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// .NAME ParticleExchange - read or get pointer to alive particles on this
//                          process and exchange dead particles with neighbors
//
// .SECTION Description
// ParticleExchange is initialized with physical size of particle space and
// the margin of dead zone desired for each processor.  It is given the
// physical x,y,z locations for particles on this processor and can get
// the number of each neighbor processor.  Since the desired goal is to
// populate every processor with the alive particles (which it enters this
// class with) and dead particles belonging on the edges of all neighbors,
// each processor categorizes its own particles and arranges to send them
// to the appropriate neighbor, and to receive particles from each neighbor
// which it adds the the location vectors.
//
// Information exchanged are x,y,z locations and vectors and integer unique
// tags per particle.  Also when the data is shared, the particle status is
// filled in with the number of the neighbor that shared the particle.  This
// is to make the halo finder faster because instead of listing a particle
// as just alive or dead, we know where the dead particle is located.
//

#ifndef ParticleExchange_h
#define ParticleExchange_h

#include "vtkCosmoHaloFinderModule.h"

#include "Message.h"

#include "Definition.h"
#include <string>
#include <vector>

using std::vector;

namespace cosmotk {


class VTKCOSMOHALOFINDER_EXPORT ParticleExchange {

public:
  ParticleExchange();
  ~ParticleExchange();

  // Set parameters particle distribution
  void setParameters(
        POSVEL_T rL,            // Box size of the physical problem
        POSVEL_T deadSize);     // Dead delta border for each processor

  // Calculate the factor to add to locations when doing wraparound shares
  void calculateOffsetFactor();

  // Set neighbor processor numbers and calculate dead regions
  void initialize();

  // Calculate physical range of alive particles which must be shared
  void calculateExchangeRegions();

  // Set alive particle vectors which were created elsewhere
  void setParticles(
        vector<POSVEL_T>* xx,
        vector<POSVEL_T>* yy,
        vector<POSVEL_T>* zz,
        vector<POSVEL_T>* vx,
        vector<POSVEL_T>* vy,
        vector<POSVEL_T>* vz,
        vector<POSVEL_T>* mass,
        vector<POTENTIAL_T>* potential,
        vector<ID_T>* tag,
        vector<MASK_T>* mask,
        vector<STATUS_T>* status);

  // Identify and exchange alive particles which must be shared with neighbors
  void exchangeParticles();
  void identifyExchangeParticles();
  void exchangeNeighborParticles();
  void exchange(
        int sendTo,             // Neighbor to send particles to
        int recvFrom,           // Neighbor to receive particles from
        Message* sendMessage,
        Message* recvMessage);

  // Return data needed by other software
  int getParticleCount()                { return this->particleCount; }

private:
  int    myProc;                // My processor number
  int    numProc;               // Total number of processors

  int    layoutSize[DIMENSION]; // Decomposition of processors
  int    layoutPos[DIMENSION];  // Position of this processor in decomposition

  POSVEL_T boxSize;             // Physical box size (rL)
  POSVEL_T deadSize;            // Border size for dead particles

  long   numberOfAliveParticles;
  long   numberOfDeadParticles;
  long   particleCount;         // Running index used to store data
                                // Ends up as the number of alive plus dead

  POSVEL_T minMine[DIMENSION];  // Minimum alive particle not exchanged
  POSVEL_T maxMine[DIMENSION];  // Maximum alive particle not exchanged
  POSVEL_T minShare[DIMENSION]; // Minimum alive particle shared
  POSVEL_T maxShare[DIMENSION]; // Maximum alive particle shared

  int      neighbor[NUM_OF_NEIGHBORS];            // Neighbor processor indices
  POSVEL_T minRange[NUM_OF_NEIGHBORS][DIMENSION]; // Range of dead particles
  POSVEL_T maxRange[NUM_OF_NEIGHBORS][DIMENSION]; // Range of dead particles

  int    overLoadFactor[NUM_OF_NEIGHBORS][DIMENSION];
                                // When sending location factor to multiply
                                // boxSize by for wraparound alteration

  vector<ID_T> neighborParticles[NUM_OF_NEIGHBORS];
                                // Particle ids sent to each neighbor as DEAD

  vector<POSVEL_T>* xx;         // X location for particles on this processor
  vector<POSVEL_T>* yy;         // Y location for particles on this processor
  vector<POSVEL_T>* zz;         // Z location for particles on this processor
  vector<POSVEL_T>* vx;         // X velocity for particles on this processor
  vector<POSVEL_T>* vy;         // Y velocity for particles on this processor
  vector<POSVEL_T>* vz;         // Z velocity for particles on this processor
  vector<POSVEL_T>* ms;         // Mass for particles on this processor
  vector<ID_T>* tag;            // Id tag for particles on this processor
  vector<STATUS_T>* status;     // Particle is ALIVE or labeled with neighbor
                                // processor index where it is ALIVE
  vector<POTENTIAL_T>* pot;     // Id tag for particles on this processor
  vector<MASK_T>* mask;         // Id tag for particles on this processor
};

}
#endif
