include <sys/time.h>
# include <time.h>
# ifdef SUPPORTDLL
#  include <dlfcn.h>
# endif
#endif

static char sys_timestring[128];
char *Sys_TimeString(const char *timeformat)
{
	time_t mytime = time(NULL);
#if _MSC_VER >= 1400
	struct tm mytm;
	localtime_s(&mytm, &mytime);
	strftime(sys_timestring, sizeof(sys_timestring), timeformat, &mytm);
#else
	strftime(sys_timestring, sizeof(sys_timestring), timeformat, localtime(&mytime));
#endif
	return sys_timestring;
}


void Sys_Quit (int returnvalue)
{
	// Unlock mutexes because the quit command may jump directly here, causing a deadlock
	if ((cmd_local)->cbuf->lock)
		Cbuf_Unlock((cmd_local)->cbuf);
	SV_UnlockThreadMutex();
	TaskQueue_Frame(true);

	if (Sys_CheckParm("-profilegameonly"))
		Sys_AllowProfiling(false);
	host.state = host_shutdown;
	Host_Shutdown();
	exit(returnvalue);
}

#ifdef __cplusplus
extern "C"
#endif
void Sys_AllowProfiling(qbool enable)
{
#ifdef __ANDROID__
#ifdef USE_PROFILER
	extern void monstartup(const char *libname);
	extern void moncleanup(void);
	if (enable)
		monstartup("libmain.so");
	else
		moncleanup();
#endif
#elif (defined(__linux__) && (defined(__GLIBC__) || defined(__GNU_LIBRARY__))) || defined(__FreeBSD__)
	extern int moncontrol(int);
	moncontrol(enable);
#endif
}


/*
===============================================================================

DLL MANAGEMENT

===============================================================================
*/

static qbool Sys_LoadDependencyFunctions(dllhandle_t dllhandle, const dllfunction_t *fcts, qbool complain, qbool has_next)
{
	const dllfunction_t *func;
	if(dllhandle)
	{
		for (func = fcts; func && func->name != NULL; func++)
			if (!(*func->funcvariable = (void *) Sys_GetProcAddress (dllhandle, func->name)))
			{
				if(complain)
				{
					Con_DPrintf (" - missing function \"%s\" - broken library!", func->name);
					if(has_next)
						Con_DPrintf("\nContinuing with");
				}
				goto notfound;
			}
		return true;

	notfound:
		for (func = fcts; func && func->name != NULL; func++)
			*func->funcvariable = NULL;
	}
	return false;
}

qbool Sys_LoadSelf(dllhandle_t *handle)
{
	dllhandle_t dllhandle = 0;

	if (handle == NULL)
		return false;
#ifdef WIN32
	dllhandle = LoadLibrary (NULL);
#else
	dllhandle = dlopen (NULL, RTLD_NOW | RTLD_GLOBAL);
#endif
	*handle = dllhandle;
	return true;
}

qbool Sys_LoadDependency (const char** dllnames, dllhandle_t* handle, const dllfunction_t *fcts)
{
#ifdef SUPPORTDLL
	const dllfunction_t *func;
	dllhandle_t dllhandle = 0;
	unsigned int i;

	if (handle == NULL)
		return false;

#ifndef WIN32
#ifdef PREFER_PRELOAD
	dllhandle = dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL);
	if(Sys_LoadDependencyFunctions(dllhandle, fcts, false, false))
	{
		Con_DPrintf ("All of %s's functions were already linked in! Not loading dynamically...\n", dllnames[0]);
		*handle = dllhandle;
		return true;
	}
	else
		Sys_FreeLibrary(&dllhandle);
notfound:
#endif
#endif

	// Initializations
	for (func = fcts; func && func->name != NULL; func++)
		*func->funcvariable = NULL;

	// Try every possible name
	Con_DPrintf ("Trying to load library...");
	for (i = 0; dllnames[i] != NULL; i++)
	{
		Con_DPrintf (" \"%s\"", dllnames[i]);
#ifdef WIN32
# ifndef DONT_USE_SETDLLDIRECTORY
#  ifdef _WIN64
		SetDllDirectory("bin64");
#  else
		SetDllDirectory("bin32");
#  endif
# endif
#endif
		if(Sys_LoadLibrary(dllnames[i], &dllhandle))
		{
			if (Sys_LoadDependencyFunctions(dllhandle, fcts, true, (dllnames[i+1] != NULL) || (strrchr(sys.argv[0], '/'))))
				break;
			else
				Sys_FreeLibrary (&dllhandle);
		}
	}

