/* 
 * screensaver calls proxy for MythTV.
 * Solves the problem of jerky video when remote is in use
 * by limiting the frequency of calls to gnome-screensaver-command
 * to no more than one a minute.
 *
 * Copyright (c) 2009 by Vitaly Blinov, vitaly@blinnov.com
 * 12 Jun 2009
 *
 * This software is distributed under GPL v2 and later as is.
 * No warranties whatsoever. 
 *
 *
 * Usage:
 * 	1. execute "which gnome-screensaver-comand"
 * 	If output is different from what you find below in
 *	DEF_PROGRAM, modify this macro accordingly.
 *
 *	2. build the program:
 *	g++ myth-screensaver-proxy.cpp -o gnome-screensaver-command
 *
 *	3. Find what directory original gnome-screensaver-command is in 
 *		(/usr/bin/ by default).
 *
 * 	4. Look at your PATH settings (printenv | grep PATH).
 *
 * 	5. copy binary buld on step 2 to any of the directories that
 * 	come in PATH before original gnome-screensaver-command directory.
 *
 */
#include <iostream>
#include <fstream>
#include <iomanip>
#include <sstream>
// NOTE - You may want to modify this line if
//	gnome-screensaver-command is installed in
//	different directory on your machine 
#define DEF_PROGRAM "/usr/bin/gnome-screensaver-command"
// NOTE - DON'T thouch this please
#define TMP_PATH "/tmp/screensaverPoke234235-"
#define DEF_MARGIN 60

/**
 * Returns timestamp file name, which includes user name
 * */
std::string getFileName()
{
	char text[255];
	FILE *pipe;
	pipe = popen("whoami", "r");
	fgets(text, sizeof(text), pipe);
	pclose(pipe);
	std::stringstream sStream;
	sStream
		<< TMP_PATH
		<< text
		;
	return sStream.str();
}

/**
 *	Stores current timestamp in a file.
 * */
void save()
{
	std::cout << "Saving current timestamp " << time(0) << std::endl;
	std::ofstream ofs(getFileName().c_str(), std::ios_base::trunc);
	ofs << time(0);
}
/**
 *	Looks if timestamp file exists. If so, reads timestamp from it
 *	and compares it with current timestamp. If the difference is
 *	bigger than DEF_MARGIN (or file does not exist), returs true;
 * */
bool allow_poke()
{
	std::ifstream ifs(getFileName().c_str());
	if (!ifs.is_open())
	{
		save();
		return true;
	}
	else
	{
		long tt;
		ifs >> tt;
		if (abs(time(0) - tt) > DEF_MARGIN)
		{
			save();
			return true;
		}
		std::cout << "Last poke was " 
			<< abs(time(0) - tt) 
			<< " seconds ago"
			<< std::endl;
		return false;
	}
}

/**
 *	Performs screensaver poke
 * */
void do_poke(int argc, char* argv[])
{
	std::stringstream sCmd;
	sCmd
		<< DEF_PROGRAM
		<< " "
		;
	if (argc > 1)
	{
		for (int i=1; i<argc; ++i)
		{
			sCmd << argv[i] << " ";
		}
	}
	std::cout << "Forwarding: " << sCmd.str() << std::endl;
	system(sCmd.str().c_str());
}

int main(int argc, char *argv[])
{
	if (argc > 1)
	{
		std::string sString(argv[1]);
		if (sString == "--poke" || sString=="-p")
		{
			if (allow_poke())
			{
				do_poke(argc, argv);
				return 0;
			}
			else
			{
				std::cout << "Not forwarding" << std::endl;
				return 0;
			}	
		}
	}
	do_poke(argc, argv);
	return 0;
}