//******************************************************************************
   //
   // Title:       Force Field X.
   // Description: Force Field X - Software for Molecular Biophysics.
   // Copyright:   Copyright (c) Michael J. Schnieders 2001-2025.
   //
   // This file is part of Force Field X.
   //
   // Force Field X is free software; you can redistribute it and/or modify it
  // under the terms of the GNU General Public License version 3 as published by
  // the Free Software Foundation.
  //
  // Force Field X is distributed in the hope that it will be useful, but WITHOUT
  // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  // FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
  // details.
  //
  // You should have received a copy of the GNU General Public License along with
  // Force Field X; if not, write to the Free Software Foundation, Inc., 59 Temple
  // Place, Suite 330, Boston, MA 02111-1307 USA
  //
  // Linking this library statically or dynamically with other modules is making a
  // combined work based on this library. Thus, the terms and conditions of the
  // GNU General Public License cover the whole combination.
  //
  // As a special exception, the copyright holders of this library give you
  // permission to link this library with independent modules to produce an
  // executable, regardless of the license terms of these independent modules, and
  // to copy and distribute the resulting executable under terms of your choice,
  // provided that you also meet, for each linked independent module, the terms
  // and conditions of the license of that module. An independent module is a
  // module which is not derived from or based on this library. If you modify this
  // library, you may extend this exception to your version of the library, but
  // you are not obligated to do so. If you do not wish to do so, delete this
  // exception statement from your version.
  //
  //******************************************************************************
  package ffx.potential.nonbonded.octree;
  
  import java.util.ArrayList;
  
  /**
   * OctreeCell: Object class for Octree method presented in the Fast Multipole Method (FMM) tutorial
   * from the Barba Group: https://github.com/barbagroup/FMM_tutorial
   */
  public class OctreeCell {
  
    /**
     * Critical (maximum allowed) number of points allowed in any one cell: If a cell already contains
     * nCritical points, it needs to be split
     */
    private int nCritical;
    /** Number of leaves in a cell */
    private int numLeaves = 0;
    /** Array of leaf indices */
    private ArrayList<Integer> leaves = new ArrayList<>();
    /** Integer whose last 8 bits keep track of the empty child cells */
    private int nChild = 0;
    /** Array of child indices, length 8 */
    private int[] children = new int[] {0, 0, 0, 0, 0, 0, 0, 0};
    /** Parent cell index */
    private int parentIndex = 0;
  
    /** Coordinates for the center of the cell */
    private double x = 0.0;
  
    private double y = 0.0;
    private double z = 0.0;
  
    /** Radius of cell */
    private double r = 0.0;
  
    /** Multipole array, length 10 */
    private double[] multipole = new double[] {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
  
    public OctreeCell(int nCritical) {
      setnCritical(nCritical);
    }
  
    public void addToMultipole(double[] calculatedMultipole) {
      for (int i = 0; i < 10; i++) {
        this.multipole[i] += calculatedMultipole[i];
      }
    }
  
    public int getChildAtIndex(int octant) {
      return children[octant];
    }
  
    public int getLeavesValueAtIndex(int index) {
      return this.leaves.get(index);
    }
  
    public double[] getMultipole() {
      return this.multipole;
    }
  
    public int getNumLeaves() {
      return this.numLeaves;
   }
 
   public void setNumLeaves(int num) {
     this.numLeaves = num;
   }
 
   public int getParentIndex() {
     return this.parentIndex;
   }
 
   public void setParentIndex(int p) {
     this.parentIndex = p;
   }
 
   /**
    * Returns cell radius
    *
    * @return Returns the cell radius.
    */
   public double getR() {
     return this.r;
   }
 
   /**
    * Sets cell radius
    *
    * @param r The radius.
    */
   public void setR(double r) {
     this.r = r;
   }
 
   /**
    * Gets x coordinate of center of cell
    *
    * @return Returns the x coordinate for center of the cell.
    */
   public double getX() {
     return this.x;
   }
 
   /**
    * Sets x coordinate of center of cell
    *
    * @param x Cell x-coordinate.
    */
   public void setX(double x) {
     this.x = x;
   }
 
   /**
    * Gets y coordinate of center of cell
    *
    * @return Returns the y coordinate for center of the cell.
    */
   public double getY() {
     return this.y;
   }
 
   /**
    * Sets y coordinate of center of cell
    *
    * @param y Cell y-coordinate.
    */
   public void setY(double y) {
     this.y = y;
   }
 
   /**
    * Gets z coordinate of center of cell
    *
    * @return Returns the z coordinate for center of the cell.
    */
   public double getZ() {
     return this.z;
   }
 
   /**
    * Sets z coordinate of center of cell
    *
    * @param z Cell z-coordinate.
    */
   public void setZ(double z) {
     this.z = z;
   }
 
   public int getnChild() {
     return this.nChild;
   }
 
   public void setnChild(int num) {
     this.nChild = num;
   }
 
   public void setChildren(int octant, int c) {
     this.children[octant] = c;
   }
 
   public void setLeaf(int index, int leaf) {
     this.leaves.set(index, leaf);
   }
 
   public void setnCritical(int nCrit) {
     this.nCritical = nCrit;
   }
 }