/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
/*=========================================================================
 *
 *  Portions of this file are subject to the VTK Toolkit Version 3 copyright.
 *
 *  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
 *
 *  For complete copyright, license and disclaimer of warranty information
 *  please refer to the NOTICE file at the top of the ITK source tree.
 *
 *=========================================================================*/
#ifndef itkPlatformMultiThreader_h
#define itkPlatformMultiThreader_h

#include "itkMultiThreaderBase.h"
#include <mutex>
#include <memory>

namespace itk
{
/** \class PlatformMultiThreader
 * \brief A class for performing multithreaded execution
 *
 * Multithreader is a class that provides support for multithreaded
 * execution using Windows or POSIX threads.
 * This class can be used to execute a single
 * method on multiple threads, or to specify a method per thread.
 *
 * \ingroup OSSystemObjects
 *
 * \ingroup ITKCommon
 */

class ITKCommon_EXPORT PlatformMultiThreader : public MultiThreaderBase
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(PlatformMultiThreader);

  /** Standard class type aliases. */
  using Self = PlatformMultiThreader;
  using Superclass = MultiThreaderBase;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  /** \see LightObject::GetNameOfClass() */
  itkOverrideGetNameOfClassMacro(PlatformMultiThreader);

#if !defined(ITK_LEGACY_REMOVE)
  /** Set/Get the maximum number of threads to use when multithreading.  It
   * will be clamped to the range [ 1, ITK_MAX_THREADS ] because several arrays
   * are already statically allocated using the ITK_MAX_THREADS number.
   * Therefore the caller of this method should check that the requested number
   * of threads was accepted. Legacy: use MultiThreaderBase to invoke these. */
  itkLegacyMacro(static void SetGlobalMaximumNumberOfThreads(ThreadIdType val))
  {
    itkGenericOutputMacro("Warning: SetGlobalMaximumNumberOfThreads should now be called on itk::MultiThreaderBase. It "
                          "can affect all MultiThreaderBase's derived classes in ITK");
    Superclass::SetGlobalMaximumNumberOfThreads(val);
  }
  itkLegacyMacro(static ThreadIdType GetGlobalMaximumNumberOfThreads())
  {
    itkGenericOutputMacro("Warning: GetGlobalMaximumNumberOfThreads should now be called on itk::MultiThreaderBase. It "
                          "can affect all MultiThreaderBase's derived classes in ITK");
    return Superclass::GetGlobalMaximumNumberOfThreads();
  }

  /** Set/Get the value which is used to initialize the NumberOfThreads in the
   * constructor.  It will be clamped to the range [1, m_GlobalMaximumNumberOfThreads ].
   * Therefore the caller of this method should check that the requested number
   * of threads was accepted. Legacy: use MultiThreaderBase to invoke these. */
  itkLegacyMacro(static void SetGlobalDefaultNumberOfThreads(ThreadIdType val))
  {
    itkGenericOutputMacro("Warning: SetGlobalDefaultNumberOfThreads should now be called on itk::MultiThreaderBase. It "
                          "can affect all MultiThreaderBase's derived classes in ITK");
    Superclass::SetGlobalDefaultNumberOfThreads(val);
  }
  itkLegacyMacro(static ThreadIdType GetGlobalDefaultNumberOfThreads())
  {
    itkGenericOutputMacro("Warning: GetGlobalDefaultNumberOfThreads should now be called on itk::MultiThreaderBase. It "
                          "can affect all MultiThreaderBase's derived classes in ITK");
    return Superclass::GetGlobalDefaultNumberOfThreads();
  }
#endif

  /** Execute the SingleMethod (as define by SetSingleMethod) using
   * m_NumberOfWorkUnits threads. As a side effect the m_NumberOfWorkUnits will be
   * checked against the current m_GlobalMaximumNumberOfThreads and clamped if
   * necessary. */
  void
  SingleMethodExecute() override;

  /** Execute the MultipleMethods (as define by calling SetMultipleMethod for
   * each of the required m_NumberOfWorkUnits methods) using m_NumberOfWorkUnits
   * threads. As a side effect the m_NumberOfWorkUnits will be checked against the
   * current m_GlobalMaximumNumberOfThreads and clamped if necessary. */
  itkLegacyMacro(void MultipleMethodExecute());

  /** Set the SingleMethod to f() and the UserData field of the
   * WorkUnitInfo that is passed to it will be data.
   * This method (and all the methods passed to SetMultipleMethod)
   * must be of type itkThreadFunctionType and must take a single argument of
   * type void *. */
  void
  SetSingleMethod(ThreadFunctionType, void * data) override;

  /** Set the MultipleMethod at the given index to f() and the UserData
   * field of the WorkUnitInfo that is passed to it will be data. */
  itkLegacyMacro(void SetMultipleMethod(ThreadIdType index, ThreadFunctionType, void * data));

  /** Create a new thread for the given function. Return a thread id
   * which is a number between 0 and ITK_MAX_THREADS - 1. This
   * id should be used to kill the thread at a later time.
   * Deprecated. Use C++11 thread support instead. */
  itkLegacyMacro(ThreadIdType SpawnThread(ThreadFunctionType, void * data));

  /** Terminate the thread that was created with a SpawnThreadExecute()
   * Deprecated. Use C++11 thread support instead. */
  itkLegacyMacro(void TerminateThread(ThreadIdType thread_id));

  void
  SetMaximumNumberOfThreads(ThreadIdType numberOfThreads) override;
  void
  SetNumberOfWorkUnits(ThreadIdType numberOfWorkUnits) override;

  struct WorkUnitInfo : MultiThreaderBase::WorkUnitInfo
  {
    int *                       ActiveFlag = nullptr;
    std::shared_ptr<std::mutex> ActiveFlagLock;
  };

protected:
  PlatformMultiThreader();
  ~PlatformMultiThreader() override;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;

private:
  /** An array of thread info containing a thread id
   *  (0, 1, 2, .. ITK_MAX_THREADS-1), the thread count, and a pointer
   *  to void so that user data can be passed to each thread. */
  WorkUnitInfo m_ThreadInfoArray[ITK_MAX_THREADS]{};

  /** Storage of MutexFunctions and ints used to control spawned
   *  threads and the spawned thread ids. */
  int                         m_SpawnedThreadActiveFlag[ITK_MAX_THREADS]{};
  std::shared_ptr<std::mutex> m_SpawnedThreadActiveFlagMutex[ITK_MAX_THREADS]{};
  ThreadProcessIdType         m_SpawnedThreadProcessID[ITK_MAX_THREADS]{};
  WorkUnitInfo                m_SpawnedThreadInfoArray[ITK_MAX_THREADS]{};

#if !defined(ITK_LEGACY_REMOVE)
  /** The methods to invoke. */
  ThreadFunctionType m_MultipleMethod[ITK_MAX_THREADS]{};

  /** Internal storage of the data. */
  void * m_MultipleData[ITK_MAX_THREADS]{};
#endif

  /** spawn a new thread for the SingleMethod */
  ThreadProcessIdType
  SpawnDispatchSingleMethodThread(WorkUnitInfo *);
  /** wait for a thread in the threadpool to finish work */
  void SpawnWaitForSingleMethodThread(ThreadProcessIdType);

  /** Friends of Multithreader.
   * ProcessObject is a friend so that it can call PrintSelf() on its
   * Multithreader. */
  friend class ProcessObject;
};
} // end namespace itk
#endif // itkPlatformMultiThreader_h