/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2009 InspIRCd Development Team
 * See: http://wiki.inspircd.org/Credits
 *
 * This program is free but copyrighted software; see
 *            the file COPYING for details.
 *
 * ---------------------------------------------------
 */

#include <vector>
#include <string>
#include <map>
#include "inspircd.h"
#include "exitcodes.h"
#include "socketengine.h"
#include <sys/epoll.h>
#include <ulimit.h>
#define EP_DELAY 5

/** A specialisation of the SocketEngine class, designed to use linux 2.6 epoll().
 */
class EPollEngine : public SocketEngine
{
private:
	/** These are used by epoll() to hold socket events
	 */
	struct epoll_event* events;
	int EngineHandle;
public:
	/** Create a new EPollEngine
	 */
	EPollEngine();
	/** Delete an EPollEngine
	 */
	virtual ~EPollEngine();
	virtual bool AddFd(EventHandler* eh, int event_mask);
	virtual void OnSetEvent(EventHandler* eh, int old_mask, int new_mask);
	virtual bool DelFd(EventHandler* eh, bool force = false);
	virtual int DispatchEvents();
	virtual std::string GetName();
};

EPollEngine::EPollEngine()
{
	int max = ulimit(4, 0);
	if (max > 0)
	{
		MAX_DESCRIPTORS = max;
	}
	else
	{
		ServerInstance->Logs->Log("SOCKET", DEFAULT, "ERROR: Can't determine maximum number of open sockets!");
		printf("ERROR: Can't determine maximum number of open sockets!\n");
		ServerInstance->Exit(EXIT_STATUS_SOCKETENGINE);
	}

	// This is not a maximum, just a hint at the eventual number of sockets that may be polled.
	EngineHandle = epoll_create(GetMaxFds() / 4);

	if (EngineHandle == -1)
	{
		ServerInstance->Logs->Log("SOCKET",DEFAULT, "ERROR: Could not initialize socket engine: %s", strerror(errno));
		ServerInstance->Logs->Log("SOCKET",DEFAULT, "ERROR: Your kernel probably does not have the proper features. This is a fatal error, exiting now.");
		printf("ERROR: Could not initialize epoll socket engine: %s\n", strerror(errno));
		printf("ERROR: Your kernel probably does not have the proper features. This is a fatal error, exiting now.\n");
		ServerInstance->Exit(EXIT_STATUS_SOCKETENGINE);
	}

	ref = new EventHandler* [GetMaxFds()];
	events = new struct epoll_event[GetMaxFds()];

	memset(ref, 0, GetMaxFds() * sizeof(EventHandler*));
}

EPollEngine::~EPollEngine()
{
	this->Close(EngineHandle);
	delete[] ref;
	delete[] events;
}

static int mask_to_epoll(int event_mask)
{
	int rv = 0;
	if (event_mask & (FD_WANT_POLL_READ | FD_WANT_POLL_WRITE | FD_WANT_SINGLE_WRITE))
	{
		// we need to use standard polling on this FD
		if (event_mask & (FD_WANT_POLL_READ | FD_WANT_FAST_READ))
			rv |= EPOLLIN;
		if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE))
			rv |= EPOLLOUT;
	}
	else
	{
		// we can use edge-triggered polling on this FD
		rv = EPOLLET;
		if (event_mask & (FD_WANT_FAST_READ | FD_WANT_EDGE_READ))
			rv |= EPOLLIN;
		if (event_mask & (FD_WANT_FAST_WRITE | FD_WANT_EDGE_WRITE))
			rv |= EPOLLOUT;
	}
	return rv;
}

bool EPollEngine::AddFd(EventHandler* eh, int event_mask)
{
	int fd = eh->GetFd();
	if ((fd < 0) || (fd > GetMaxFds() - 1))
	{
		ServerInstance->Logs->Log("SOCKET",DEBUG,"AddFd out of range: (fd: %d, max: %d)", fd, GetMaxFds());
		return false;
	}

	if (ref[fd])
	{
		ServerInstance->Logs->Log("SOCKET",DEBUG,"Attempt to add duplicate fd: %d", fd);
		return false;
	}

	struct epoll_event ev;
	memset(&ev,0,sizeof(ev));
	ev.events = mask_to_epoll(event_mask);
	ev.data.fd = fd;
	int i = epoll_ctl(EngineHandle, EPOLL_CTL_ADD, fd, &ev);
	if (i < 0)
	{
		ServerInstance->Logs->Log("SOCKET",DEBUG,"Error adding fd: %d to socketengine: %s", fd, strerror(errno));
		return false;
	}

