/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2010  PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 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 PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once

#ifdef _WIN32
// thanks I hate it.
#include <wx/filefn.h>
#define HAVE_MODE_T
#endif
#include <semaphore.h>
#include <errno.h> // EBUSY
#include <pthread.h>
#ifdef __APPLE__
#include <mach/semaphore.h>
#endif
#include "common/Pcsx2Defs.h"
#include "common/TraceLog.h"

#undef Yield // release the burden of windows.h global namespace spam.

#define AffinityAssert_AllowFrom_MainUI() \
	pxAssertMsg(wxThread::IsMain(), "Thread affinity violation: Call allowed from main thread only.")

// --------------------------------------------------------------------------------------
//  pxThreadLog / ConsoleLogSource_Threading
// --------------------------------------------------------------------------------------

class ConsoleLogSource_Threading : ConsoleLogSource
{
	typedef ConsoleLogSource _parent;

public:
	using _parent::IsActive;

	ConsoleLogSource_Threading();

	bool Write(const wxString& thrname, const wxChar* msg)
	{
		return _parent::Write(wxsFormat(L"(thread:%s) ", WX_STR(thrname)) + msg);
	}
	bool Warn(const wxString& thrname, const wxChar* msg)
	{
		return _parent::Warn(wxsFormat(L"(thread:%s) ", WX_STR(thrname)) + msg);
	}
	bool Error(const wxString& thrname, const wxChar* msg)
	{
		return _parent::Error(wxsFormat(L"(thread:%s) ", WX_STR(thrname)) + msg);
	}
};

extern ConsoleLogSource_Threading pxConLog_Thread;

#define pxThreadLog pxConLog_Thread.IsActive() && pxConLog_Thread


// --------------------------------------------------------------------------------------
//  PCSX2_THREAD_LOCAL - Defines platform/operating system support for Thread Local Storage
// --------------------------------------------------------------------------------------
//
// TLS is enabled by default. It will be disabled at compile time for Linux plugin.
// If you link SPU2X/ZZOGL with a TLS library, you will consume a DVT slots. Slots
// are rather limited and it ends up to "impossible to dlopen the library"
// None of the above plugin uses TLS variable in a multithread context
#ifndef PCSX2_THREAD_LOCAL
#define PCSX2_THREAD_LOCAL 1
#endif

#if PCSX2_THREAD_LOCAL
#define DeclareTls(x) thread_local x
#else
#define DeclareTls(x) x
#endif

class wxTimeSpan;

namespace Threading
{
	class pxThread;
	class RwMutex;

	extern void pxTestCancel();
	extern pxThread* pxGetCurrentThread();
	extern wxString pxGetCurrentThreadName();
	extern u64 GetThreadCpuTime();
	extern u64 GetThreadTicksPerSecond();

	// Yields the current thread and provides cancellation points if the thread is managed by
	// pxThread.  Unmanaged threads use standard Sleep.
	extern void pxYield(int ms);
} // namespace Threading

namespace Exception
{
	class BaseThreadError : public RuntimeError
	{
		DEFINE_EXCEPTION_COPYTORS(BaseThreadError, RuntimeError)
		DEFINE_EXCEPTION_MESSAGES(BaseThreadError)

	public:
		Threading::pxThread* m_thread;

	protected:
		BaseThreadError()
		{
			m_thread = NULL;
		}

	public:
		explicit BaseThreadError(Threading::pxThread* _thread)
		{
			m_thread = _thread;
			m_message_diag = L"An unspecified thread-related error occurred (thread=%s)";
		}

		explicit BaseThreadError(Threading::pxThread& _thread)
		{
			m_thread = &_thread;
			m_message_diag = L"An unspecified thread-related error occurred (thread=%s)";
		}

		virtual wxString FormatDiagnosticMessage() const;
		virtual wxString FormatDisplayMessage() const;

