/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2019-2023 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2013-2015 Attila Molnar <attilamolnar@hush.com>
 *   Copyright (C) 2012 Robby <robby@chatbelgie.be>
 *   Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
 *   Copyright (C) 2008 Craig Edwards <brain@inspircd.org>
 *
 * This file is part of InspIRCd.  InspIRCd 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, version 2.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */


#include "inspircd.h"
#include "threadsocket.h"

bool Thread::Start()
{
	try
	{
		if (thread)
			return false;

		thread = new std::thread(Thread::StartInternal, this);
		return true;
	}
	catch (const std::system_error& err)
	{
		throw CoreException("Unable to start new thread: " + std::string(err.what()));
	}
}

void Thread::StartInternal(Thread* thread)
{
#ifndef _WIN32
	// C++ does not have an API for this so we still need to use pthreads.
	sigset_t set;
	sigemptyset(&set);
	sigaddset(&set, SIGPIPE);
	pthread_sigmask(SIG_BLOCK, &set, nullptr);
#endif

	thread->OnStart();
}

bool Thread::Stop()
{
	if (!thread)
		return false;

	OnStop();
	stopping = true;
	thread->join();

	stdalgo::delete_zero(thread);
	return true;
}

#if __has_include(<sys/eventfd.h>)
#include <sys/eventfd.h>

class ThreadSignalSocket final
	: public EventHandler
{
private:
	SocketThread* parent = nullptr;

public:
	ThreadSignalSocket(SocketThread* p, int newfd)
		: parent(p)
	{
		SetFd(newfd);
		SocketEngine::AddFd(this, FD_WANT_FAST_READ | FD_WANT_NO_WRITE);
	}

	~ThreadSignalSocket() override
	{
		SocketEngine::Close(this);
	}

	void Notify()
	{
		eventfd_write(GetFd(), 1);
	}

	void OnEventHandlerRead() override
	{
		eventfd_t dummy;
		eventfd_read(GetFd(), &dummy);
		parent->OnNotify();
	}

	void OnEventHandlerWrite() override
	{
		ServerInstance->GlobalCulls.AddItem(this);
	}

	void OnEventHandlerError(int errcode) override
	{
		ThreadSignalSocket::OnEventHandlerWrite();
	}
};

SocketThread::SocketThread()
{
	int fd = eventfd(0, EFD_NONBLOCK);
	if (fd < 0)
		throw CoreException("Could not create pipe " + std::string(strerror(errno)));

	socket = new ThreadSignalSocket(this, fd);
}
#else

# ifdef _WIN32
#  define pipe(fd) _pipe(fd, 1, 0)
# else
#  include <unistd.h>
# endif

class ThreadSignalSocket final
	: public EventHandler
{
private:
	SocketThread* parent;
	int send_fd;

public:
	ThreadSignalSocket(SocketThread* p, int recvfd, int sendfd)
		: parent(p)
		, send_fd(sendfd)
	{
		SetFd(recvfd);
		SocketEngine::NonBlocking(GetFd());
		SocketEngine::AddFd(this, FD_WANT_FAST_READ | FD_WANT_NO_WRITE);
	}

	~ThreadSignalSocket()
	{
		SocketEngine::Close(send_fd);
		SocketEngine::Close(this);
	}

	void Notify()
	{
		static constexpr char dummy = '*';
		write(send_fd, &dummy, 1);
	}

	void OnEventHandlerRead() override
	{
		char dummy[128];
		read(GetFd(), dummy, 128);
		parent->OnNotify();
	}

	void OnEventHandlerWrite() override
	{
		ServerInstance->GlobalCulls.AddItem(this);
	}

	void OnEventHandlerError(int errcode) override
	{
		ThreadSignalSocket::OnEventHandlerWrite();
	}
};

SocketThread::SocketThread()
{
	socket = nullptr;
	int fds[2];
	if (pipe(fds))
		throw CoreException("Could not create pipe " + std::string(strerror(errno)));
	socket = new ThreadSignalSocket(this, fds[0], fds[1]);
}
#endif

void SocketThread::NotifyParent()
{
	socket->Notify();
}

SocketThread::~SocketThread()
{
	if (socket)
	{
		socket->Cull();
		delete socket;
	}
}