/******************************************************************************
 * Icinga 2                                                                   *
 * Copyright (C) 2012-2014 Icinga Development Team (http://www.icinga.org)    *
 *                                                                            *
 * This program is free software; you can redistribute it and/or              *
 * modify it under the terms of the GNU General Public License                *
 * as published by the Free Software Foundation; either version 2             *
 * of the License, or (at your option) any later version.                     *
 *                                                                            *
 * This program is distributed in the hope that it will be useful,            *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of             *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the              *
 * GNU General Public License for more details.                               *
 *                                                                            *
 * You should have received a copy of the GNU General Public License          *
 * along with this program; if not, write to the Free Software Foundation     *
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ******************************************************************************/

#include "cli/daemoncommand.hpp"
#include "config/configcompilercontext.hpp"
#include "config/configcompiler.hpp"
#include "config/configitembuilder.hpp"
#include "base/logger_fwd.hpp"
#include "base/clicommand.hpp"
#include "base/application.hpp"
#include "base/logger.hpp"
#include "base/timer.hpp"
#include "base/utility.hpp"
#include "base/exception.hpp"
#include "base/convert.hpp"
#include "base/scriptvariable.hpp"
#include "base/context.hpp"
#include "config.h"
#include <boost/program_options.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/foreach.hpp>
#include <iostream>

using namespace icinga;
namespace po = boost::program_options;

static po::variables_map g_AppParams;

REGISTER_CLICOMMAND("daemon", DaemonCommand);

static String LoadAppType(const String& typeSpec)
{
	Log(LogInformation, "cli", "Loading application type: " + typeSpec);

	String::SizeType index = typeSpec.FindFirstOf('/');

	if (index == String::NPos)
		return typeSpec;

	String library = typeSpec.SubStr(0, index);

	(void) Utility::LoadExtensionLibrary(library);

	return typeSpec.SubStr(index + 1);
}

static void IncludeZoneDirRecursive(const String& path)
{
	String zoneName = Utility::BaseName(path);
	Utility::GlobRecursive(path, "*.conf", boost::bind(&ConfigCompiler::CompileFile, _1, zoneName), GlobFile);
}

static void IncludeNonLocalZone(const String& zonePath)
{
	String etcPath = Application::GetZonesDir() + "/" + Utility::BaseName(zonePath);

	if (Utility::PathExists(etcPath))
		return;

	IncludeZoneDirRecursive(zonePath);
}

static bool LoadConfigFiles(const boost::program_options::variables_map& vm, const String& appType, const String& objectsFile = String())
{
	ConfigCompilerContext::GetInstance()->Reset();

	if (vm.count("config") > 0) {
		BOOST_FOREACH(const String& configPath, vm["config"].as<std::vector<std::string> >()) {
			ConfigCompiler::CompileFile(configPath);
		}
	} else if (!vm.count("no-config"))
		ConfigCompiler::CompileFile(Application::GetSysconfDir() + "/icinga2/icinga2.conf");

	/* Load cluster config files - this should probably be in libremote but
	* unfortunately moving it there is somewhat non-trivial. */
	String zonesEtcDir = Application::GetZonesDir();
	if (!zonesEtcDir.IsEmpty() && Utility::PathExists(zonesEtcDir))
		Utility::Glob(zonesEtcDir + "/*", &IncludeZoneDirRecursive, GlobDirectory);

	String zonesVarDir = Application::GetLocalStateDir() + "/lib/icinga2/api/zones";
	if (Utility::PathExists(zonesVarDir))
		Utility::Glob(zonesVarDir + "/*", &IncludeNonLocalZone, GlobDirectory);

	String name, fragment;
	BOOST_FOREACH(boost::tie(name, fragment), ConfigFragmentRegistry::GetInstance()->GetItems()) {
		ConfigCompiler::CompileText(name, fragment);
	}

