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// .NAME HaloCenterFinder - find the particle in the center of halo particles
//
// HaloCenterFinder takes location data and a means of recognizing individual
// halos within the location and finds the most bound particle or the most
// connect particle.
//
// The class can be called with an array of locations, or can be called with
// all locations on a processor and two arrays used to thread halos through
// all particles.  The first array gives the index of the first particle
// in the halo and the second array takes that index and gives the index
// of the next particle in the halo.  Follow this until -1 which is the
// end of the halo.
//
// Can operate on FOF halos, subhalos or SOD halos depending on the form
// of the input.

#ifndef HaloCenterFinder_h
#define HaloCenterFinder_h

#include "vtkCosmoHaloFinderModule.h"

#include "Definition.h"

#include "ChainingMesh.h"
#include <string>

using std::string;

namespace cosmotk {


class VTKCOSMOHALOFINDER_EXPORT HaloCenterFinder {

public:
  HaloCenterFinder();
  ~HaloCenterFinder();

  // Set parameters for sizes of the dead/alive space
  void setParameters(
        POSVEL_T bb,                  // Inter particle distance for halos
        POSVEL_T rSmooth,             // smoothing scale for potential (physical units)
        POSVEL_T distConvertFactor,   // Scale positions by
        POSVEL_T rL_,
        int np_,
        float omega_matter_,
        float omega_cb_,
        float hubble_,
        float redshift_);

  // Set alive particle vectors which were created elsewhere
  void setParticles(
        long particleCount,
        POSVEL_T* xLoc,
        POSVEL_T* yLoc,
        POSVEL_T* zLoc,
        POSVEL_T* massHalo,
        ID_T* id);

  // Find the halo centers using most bound particle (N^2/2)
  int  mostBoundParticleN2(POTENTIAL_T* minPotential);

  // Initial guess of A* contains an actual part and an estimated part
  int  mostBoundParticleAStar(POTENTIAL_T* minPotential);

  // Calculate actual values between particles within a bucket
  void aStarThisBucketPart(
        ChainingMesh* haloChain,        // Buckets of particles
        int* bucketID,                  // Map from particle to bucket
        POSVEL_T* estimate);            // Running minimum potential

  // Calculate actual values for 26 neighbors in the center of halo
  // Level 1 refinement done for initial guess
  void aStarActualNeighborPart(
        ChainingMesh* haloChain,        // Buckets of particles
        int* minActual,                 // Range for doing actual vs estimated
        int* maxActual,
        int* refineLevel,               // Refinement level of each particle
        POSVEL_T* estimate);            // Running minimum potential

  // Calculate estimated values for 26 neighbors around the edges of halo
  // Level 0 refinement done for initial guess
  void aStarEstimatedNeighborPart(
        ChainingMesh* haloChain,        // Buckets of particles
        int* minActual,                 // Range for doing actual vs estimated
        int* maxActual,
        int* refineLevel,               // Refinement level of each particle
        POSVEL_T* estimate,             // Running minimum potential
        POSVEL_T boundarySize);         // Boundary around bucket for estimation

  // Calculate estimates for all buckets beyond the 27 closest
  void aStarEstimatedPart(
        ChainingMesh* haloChain,        // Buckets of particles
        POSVEL_T* estimate);            // Running minimum potential

  // Refinement of 0 to 1
  void refineAStarLevel_1(
        ChainingMesh* haloChain,        // Buckets of particles
        int bi,                         // Bucket containing particle to refine
        int bj,
        int bk,
        int* minActual,                 // Range for doing actual vs estimated
        int* maxActual,
        int minParticle,                // Particle to refine
        POSVEL_T* estimate,             // Running minimum potential
        POSVEL_T boundarySize);         // Boundary around bucket for estimation

  // Refinement of 1 to N
  void refineAStarLevel_N(
        ChainingMesh* haloChain,        // Buckets of particles
        int bi,                         // Bucket containing particle to refine
        int bj,
        int bk,
        int minParticle,                // Particle to refine
        POSVEL_T* estimate,             // Running minimum potential
        int winDelta);                  // Number of buckets to refine out to

  // Find the halo centers using most connected particle (N^2/2)
  int  mostConnectedParticleN2();
  int  mostConnectedParticleChainMesh();

  //Find the Halo Centers using faster histogram method of conneted particles:
  int mostConnectedParticleHist();

  // Build a chaining mesh of halo particles
  ChainingMesh* buildChainingMesh(
        POSVEL_T chainSize);

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

  string outFile;               // File of particles written by this processor


  POSVEL_T deadSize;            // Border size for dead particles
  POSVEL_T bb;                  // Interparticle distance for halos
  POSVEL_T rSmooth;             // smoothing scale for potential (physical units)
  POSVEL_T distFactor;          // Scale positions by, used in chain size

  long   particleCount;         // Total particles on this processor

  POSVEL_T* xx;                 // X location for particles on this processor
  POSVEL_T* yy;                 // Y location for particles on this processor
  POSVEL_T* zz;                 // Z location for particles on this processor
  POSVEL_T* mass;               // mass for particles on this processor
  ID_T* tag;                    // Id tag for particles on this processor

  POSVEL_T rL;                  // Physical box size of the data set
  int np;
  float omega_matter;
  float omega_cb;
  float hubble;
  float redshift;
};

}

#endif