	// see if the names can be loaded relative to the executable path
	// (this is for Mac OSX which does not check next to the executable)
	if (!dllhandle && strrchr(sys.argv[0], '/'))
	{
		char path[MAX_OSPATH];
		strlcpy(path, sys.argv[0], sizeof(path));
		strrchr(path, '/')[1] = 0;
		for (i = 0; dllnames[i] != NULL; i++)
		{
			char temp[MAX_OSPATH];
			strlcpy(temp, path, sizeof(temp));
			strlcat(temp, dllnames[i], sizeof(temp));
			Con_DPrintf (" \"%s\"", temp);

			if(Sys_LoadLibrary(temp, &dllhandle))
			{
				if (Sys_LoadDependencyFunctions(dllhandle, fcts, true, (dllnames[i+1] != NULL) || (strrchr(sys.argv[0], '/'))))
					break;
				else
					Sys_FreeLibrary (&dllhandle);
			}
		}
	}

	// No DLL found
	if (! dllhandle)
	{
		Con_DPrintf(" - failed.\n");
		return false;
	}

	Con_DPrintf(" - loaded.\n");
	Con_Printf("Loaded library \"%s\"\n", dllnames[i]);

	*handle = dllhandle;
	return true;
#else
	return false;
#endif
}

qbool Sys_LoadLibrary(const char *name, dllhandle_t *handle)
{
	dllhandle_t dllhandle = 0;

	if(handle == NULL)
		return false;

#ifdef SUPPORTDLL
# ifdef WIN32
	dllhandle = LoadLibrary (name);
# else
	dllhandle = dlopen (name, RTLD_LAZY | RTLD_GLOBAL);
# endif
#endif
	if(!dllhandle)
		return false;

	*handle = dllhandle;
	return true;
}

void Sys_FreeLibrary (dllhandle_t* handle)
{
#ifdef SUPPORTDLL
	if (handle == NULL || *handle == NULL)
		return;

#ifdef WIN32
	FreeLibrary (*handle);
#else
	dlclose (*handle);
#endif

	*handle = NULL;
#endif
}

void* Sys_GetProcAddress (dllhandle_t handle, const char* name)
{
#ifdef SUPPORTDLL
#ifdef WIN32
	return (void *)GetProcAddress (handle, name);
#else
	return (void *)dlsym (handle, name);
#endif
#else
	return NULL;
#endif
}

#ifdef WIN32
# define HAVE_TIMEGETTIME 1
# define HAVE_QUERYPERFORMANCECOUNTER 1
# define HAVE_Sleep 1
#endif

#ifndef WIN32
#if defined(CLOCK_MONOTONIC) || defined(CLOCK_HIRES)
# define HAVE_CLOCKGETTIME 1
#endif
// FIXME improve this check, manpage hints to DST_NONE
# define HAVE_GETTIMEOFDAY 1
#endif

#ifndef WIN32
// on Win32, select() cannot be used with all three FD list args being NULL according to MSDN
// (so much for POSIX...)
# ifdef FD_SET
#  define HAVE_SELECT 1
# endif
#endif

#ifndef WIN32
// FIXME improve this check
# define HAVE_USLEEP 1
#endif

// these are referenced elsewhere
cvar_t sys_usenoclockbutbenchmark = {CF_CLIENT | CF_SERVER | CF_ARCHIVE, "sys_usenoclockbutbenchmark", "0", "don't use ANY real timing, and simulate a clock (for benchmarking); the game then runs as fast as possible. Run a QC mod with bots that does some stuff, then does a quit at the end, to benchmark a server. NEVER do this on a public server."};
cvar_t sys_libdir = {CF_READONLY | CF_CLIENT | CF_SERVER, "sys_libdir", "", "Default engine library directory"};

// these are not
static cvar_t sys_debugsleep = {CF_CLIENT | CF_SERVER, "sys_debugsleep", "0", "write requested and attained sleep times to standard output, to be used with gnuplot"};
static cvar_t sys_usesdlgetticks = {CF_CLIENT | CF_SERVER | CF_ARCHIVE, "sys_usesdlgetticks", "0", "use SDL_GetTicks() timer (less accurate, for debugging)"};
static cvar_t sys_usesdldelay = {CF_CLIENT | CF_SERVER | CF_ARCHIVE, "sys_usesdldelay", "0", "use SDL_Delay() (less accurate, for debugging)"};
#if HAVE_QUERYPERFORMANCECOUNTER
static cvar_t sys_usequeryperformancecounter = {CF_CLIENT | CF_SERVER | CF_ARCHIVE, "sys_usequeryperformancecounter", "0", "use windows QueryPerformanceCounter timer (which has issues on multicore/multiprocessor machines and processors which are designed to conserve power) for timing rather than timeGetTime function (which has issues on some motherboards)"};
#endif
#if HAVE_CLOCKGETTIME
static cvar_t sys_useclockgettime = {CF_CLIENT | CF_SERVER | CF_ARCHIVE, "sys_useclockgettime", "1", "use POSIX clock_gettime function (not adjusted by NTP on some older Linux kernels) for timing rather than gettimeofday (which has issues if the system time is stepped by ntpdate, or apparently on some Xen installations)"};
#endif

