////////////////////////////////////////////////////////////////////////////////////////////////////
//

#include "projal.h"
#include "logfile.h"
#include "fileutil.h"
#include "strutil.h"
#include <getopt.h>
#include <signal.h>
#include <unistd.h>
#include <linux/limits.h>
#include <climits>
#include "processclock.h"
#include "instance.h"
#include "debug.h"

////////////////////////////////////////////////////////////////////////////////////////////////////

#define _USE_SIG_INFO						0

////////////////////////////////////////////////////////////////////////////////////////////////////
// app control

#define _APPID								GFA_APPCTRL_APPID_REMANENT
#define _APPNAME							"Remanent"

////////////////////////////////////////////////////////////////////////////////////////////////////

#define _DEFAULT_SCAN_INTERVAL_MS			1000 // 1 sec
#define _MIN_SCAN_INTERVAL_MS				100 // 100 ms

////////////////////////////////////////////////////////////////////////////////////////////////////

#define _NANOSECS_PER_SEC					1000000000
#define _MAX_WRITE_CREDITS					60
#define _MAX_WRITES_PER_MINUTE				6
#define _SECS_PER_WRITE_INTERVAL			(60 / _MAX_WRITES_PER_MINUTE)

#define _LOGFILE_NAME						"remanent.log"

////////////////////////////////////////////////////////////////////////////////////////////////////

#define _SIG_BLOCK(s)						sigprocmask(SIG_BLOCK, (s), NULL)
#define _SIG_UNBLOCK(s)						sigprocmask(SIG_UNBLOCK, (s), NULL)

////////////////////////////////////////////////////////////////////////////////////////////////////

static volatile bool						g_fRun			= false;
static volatile bool						g_fPauseImp		= false;
static volatile bool						g_fPauseCmd		= false;
static volatile bool						g_fZombie		= false;
static int									g_nLastSig		= -1;
static sigset_t								g_set;
static CLogfile								g_lf;

////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
//

#if _USE_SIG_INFO
static void _OnSigAction(int sig, siginfo_t *psi, void *p)
{
	TRACE("Received signal '%s', PID: %d, Code: %d.\n", strsignal(sig), psi->si_pid, psi->si_code);
	g_lf.Info("Received signal '%s', PID: %d, Code: %d.\n", strsignal(sig), psi->si_pid, psi->si_code);

	if((sig != SIGINT) || !psi->si_pid)
	{
		g_nLastSig = sig;
		g_fRun = g_fPauseImp = g_fPauseCmd = g_fZombie = false;
	}
}
#else
static void _SigHandler(int sig)
{
	g_nLastSig = sig;
	g_fRun = g_fPauseImp = g_fPauseCmd = g_fZombie = false;
//	g_lf.Info("Received signal '%s'.\n", strsignal(g_nLastSig));
}
#endif

////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////
//

static long long _TimeSpecDiffNs(const struct timespec *pts1, const struct timespec *pts2)
{
	long long ns1 = (long long)pts1->tv_sec * _NANOSECS_PER_SEC + pts1->tv_nsec;
	long long ns2 = (long long)pts2->tv_sec * _NANOSECS_PER_SEC + pts2->tv_nsec;
	return (ns2 - ns1);
}

static bool _IntervalElapsed(struct timespec *pts, long nIntvSeconds)
{
	struct timespec ts;
	clock_gettime(CLOCK_MONOTONIC, &ts);
	long long diff = _TimeSpecDiffNs(pts, &ts) / _NANOSECS_PER_SEC;

	if(diff >= (long long)nIntvSeconds)
	{
		pts->tv_sec += nIntvSeconds;
		return true;
	}

	return false;
}

static const char* _GetBaseDir(std::string &rstrBaseDir)
{
	char szBaseDir[PATH_MAX];
	const char *pszBaseDir = NULL;

