// ******************************************************************************
   //
   // 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
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  package ffx.potential.parameters;
  
  import ffx.utilities.FFXProperty;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  
  import java.util.Arrays;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  import static ffx.potential.parameters.ForceField.ForceFieldType.UREYBRAD;
  import static ffx.utilities.Constants.ANG_TO_NM;
  import static ffx.utilities.Constants.KCAL_TO_KJ;
  import static ffx.utilities.PropertyGroup.EnergyUnitConversion;
  import static ffx.utilities.PropertyGroup.LocalGeometryFunctionalForm;
  import static ffx.utilities.PropertyGroup.PotentialFunctionParameter;
  import static java.lang.Double.parseDouble;
  import static java.lang.Integer.parseInt;
  import static java.lang.String.format;
  import static java.lang.String.valueOf;
  
  /**
   * The UreyBradleyType class defines one harmonic UreyBradley cross term.
   *
   * @author Michael J. Schnieders
   * @since 1.0
   */
  @FFXProperty(name = "ureybrad", clazz = String.class, propertyGroup = PotentialFunctionParameter, description = """
      [3 integers and 2 reals]
      Provides the values for a single Urey-Bradley cross term potential parameter.
      The integer modifiers give the atom class numbers for the three kinds of atoms
      involved in the angle for which a Urey-Bradley term is to be defined.
      The real number modifiers give the force constant value for the term and the target value for the 1-3 distance in Angstroms.
      The default units for the force constant are kcal/mole/Ang^2, but this can be controlled via the ureyunit keyword
      """)
  public final class UreyBradleyType extends BaseType implements Comparator<String> {
  
    /**
     * Default conversion Urey-Bradley stretch energy to kcal/mole.
     */
    public static final double DEFAULT_UREY_UNIT = 1.0;
    /**
     * Default cubic coefficient in Urey-Bradley stretch potential.
     */
    public static final double DEFAULT_UREY_CUBIC = 0.0;
    /**
     * Default quartic coefficient in Urey-Bradley stretch potential.
     */
    public static final double DEFAULT_UREY_QUARTIC = 0.0;
  
    /**
     * Convert Urey-Bradley stretch energy to kcal/mole.
     */
    @FFXProperty(name = "ureyunit", propertyGroup = EnergyUnitConversion, defaultValue = "1.0", description = """
        Sets the scale factor needed to convert the energy value computed by the Urey-Bradley potential into units of kcal/mole.
        The correct value is force field dependent and typically provided in the header of the master force field parameter file.
        """)
    public double ureyUnit = DEFAULT_UREY_UNIT;
  
   /**
    * Cubic coefficient in bond stretch potential.
    */
   @FFXProperty(name = "urey-cubic", propertyGroup = LocalGeometryFunctionalForm, defaultValue = "0.0", description = """
       Sets the value of the cubic term in the Taylor series expansion form of the Urey-Bradley potential energy.
       The real number modifier gives the value of the coefficient as a multiple of the quadratic coefficient.
       The default value in the absence of the urey-cubic keyword is zero; i.e., the cubic Urey-Bradley term is omitted.
       """)
   public double cubic = DEFAULT_UREY_CUBIC;
 
   /**
    * Quartic coefficient in bond stretch potential.
    */
   @FFXProperty(name = "urey-quartic", propertyGroup = LocalGeometryFunctionalForm, defaultValue = "0.0", description = """
       Sets the value of the quartic term in the Taylor series expansion form of the Urey-Bradley potential energy.
       The real number modifier gives the value of the coefficient as a multiple of the quadratic coefficient.
       The default value in the absence of the urey-quartic keyword is zero; i.e., the quartic Urey-Bradley term is omitted.
       """)
   public double quartic = DEFAULT_UREY_QUARTIC;
 
