/** \file linkedcell.cpp
 *
 * Function implementations for the class LinkedCell.
 *
 */


#include "atom.hpp"
#include "helpers.hpp"
#include "linkedcell.hpp"
#include "log.hpp"
#include "molecule.hpp"
#include "tesselation.hpp"
#include "vector.hpp"

// ========================================================= class LinkedCell ===========================================


/** Constructor for class LinkedCell.
 */
LinkedCell::LinkedCell()
{
  LC = NULL;
  for(int i=0;i<NDIM;i++)
    N[i] = 0;
  index = -1;
  RADIUS = 0.;
  max.Zero();
  min.Zero();
};

/** Puts all atoms in \a *mol into a linked cell list with cell's lengths of \a RADIUS
 * \param *set LCNodeSet class with all LCNode's
 * \param RADIUS edge length of cells
 */
LinkedCell::LinkedCell(const PointCloud * const set, const double radius)
{
  TesselPoint *Walker = NULL;

  RADIUS = radius;
  LC = NULL;
  for(int i=0;i<NDIM;i++)
    N[i] = 0;
  index = -1;
  max.Zero();
  min.Zero();
  DoLog(1) && (Log() << Verbose(1) << "Begin of LinkedCell" << endl);
  if ((set == NULL) || (set->IsEmpty())) {
    DoeLog(1) && (eLog()<< Verbose(1) << "set is NULL or contains no linked cell nodes!" << endl);
    return;
  }
  // 1. find max and min per axis of atoms
  set->GoToFirst();
  Walker = set->GetPoint();
  for (int i=0;i<NDIM;i++) {
    max.x[i] = Walker->node->x[i];
    min.x[i] = Walker->node->x[i];
  }
  set->GoToFirst();
  while (!set->IsEnd()) {
    Walker = set->GetPoint();
    for (int i=0;i<NDIM;i++) {
      if (max.x[i] < Walker->node->x[i])
        max.x[i] = Walker->node->x[i];
      if (min.x[i] > Walker->node->x[i])
        min.x[i] = Walker->node->x[i];
    }
    set->GoToNext();
  }
  DoLog(2) && (Log() << Verbose(2) << "Bounding box is " << min << " and " << max << "." << endl);

  // 2. find then number of cells per axis
  for (int i=0;i<NDIM;i++) {
    N[i] = (int)floor((max.x[i] - min.x[i])/RADIUS)+1;
  }
  DoLog(2) && (Log() << Verbose(2) << "Number of cells per axis are " << N[0] << ", " << N[1] << " and " << N[2] << "." << endl);

  // 3. allocate the lists
  DoLog(2) && (Log() << Verbose(2) << "Allocating cells ... ");
  if (LC != NULL) {
    DoeLog(1) && (eLog()<< Verbose(1) << "Linked Cell list is already allocated, I do nothing." << endl);
    return;
  }
  LC = new LinkedNodes[N[0]*N[1]*N[2]];
  for (index=0;index<N[0]*N[1]*N[2];index++) {
    LC [index].clear();
  }
  DoLog(0) && (Log() << Verbose(0) << "done."  << endl);

  // 4. put each atom into its respective cell
  DoLog(2) && (Log() << Verbose(2) << "Filling cells ... ");
  set->GoToFirst();
  while (!set->IsEnd()) {
    Walker = set->GetPoint();
    for (int i=0;i<NDIM;i++) {
      n[i] = (int)floor((Walker->node->x[i] - min.x[i])/RADIUS);
    }
    index = n[0] * N[1] * N[2] + n[1] * N[2] + n[2];
    LC[index].push_back(Walker);
    //Log() << Verbose(2) << *Walker << " goes into cell " << n[0] << ", " << n[1] << ", " << n[2] << " with No. " << index << "." << endl;
    set->GoToNext();
  }
  DoLog(0) && (Log() << Verbose(0) << "done."  << endl);
  DoLog(1) && (Log() << Verbose(1) << "End of LinkedCell" << endl);
};