#ifdef _LOG_BASE_DIR
	pszBaseDir = _LOG_BASE_DIR;
	if(!pszBaseDir || !*pszBaseDir || !::DirectoryExist(pszBaseDir))
	{
		CLogfile::StdErr("Invalid base directory config! Using app directory!\n");
		pszBaseDir = ::GetAppDirectory(szBaseDir, sizeof(szBaseDir));
	}
	rstrBaseDir = pszBaseDir;
#else	//	_LOG_BASE_DIR
    UNUSED(pszBaseDir);
	rstrBaseDir = ::GetAppDirectory(szBaseDir, sizeof(szBaseDir));
#endif	//	_LOG_BASE_DIR

	rtrim(rstrBaseDir, "/");
	return rstrBaseDir.c_str();
}

////////////////////////////////////////////////////////////////////////////////////////////////////

static void _ProcessCtrlMessages(HAPPCTRL hAC, HAPPINFO hAI)
{
    ctrlmsg_t nCtrlMsg;

	while(g_fRun && (nCtrlMsg = ::GfaIpcAppCtrlGetNextCtrlMsg(hAI)))
	{
		switch(nCtrlMsg)
		{
		case GFA_APPCTRL_CTRLMSG_STOP:
			g_fRun = false;
			g_fPauseImp = false;
			g_fPauseCmd = false;
			g_fZombie = false;
			g_lf.Info("Received Control Message 'Stop'\n");
			break;
		case GFA_APPCTRL_CTRLMSG_PAUSE:
			if(!g_fPauseCmd)
			{
				g_fPauseCmd = true;
				if(!g_fPauseImp)
				{
					::GfaIpcAppCtrlSetState(hAC, GIAS_Paused);
					g_lf.Info("Received Control Message 'Pause'\n");
					g_lf.Info("Enter state %s ...\n", ::GfaIpcAppCtrlGetStateText(GIAS_Paused));
					TRACE("%-8s: State: %s\n", "Me", ::GfaIpcAppCtrlGetStateText(GIAS_Paused));
				}
			}
			break;
		case GFA_APPCTRL_CTRLMSG_RESUME:
			if(g_fPauseCmd)
			{
				g_fPauseCmd = false;
				if(!g_fPauseImp)
				{
					g_lf.Info("Received Control Message 'Resume'\n");
					g_lf.Info("Enter state %s ...\n", ::GfaIpcAppCtrlGetStateText(GIAS_Running));
					::GfaIpcAppCtrlSetState(hAC, GIAS_Running);
					TRACE("%-8s: State: %s\n", "Me", ::GfaIpcAppCtrlGetStateText(GIAS_Running));
				}
			}
			break;
		default:
			break;
		}
	}
}

////////////////////////////////////////////////////////////////////////////////////////////////////
//

int main(int argc, char **argv)
{
	CProcessInstance pi;
	int nRet = 0, c;
	HSHM hShm = NULL;
	void *pShm = NULL;
	HAPPCTRL hAC = NULL;
	HAPPINFO hAI;
	Json::Value root;
	bool bDbgInvolved = false;
	bool bHasJSON = false;
	char szWriteFile[PATH_MAX];
	char szBackupFile[PATH_MAX];
	char szLogFile[PATH_MAX];
	CHECK_UPDATE_SHM_RETVAL rv;
	struct timespec tsWriteCredits, tsScanIntv;
	unsigned long cntVals = 0;
	char *pszEndPtr = NULL;
	clock64_t nCycleIntervalMS = _DEFAULT_SCAN_INTERVAL_MS;
	int nWriteCredits = _MAX_WRITE_CREDITS;
	unsigned int nPendingChanges = 0;
	struct sigaction sa;
	std::string strBaseDir;
	const char *pszBaseDir = NULL;
	unsigned long long nUsecWorkTime = 0;
	CProcessClock pcWork, pcPerf;
	std::string sPerf;

	////////////////////////////////////////////////////////////////////////////////////////////////
	// check for multiple instances

    if(!pi.LockInstance(UUID_SHM))
	{
		CLogfile::StdErr("Failed to start instance!\n");
		return -1;
	}