   /**
    * A Logger for the UreyBradleyType class.
    */
   private static final Logger logger = Logger.getLogger(UreyBradleyType.class.getName());
   /**
    * Atom classes that form this Urey-Bradley cross term.
    */
   public final int[] atomClasses;
   /**
    * Force constant (Kcal/mole/angstroms^2).
    */
   public final double forceConstant;
   /**
    * Equilibrium 1-3 separation (Angstroms).
    */
   public final double distance;
 
   /**
    * UreyBradleyType constructor.
    *
    * @param atomClasses   Atom classes.
    * @param forceConstant Force constant (Kcal/mole/angstroms^2).
    * @param distance      Equilibrium 1-3 separation (Angstroms).
    */
   public UreyBradleyType(int[] atomClasses, double forceConstant, double distance) {
     super(UREYBRAD, sortKey(atomClasses));
     this.atomClasses = atomClasses;
     this.forceConstant = forceConstant;
     this.distance = distance;
   }
 
   /**
    * average.
    *
    * @param ureyBradleyType1 a {@link ffx.potential.parameters.UreyBradleyType} object.
    * @param ureyBradleyType2 a {@link ffx.potential.parameters.UreyBradleyType} object.
    * @param atomClasses      an array of {@link int} objects.
    * @return a {@link ffx.potential.parameters.UreyBradleyType} object.
    */
   public static UreyBradleyType average(UreyBradleyType ureyBradleyType1,
                                         UreyBradleyType ureyBradleyType2, int[] atomClasses) {
     if (ureyBradleyType1 == null || ureyBradleyType2 == null || atomClasses == null) {
       return null;
     }
 
     double forceConstant = (ureyBradleyType1.forceConstant + ureyBradleyType2.forceConstant) / 2.0;
     double distance = (ureyBradleyType1.distance + ureyBradleyType2.distance) / 2.0;
 
     return new UreyBradleyType(atomClasses, forceConstant, distance);
   }
 
   /**
    * Construct a UreyBradleyType from an input string.
    *
    * @param input  The overall input String.
    * @param tokens The input String tokenized.
    * @return a UreyBradleyType instance.
    */
   public static UreyBradleyType parse(String input, String[] tokens) {
     if (tokens.length < 5) {
       logger.log(Level.WARNING, "Invalid UREYBRAD type:\n{0}", input);
     } else {
       try {
         int[] atomClasses = new int[3];
         atomClasses[0] = parseInt(tokens[1]);
         atomClasses[1] = parseInt(tokens[2]);
         atomClasses[2] = parseInt(tokens[3]);
         double forceConstant = parseDouble(tokens[4]);
         double distance = parseDouble(tokens[5]);
         return new UreyBradleyType(atomClasses, forceConstant, distance);
       } catch (NumberFormatException e) {
         String message = "Exception parsing UREYBRAD type:\n" + input + "\n";
         logger.log(Level.SEVERE, message, e);
       }
     }
     return null;
   }
 
   /**
    * This method sorts the atom classes as: min, c[1], max
    *
    * @param c atomClasses
    * @return lookup key
    */
   public static String sortKey(int[] c) {
     if (c == null || c.length != 3) {
       return null;
     }
     if (c[0] > c[2]) {
       int temp = c[0];
       c[0] = c[2];
       c[2] = temp;
     }
 
     return c[0] + " " + c[1] + " " + c[2];
   }
 
   /**
    * {@inheritDoc}
    */
   @Override
   public int compare(String key1, String key2) {
     String[] keys1 = key1.split(" ");
     String[] keys2 = key2.split(" ");
     int[] c1 = new int[3];
     int[] c2 = new int[3];
     for (int i = 0; i < 3; i++) {
       c1[i] = parseInt(keys1[i]);
       c2[i] = parseInt(keys2[i]);
     }
     if (c1[1] < c2[1]) {
       return -1;
     } else if (c1[1] > c2[1]) {
       return 1;
     } else if (c1[0] < c2[0]) {
       return -1;
     } else if (c1[0] > c2[0]) {
       return 1;
     } else if (c1[2] < c2[2]) {
       return -1;
     } else if (c1[2] > c2[2]) {
       return 1;
     }
     return 0;
   }
 