static double benchmark_time; // actually always contains an integer amount of milliseconds, will eventually "overflow"

/*
================
Sys_CheckParm

Returns the position (1 to argc-1) in the program's argument list
where the given parameter apears, or 0 if not present
================
*/
int Sys_CheckParm (const char *parm)
{
	int i;

	for (i=1 ; i<sys.argc ; i++)
	{
		if (!sys.argv[i])
			continue;               // NEXTSTEP sometimes clears appkit vars.
		if (!strcmp (parm,sys.argv[i]))
			return i;
	}

	return 0;
}

void Sys_Init_Commands (void)
{
	Cvar_RegisterVariable(&sys_debugsleep);
	Cvar_RegisterVariable(&sys_usenoclockbutbenchmark);
	Cvar_RegisterVariable(&sys_libdir);
#if HAVE_TIMEGETTIME || HAVE_QUERYPERFORMANCECOUNTER || HAVE_CLOCKGETTIME || HAVE_GETTIMEOFDAY
	if(sys_supportsdlgetticks)
	{
		Cvar_RegisterVariable(&sys_usesdlgetticks);
		Cvar_RegisterVariable(&sys_usesdldelay);
	}
#endif
#if HAVE_QUERYPERFORMANCECOUNTER
	Cvar_RegisterVariable(&sys_usequeryperformancecounter);
#endif
#if HAVE_CLOCKGETTIME
	Cvar_RegisterVariable(&sys_useclockgettime);
#endif
}

double Sys_DirtyTime(void)
{
	// first all the OPTIONAL timers

	// benchmark timer (fake clock)
	if(sys_usenoclockbutbenchmark.integer)
	{
		double old_benchmark_time = benchmark_time;
		benchmark_time += 1;
		if(benchmark_time == old_benchmark_time)
			Sys_Error("sys_usenoclockbutbenchmark cannot run any longer, sorry");
		return benchmark_time * 0.000001;
	}
#if HAVE_QUERYPERFORMANCECOUNTER
	if (sys_usequeryperformancecounter.integer)
	{
		// LadyHavoc: note to people modifying this code, DWORD is specifically defined as an unsigned 32bit number, therefore the 65536.0 * 65536.0 is fine.
		// QueryPerformanceCounter
		// platform:
		// Windows 95/98/ME/NT/2000/XP
		// features:
		// very accurate (CPU cycles)
		// known issues:
		// does not necessarily match realtime too well (tends to get faster and faster in win98)
		// wraps around occasionally on some platforms (depends on CPU speed and probably other unknown factors)
		double timescale;
		LARGE_INTEGER PerformanceFreq;
		LARGE_INTEGER PerformanceCount;

		if (QueryPerformanceFrequency (&PerformanceFreq))
		{
			QueryPerformanceCounter (&PerformanceCount);
	
			timescale = 1.0 / ((double) PerformanceFreq.LowPart + (double) PerformanceFreq.HighPart * 65536.0 * 65536.0);
			return ((double) PerformanceCount.LowPart + (double) PerformanceCount.HighPart * 65536.0 * 65536.0) * timescale;
		}
		else
		{
			Con_Printf("No hardware timer available\n");
			// fall back to other clock sources
			Cvar_SetValueQuick(&sys_usequeryperformancecounter, false);
		}
	}
#endif

#if HAVE_CLOCKGETTIME
	if (sys_useclockgettime.integer)
	{
		struct timespec ts;
#  ifdef CLOCK_MONOTONIC
		// linux
		clock_gettime(CLOCK_MONOTONIC, &ts);
#  else
		// sunos
		clock_gettime(CLOCK_HIGHRES, &ts);
#  endif
		return (double) ts.tv_sec + ts.tv_nsec / 1000000000.0;
	}
#endif

