#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/file.h>
#include <linux/limits.h>
#include <unistd.h>
#include "instance.h"
#include "fileutil.h"
#include "debug.h"

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

#define _PIDFILE_ROOT_DIR			"/tmp"

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

int CProcessInstance::m_fdPid = -1;

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

CProcessInstance::CProcessInstance(void)
{
	m_pid = getpid();
#if _USE_BINARY_LOCK
	memset(m_szBinaryPath, 0, sizeof(m_szBinaryPath));
#else	//	_USE_BINARY_LOCK
	memset(m_szPidFileDir, 0, sizeof(m_szPidFileDir));
	memset(m_szPidFilePath, 0, sizeof(m_szPidFilePath));
#endif	//	_USE_BINARY_LOCK
}

CProcessInstance::~CProcessInstance(void)
{
	UnlockInstance();
}

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

bool CProcessInstance::LockInstance(const char *pszUuid)
{
	extern char *__progname;
	int nRet, nRead, fdPid;

	if(m_fdPid >= 0)
	{
		TRACE("%s: Instance lock already acquired!\n", __progname);
		return true;
	}

#if _USE_BINARY_LOCK
	if(!GetAppPath(m_szBinaryPath, sizeof(m_szBinaryPath)))
	{
		TRACE("Failed to retrieve binary path!\n");
		return false;
	}

	fdPid = open(m_szBinaryPath, O_RDONLY);

	if(fdPid < 0)
	{
		TRACE("Failed to open binary file: %s\n", m_szBinaryPath);
		TRACE("errno: %d\n", errno);
		return false;
	}
#else	//	_USE_BINARY_LOCK
    sprintf(m_szPidFileDir, "%s/%s", _PIDFILE_ROOT_DIR, pszUuid);
	sprintf(m_szPidFilePath, "%s/%s/%s.pid", _PIDFILE_ROOT_DIR, pszUuid, __progname);

	if(!DirectoryExist(m_szPidFileDir))
	{
		if(!CreateDirectory(m_szPidFileDir))
		{
			TRACE("Failed to create run directory!\n");
			return false;
		}
	}

	fdPid = open(m_szPidFilePath, O_CREAT | O_RDWR, 0666);

	if(fdPid < 0)
	{
		TRACE("Failed to open PID file: %s\n", m_szPidFilePath);
		TRACE("errno: %d\n", errno);
		return false;
	}
#endif	//	_USE_BINARY_LOCK

	if((nRet = flock(fdPid, LOCK_EX | LOCK_NB)))
	{
		if(errno == EWOULDBLOCK)
		{
#if !_USE_BINARY_LOCK
			char szPid[32];
			if((nRead = (int)read(fdPid, szPid, sizeof(szPid) - 1)) > 0)
			{
				szPid[nRead] = '\0';
				TRACE("%s: another instance is already running -> PID: %s\n", __progname, szPid);
			}
			else
#endif	//	_USE_BINARY_LOCK
			{
				TRACE("%s: another instance is already running!\n", __progname);
			}
			close(fdPid);
			return false;
		}
		else
		{
			TRACE("flock failed with code %d\n", errno);
			close(fdPid);
			return false;
		}
	}
	else
	{
#if !_USE_BINARY_LOCK
		char szPid[32];
		int nLen = sprintf(szPid, "%d", getpid());
		write(fdPid, szPid, (size_t)nLen);
#endif	//	_USE_BINARY_LOCK
		m_fdPid = fdPid;
	}

	return true;
}

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

void CProcessInstance::UnlockInstance(void)
{
	if(m_fdPid >= 0)
	{
		int fdPid = m_fdPid;
		m_fdPid = -1;
		flock(fdPid, LOCK_UN);
		close(fdPid);
	}

#if _USE_BINARY_LOCK
	memset(m_szBinaryPath, 0, sizeof(m_szBinaryPath));
#else	//	_USE_BINARY_LOCK
	memset(m_szPidFileDir, 0, sizeof(m_szPidFileDir));
	memset(m_szPidFilePath, 0, sizeof(m_szPidFilePath));
#endif	//	_USE_BINARY_LOCK

	m_pid = -1;
}