// ******************************************************************************
   //
   // 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
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  // 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.terms;
  
  import ffx.potential.bonded.AngleTorsion;
  import ffx.potential.bonded.BondedTerm;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  import java.util.logging.Logger;
  
  import static java.lang.String.format;
  
  /**
   * Angle-Torsion potential energy term using {@link ffx.potential.bonded.AngleTorsion} instances.
   */
  public class AngleTorsionPotentialEnergy extends EnergyTerm {
  
    private static final Logger logger = Logger.getLogger(AngleTorsionPotentialEnergy.class.getName());
  
  
    /**
     * Internal list of AngleTorsion instances.
     */
    private final List<AngleTorsion> angleTorsions = new ArrayList<>();
  
    /**
     * Create an AngleTorsionPotentialEnergy with the provided name.
     *
     * @param name Name for this term.
     */
    public AngleTorsionPotentialEnergy(String name) {
      super(name);
    }
  
    /**
     * Create an AngleTorsionPotentialEnergy with the provided name and force group.
     *
     * @param name       Name for this term.
     * @param forceGroup Integer force group identifier.
     */
    public AngleTorsionPotentialEnergy(String name, int forceGroup) {
      super(name, forceGroup);
    }
  
    /**
     * Create an AngleTorsionPotentialEnergy initialized with a list of terms and force group.
     *
     * @param name          Name for this term.
     * @param forceGroup    Force group identifier.
     * @param angleTorsions List of AngleTorsion instances to add (null-safe).
     */
    public AngleTorsionPotentialEnergy(String name, int forceGroup, List<AngleTorsion> angleTorsions) {
      super(name, forceGroup);
      if (angleTorsions != null) {
        Collections.sort(angleTorsions);
        this.angleTorsions.addAll(angleTorsions);
        logger.info(format("  Angle-Torsions:                    %10d", getNumberOfAngleTorsions()));
      }
    }
  
    /**
    * {@inheritDoc}
    */
   @Override
   public int getNumberOfTerms() {
     return getNumberOfAngleTorsions();
   }
 
   /**
    * {@inheritDoc}
    */
   @Override
   public BondedTerm[] getBondedTermsArray() {
     return getAngleTorsionArray();
   }
 
   /**
    * Create an AngleTorsionPotentialEnergy initialized with a collection of terms.
    *
    * @param name          Name for this term (may be null).
    * @param angleTorsions Collection of AngleTorsion instances to add (null-safe).
    */
   public AngleTorsionPotentialEnergy(String name, Collection<AngleTorsion> angleTorsions) {
     super(name);
     if (angleTorsions != null) {
       this.angleTorsions.addAll(angleTorsions);
     }
   }
 
   /**
    * Add an AngleTorsion to this term.
    *
    * @param angleTorsion AngleTorsion to add (ignored if null).
    * @return true if it was added.
    */
   public boolean addAngleTorsion(AngleTorsion angleTorsion) {
     if (angleTorsion == null) {
       return false;
     }
     return angleTorsions.add(angleTorsion);
   }
 
   /**
    * Add an array of AngleTorsions to this term.
    *
    * @param angleTorsions Array of AngleTorsion instances to add.
    * @return true if they were added.
    */
   public boolean addAngleTorsions(AngleTorsion[] angleTorsions) {
     if (angleTorsions == null) {
       return false;
     }
     Collections.addAll(this.angleTorsions, angleTorsions);
     return true;
   }
 
   /**
    * Add a list of AngleTorsions to this term.
    *
    * @param angleTorsions List of AngleTorsion instances to add.
    * @return true if they were added.
    */
   public boolean addAngleTorsions(List<AngleTorsion> angleTorsions) {
     if (angleTorsions == null) {
       return false;
     }
     this.angleTorsions.addAll(angleTorsions);
     return true;
   }
 
   /**
    * Remove an AngleTorsion from this term.
    *
    * @param angleTorsion AngleTorsion to remove (ignored if null).
    * @return true if it was present and removed.
    */
   public boolean removeAngleTorsion(AngleTorsion angleTorsion) {
     if (angleTorsion == null) {
       return false;
     }
     return angleTorsions.remove(angleTorsion);
   }
 
   /**
    * Get the AngleTorsion at a given index.
    *
    * @param index Index in the internal list.
    * @return AngleTorsion at the specified index.
    * @throws IndexOutOfBoundsException if index is invalid.
    */
   public AngleTorsion getAngleTorsion(int index) {
     return angleTorsions.get(index);
   }
 
   /**
    * Get an unmodifiable view of the AngleTorsions in this term.
    *
    * @return Unmodifiable List of AngleTorsions.
    */
   public List<AngleTorsion> getAngleTorsions() {
     return Collections.unmodifiableList(angleTorsions);
   }
 
   /**
    * Get an array of AngleTorsions in this term.
    *
    * @return Array of AngleTorsions.
    */
   public AngleTorsion[] getAngleTorsionArray() {
     return angleTorsions.toArray(new AngleTorsion[0]);
   }
 
   /**
    * Get the number of AngleTorsions in this term.
    *
    * @return The number of AngleTorsions.
    */
   public int getNumberOfAngleTorsions() {
     return angleTorsions.size();
   }
 
   /**
    * Log the details of Angle-Torsion interactions.
    */
   @Override
   public void log() {
     if (getNumberOfAngleTorsions() <= 0) {
       return;
     }
     logger.info("\n Angle-Torsion Interactions:");
     for (AngleTorsion angleTorsion : getAngleTorsions()) {
       logger.info(" Angle-Torsion \t" + angleTorsion.toString());
     }
   }
 
   @Override
   public String toPDBString() {
     if (getNumberOfAngleTorsions() <= 0) {
       return "";
     }
     return format("REMARK   3   %s %g (%d)\n", "ANGLE-TORSION              : ", getEnergy(), getNumberOfAngleTorsions());
   }
 
   @Override
   public String toString() {
     return format("  %s %20.8f %12d %12.3f\n", "Angle-Torsion     ",
         getEnergy(), getNumberOfAngleTorsions(), getTime());
   }
 }