	////////////////////////////////////////////////////////////////////////////////////////////////
	// parse command line options

	while((c = getopt(argc, argv, "b:c:d")) != -1)
	{
		switch(c)
		{
		case 'b':
			if(DirectoryExist(optarg))
			{
				strBaseDir = optarg;
				rtrim(strBaseDir, "/");
				pszBaseDir = strBaseDir.c_str();
			}
			else
			{
				CLogfile::StdErr("Invalid base directory option!\n");
			}
			break;
		case 'c':
			nCycleIntervalMS = strtoll(optarg, &pszEndPtr, 10);

			if((((nCycleIntervalMS == LLONG_MIN) || (nCycleIntervalMS == LLONG_MAX)) && (errno == ERANGE)) || (pszEndPtr && *pszEndPtr))
			{
				nCycleIntervalMS = _DEFAULT_SCAN_INTERVAL_MS;
				CLogfile::StdErr("Invalid cycle interval: \"%s\"! Setting default value (%u)\n", optarg, _DEFAULT_SCAN_INTERVAL_MS);
			}
			else if(nCycleIntervalMS < _MIN_SCAN_INTERVAL_MS)
			{
				nCycleIntervalMS = _MIN_SCAN_INTERVAL_MS;
				CLogfile::StdErr("Invalid cycle interval: \"%s\"! Limiting to minimal value (%u)\n", optarg, _MIN_SCAN_INTERVAL_MS);
			}
			break;
		case 'd':
			bDbgInvolved = true;
			break;
		case '?':
			break;
		}
	}

	do
	{
		g_fZombie = true;

		////////////////////////////////////////////////////////////////////////////////////////////
		// get the base directory for output files if not provided by cmd line

		if(!pszBaseDir)
			pszBaseDir = _GetBaseDir(strBaseDir);

		CLogfile::StdOut("Using base directory \"%s\".\n", pszBaseDir);

		////////////////////////////////////////////////////////////////////////////////////////////
		// initialize log file

		sprintf(szLogFile, "%s/%s", pszBaseDir, _LOGFILE_NAME);

		if(!g_lf.Open(szLogFile, true, CLogfile::VB_Inf))
		{
			CLogfile::StdErr("Failed to create/open log file!\n");
			nRet = -1;
			break;
		}

		g_lf.Info("Process started.\n");

		////////////////////////////////////////////////////////////////////////////////////////////
		// initialize app control

		g_lf.Info("Acquire AppCtrl-Handle.\n");

		if(!(hAC = ::GfaIpcAppCtrlAcquire(_APPID, _APPNAME, nCycleIntervalMS * 1000, nCycleIntervalMS * 3000)))
		{
			g_lf.Error("Failed to acquire AppCtrl-Handle!\n");
			nRet = -1;
			break;
		}

		::GfaIpcAppCtrlSetState(hAC, GIAS_Initializing);
		g_lf.Info("Enter state %s ...\n", ::GfaIpcAppCtrlGetStateText(GIAS_Initializing));

		////////////////////////////////////////////////////////////////////////////////////////////
		// validate config parameters

#ifdef _LOG_DB_NAME

		time_t ts;
		bool bLogDbActive = false;

		if(strlen(_LOG_DB_NAME) >= _RL_MAX_DB_NAME_LENGTH)
		{
			g_lf.Error("Log database name too long! %s\n", _LOG_DB_NAME);
			nRet = -1;
			break;
		}

		if(strlen(_LOG_DB_USER) >= _RL_MAX_DB_USER_LENGTH)
		{
			g_lf.Error("Log database user name too long! %s\n", _LOG_DB_USER);
			nRet = -1;
			break;
		}

		if(strlen(_LOG_DB_PASS) >= _RL_MAX_DB_PASS_LENGTH)
		{
			g_lf.Error("Log database password too long!\n");
			nRet = -1;
			break;
		}

		if(strlen(_LOG_LOGS_TABLE) >= _RL_MAX_TABLE_NAME_LENGTH)
		{
			g_lf.Error("Log table name too long! %s\n", _LOG_LOGS_TABLE);
			nRet = -1;
			break;
		}

		////////////////////////////////////////////////////////////////////////////////////////////
		// configure remanent logger