		Threading::pxThread& Thread();
		const Threading::pxThread& Thread() const;
	};

	class ThreadCreationError : public BaseThreadError
	{
		DEFINE_EXCEPTION_COPYTORS(ThreadCreationError, BaseThreadError)

	public:
		explicit ThreadCreationError(Threading::pxThread* _thread)
		{
			m_thread = _thread;
			SetBothMsgs(L"Thread creation failure.  An unspecified error occurred while trying to create the %s thread.");
		}

		explicit ThreadCreationError(Threading::pxThread& _thread)
		{
			m_thread = &_thread;
			SetBothMsgs(L"Thread creation failure.  An unspecified error occurred while trying to create the %s thread.");
		}
	};
} // namespace Exception


namespace Threading
{
	// --------------------------------------------------------------------------------------
	//  Platform Specific External APIs
	// --------------------------------------------------------------------------------------
	// The following set of documented functions have Linux/Win32 specific implementations,
	// which are found in WinThreads.cpp and LnxThreads.cpp

	// Releases a timeslice to other threads.
	extern void Timeslice();

	// For use in spin/wait loops.
	extern void SpinWait();

	// Optional implementation to enable hires thread/process scheduler for the operating system.
	// Needed by Windows, but might not be relevant to other platforms.
	extern void EnableHiresScheduler();
	extern void DisableHiresScheduler();

	// sleeps the current thread for the given number of milliseconds.
	extern void Sleep(int ms);

// pthread Cond is an evil api that is not suited for Pcsx2 needs.
// Let's not use it. Use mutexes and semaphores instead to create waits. (Air)
#if 0
	struct WaitEvent
	{
		pthread_cond_t cond;
		pthread_mutex_t mutex;

		WaitEvent();
		~WaitEvent();

		void Set();
		void Wait();
	};
#endif

	// --------------------------------------------------------------------------------------
	//  NonblockingMutex
	// --------------------------------------------------------------------------------------
	// This is a very simple non-blocking mutex, which behaves similarly to pthread_mutex's
	// trylock(), but without any of the extra overhead needed to set up a structure capable
	// of blocking waits.  It basically optimizes to a single InterlockedExchange.
	//
	// Simple use: if TryAcquire() returns false, the Bool is already interlocked by another thread.
	// If TryAcquire() returns true, you've locked the object and are *responsible* for unlocking
	// it later.
	//
	class NonblockingMutex
	{
	protected:
		std::atomic_flag val;

	public:
		NonblockingMutex() { val.clear(); }
		virtual ~NonblockingMutex() = default;

		bool TryAcquire() noexcept
		{
			return !val.test_and_set();
		}

		// Can be done with a TryAcquire/Release but it is likely better to do it outside of the object
		bool IsLocked()
		{
			pxAssertMsg(0, "IsLocked isn't supported for NonblockingMutex");
			return false;
		}

		void Release()
		{
			val.clear();
		}
	};

	class Semaphore
	{
	protected:
#ifdef __APPLE__
		semaphore_t m_sema;
		int m_counter;
#else
		sem_t m_sema;
#endif

	public:
		Semaphore();
		virtual ~Semaphore();

		void Reset();
		void Post();
		void Post(int multiple);

		void WaitWithoutYield();
		bool WaitWithoutYield(const wxTimeSpan& timeout);
		void WaitNoCancel();
		void WaitNoCancel(const wxTimeSpan& timeout);
		int Count();

		void Wait();
		bool Wait(const wxTimeSpan& timeout);
	};

	class Mutex
	{
	protected:
		pthread_mutex_t m_mutex;

	public:
		Mutex();
		virtual ~Mutex();
		virtual bool IsRecursive() const { return false; }

		void Recreate();
		bool RecreateIfLocked();
		void Detach();

		void Acquire();
		bool Acquire(const wxTimeSpan& timeout);
		bool TryAcquire();
		void Release();

		void AcquireWithoutYield();
		bool AcquireWithoutYield(const wxTimeSpan& timeout);

		void Wait();
		bool Wait(const wxTimeSpan& timeout);
		void WaitWithoutYield();
		bool WaitWithoutYield(const wxTimeSpan& timeout);

	protected:
		// empty constructor used by MutexLockRecursive
		Mutex(bool) {}
	};

	class MutexRecursive : public Mutex
	{
	public:
		MutexRecursive();
		virtual ~MutexRecursive();
		virtual bool IsRecursive() const { return true; }
	};