/** Puts all atoms in \a *mol into a linked cell list with cell's lengths of \a RADIUS
 * \param *set LCNodeSet class with all LCNode's
 * \param RADIUS edge length of cells
 */
LinkedCell::LinkedCell(LinkedNodes *set, const double radius)
{
  class TesselPoint *Walker = NULL;
  RADIUS = radius;
  LC = NULL;
  for(int i=0;i<NDIM;i++)
    N[i] = 0;
  index = -1;
  max.Zero();
  min.Zero();
  DoLog(1) && (Log() << Verbose(1) << "Begin of LinkedCell" << endl);
  if (set->empty()) {
    DoeLog(1) && (eLog()<< Verbose(1) << "set contains no linked cell nodes!" << endl);
    return;
  }
  // 1. find max and min per axis of atoms
  LinkedNodes::iterator Runner = set->begin();
  for (int i=0;i<NDIM;i++) {
    max.x[i] = (*Runner)->node->x[i];
    min.x[i] = (*Runner)->node->x[i];
  }
  for (LinkedNodes::iterator Runner = set->begin(); Runner != set->end(); Runner++) {
    Walker = *Runner;
    for (int i=0;i<NDIM;i++) {
      if (max.x[i] < Walker->node->x[i])
        max.x[i] = Walker->node->x[i];
      if (min.x[i] > Walker->node->x[i])
        min.x[i] = Walker->node->x[i];
    }
  }
  DoLog(2) && (Log() << Verbose(2) << "Bounding box is " << min << " and " << max << "." << endl);

  // 2. find then number of cells per axis
  for (int i=0;i<NDIM;i++) {
    N[i] = (int)floor((max.x[i] - min.x[i])/RADIUS)+1;
  }
  DoLog(2) && (Log() << Verbose(2) << "Number of cells per axis are " << N[0] << ", " << N[1] << " and " << N[2] << "." << endl);

  // 3. allocate the lists
  DoLog(2) && (Log() << Verbose(2) << "Allocating cells ... ");
  if (LC != NULL) {
    DoeLog(1) && (eLog()<< Verbose(1) << "Linked Cell list is already allocated, I do nothing." << endl);
    return;
  }
  LC = new LinkedNodes[N[0]*N[1]*N[2]];
  for (index=0;index<N[0]*N[1]*N[2];index++) {
    LC [index].clear();
  }
  DoLog(0) && (Log() << Verbose(0) << "done."  << endl);

  // 4. put each atom into its respective cell
  DoLog(2) && (Log() << Verbose(2) << "Filling cells ... ");
  for (LinkedNodes::iterator Runner = set->begin(); Runner != set->end(); Runner++) {
    Walker = *Runner;
    for (int i=0;i<NDIM;i++) {
      n[i] = (int)floor((Walker->node->x[i] - min.x[i])/RADIUS);
    }
    index = n[0] * N[1] * N[2] + n[1] * N[2] + n[2];
    LC[index].push_back(Walker);
    //Log() << Verbose(2) << *Walker << " goes into cell " << n[0] << ", " << n[1] << ", " << n[2] << " with No. " << index << "." << endl;
  }
  DoLog(0) && (Log() << Verbose(0) << "done."  << endl);
  DoLog(1) && (Log() << Verbose(1) << "End of LinkedCell" << endl);
};

/** Destructor for class LinkedCell.
 */
LinkedCell::~LinkedCell()
{
  if (LC != NULL)
  for (index=0;index<N[0]*N[1]*N[2];index++)
    LC[index].clear();
  delete[](LC);
  for(int i=0;i<NDIM;i++)
    N[i] = 0;
  index = -1;
  max.Zero();
  min.Zero();
};

/** Checks whether LinkedCell::n[] is each within [0,N[]].
 * \return if all in intervals - true, else -false
 */
bool LinkedCell::CheckBounds() const
{
  bool status = true;
  for(int i=0;i<NDIM;i++)
    status = status && ((n[i] >=0) && (n[i] < N[i]));
  if (!status)
  DoeLog(1) && (eLog()<< Verbose(1) << "indices are out of bounds!" << endl);
  return status;
};

/** Checks whether LinkedCell::n[] plus relative offset is each within [0,N[]].
 * Note that for this check we don't admonish if out of bounds.
 * \param relative[NDIM] relative offset to current cell
 * \return if all in intervals - true, else -false
 */
bool LinkedCell::CheckBounds(const int relative[NDIM]) const
{
  bool status = true;
  for(int i=0;i<NDIM;i++)
    status = status && ((n[i]+relative[i] >=0) && (n[i]+relative[i] < N[i]));
  return status;
};