	ServerInstance->Logs->Log("SOCKET",DEBUG,"New file descriptor: %d", fd);

	ref[fd] = eh;
	SocketEngine::SetEventMask(eh, event_mask);
	CurrentSetSize++;
	return true;
}

void EPollEngine::OnSetEvent(EventHandler* eh, int old_mask, int new_mask)
{
	int old_events = mask_to_epoll(old_mask);
	int new_events = mask_to_epoll(new_mask);
	if (old_events != new_events)
	{
		// ok, we actually have something to tell the kernel about
		struct epoll_event ev;
		memset(&ev,0,sizeof(ev));
		ev.events = new_events;
		ev.data.fd = eh->GetFd();
		epoll_ctl(EngineHandle, EPOLL_CTL_MOD, eh->GetFd(), &ev);
	}
}

bool EPollEngine::DelFd(EventHandler* eh, bool force)
{
	int fd = eh->GetFd();
	if ((fd < 0) || (fd > GetMaxFds() - 1))
	{
		ServerInstance->Logs->Log("SOCKET",DEBUG,"DelFd out of range: (fd: %d, max: %d)", fd, GetMaxFds());
		return false;
	}

	struct epoll_event ev;
	memset(&ev,0,sizeof(ev));
	ev.data.fd = fd;
	int i = epoll_ctl(EngineHandle, EPOLL_CTL_DEL, fd, &ev);

	if (i < 0 && !force)
	{
		ServerInstance->Logs->Log("SOCKET",DEBUG,"Cant remove socket: %s", strerror(errno));
		return false;
	}

	ref[fd] = NULL;

	ServerInstance->Logs->Log("SOCKET",DEBUG,"Remove file descriptor: %d", fd);
	CurrentSetSize--;
	return true;
}

int EPollEngine::DispatchEvents()
{
	socklen_t codesize = sizeof(int);
	int errcode;
	int i = epoll_wait(EngineHandle, events, GetMaxFds() - 1, 1000);

	TotalEvents += i;

	for (int j = 0; j < i; j++)
	{
		EventHandler* eh = ref[events[j].data.fd];
		if (!eh)
			continue;
		if (events[j].events & EPOLLHUP)
		{
			ErrorEvents++;
			eh->HandleEvent(EVENT_ERROR, 0);
			continue;
		}
		if (events[j].events & EPOLLERR)
		{
			ErrorEvents++;
			/* Get error number */
			if (getsockopt(events[j].data.fd, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
				errcode = errno;
			eh->HandleEvent(EVENT_ERROR, errcode);
			continue;
		}
		int mask = eh->GetEventMask();
		if (events[j].events & EPOLLIN)
			mask &= ~FD_READ_WILL_BLOCK;
		if (events[j].events & EPOLLOUT)
		{
			mask &= ~FD_WRITE_WILL_BLOCK;
			if (mask & FD_WANT_SINGLE_WRITE)
			{
				int nm = mask & ~FD_WANT_SINGLE_WRITE;
				OnSetEvent(eh, mask, nm);
				mask = nm;
			}
		}
		SetEventMask(eh, mask);
		if (events[j].events & EPOLLIN)
		{
			ReadEvents++;
			eh->HandleEvent(EVENT_READ);
		}
		if (events[j].events & EPOLLOUT)
		{
			WriteEvents++;
			eh->HandleEvent(EVENT_WRITE);
		}
	}

	return i;
}

std::string EPollEngine::GetName()
{
	return "epoll";
}

SocketEngine* CreateSocketEngine()
{
	return new EPollEngine;
}