	ConfigItemBuilder::Ptr builder = make_shared<ConfigItemBuilder>();
	builder->SetType(appType);
	builder->SetName("application");
	ConfigItem::Ptr item = builder->Compile();
	item->Register();

	bool result = ConfigItem::ValidateItems(objectsFile);

	int warnings = 0, errors = 0;

	BOOST_FOREACH(const ConfigCompilerMessage& message, ConfigCompilerContext::GetInstance()->GetMessages()) {
		std::ostringstream locbuf;
		ShowCodeFragment(locbuf, message.Location, true);
		String location = locbuf.str();

		String logmsg;

		if (!location.IsEmpty())
			logmsg = "Location:\n" + location;

		logmsg += String("\nConfig ") + (message.Error ? "error" : "warning") + ": " + message.Text;

		if (message.Error) {
			Log(LogCritical, "config", logmsg);
			errors++;
		} else {
			Log(LogWarning, "config", logmsg);
			warnings++;
		}
	}

	if (warnings > 0 || errors > 0) {
		LogSeverity severity;

		if (errors == 0)
			severity = LogWarning;
		else
			severity = LogCritical;

		Log(severity, "config", Convert::ToString(errors) + " errors, " + Convert::ToString(warnings) + " warnings.");
	}

	if (!result)
		return false;

	return true;
}

#ifndef _WIN32
static void SigHupHandler(int)
{
	Application::RequestRestart();
}
#endif /* _WIN32 */

static bool Daemonize(void)
{
#ifndef _WIN32
	pid_t pid = fork();
	if (pid == -1) {
		return false;
	}

	if (pid) {
		// systemd requires that the pidfile of the daemon is written before the forking
		// process terminates. So wait till either the forked daemon has written a pidfile or died.

		int status;
		int ret;
		pid_t readpid;
		do {
			Utility::Sleep(0.1);

			readpid = Application::ReadPidFile(Application::GetPidPath());
			ret = waitpid(pid, &status, WNOHANG);
		} while (readpid != pid && ret == 0);

		if (ret == pid) {
			Log(LogCritical, "cli", "The daemon could not be started. See log output for details.");
			exit(EXIT_FAILURE);
		} else if (ret == -1) {
			std::ostringstream msgbuf;
			msgbuf << "waitpid() failed with error code " << errno << ", \"" << Utility::FormatErrorNumber(errno) << "\"";
			Log(LogCritical, "cli",  msgbuf.str());
			exit(EXIT_FAILURE);
		}

		exit(0);
	}
#endif /* _WIN32 */

	return true;
}

static bool SetDaemonIO(const String& stderrFile)
{
#ifndef _WIN32
	int fdnull = open("/dev/null", O_RDWR);
	if (fdnull >= 0) {
		if (fdnull != 0)
			dup2(fdnull, 0);

		if (fdnull != 1)
			dup2(fdnull, 1);

		if (fdnull > 1)
			close(fdnull);
	}

	const char *errPath = "/dev/null";

	if (!stderrFile.IsEmpty())
		errPath = stderrFile.CStr();

	int fderr = open(errPath, O_WRONLY | O_APPEND);

	if (fderr < 0 && errno == ENOENT)
		fderr = open(errPath, O_CREAT | O_WRONLY | O_APPEND, 0600);

	if (fderr > 0) {
		if (fderr != 2)
			dup2(fderr, 2);

		if (fderr > 2)
			close(fderr);
	}

	pid_t sid = setsid();
	if (sid == -1) {
		return false;
	}
#endif

	return true;
}

/**
 * Terminate another process and wait till it has ended
 *
 * @params target PID of the process to end
 */
static void TerminateAndWaitForEnd(pid_t target)
{
#ifndef _WIN32
	// allow 30 seconds timeout
	double timeout = Utility::GetTime() + 30;

	int ret = kill(target, SIGTERM);

	while (Utility::GetTime() < timeout && (ret == 0 || errno != ESRCH)) {
		Utility::Sleep(0.1);
		ret = kill(target, 0);
	}