/** Returns a pointer to the current cell.
 * \return LinkedAtoms pointer to current cell, NULL if LinkedCell::n[] are out of bounds.
 */
const LinkedCell::LinkedNodes* LinkedCell::GetCurrentCell() const
{
  if (CheckBounds()) {
    index = n[0] * N[1] * N[2] + n[1] * N[2] + n[2];
    return (&(LC[index]));
  } else {
    return NULL;
  }
};

/** Returns a pointer to the current cell.
 * \param relative[NDIM] offset for each axis with respect to the current cell LinkedCell::n[NDIM]
 * \return LinkedAtoms pointer to current cell, NULL if LinkedCell::n[]+relative[] are out of bounds.
 */
const LinkedCell::LinkedNodes* LinkedCell::GetRelativeToCurrentCell(const int relative[NDIM]) const
{
  if (CheckBounds(relative)) {
    index = (n[0]+relative[0]) * N[1] * N[2] + (n[1]+relative[1]) * N[2] + (n[2]+relative[2]);
    return (&(LC[index]));
  } else {
    return NULL;
  }
};

/** Set the index to the cell containing a given Vector *x.
 * \param *x Vector with coordinates
 * \return Vector is inside bounding box - true, else - false
 */
bool LinkedCell::SetIndexToVector(const Vector * const x) const
{
  for (int i=0;i<NDIM;i++)
    n[i] = (int)floor((x->x[i] - min.x[i])/RADIUS);

  return CheckBounds();
};

/** Calculates the index for a given LCNode *Walker.
 * \param *Walker LCNode to set index tos
 * \return if the atom is also found in this cell - true, else - false
 */
bool LinkedCell::SetIndexToNode(const TesselPoint * const Walker) const
{
  bool status = false;
  for (int i=0;i<NDIM;i++) {
    n[i] = (int)floor((Walker->node->x[i] - min.x[i])/RADIUS);
  }
  index = n[0] * N[1] * N[2] + n[1] * N[2] + n[2];
  if (CheckBounds()) {
    for (LinkedNodes::iterator Runner = LC[index].begin(); Runner != LC[index].end(); Runner++)
      status = status || ((*Runner) == Walker);
    return status;
  } else {
    DoeLog(1) && (eLog()<< Verbose(1) << "Node at " << *Walker << " is out of bounds." << endl);
    return false;
  }
};

/** Calculates the interval bounds of the linked cell grid.
 * \param *lower lower bounds
 * \param *upper upper bounds
 * \param step how deep to check the neighbouring cells (i.e. number of layers to check)
 */
void LinkedCell::GetNeighbourBounds(int lower[NDIM], int upper[NDIM], int step) const
{
  for (int i=0;i<NDIM;i++) {
    lower[i] = n[i];
    for (int s=step; s>0;--s)
      if ((n[i]-s) >= 0) {
        lower[i] = n[i]-s;
        break;
      }
    upper[i] = n[i];
    for (int s=step; s>0;--s)
      if ((n[i]+s) < N[i]) {
        upper[i] = n[i]+s;
        break;
      }
    //Log() << Verbose(0) << "axis " << i << " has bounds [" << lower[i] << "," << upper[i] << "]" << endl;
  }
};

/** Returns a list with all neighbours from the current LinkedCell::index.
 * \param distance (if no distance, then adjacent cells are taken)
 * \return list of tesselpoints
 */
LinkedCell::LinkedNodes* LinkedCell::GetallNeighbours(const double distance) const
{
  int Nlower[NDIM], Nupper[NDIM];
  TesselPoint *Walker = NULL;
  LinkedNodes *TesselList = new LinkedNodes;

  // then go through the current and all neighbouring cells and check the contained points for possible candidates
  const int step = (distance == 0) ? 1 : (int)floor(distance/RADIUS + 1.);
  GetNeighbourBounds(Nlower, Nupper, step);

  //Log() << Verbose(0) << endl;
  for (n[0] = Nlower[0]; n[0] <= Nupper[0]; n[0]++)
    for (n[1] = Nlower[1]; n[1] <= Nupper[1]; n[1]++)
      for (n[2] = Nlower[2]; n[2] <= Nupper[2]; n[2]++) {
        const LinkedNodes *List = GetCurrentCell();
        //Log() << Verbose(1) << "Current cell is " << n[0] << ", " << n[1] << ", " << n[2] << " with No. " << index << "." << endl;
        if (List != NULL) {
          for (LinkedNodes::const_iterator Runner = List->begin(); Runner != List->end(); Runner++) {
            Walker = *Runner;
            TesselList->push_back(Walker);
          }
        }
      }
  return TesselList;
};

