/******************************************************************************
 * Icinga 2                                                                   *
 * Copyright (C) 2012 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 "i2-checker.h"

using namespace icinga;

void CheckerComponent::Start(void)
{
	m_Endpoint = Endpoint::MakeEndpoint("checker", true);

	/* dummy registration so the delegation module knows this is a checker
	   TODO: figure out a better way for this */
	m_Endpoint->RegisterSubscription("checker");

	Service::OnCheckerChanged.connect(bind(&CheckerComponent::CheckerChangedHandler, this, _1));
	DynamicObject::OnUnregistered.connect(bind(&CheckerComponent::ObjectRemovedHandler, this, _1));

	m_CheckTimer = boost::make_shared<Timer>();
	m_CheckTimer->SetInterval(1);
	m_CheckTimer->OnTimerExpired.connect(boost::bind(&CheckerComponent::CheckTimerHandler, this));
	m_CheckTimer->Start();

	/* TODO: figure out a way to register check types */
	PluginCheckTask::Register();
	NullCheckTask::Register();

	m_ResultTimer = boost::make_shared<Timer>();
	m_ResultTimer->SetInterval(5);
	m_ResultTimer->OnTimerExpired.connect(boost::bind(&CheckerComponent::ResultTimerHandler, this));
	m_ResultTimer->Start();
}

void CheckerComponent::Stop(void)
{
	m_Endpoint->Unregister();
}

void CheckerComponent::CheckTimerHandler(void)
{
	Logger::Write(LogDebug, "checker", "CheckTimerHandler entered.");

	double now = Utility::GetTime();
	long tasks = 0;

	int missedServices = 0, missedChecks = 0;

	while (!m_IdleServices.empty()) {
		typedef nth_index<ServiceSet, 1>::type CheckTimeView;
		CheckTimeView& idx = boost::get<1>(m_IdleServices);

		CheckTimeView::iterator it = idx.begin();
		Service::Ptr service = *it;

		if (service->GetNextCheck() > now)
			break;

		idx.erase(it);

		Dictionary::Ptr cr = service->GetLastCheckResult();

		if (cr) {
			double lastCheck = cr->Get("execution_end");
			int missed = (Utility::GetTime() - lastCheck) / service->GetCheckInterval() - 1;

			if (missed > 0) {
				missedChecks += missed;
				missedServices++;
			}
		}

		Logger::Write(LogDebug, "checker", "Executing service check for '" + service->GetName() + "'");

		m_PendingServices.insert(service);

		vector<Value> arguments;
		arguments.push_back(service);
		ScriptTask::Ptr task;
		task = service->InvokeMethod("check", arguments, boost::bind(&CheckerComponent::CheckCompletedHandler, this, service, _1));
		assert(task); /* TODO: gracefully handle missing methods */

		service->Set("current_task", task);

		tasks++;
	}

	Logger::Write(LogDebug, "checker", "CheckTimerHandler: past loop.");

	if (missedServices > 0) {
		stringstream msgbuf;
		msgbuf << "Missed " << missedChecks << " checks for " << missedServices << " services";;
		Logger::Write(LogWarning, "checker", msgbuf.str());
	}

	stringstream msgbuf;
	msgbuf << "CheckTimerHandler: created " << tasks << " tasks";
	Logger::Write(LogInformation, "checker", msgbuf.str());
}

void CheckerComponent::CheckCompletedHandler(const Service::Ptr& service, const ScriptTask::Ptr& task)
{
	service->Set("current_task", Empty);

	try {
		Value vresult = task->GetResult();

		if (vresult.IsObjectType<Dictionary>()) {
			Dictionary::Ptr result = vresult;

			service->ApplyCheckResult(result);

			RequestMessage rm;
			rm.SetMethod("checker::ServiceStateChange");

			/* TODO: add _old_ state to message */
			ServiceStateChangeMessage params;
			params.SetService(service->GetName());

			rm.SetParams(params);

			EndpointManager::GetInstance()->SendMulticastMessage(m_Endpoint, rm);
		}
	} catch (const exception& ex) {
		stringstream msgbuf;
		msgbuf << "Exception occured during check for service '"
		       << service->GetName() << "': " << ex.what();
		Logger::Write(LogWarning, "checker", msgbuf.str());
	}

	/* figure out when the next check is for this service; the call to
	 * ApplyCheckResult() should've already done this but lets do it again
	 * just in case there was no check result. */
	service->UpdateNextCheck();

	/* remove the service from the list of pending services; if it's not in the
	 * list this was a manual (i.e. forced) check and we must not re-add the
	 * service to the services list because it's already there. */
	CheckerComponent::ServiceSet::iterator it;
	it = m_PendingServices.find(service);
	if (it != m_PendingServices.end()) {
		m_PendingServices.erase(it);
		m_IdleServices.insert(service);
	}

	Logger::Write(LogDebug, "checker", "Check finished for service '" + service->GetName() + "'");
}

void CheckerComponent::ResultTimerHandler(void)
{
	Logger::Write(LogDebug, "checker", "ResultTimerHandler entered.");

	stringstream msgbuf;
	msgbuf << "Pending services: " << m_PendingServices.size() << "; Idle services: " << m_IdleServices.size();
	Logger::Write(LogInformation, "checker", msgbuf.str());
}

void CheckerComponent::CheckerChangedHandler(const Service::Ptr& service)
{
	String checker = service->GetChecker();

	if (checker == EndpointManager::GetInstance()->GetIdentity() || checker == m_Endpoint->GetName()) {
		if (m_PendingServices.find(service) != m_PendingServices.end())
			return;

		m_IdleServices.insert(service);
	} else {
		m_IdleServices.erase(service);
		m_PendingServices.erase(service);
	}
}

void CheckerComponent::ObjectRemovedHandler(const DynamicObject::Ptr& object)
{
	Service::Ptr service = dynamic_pointer_cast<Service>(object);

	/* ignore it if the removed object is not a service */
	if (!service)
		return;

	m_IdleServices.erase(service);
	m_PendingServices.erase(service);
}

EXPORT_COMPONENT(checker, CheckerComponent);