	// --------------------------------------------------------------------------------------
	//  ScopedLock
	// --------------------------------------------------------------------------------------
	// Helper class for using Mutexes.  Using this class provides an exception-safe (and
	// generally clean) method of locking code inside a function or conditional block.  The lock
	// will be automatically released on any return or exit from the function.
	//
	// Const qualification note:
	//  ScopedLock takes const instances of the mutex, even though the mutex is modified
	//  by locking and unlocking.  Two rationales:
	//
	//  1) when designing classes with accessors (GetString, GetValue, etc) that need mutexes,
	//     this class needs a const hack to allow those accessors to be const (which is typically
	//     *very* important).
	//
	//  2) The state of the Mutex is guaranteed to be unchanged when the calling function or
	//     scope exits, by any means.  Only via manual calls to Release or Acquire does that
	//     change, and typically those are only used in very special circumstances of their own.
	//
	class ScopedLock
	{
		DeclareNoncopyableObject(ScopedLock);

	protected:
		Mutex* m_lock;
		bool m_IsLocked;

	public:
		virtual ~ScopedLock();
		explicit ScopedLock(const Mutex* locker = NULL);
		explicit ScopedLock(const Mutex& locker);
		void AssignAndLock(const Mutex& locker);
		void AssignAndLock(const Mutex* locker);

		void Assign(const Mutex& locker);
		void Assign(const Mutex* locker);

		void Release();
		void Acquire();

		bool IsLocked() const { return m_IsLocked; }

	protected:
		// Special constructor used by ScopedTryLock
		ScopedLock(const Mutex& locker, bool isTryLock);
	};

	class ScopedTryLock : public ScopedLock
	{
	public:
		ScopedTryLock(const Mutex& locker)
			: ScopedLock(locker, true)
		{
		}
		virtual ~ScopedTryLock() = default;
		bool Failed() const { return !m_IsLocked; }
	};

	// --------------------------------------------------------------------------------------
	//  ScopedNonblockingLock
	// --------------------------------------------------------------------------------------
	// A ScopedTryLock branded for use with Nonblocking mutexes.  See ScopedTryLock for details.
	//
	class ScopedNonblockingLock
	{
		DeclareNoncopyableObject(ScopedNonblockingLock);

	protected:
		NonblockingMutex& m_lock;
		bool m_IsLocked;

	public:
		ScopedNonblockingLock(NonblockingMutex& locker)
			: m_lock(locker)
			, m_IsLocked(m_lock.TryAcquire())
		{
		}

		virtual ~ScopedNonblockingLock()
		{
			if (m_IsLocked)
				m_lock.Release();
		}

		bool Failed() const { return !m_IsLocked; }
	};

	// --------------------------------------------------------------------------------------
	//  ScopedLockBool
	// --------------------------------------------------------------------------------------
	// A ScopedLock in which you specify an external bool to get updated on locks/unlocks.
	// Note that the isLockedBool should only be used as an indicator for the locked status,
	// and not actually depended on for thread synchronization...

	struct ScopedLockBool
	{
		ScopedLock m_lock;
		std::atomic<bool>& m_bool;

		ScopedLockBool(Mutex& mutexToLock, std::atomic<bool>& isLockedBool)
			: m_lock(mutexToLock)
			, m_bool(isLockedBool)
		{
			m_bool.store(m_lock.IsLocked(), std::memory_order_relaxed);
		}
		virtual ~ScopedLockBool()
		{
			m_bool.store(false, std::memory_order_relaxed);
		}
		void Acquire()
		{
			m_lock.Acquire();
			m_bool.store(m_lock.IsLocked(), std::memory_order_relaxed);
		}
		void Release()
		{
			m_bool.store(false, std::memory_order_relaxed);
			m_lock.Release();
		}
	};
} // namespace Threading