		RLPARAMS rlp;
		memset(&rlp, 0, sizeof(rlp));
		strncpy(rlp.szDBName, _LOG_DB_NAME, _RL_MAX_DB_NAME_LENGTH - 1);
		strncpy(rlp.szDBUser, _LOG_DB_USER, _RL_MAX_DB_USER_LENGTH - 1);
		strncpy(rlp.szDBPass, _LOG_DB_PASS, _RL_MAX_DB_PASS_LENGTH - 1);
		strncpy(rlp.szLogsTable, _LOG_LOGS_TABLE, _RL_MAX_TABLE_NAME_LENGTH - 1);
#endif	//	_LOG_DB_NAME

		////////////////////////////////////////////////////////////////////////////////////////////

	    _CreateJSONWriteFileName(pszBaseDir, szWriteFile,  _COUNTOF(szWriteFile));
	    _CreateJSONBackupFileName(pszBaseDir, szBackupFile, _COUNTOF(szBackupFile));

		////////////////////////////////////////////////////////////////////////////////////////////
		// configure signal handling

		::sigfillset(&g_set);
		memset(&sa, 0, sizeof(sa));

#if _USE_SIG_INFO
		sa.sa_flags = SA_SIGINFO;
		sa.sa_sigaction = _OnSigAction;
#else
		sa.sa_handler = _SigHandler;
#endif
	    sigaction(SIGHUP, &sa, NULL);	// handles user's terminal disconnect
	    sigaction(SIGQUIT, &sa, NULL);	// handles Ctrl + '\'
		sigaction(SIGTERM, &sa, NULL);	// handles normal termination
		sigaction(SIGABRT, &sa, NULL);	// handles abnormal termination (i.e. abort())
		sigaction(SIGINT, &sa, NULL);	// handles Ctrl + 'C'

#if _USE_SIG_INFO
		sa.sa_flags = 0;
#endif
		sa.sa_handler = SIG_IGN;
	    sigaction(SIGTSTP, &sa, NULL);	// ignores Ctrl + 'Z'
	    sigaction(SIGSTOP, &sa, NULL);	// ignores Stop
	    sigaction(SIGCONT, &sa, NULL);	// ignores Continue
	    sigaction(SIGCHLD, &sa, NULL);	// ignores child process termination
	    sigaction(0, &sa, NULL);		// ignores shell termination

		////////////////////////////////////////////////////////////////////////////////////////////
		// configure timers

		clock_gettime(CLOCK_MONOTONIC, &tsWriteCredits);
		tsScanIntv.tv_sec	= nCycleIntervalMS / 1000;
		tsScanIntv.tv_nsec	= (nCycleIntervalMS % 1000) * 1000000;

		////////////////////////////////////////////////////////////////////////////////////////////
		// read input SHM file, if any ...

		pcPerf.ClockTrigger();
	    bHasJSON = ::ParseJSONFile(pszBaseDir, root, g_lf);
		sPerf = CProcessClock::Interval2String(pcPerf.ClockGetElapsed());
		
		if(bHasJSON)
		{
			g_lf.Info("Parsing time: %s\n", sPerf.c_str());
			TRACE("JSON parsing time: %s\n", sPerf.c_str());
		}

		////////////////////////////////////////////////////////////////////////////////////////////

	    if(!(hShm = ::acquire_shm(sizeof(shm_t), 1)))
	    {
			g_lf.Error("Unable to acquire SHM Handle!\n");
			nRet = -1;
			break;
	    }

		g_lf.Info("Acquired SHM Handle.\n");

        if(!(pShm = ::GfaIpcAcquirePointer(hShm)))
        {
			g_lf.Error("Unable to acquire SHM Pointer!\n");
			nRet = -1;
			break;
        }

		g_lf.Info("Acquired SHM Pointer.\n");
        ::GfaIpcDumpSHMROT();

#ifdef _LOG_DB_NAME
		CRemLogger rl(&rlp);
		if(!(bLogDbActive = rl.InitDatabase(false)))
		{
			g_lf.Error("Failed to initialize Log Database - %s\n", rl.LastError().c_str());
			g_lf.Warning("Logging will be disabled!\n");
		}
#endif	//	_LOG_DB_NAME

