/*
 * Copyright (C) 2004-2011  See the AUTHORS file for details.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include "znc.h"
#include "FileUtils.h"
#include <sys/wait.h>
#include <signal.h>

#ifdef HAVE_GETOPT_LONG
#include <getopt.h>
#else
#define no_argument 0
#define required_argument 1
#define optional_argument 2

struct option {
	const char *a;
	int opt;
	int *flag;
	int val;
};

static inline int getopt_long(int argc, char * const argv[], const char *optstring, const struct option *, int *)
{
	return getopt(argc, argv, optstring);
}
#endif

static const struct option g_LongOpts[] = {
	{ "help",        no_argument,       0, 'h' },
	{ "version",     no_argument,       0, 'v' },
	{ "debug",       no_argument,       0, 'D' },
	{ "foreground",  no_argument,       0, 'f' },
	{ "no-color",    no_argument,       0, 'n' },
	{ "allow-root",  no_argument,       0, 'r' },
	{ "makeconf",    no_argument,       0, 'c' },
	{ "makepass",    no_argument,       0, 's' },
	{ "makepem",     no_argument,       0, 'p' },
	{ "datadir",     required_argument, 0, 'd' },
	{ 0, 0, 0, 0 }
};

static void GenerateHelp(const char *appname) {
	CUtils::PrintMessage("USAGE: " + CString(appname) + " [options]");
	CUtils::PrintMessage("Options are:");
	CUtils::PrintMessage("\t-h, --help         List available command line options (this page)");
	CUtils::PrintMessage("\t-v, --version      Output version information and exit");
	CUtils::PrintMessage("\t-f, --foreground   Don't fork into the background");
	CUtils::PrintMessage("\t-D, --debug        Output debugging information (Implies -f)");
	CUtils::PrintMessage("\t-n, --no-color     Don't use escape sequences in the output");
	CUtils::PrintMessage("\t-r, --allow-root   Don't complain if ZNC is run as root");
	CUtils::PrintMessage("\t-c, --makeconf     Interactively create a new config");
	CUtils::PrintMessage("\t-s, --makepass     Generates a password for use in config");
#ifdef HAVE_LIBSSL
	CUtils::PrintMessage("\t-p, --makepem      Generates a pemfile for use with SSL");
#endif /* HAVE_LIBSSL */
	CUtils::PrintMessage("\t-d, --datadir      Set a different ZNC repository (default is ~/.znc)");
}

static void die(int sig) {
	signal(SIGPIPE, SIG_DFL);

	CUtils::PrintMessage("Exiting on SIG [" + CString(sig) + "]");

	delete &CZNC::Get();
	exit(sig);
}

static void signalHandler(int sig) {
	switch (sig) {
	case SIGHUP:
		CUtils::PrintMessage("Caught SIGHUP");
		CZNC::Get().SetConfigState(CZNC::ECONFIG_NEED_REHASH);
		break;
	case SIGUSR1:
		CUtils::PrintMessage("Caught SIGUSR1");
		CZNC::Get().SetConfigState(CZNC::ECONFIG_NEED_WRITE);
		break;
	default:
		CUtils::PrintMessage("WTF? Signal handler called for a signal it doesn't know?");
	}
}

static bool isRoot() {
	// User root? If one of these were root, we could switch the others to root, too
	return (geteuid() == 0 || getuid() == 0);
}

static void seedPRNG() {
	struct timeval tv;
	unsigned int seed;

	// Try to find a seed which can't be as easily guessed as only time()

	if (gettimeofday(&tv, NULL) == 0) {
		seed  = tv.tv_sec;

		// This is in [0:1e6], which means that roughly 20 bits are
		// actually used, let's try to shuffle the high bits.
		seed ^= (tv.tv_usec << 10) | tv.tv_usec;
	} else
		seed = time(NULL);

	seed ^= rand();
	seed ^= getpid();

	srand(seed);
}

int main(int argc, char** argv) {
	CString sConfig;
	CString sDataDir = "";

	seedPRNG();
	CDebug::SetStdoutIsTTY(isatty(1));

	int iArg, iOptIndex = -1;
	bool bMakeConf = false;
	bool bMakePass = false;
	bool bAllowRoot = false;
	bool bForeground = false;
#ifdef ALWAYS_RUN_IN_FOREGROUND
	bForeground = true;
#endif
#ifdef HAVE_LIBSSL
	bool bMakePem = false;
#endif

	while ((iArg = getopt_long(argc, argv, "hvnrcspd:Df", g_LongOpts, &iOptIndex)) != -1) {
		switch (iArg) {
		case 'h':
			GenerateHelp(argv[0]);
			return 0;
		case 'v':
			cout << CZNC::GetTag() << endl;
			return 0;
		case 'n':
			CDebug::SetStdoutIsTTY(false);
			break;
		case 'r':
			bAllowRoot = true;
			break;
		case 'c':
			bMakeConf = true;
			break;
		case 's':
			bMakePass = true;
			break;
		case 'p':
#ifdef HAVE_LIBSSL
			bMakePem = true;
			break;
#else
			CUtils::PrintError("ZNC is compiled without SSL support.");
			return 1;
#endif /* HAVE_LIBSSL */
		case 'd':
			sDataDir = CString(optarg);
			break;
		case 'f':
			bForeground = true;
			break;
		case 'D':
			bForeground = true;
			CDebug::SetDebug(true);
			break;
		case '?':
		default:
			GenerateHelp(argv[0]);
			return 1;
		}
	}

	if (optind < argc) {
		CUtils::PrintError("Specifying a config file as an argument isn't supported anymore.");
		CUtils::PrintError("Use --datadir instead.");
		return 1;
	}