	// timeout and the process still seems to live: kill it
	if (ret == 0 || errno != ESRCH)
		kill(target, SIGKILL);

#else
	// TODO: implement this for Win32
#endif /* _WIN32 */
}

String DaemonCommand::GetDescription(void) const
{
	return "Starts Icinga 2.";
}

String DaemonCommand::GetShortDescription(void) const
{
	return "starts Icinga 2";
}

void DaemonCommand::InitParameters(boost::program_options::options_description& visibleDesc,
    boost::program_options::options_description& hiddenDesc,
    ArgumentCompletionDescription& argCompletionDesc) const
{
	visibleDesc.add_options()
		("config,c", po::value<std::vector<std::string> >(), "parse a configuration file")
		("no-config,z", "start without a configuration file")
		("validate,C", "exit after validating the configuration")
		("errorlog,e", po::value<std::string>(), "log fatal errors to the specified log file (only works in combination with --daemonize)")
#ifndef _WIN32
		("daemonize,d", "detach from the controlling terminal")
#endif /* _WIN32 */
	;

#ifndef _WIN32
	hiddenDesc.add_options()
		("reload-internal", po::value<int>(), "used internally to implement config reload: do not call manually, send SIGHUP instead");
#endif /* _WIN32 */

	argCompletionDesc["config"] = BashArgumentCompletion("file");
	argCompletionDesc["errorlog"] = BashArgumentCompletion("file");
}

/**
 * The entry point for the "daemon" CLI command.
 *
 * @returns An exit status.
 */
int DaemonCommand::Run(const po::variables_map& vm, const std::vector<std::string>& ap) const
{
	ScriptVariable::Set("UseVfork", true, false, true);

	Application::MakeVariablesConstant();

	Log(LogInformation, "cli", "Icinga application loader (version: " + Application::GetVersion() + ")");

	String appType = LoadAppType(Application::GetApplicationType());

	if (!vm.count("validate") && !vm.count("reload-internal")) {
		pid_t runningpid = Application::ReadPidFile(Application::GetPidPath());
		if (runningpid > 0) {
			Log(LogCritical, "cli", "Another instance of Icinga already running with PID " + Convert::ToString(runningpid));
			return EXIT_FAILURE;
		}
	}

	if (!LoadConfigFiles(vm, appType, Application::GetObjectsPath()))
		return EXIT_FAILURE;

	if (vm.count("validate")) {
		Log(LogInformation, "cli", "Finished validating the configuration file(s).");
		return EXIT_SUCCESS;
	}

	if(vm.count("reload-internal")) {
		int parentpid = vm["reload-internal"].as<int>();
		Log(LogInformation, "cli", "Terminating previous instance of Icinga (PID " + Convert::ToString(parentpid) + ")");
		TerminateAndWaitForEnd(parentpid);
		Log(LogInformation, "cli", "Previous instance has ended, taking over now.");
	}

	if (vm.count("daemonize")) {
		if (!vm.count("reload-internal")) {
			// no additional fork neccessary on reload
			try {
				Daemonize();
			} catch (std::exception&) {
				Log(LogCritical, "cli", "Daemonize failed. Exiting.");
				return EXIT_FAILURE;
			}
		}
	}

	// activate config only after daemonization: it starts threads and that is not compatible with fork()
	if (!ConfigItem::ActivateItems()) {
		Log(LogCritical, "cli", "Error activating configuration.");
		return EXIT_FAILURE;
	}

	if (vm.count("daemonize")) {
		String errorLog;
		if (vm.count("errorlog"))
			errorLog = vm["errorlog"].as<std::string>();

		SetDaemonIO(errorLog);
		Logger::DisableConsoleLog();
	}

#ifndef _WIN32
	struct sigaction sa;
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = &SigHupHandler;
	sigaction(SIGHUP, &sa, NULL);
#endif /* _WIN32 */

	return Application::GetInstance()->Run();
}