    	CRemVarTable map;
        CShm_t shm(pShm, hShm);

		pcPerf.ClockTrigger();
        shm.InitPath(NULL, NULL);
		sPerf = CProcessClock::Interval2String(pcPerf.ClockGetElapsed());
		TRACE("InitPath (%s).\n", sPerf.c_str());
		pcPerf.ClockTrigger();
        shm.CreateMembersTable(map);
		sPerf = CProcessClock::Interval2String(pcPerf.ClockGetElapsed());
		TRACE("CreateMembersTable (%s).\n", sPerf.c_str());

		if(bHasJSON)
		{
			pcPerf.ClockTrigger();
        	cntVals = map.LoadJSONValues(root);
			sPerf = CProcessClock::Interval2String(pcPerf.ClockGetElapsed());
			g_lf.Info("Successfully restored %lu values from JSON file (%s).\n", cntVals, sPerf.c_str());
			TRACE("Successfully restored %lu remanent values from JSON file (%s).\n", cntVals, sPerf.c_str());
        }
        else
        {
			_SIG_BLOCK(&g_set);
			bool bRet = ::WriteJSONFile(szWriteFile, szBackupFile, static_cast<CRemanent&>(shm));
			_SIG_UNBLOCK(&g_set);
			if(!bRet)
			{
				g_lf.Error("Failed to initialize JSON file! - %s\n", strerror(errno));
				TRACE("Failed to initialize JSON file! - %s\n", strerror(errno));
				break;
			}
		}

#ifdef _DL_DB_NAME
		CDbPersist perst(_DL_DB_NAME, _DL_TAGS_TABLE, _DL_LOGS_TABLE, _DL_DB_USER, _DL_DB_PASS);
		pcPerf.ClockTrigger();
		int nRestored = perst.RestoreValues(map, g_lf);
		sPerf = CProcessClock::Interval2String(pcPerf.ClockGetElapsed());

		if(nRestored > 0)
		{
			g_lf.Info("Successfully restored %d Database-persistent values from Datalogger Database (%s).\n", nRestored, sPerf.c_str());
			TRACE("Successfully restored %d Database-persistent values from Datalogger Database (%s).\n", nRestored, sPerf.c_str());
		}
#endif	//	_DL_DB_NAME

		g_fZombie = false;
		g_fRun = true;
		::GfaIpcAppCtrlSetState(hAC, GIAS_Running);
   		g_lf.Info("Enter monitoring loop.\n");

        while(g_fRun)
    	{
			////////////////////////////////////////////////////////////////////////////////////////
			// update app control info

			if((hAI = ::GfaIpcAppCtrlInfoUpdate(hAC, nUsecWorkTime)))
			{
				_ProcessCtrlMessages(hAC, hAI);
				if(!g_fRun)
					break;
//				_ProcessStateEvents(hAC, hAI);
			}

			////////////////////////////////////////////////////////////////////////////////////////

            if(::nanosleep(&tsScanIntv, NULL) < 0)
            {
            	if(!g_fRun)
            		break;
            }

			pcWork.ClockTrigger();

			if(!g_fPauseImp && !g_fPauseCmd)
			{
				if(_IntervalElapsed(&tsWriteCredits, _SECS_PER_WRITE_INTERVAL))
				{
					if(nWriteCredits < _MAX_WRITE_CREDITS)
					{
						nWriteCredits++;
			            TRACE("%d sec elapsed - write credits: %d\n", _SECS_PER_WRITE_INTERVAL, nWriteCredits);
					}
				}

	        	rv.nRetval = shm.CheckUpdateShm(true);

	        	if(rv.nUpdated || nPendingChanges)
	    		{
	    			if(nWriteCredits > 0)
	    			{
	    				if(nPendingChanges)
	    				{
	    					g_lf.Warning("Reacquired write credit(s). Total %d\n", nWriteCredits);
	    				}

			            TRACE("%u SHM values changed ...\n", rv.nUpdated ? rv.nUpdated : nPendingChanges);