	CZNC* pZNC = &CZNC::Get();
	pZNC->InitDirs(((argc) ? argv[0] : ""), sDataDir);

#ifdef HAVE_LIBSSL
	if (bMakePem) {
		pZNC->WritePemFile();

		delete pZNC;
		return 0;
	}
#endif /* HAVE_LIBSSL */

	if (bMakePass) {
		CString sSalt;
		CString sHash = CUtils::GetSaltedHashPass(sSalt);
		CUtils::PrintMessage("Use this in the <User> section of your config:");
		CUtils::PrintMessage("Pass = " + CUtils::sDefaultHash + "#" + sHash + "#" + sSalt + "#");

		delete pZNC;
		return 0;
	}

#ifndef RUN_FROM_SOURCE
	if (CFile::Exists(pZNC->GetCurPath() + "/znc-uninstalled.pc")) {
		CUtils::PrintError("It looks like you are running ZNC without installing it first.");
		CUtils::PrintError("Recompile with --enable-run-from-source if you intend to do that.");
	}
#endif

	if (isRoot()) {
		CUtils::PrintError("You are running ZNC as root! Don't do that! There are not many valid");
		CUtils::PrintError("reasons for this and it can, in theory, cause great damage!");
		if (!bAllowRoot) {
			delete pZNC;
			return 1;
		}
		CUtils::PrintError("You have been warned.");
		CUtils::PrintError("Hit CTRL+C now if you don't want to run ZNC as root.");
		CUtils::PrintError("ZNC will start in 30 seconds.");
		sleep(30);
	}

	if (bMakeConf) {
		if (!pZNC->WriteNewConfig(sConfig)) {
			delete pZNC;
			return 0;
		}
		/* Fall through to normal bootup */
	}

	if (!pZNC->ParseConfig(sConfig)) {
		CUtils::PrintError("Unrecoverable config error.");
		delete pZNC;
		return 1;
	}

	if (!pZNC->OnBoot()) {
		CUtils::PrintError("Exiting due to module boot errors.");
		delete pZNC;
		return 1;
	}

	if (bForeground) {
		int iPid = getpid();
		CUtils::PrintMessage("Staying open for debugging [pid: " + CString(iPid) + "]");

		pZNC->WritePidFile(iPid);
		CUtils::PrintMessage(CZNC::GetTag());
	} else {
		CUtils::PrintAction("Forking into the background");

		int iPid = fork();

		if (iPid == -1) {
			CUtils::PrintStatus(false, strerror(errno));
			delete pZNC;
			return 1;
		}

		if (iPid > 0) {
			// We are the parent. We are done and will go to bed.
			CUtils::PrintStatus(true, "[pid: " + CString(iPid) + "]");

			pZNC->WritePidFile(iPid);
			CUtils::PrintMessage(CZNC::GetTag());
			/* Don't destroy pZNC here or it will delete the pid file. */
			return 0;
		}

		/* fcntl() locks don't necessarily propagate to forked()
		 *   children.  Reacquire the lock here.  Use the blocking
		 *   call to avoid race condition with parent exiting.
		 */
		if (!pZNC->WaitForChildLock()) {
			CUtils::PrintError("Child was unable to obtain lock on config file.");
			delete pZNC;
			return 1;
		}

		// Redirect std in/out/err to /dev/null
		close(0); open("/dev/null", O_RDONLY);
		close(1); open("/dev/null", O_WRONLY);
		close(2); open("/dev/null", O_WRONLY);

		CDebug::SetStdoutIsTTY(false);

		// We are the child. There is no way we can be a process group
		// leader, thus setsid() must succeed.
		setsid();
		// Now we are in our own process group and session (no
		// controlling terminal). We are independent!
	}

	struct sigaction sa;
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);

	sa.sa_handler = SIG_IGN;
	sigaction(SIGPIPE, &sa, (struct sigaction*) NULL);

	sa.sa_handler = signalHandler;
	sigaction(SIGHUP,  &sa, (struct sigaction*) NULL);
	sigaction(SIGUSR1, &sa, (struct sigaction*) NULL);

	// Once this signal is caught, the signal handler is reset
	// to SIG_DFL. This avoids endless loop with signals.
	sa.sa_flags = SA_RESETHAND;
	sa.sa_handler = die;
	sigaction(SIGINT,  &sa, (struct sigaction*) NULL);
	sigaction(SIGQUIT, &sa, (struct sigaction*) NULL);
	sigaction(SIGTERM, &sa, (struct sigaction*) NULL);

	int iRet = 0;

	try {
		pZNC->Loop();
	} catch (CException e) {
		switch (e.GetType()) {
			case CException::EX_Shutdown:
				iRet = 0;
				break;
			case CException::EX_Restart: {
				// strdup() because GCC is stupid
				char *args[] = {
					strdup(argv[0]),
					strdup("--datadir"),
					strdup(pZNC->GetZNCPath().c_str()),
					NULL,
					NULL,
					NULL,
					NULL
				};
				int pos = 3;
				if (CDebug::Debug())
					args[pos++] = strdup("--debug");
				else if (bForeground)
					args[pos++] = strdup("--foreground");
				if (!CDebug::StdoutIsTTY())
					args[pos++] = strdup("--no-color");
				if (bAllowRoot)
					args[pos++] = strdup("--allow-root");
				// The above code adds 3 entries to args tops
				// which means the array should be big enough

				delete pZNC;
				execvp(args[0], args);
				CUtils::PrintError("Unable to restart ZNC [" + CString(strerror(errno)) + "]");
			} /* Fall through */
			default:
				iRet = 1;
		}
	}

	delete pZNC;

	return iRet;
}