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

#include "quakedef.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
# 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;
}


extern qboolean host_shuttingdown;
void Sys_Quit (int returnvalue)
{
	if (COM_CheckParm("-profilegameonly"))
		Sys_AllowProfiling(false);
	host_shuttingdown = true;
	Host_Shutdown();
	exit(returnvalue);
}

#if defined(__linux__) || defined(__FreeBSD__)
#ifdef __cplusplus
extern "C"
#endif
int moncontrol(int);
#endif

void Sys_AllowProfiling(qboolean enable)
{
#if defined(__linux__) || defined(__FreeBSD__)
	moncontrol(enable);
#endif
}


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

DLL MANAGEMENT

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

static qboolean Sys_LoadLibraryFunctions(dllhandle_t dllhandle, const dllfunction_t *fcts, qboolean complain, qboolean 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;
}

qboolean Sys_LoadLibrary (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_LoadLibraryFunctions(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_UnloadLibrary(&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
		dllhandle = LoadLibrary (dllnames[i]);
		// no need to unset this - we want ALL dlls to be loaded from there, anyway
#else
		dllhandle = dlopen (dllnames[i], RTLD_LAZY | RTLD_GLOBAL);
#endif
		if (Sys_LoadLibraryFunctions(dllhandle, fcts, true, (dllnames[i+1] != NULL) || (strrchr(com_argv[0], '/'))))
			break;
		else
			Sys_UnloadLibrary (&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(com_argv[0], '/'))
	{
		char path[MAX_OSPATH];
		strlcpy(path, com_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);
#ifdef WIN32
			dllhandle = LoadLibrary (temp);
#else
			dllhandle = dlopen (temp, RTLD_LAZY | RTLD_GLOBAL);
#endif
			if (Sys_LoadLibraryFunctions(dllhandle, fcts, true, dllnames[i+1] != NULL))
				break;
			else
				Sys_UnloadLibrary (&dllhandle);
		}
	}

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

	Con_DPrintf(" - loaded.\n");

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

void Sys_UnloadLibrary (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

#if defined(CLOCK_MONOTONIC) || defined(CLOCK_HIRES)
# define HAVE_CLOCKGETTIME 1
#endif

#ifndef WIN32
// 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

// this one is referenced elsewhere
cvar_t sys_usenoclockbutbenchmark = {CVAR_SAVE, "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."};

// these are not
static cvar_t sys_debugsleep = {0, "sys_debugsleep", "0", "write requested and attained sleep times to standard output, to be used with gnuplot"};
static cvar_t sys_usesdlgetticks = {CVAR_SAVE, "sys_usesdlgetticks", "0", "use SDL_GetTicks() timer (less accurate, for debugging)"};
static cvar_t sys_usesdldelay = {CVAR_SAVE, "sys_usesdldelay", "0", "use SDL_Delay() (less accurate, for debugging)"};
#if HAVE_QUERYPERFORMANCECOUNTER
static cvar_t sys_usequeryperformancecounter = {CVAR_SAVE, "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 = {CVAR_SAVE, "sys_useclockgettime", "0", "use POSIX clock_gettime function (which has issues if the system clock speed is far off, as it can't get fixed by NTP) 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"

void Sys_Init_Commands (void)
{
	Cvar_RegisterVariable(&sys_debugsleep);
	Cvar_RegisterVariable(&sys_usenoclockbutbenchmark);
#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)
	{
		// LordHavoc: 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);
	
			#ifdef __BORLANDC__
			timescale = 1.0 / ((double) PerformanceFreq.u.LowPart + (double) PerformanceFreq.u.HighPart * 65536.0 * 65536.0);
			return ((double) PerformanceCount.u.LowPart + (double) PerformanceCount.u.HighPart * 65536.0 * 65536.0) * timescale;
			#else
			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;
			#endif
		}
		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 com_argv[0];
#else
	static char exenamebuf[MAX_OSPATH+1];
	ssize_t n = -1;
#if defined(__FreeBSD__)
	n = readlink("/proc/curproc/file", exenamebuf, sizeof(exenamebuf)-1);
#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(com_argv[0], '/'))
		return com_argv[0]; // possibly a relative path
	else
		return Sys_FindInPATH(com_argv[0], '/', getenv("PATH"), ':', exenamebuf, sizeof(exenamebuf));
#endif
}

void Sys_ProvideSelfFD(void)
{
	if(com_selffd != -1)
		return;
	com_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(__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;
}

qboolean Sys_HaveSSE(void)
{
	// COMMANDLINEOPTION: SSE: -nosse disables SSE support and detection
	if(COM_CheckParm("-nosse"))
		return false;
	// COMMANDLINEOPTION: SSE: -forcesse enables SSE support and disables detection
	if(COM_CheckParm("-forcesse") || COM_CheckParm("-forcesse2"))
		return true;
	if(CPUID_Features() & (1 << 25))
		return true;
	return false;
}

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

/// called to set process priority for dedicated servers
#if defined(__linux__)
#include <sys/resource.h>
#include <errno.h>
static int nicelevel;
static qboolean nicepossible;
static qboolean isnice;
void Sys_InitProcessNice (void)
{
	struct rlimit lim;
	nicepossible = false;
	if(COM_CheckParm("-nonice"))
		return;
	errno = 0;
	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 && nicelevel < (int) (20 - lim.rlim_cur))
	{
		Con_Printf("Current nice level is below the soft limit - cannot use niceness\n");
		return;
	}
	nicepossible = true;
	isnice = false;
}
void Sys_MakeProcessNice (void)
{
	if(!nicepossible)
		return;
	if(isnice)
		return;
	Con_DPrintf("Process is becoming 'nice'...\n");
	if(setpriority(PRIO_PROCESS, 0, 19))
		Con_Printf("Failed to raise nice level to %d\n", 19);
	isnice = true;
}
void Sys_MakeProcessMean (void)
{
	if(!nicepossible)
		return;
	if(!isnice)
		return;
	Con_DPrintf("Process is becoming 'mean'...\n");
	if(setpriority(PRIO_PROCESS, 0, nicelevel))
		Con_Printf("Failed to lower nice level to %d\n", nicelevel);
	isnice = false;
}
#else
void Sys_InitProcessNice (void)
{
}
void Sys_MakeProcessNice (void)
{
}
void Sys_MakeProcessMean (void)
{
}
#endif