						_SIG_BLOCK(&g_set);
						bool bRet = ::WriteJSONFile(szWriteFile, szBackupFile, static_cast<CRemanent&>(shm));
						_SIG_UNBLOCK(&g_set);
			            if(!bRet)
			            {
							g_lf.Error("Failed to write JSON file! - %s\n", strerror(errno));
							TRACE("Failed to write JSON file! - %s\n", strerror(errno));
							g_fRun = false;
							g_fZombie = true;
							break;
			            }
			            nWriteCredits--;
			        	nPendingChanges = 0;
#ifdef _LOG_DB_NAME
						if(bLogDbActive)
						{
							ts = ::time(NULL);
				        	shm.Log(ts, rl);
				        	if(!rl.Flush(ts))
				        	{
								g_lf.Error("Failed to log to Database - %s\n", rl.LastError().c_str());
								g_lf.Warning("Logging will be disabled!\n");
								bLogDbActive = false;
				        	}
				        }
#endif	//	_LOG_DB_NAME
			            TRACE("write credits left: %d\n", nWriteCredits);
			        }
			        else if(!nPendingChanges)
			        {
			            std::vector<const CRemanent*> vars;
			        	nPendingChanges = rv.nUpdated;

			            TRACE("%u SHM value(s) changed, but no write credits left!!!\n", rv.nUpdated);
						g_lf.Warning("%u SHM value(s) changed, but no write credits left.\n", rv.nUpdated);

#ifdef _DEBUG
			            if(map.GetMaxUpdateVariables(vars, 5))
		            	{
		            		for(auto i = vars.begin(); i != vars.end(); i++)
		            		{
		            			const CRemanent *pVar = *i;
		            			TRACE("%s -> %llu\n", pVar->GetPath(), pVar->GetUpdateCount());
		            		}
		            	}
#endif	//	_DEBUG
			        }

		    		g_lf.Flush();
	    		}
	    	}

			nUsecWorkTime = pcWork.ClockGetElapsed() / 1000;
		}

        TRACE("Process terminating...\n");
   		g_lf.Info("Leave monitoring loop.\n");

   		if(!g_fZombie && !bDbgInvolved)
   		{
			_SIG_BLOCK(&g_set);
			bool bRet = ::WriteJSONFile(szWriteFile, szBackupFile, static_cast<CRemanent&>(shm));
			_SIG_UNBLOCK(&g_set);
	        if(!bRet)
	        {
				g_lf.Error("Failed to write JSON file! - %s\n", strerror(errno));
				TRACE("Failed to write JSON file! - %s\n", strerror(errno));
				g_fZombie = true;
	        }
	    }

#ifdef _LOG_DB_NAME
		if(bLogDbActive)
		{
			ts = ::time(NULL);
	    	shm.Log(ts, rl);
        	if(!rl.Flush(ts))
        	{
				g_lf.Error("Failed to log to Database on exit - %s\n", rl.LastError().c_str());
				bLogDbActive = false;
        	}
	    }
#endif	//	_LOG_DB_NAME
	}
	while(false);

	if(g_nLastSig >= 0)
	{
		g_lf.Info("Received signal '%s'.\n", strsignal(g_nLastSig));
		g_nLastSig = -1;
	}

	if(hShm)
	{
		if(pShm)
		{
			g_lf.Info("Releasing SHM Pointer ...\n");
		    ::GfaIpcReleasePointer(hShm, pShm);
	    }

		g_lf.Info("Releasing SHM Handle ...\n");
	    ::GfaIpcReleaseSHM(hShm);
    }

	if(g_fZombie)
	{
		if(hAC)
			::GfaIpcAppCtrlSetState(hAC, GIAS_Zombie);
		TRACE("Enter Zombie state ...\n");
		g_lf.Warning("Enter Zombie state ...\n");
		g_lf.Flush();
		pause();

		if(g_nLastSig >= 0)
			g_lf.Info("Received signal '%s'.\n", strsignal(g_nLastSig));
	}

	if(hAC)
	{
		g_lf.Info("Enter state %s ...\n", ::GfaIpcAppCtrlGetStateText(GIAS_Terminating));
		::GfaIpcAppCtrlSetState(hAC, GIAS_Terminating);
		g_lf.Info("Releasing App Control ...\n");
		::GfaIpcAppCtrlRelease(hAC);
	}

	g_lf.Info("Process exit.\n\n");
	g_lf.Close();
	CLogfile::StdErr("Remanent exit.\n");
	return 0;
}