   /**
    * {@inheritDoc}
    */
   @Override
   public boolean equals(Object o) {
     if (this == o) {
       return true;
     }
     if (o == null || getClass() != o.getClass()) {
       return false;
     }
     UreyBradleyType ureyBradleyType = (UreyBradleyType) o;
     return Arrays.equals(atomClasses, ureyBradleyType.atomClasses);
   }
 
   /**
    * {@inheritDoc}
    */
   @Override
   public int hashCode() {
     return Arrays.hashCode(atomClasses);
   }
 
   /**
    * Increment the atom classes by a specified amount.
    *
    * @param increment The increment to apply to the atom classes.
    */
   public void incrementClasses(int increment) {
     for (int i = 0; i < atomClasses.length; i++) {
       atomClasses[i] += increment;
     }
     setKey(sortKey(atomClasses));
   }
 
   /**
    * Remap new atom classes to known internal ones.
    *
    * @param typeMap a lookup between new atom types and known atom types.
    */
   public void patchClasses(HashMap<AtomType, AtomType> typeMap) {
     int count = 0;
     for (AtomType newType : typeMap.keySet()) {
       for (int atomClass : atomClasses) {
         if (atomClass == newType.atomClass) {
           count++;
         }
       }
     }
     if (count > 0 && count < atomClasses.length) {
       for (AtomType newType : typeMap.keySet()) {
         for (int i = 0; i < atomClasses.length; i++) {
           if (atomClasses[i] == newType.atomClass) {
             AtomType knownType = typeMap.get(newType);
             atomClasses[i] = knownType.atomClass;
           }
         }
       }
       setKey(sortKey(atomClasses));
     }
   }
 
   /**
    * {@inheritDoc}
    *
    * <p>Nicely formatted Urey-Bradley string.
    */
   @Override
   public String toString() {
     return format("ureybrad  %5d  %5d  %5d  %6.2f  %7.4f", atomClasses[0], atomClasses[1],
         atomClasses[2], forceConstant, distance);
   }
 
   /**
    * Create an AmoebaUreyBradleyForce element.
    *
    * @param doc        the Document instance.
    * @param forceField the ForceField to grab constants from.
    * @return the AmoebaUreyBradleyForce element.
    */
   public static Element getXMLForce(Document doc, ForceField forceField) {
     Map<String, UreyBradleyType> types = forceField.getUreyBradleyTypes();
     if (!types.values().isEmpty()) {
       Element node = doc.createElement("AmoebaUreyBradleyForce");
       node.setAttribute("cubic", valueOf(forceField.getDouble("urey-cubic", DEFAULT_UREY_CUBIC)));
       node.setAttribute("quartic", valueOf(forceField.getDouble("urey-quartic", DEFAULT_UREY_QUARTIC)));
       for (UreyBradleyType ureyBradleyType : types.values()) {
         node.appendChild(ureyBradleyType.toXML(doc));
       }
       return node;
     }
     return null;
   }
 
   /**
    * Write UreyBradleyType to OpenMM XML format.
    */
   public Element toXML(Document doc) {
     Element node = doc.createElement("UreyBradley");
     node.setAttribute("class1", format("%d", atomClasses[0]));
     node.setAttribute("class2", format("%d", atomClasses[1]));
     node.setAttribute("class3", format("%d", atomClasses[2]));
     // Convert from kcal/mol/A^2 to KJ/mol/nm^2
     node.setAttribute("k", format("%f", forceConstant * KCAL_TO_KJ / (ANG_TO_NM * ANG_TO_NM)));
     // Convert from Angstroms to nm
     node.setAttribute("d", format("%f", distance * ANG_TO_NM));
     return node;
   }
 }