/*
 * Thread Pool Class
 * Copyright (C) Burlex <burlex@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef __THREADPOOL_H
#define __THREADPOOL_H

#include "common.h"

#ifdef WIN32

class ThreadController
{
	public:
		HANDLE hThread;
		uint32 thread_id;

		void Setup(HANDLE h)
		{
			hThread = h;
			// whoops! GetThreadId is for windows 2003 and up only! :<		 - Burlex
			//thread_id = (uint32)GetThreadId(h);
		}

		void Suspend()
		{
			// We can't be suspended by someone else. That is a big-no-no and will lead to crashes.
			ASSERT(GetCurrentThreadId() == thread_id);
			SuspendThread(hThread);
		}

		void Resume()
		{
			// This SHOULD be called by someone else.
			ASSERT(GetCurrentThreadId() != thread_id);
			if(ResumeThread(hThread) == DWORD(-1))
			{
				DWORD le = GetLastError();
				printf("lasterror: %u\n", le);
			}
		}

		void Join()
		{
			WaitForSingleObject(hThread, INFINITE);
		}

		uint32 GetId() { return thread_id; }
};

#else
#ifndef HAVE_DARWIN
#include <semaphore.h>
int GenerateThreadId();

class ThreadController
{
		sem_t sem;
		pthread_t handle;
		int thread_id;
	public:
		void Setup(pthread_t h)
		{
			handle = h;
			sem_init(&sem, PTHREAD_PROCESS_PRIVATE, 0);
			thread_id = GenerateThreadId();
		}
		~ThreadController()
		{
			sem_destroy(&sem);
		}

		void Suspend()
		{
			assert(pthread_equal(pthread_self(), handle));
			sem_wait(&sem);
		}

		void Resume()
		{
			assert(!pthread_equal(pthread_self(), handle));
			sem_post(&sem);
		}

		void Join()
		{
			// waits until the thread finishes then returns
			pthread_join(handle, NULL);
		}

		inline uint32 GetId() { return (uint32)thread_id; }
};

#else
int GenerateThreadId();
class ThreadController
{
		pthread_cond_t cond;
		pthread_mutex_t mutex;
		int thread_id;
		pthread_t handle;
	public:
		void Setup(pthread_t h)
		{
			handle = h;
			pthread_mutex_init(&mutex, NULL);
			pthread_cond_init(&cond, NULL);
			thread_id = GenerateThreadId();
		}
		~ThreadController()
		{
			pthread_mutex_destroy(&mutex);
			pthread_cond_destroy(&cond);
		}
		void Suspend()
		{
			pthread_cond_wait(&cond, &mutex);
		}
		void Resume()
		{
			pthread_cond_signal(&cond);
		}
		void Join()
		{
			pthread_join(handle, NULL);
		}
		ARCEMU_INLINE uint32 GetId() { return (uint32)thread_id; }
};

#endif

#endif

struct Thread
{
	ThreadBase* ExecutionTarget;
	ThreadController ControlInterface;
	Mutex SetupMutex;
	bool DeleteAfterExit;
};

typedef std::set<Thread*> ThreadSet;

class CThreadPool
{
		int GetNumCpus();

		uint32 _threadsRequestedSinceLastCheck;
		uint32 _threadsFreedSinceLastCheck;
		uint32 _threadsExitedSinceLastCheck;
		uint32 _threadsToExit;
		int32 _threadsEaten;
		Mutex _mutex;

		ThreadSet m_activeThreads;
		ThreadSet m_freeThreads;

	public:
		CThreadPool();

		// call every 2 minutes or so.
		void IntegrityCheck();

		// call at startup
		void Startup();

		// shutdown all threads
		void Shutdown();

		// return true - suspend ourselves, and wait for a future task.
		// return false - exit, we're shutting down or no longer needed.
		bool ThreadExit(Thread* t);

		// creates a thread, returns a handle to it.
		Thread* StartThread(ThreadBase* ExecutionTarget);

		// grabs/spawns a thread, and tells it to execute a task.
		void ExecuteTask(ThreadBase* ExecutionTarget);

		// prints some neat debug stats
		void ShowStats();

		// kills x free threads
		void KillFreeThreads(uint32 count);

		// resets the gobble counter
		inline void Gobble() { _threadsEaten = (int32)m_freeThreads.size(); }

		// gets active thread count
		inline uint32 GetActiveThreadCount() { return (uint32)m_activeThreads.size(); }

		// gets free thread count
		inline uint32 GetFreeThreadCount() { return (uint32)m_freeThreads.size(); }
};

extern CThreadPool ThreadPool;

#endif