	// now all the FALLBACK timers
	if(sys_supportsdlgetticks && sys_usesdlgetticks.integer)
		return (double) Sys_SDL_GetTicks() / 1000.0;
#if HAVE_GETTIMEOFDAY
	{
		struct timeval tp;
		gettimeofday(&tp, NULL);
		return (double) tp.tv_sec + tp.tv_usec / 1000000.0;
	}
#elif HAVE_TIMEGETTIME
	{
		static int firsttimegettime = true;
		// timeGetTime
		// platform:
		// Windows 95/98/ME/NT/2000/XP
		// features:
		// reasonable accuracy (millisecond)
		// issues:
		// wraps around every 47 days or so (but this is non-fatal to us, odd times are rejected, only causes a one frame stutter)

		// make sure the timer is high precision, otherwise different versions of windows have varying accuracy
		if (firsttimegettime)
		{
			timeBeginPeriod(1);
			firsttimegettime = false;
		}

		return (double) timeGetTime() / 1000.0;
	}
#else
	// fallback for using the SDL timer if no other timer is available
	// this calls Sys_Error() if not linking against SDL
	return (double) Sys_SDL_GetTicks() / 1000.0;
#endif
}

void Sys_Sleep(int microseconds)
{
	double t = 0;
	if(sys_usenoclockbutbenchmark.integer)
	{
		if(microseconds)
		{
			double old_benchmark_time = benchmark_time;
			benchmark_time += microseconds;
			if(benchmark_time == old_benchmark_time)
				Sys_Error("sys_usenoclockbutbenchmark cannot run any longer, sorry");
		}
		return;
	}
	if(sys_debugsleep.integer)
	{
		t = Sys_DirtyTime();
	}
	if(sys_supportsdlgetticks && sys_usesdldelay.integer)
	{
		Sys_SDL_Delay(microseconds / 1000);
	}
#if HAVE_SELECT
	else
	{
		struct timeval tv;
		tv.tv_sec = microseconds / 1000000;
		tv.tv_usec = microseconds % 1000000;
		select(0, NULL, NULL, NULL, &tv);
	}
#elif HAVE_USLEEP
	else
	{
		usleep(microseconds);
	}
#elif HAVE_Sleep
	else
	{
		Sleep(microseconds / 1000);
	}
#else
	else
	{
		Sys_SDL_Delay(microseconds / 1000);
	}
#endif
	if(sys_debugsleep.integer)
	{
		t = Sys_DirtyTime() - t;
		Sys_PrintfToTerminal("%d %d # debugsleep\n", microseconds, (unsigned int)(t * 1000000));
	}
}

void Sys_PrintfToTerminal(const char *fmt, ...)
{
	va_list argptr;
	char msg[MAX_INPUTLINE];

	va_start(argptr,fmt);
	dpvsnprintf(msg,sizeof(msg),fmt,argptr);
	va_end(argptr);

	Sys_PrintToTerminal(msg);
}

#ifndef WIN32
static const char *Sys_FindInPATH(const char *name, char namesep, const char *PATH, char pathsep, char *buf, size_t bufsize)
{
	const char *p = PATH;
	const char *q;
	if(p && name)
	{
		while((q = strchr(p, ':')))
		{
			dpsnprintf(buf, bufsize, "%.*s%c%s", (int)(q-p), p, namesep, name);
			if(FS_SysFileExists(buf))
				return buf;
			p = q + 1;
		}
		if(!q) // none found - try the last item
		{
			dpsnprintf(buf, bufsize, "%s%c%s", p, namesep, name);
			if(FS_SysFileExists(buf))
				return buf;
		}
	}
	return name;
}
#endif

static const char *Sys_FindExecutableName(void)
{
#if defined(WIN32)
	return sys.argv[0];
#else
	static char exenamebuf[MAX_OSPATH+1];
	ssize_t n = -1;
#if defined(__FreeBSD__)
	int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
	size_t exenamebuflen = sizeof(exenamebuf)-1;
	if (sysctl(mib, 4, exenamebuf, &exenamebuflen, NULL, 0) == 0)
	{
		n = exenamebuflen;
	}
#elif defined(__linux__)
	n = readlink("/proc/self/exe", exenamebuf, sizeof(exenamebuf)-1);
#endif
	if(n > 0 && (size_t)(n) < sizeof(exenamebuf))
	{
		exenamebuf[n] = 0;
		return exenamebuf;
	}
	if(strchr(sys.argv[0], '/'))
		return sys.argv[0]; // possibly a relative path
	else
		return Sys_FindInPATH(sys.argv[0], '/', getenv("PATH"), ':', exenamebuf, sizeof(exenamebuf));
#endif
}

void Sys_ProvideSelfFD(void)
{
	if(sys.selffd != -1)
		return;
	sys.selffd = FS_SysOpenFD(Sys_FindExecutableName(), "rb", false);
}

