#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/statvfs.h>
#include <sys/statfs.h>
#include <sys/types.h>
#include <signal.h>
#include <poll.h>
#include <fcntl.h>
#include <errno.h>

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

#ifdef _DEBUG
#define TRACE(...)							fprintf(stdout, __VA_ARGS__), fflush(stdout)
#else	//	_DEBUG
#define TRACE(...)
#endif	//	_DEBUG

#define UNUSED(v)							(void)v
#define _countof(a)							(sizeof(a) / sizeof(*a))

#define _CYCLE_INTV							500

static bool g_bRun = true;

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

typedef struct _ATTRIBS
{
	const char *pszName;
	double (*fmt)(const char*);
}ATTRIBS, *LPATTRIBS;
typedef const ATTRIBS *LPCATTRIBS;

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

static void _SigHandler(int sig)
{
	UNUSED(sig);
	g_bRun = false;
}

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

static double _FmtUVers(const char *pszVal)
{
	int nVal = atoi(pszVal);
	return (double)nVal / 100.0 + 0.4;
}

static double _FmtUBatV3(const char *pszVal)
{
	int nVal = atoi(pszVal);
	return (double)nVal / 100.0;
}

static double _FmtTemp(const char *pszVal)
{
	int nVal = atoi(pszVal);
	return (double)nVal / 10.0;
}

static double _FmtUV5Vsys(const char *pszVal)
{
	int nVal = atoi(pszVal);
	return (double)nVal / 100.0;
}

static double _FmtUV3V6Bat(const char *pszVal)
{
	int nVal = atoi(pszVal);
	return (double)nVal / 100.0;
}

static double _FmtTempTIVA(const char *pszVal)
{
	int nVal = atoi(pszVal);
	return 147.5 - 187.5 * (double)nVal / 4096.0;
}

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

int main(int argc, char *argv[])
{
	static const ATTRIBS attribs[] =
	{
		{
			.pszName = "UVers",
			.fmt = _FmtUVers
		},
		{
			.pszName = "UBatV3",
			.fmt = _FmtUBatV3
		},
		{
			.pszName = "Temp",
			.fmt = _FmtTemp
		},
		{
			.pszName = "UV5Vsys",
			.fmt = _FmtUV5Vsys
		},
		{
			.pszName = "UV3V6Bat",
			.fmt = _FmtUV3V6Bat
		},
		{
			.pszName = "TempTIVA",
			.fmt = _FmtTempTIVA
		}
	};

	const ATTRIBS *attribsCur[_countof(attribs)];

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

	int nRet, nCntAtts, i;
	char szBuf[256];
	struct pollfd pfd[6];
	struct sigaction sa;

	memset(pfd, 0, sizeof(pfd));
	memset(&sa, 0, sizeof(sa));
	UNUSED(argc);
	UNUSED(argv);

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

	// handle signals
	sa.sa_handler = _SigHandler;
    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'

	// ignore signals
	sa.sa_handler = SIG_IGN;
    sigaction(SIGTSTP, &sa, NULL);	// ignores Ctrl + 'Z'
    sigaction(SIGCHLD, &sa, NULL);	// ignores child process termination
    sigaction(0, &sa, NULL);		// ignores shell termination

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

	for(i = 0, nCntAtts = 0; i < (int)_countof(attribs); ++i)
	{
		int fd;
		char szDevNode[128];
		sprintf(szDevNode, "/sys/gfa/tiva/%s", attribs[i].pszName);

		if((fd = open(szDevNode, O_RDONLY, 0)) >= 0)
		{
			pfd[nCntAtts].fd = fd;
			pfd[nCntAtts].events = POLLPRI;
			attribsCur[nCntAtts] = &attribs[i];
			++nCntAtts;
		}
	}

	/////////////////////////////////////////////////////////////////////////
	
	if(nCntAtts > 0)
	{
		while(g_bRun && ((nRet = poll(pfd, nCntAtts, _CYCLE_INTV)) >= 0))
		{
			if(nRet > 0)
			{
				for(i = 0; i < nCntAtts; ++i)
				{
					if(pfd[i].revents & POLLPRI)
					{
						szBuf[0] = '\0';

						if((nRet = read(pfd[i].fd, szBuf, sizeof(szBuf))) >= 0)
						{
							szBuf[nRet] = '\0';
							lseek(pfd[i].fd, 0, SEEK_SET);
							TRACE("%-8s: %.2f\n", attribsCur[i]->pszName, attribsCur[i]->fmt(szBuf));
						}
						else
						{
							g_bRun = false;
							break;
						}
					}
				}
			}
		}

		if(nRet < 0)
		{
			TRACE("%s\n", strerror(errno));
		}
	}

	for(i = 0; i < nCntAtts; ++i)
	{
		if(pfd[i].fd >= 0)
			close(pfd[i].fd);
	}

	return 0;
}