/** Set the index to the cell containing a given Vector *x, which is not inside the LinkedCell's domain
 * Note that as we have to check distance from every corner of the closest cell, this function is faw more
 * expensive and if Vector is known to be inside LinkedCell's domain, then SetIndexToVector() should be used.
 * \param *x Vector with coordinates
 * \return minimum squared distance of cell to given vector (if inside of domain, distance is 0)
 */
double LinkedCell::SetClosestIndexToOutsideVector(const Vector * const x) const
{
  for (int i=0;i<NDIM;i++) {
    n[i] = (int)floor((x->x[i] - min.x[i])/RADIUS);
    if (n[i] < 0)
      n[i] = 0;
    if (n[i] >= N[i])
      n[i] = N[i]-1;
  }

  // calculate distance of cell to vector
  double distanceSquared = 0.;
  bool outside = true;  // flag whether x is found in- or outside of LinkedCell's domain/closest cell
  Vector corner; // current corner of closest cell
  Vector tester; // Vector pointing from corner to center of closest cell
  Vector Distance;  // Vector from corner of closest cell to x

  Vector center;  // center of the closest cell
  for (int i=0;i<NDIM;i++)
    center.x[i] = min.x[i]+((double)n[i]+.5)*RADIUS;

  int c[NDIM];
  for (c[0]=0;c[0]<=1;c[0]++)
    for (c[1]=0; c[1]<=1;c[1]++)
      for (c[2]=0; c[2]<=1;c[2]++) {
        // set up corner
        for (int i=0;i<NDIM;i++)
          corner.x[i] = min.x[i]+RADIUS*((double)n[i]+c[i]);
        // set up distance vector
        Distance.CopyVector(x);
        Distance.SubtractVector(&corner);
        const double dist = Distance.NormSquared();
        // check whether distance is smaller
        if (dist< distanceSquared)
          distanceSquared = dist;
        // check whether distance vector goes inside or outside
        tester.CopyVector(&center);
        tester.SubtractVector(&corner);
        if (tester.ScalarProduct(&Distance) < 0)
          outside = false;
      }
  return (outside ? distanceSquared : 0.);
};

/** Returns a list of all TesselPoint with distance less than \a radius to \a *Center.
 * \param radius radius of sphere
 * \param *center center of sphere
 * \return list of all points inside sphere
 */
LinkedCell::LinkedNodes* LinkedCell::GetPointsInsideSphere(const double radius, const Vector * const center) const
{
  const double radiusSquared = radius*radius;
  TesselPoint *Walker = NULL;
  LinkedNodes *TesselList = new LinkedNodes;
  LinkedNodes *NeighbourList = NULL;

  // set index of LC to center of sphere
  const double dist = SetClosestIndexToOutsideVector(center);
  if (dist > 2.*radius) {
    DoeLog(1) && (eLog()<< Verbose(1) << "Vector " << *center << " is too far away from any atom in LinkedCell's bounding box." << endl);
    return TesselList;
  } else
    DoLog(1) && (Log() << Verbose(1) << "Distance of closest cell to center of sphere with radius " << radius << " is " << dist << "." << endl);

  // gather all neighbours first, then look who fulfills distance criteria
  NeighbourList = GetallNeighbours(2.*radius-dist);
  //Log() << Verbose(1) << "I found " << NeighbourList->size() << " neighbours to check." << endl;
  if (NeighbourList != NULL) {
    for (LinkedNodes::const_iterator Runner = NeighbourList->begin(); Runner != NeighbourList->end(); Runner++) {
      Walker = *Runner;
      //Log() << Verbose(1) << "Current neighbour is at " << *Walker->node << "." << endl;
      if ((center->DistanceSquared(Walker->node) - radiusSquared) < MYEPSILON) {
        TesselList->push_back(Walker);
      }
    }
    delete(NeighbourList);
  } else
    DoeLog(2) && (eLog()<< Verbose(2) << "Around vector " << *center << " there are no atoms." << endl);
  return TesselList;
};