/***************************************************************************
                          Host.h  -  description
                             -------------------
    begin                : Nov 7, 2012
    copyright            : (C) 2012 by Tomas Oberhuber
    email                : tomas.oberhuber@fjfi.cvut.cz
 ***************************************************************************/

/* See Copyright Notice in tnl/Copyright */

#pragma once

#include <TNL/String.h>
#include <TNL/Config/ConfigDescription.h>
#include <TNL/Config/ParameterContainer.h>

#ifdef HAVE_OPENMP
#include <omp.h>
#endif

namespace TNL {
namespace Devices {

class Host
{
public:
   static void disableOMP()
   {
      ompEnabled() = false;
   }

   static void enableOMP()
   {
      ompEnabled() = true;
   }

   static inline bool isOMPEnabled()
   {
#ifdef HAVE_OPENMP
      return ompEnabled();
#else
      return false;
#endif
   }

   static void setMaxThreadsCount( int maxThreadsCount_ )
   {
      maxThreadsCount() = maxThreadsCount_;
#ifdef HAVE_OPENMP
      omp_set_num_threads( maxThreadsCount() );
#endif
   }

   static int getMaxThreadsCount()
   {
#ifdef HAVE_OPENMP
      if( maxThreadsCount() == -1 )
         return omp_get_max_threads();
      return maxThreadsCount();
#else
      return 0;
#endif
   }

   static int getThreadIdx()
   {
#ifdef HAVE_OPENMP
      return omp_get_thread_num();
#else
      return 0;
#endif
   }

   static void configSetup( Config::ConfigDescription& config,
                            const String& prefix = "" )
   {
#ifdef HAVE_OPENMP
      config.addEntry< bool >( prefix + "openmp-enabled", "Enable support of OpenMP.", true );
      config.addEntry<  int >( prefix + "openmp-max-threads", "Set maximum number of OpenMP threads.", omp_get_max_threads() );
#else
      config.addEntry< bool >( prefix + "openmp-enabled", "Enable support of OpenMP (not supported on this system).", false );
      config.addEntry<  int >( prefix + "openmp-max-threads", "Set maximum number of OpenMP threads (not supported on this system).", 0 );
#endif
   }

   static bool setup( const Config::ParameterContainer& parameters,
                      const String& prefix = "" )
   {
      if( parameters.getParameter< bool >( prefix + "openmp-enabled" ) ) {
#ifdef HAVE_OPENMP
         enableOMP();
#else
         std::cerr << "OpenMP is not supported - please recompile the TNL library with OpenMP." << std::endl;
         return false;
#endif
      }
      else
         disableOMP();
      const int threadsCount = parameters.getParameter< int >( prefix + "openmp-max-threads" );
      if( threadsCount > 1 && ! isOMPEnabled() )
         std::cerr << "Warning: openmp-max-threads was set to " << threadsCount << ", but OpenMP is disabled." << std::endl;
      setMaxThreadsCount( threadsCount );
      return true;
   }

   protected:
      static bool& ompEnabled()
      {
#ifdef HAVE_OPENMP
         static bool ompEnabled = true;
#else
         static bool ompEnabled = false;
#endif
         return ompEnabled;
      }

      static int& maxThreadsCount()
      {
         static int maxThreadsCount = -1;
         return maxThreadsCount;
      }
};

} // namespace Devices
} // namespace TNL