// for x86 cpus only...  (x64 has SSE2_PRESENT)
#if defined(SSE_POSSIBLE) && !defined(SSE2_PRESENT)
// code from SDL, shortened as we can expect CPUID to work
static int CPUID_Features(void)
{
	int features = 0;
# if (defined(__GNUC__) || defined(__clang__) || defined(__TINYC__)) && defined(__i386__)
        __asm__ (
"        movl    %%ebx,%%edi\n"
"        xorl    %%eax,%%eax                                           \n"
"        incl    %%eax                                                 \n"
"        cpuid                       # Get family/model/stepping/features\n"
"        movl    %%edx,%0                                              \n"
"        movl    %%edi,%%ebx\n"
        : "=m" (features)
        :
        : "%eax", "%ecx", "%edx", "%edi"
        );
# elif (defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)
        __asm {
        xor     eax, eax
        inc     eax
        cpuid                       ; Get family/model/stepping/features
        mov     features, edx
        }
# else
#  error SSE_POSSIBLE set but no CPUID implementation
# endif
	return features;
}
#endif

#ifdef SSE_POSSIBLE
qbool Sys_HaveSSE(void)
{
	// COMMANDLINEOPTION: SSE: -nosse disables SSE support and detection
	if(Sys_CheckParm("-nosse"))
		return false;
#ifdef SSE_PRESENT
	return true;
#else
	// COMMANDLINEOPTION: SSE: -forcesse enables SSE support and disables detection
	if(Sys_CheckParm("-forcesse") || Sys_CheckParm("-forcesse2"))
		return true;
	if(CPUID_Features() & (1 << 25))
		return true;
	return false;
#endif
}

qbool Sys_HaveSSE2(void)
{
	// COMMANDLINEOPTION: SSE2: -nosse2 disables SSE2 support and detection
	if(Sys_CheckParm("-nosse") || Sys_CheckParm("-nosse2"))
		return false;
#ifdef SSE2_PRESENT
	return true;
#else
	// COMMANDLINEOPTION: SSE2: -forcesse2 enables SSE2 support and disables detection
	if(Sys_CheckParm("-forcesse2"))
		return true;
	if((CPUID_Features() & (3 << 25)) == (3 << 25)) // SSE is 1<<25, SSE2 is 1<<26
		return true;
	return false;
#endif
}
#endif

/// called to set process priority for dedicated servers
#if defined(__linux__)
#include <sys/resource.h>
#include <errno.h>

void Sys_InitProcessNice (void)
{
	struct rlimit lim;
	sys.nicepossible = false;
	if(Sys_CheckParm("-nonice"))
		return;
	errno = 0;
	sys.nicelevel = getpriority(PRIO_PROCESS, 0);
	if(errno)
	{
		Con_Printf("Kernel does not support reading process priority - cannot use niceness\n");
		return;
	}
	if(getrlimit(RLIMIT_NICE, &lim))
	{
		Con_Printf("Kernel does not support lowering nice level again - cannot use niceness\n");
		return;
	}
	if(lim.rlim_cur != RLIM_INFINITY && sys.nicelevel < (int) (20 - lim.rlim_cur))
	{
		Con_Printf("Current nice level is below the soft limit - cannot use niceness\n");
		return;
	}
	sys.nicepossible = true;
	sys.isnice = false;
}
void Sys_MakeProcessNice (void)
{
	if(!sys.nicepossible)
		return;
	if(sys.isnice)
		return;
	Con_DPrintf("Process is becoming 'nice'...\n");
	if(setpriority(PRIO_PROCESS, 0, 19))
		Con_Printf(CON_ERROR "Failed to raise nice level to %d\n", 19);
	sys.isnice = true;
}
void Sys_MakeProcessMean (void)
{
	if(!sys.nicepossible)
		return;
	if(!sys.isnice)
		return;
	Con_DPrintf("Process is becoming 'mean'...\n");
	if(setpriority(PRIO_PROCESS, 0, sys.nicelevel))
		Con_Printf(CON_ERROR "Failed to lower nice level to %d\n", sys.nicelevel);
	sys.isnice = false;
}
#else
void Sys_InitProcessNice (void)
{
}
void Sys_MakeProcessNice (void)
{
}
void Sys_MakeProcessMean (void)
{
}
#endif