package org.djunits.unit;
   
   import static org.djunits.unit.unitsystem.UnitSystem.IMPERIAL;
   import static org.djunits.unit.unitsystem.UnitSystem.OTHER;
   import static org.djunits.unit.unitsystem.UnitSystem.SI_DERIVED;
   
   import org.djunits.unit.unitsystem.UnitSystem;
   
   /**
   * The units of torque (moment of force).
   * <p>
   * Copyright (c) 2015-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://djunits.org/docs/license.html">DJUNITS License</a>.
   * <p>
   * $LastChangedDate: 2019-03-02 19:06:46 +0100 (Sat, 02 Mar 2019) $, @version $Revision: 342 $, by $Author: averbraeck $,
   * initial version May 15, 2014 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   */
  public class TorqueUnit extends LinearUnit<TorqueUnit>
  {
      /** */
      private static final long serialVersionUID = 20140607L;
  
      /** The unit of mass for the torque unit, e.g., kilogram. */
      private final MassUnit massUnit;
  
      /** The unit of length for the torque unit, e.g., length. */
      private final LengthUnit lengthUnit;
  
      /** The unit of time for the torque unit, e.g., second. */
      private final DurationUnit durationUnit;
  
      /** The SI unit for torque is Newton meter. */
      public static final TorqueUnit SI;
  
      /** Newton meter. */
      public static final TorqueUnit NEWTON_METER;
  
      /** meter kilogram-force. */
      public static final TorqueUnit METER_KILOGRAM_FORCE;
  
      /** Pound foot. */
      public static final TorqueUnit POUND_FOOT;
  
      /** Pound inch. */
      public static final TorqueUnit POUND_INCH;
  
      static
      {
          SI = new TorqueUnit(MassUnit.KILOGRAM, LengthUnit.METER, DurationUnit.SECOND, "TorqueUnit.N.m", SI_DERIVED);
          NEWTON_METER = SI;
          METER_KILOGRAM_FORCE = new TorqueUnit(ForceUnit.KILOGRAM_FORCE, LengthUnit.METER, "TorqueUnit.m.kgf", OTHER);
          POUND_FOOT = new TorqueUnit(ForceUnit.POUND_FORCE, LengthUnit.FOOT, "TorqueUnit.lbf.ft", IMPERIAL);
          POUND_INCH = new TorqueUnit(ForceUnit.POUND_FORCE, LengthUnit.INCH, "TorqueUnit.lbf.in", IMPERIAL);
      }
  
      /**
       * Create a torque unit from mass, length and time units.
       * @param massUnit MassUnit; the unit of mass for the torque unit, e.g., kilogram
       * @param lengthUnit LengthUnit; the unit of length for the torque unit, e.g., meter
       * @param durationUnit DurationUnit; the unit of time for the torque unit, e.g., second
       * @param abbreviationKey String; the key to the locale file for the abbreviation of the unit
       * @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
       */
      private TorqueUnit(final MassUnit massUnit, final LengthUnit lengthUnit, final DurationUnit durationUnit,
              final String abbreviationKey, final UnitSystem unitSystem)
      {
          super(abbreviationKey, unitSystem, NEWTON_METER, massUnit.getScaleFactor() * lengthUnit.getScaleFactor()
                  * lengthUnit.getScaleFactor() / (durationUnit.getScaleFactor() * durationUnit.getScaleFactor()));
          this.massUnit = massUnit;
          this.lengthUnit = lengthUnit;
          this.durationUnit = durationUnit;
      }
  
      /**
       * Create a user-defined torque unit from mass, length and time units.
       * @param massUnit MassUnit; the unit of mass for the torque unit, e.g., kilogram
       * @param lengthUnit LengthUnit; the unit of length for the torque unit, e.g., meter
       * @param durationUnit DurationUnit; the unit of time for the torque unit, e.g., second
       * @param name String; the long name of the unit
       * @param abbreviation String; the abbreviation of the unit
       * @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
       */
      public TorqueUnit(final MassUnit massUnit, final LengthUnit lengthUnit, final DurationUnit durationUnit, final String name,
              final String abbreviation, final UnitSystem unitSystem)
      {
          super(name, abbreviation, unitSystem, NEWTON_METER, massUnit.getScaleFactor() * lengthUnit.getScaleFactor()
                  * lengthUnit.getScaleFactor() / (durationUnit.getScaleFactor() * durationUnit.getScaleFactor()));
          this.massUnit = massUnit;
          this.lengthUnit = lengthUnit;
          this.durationUnit = durationUnit;
      }
  
      /**
       * Create a torque unit from force and length units.
       * @param forceUnit ForceUnit; the unit of force for the torque unit, e.g., Newton
       * @param lengthUnit LengthUnit; the unit of length for the torque unit, e.g., meter
       * @param abbreviationKey String; the key to the locale file for the abbreviation of the unit
       * @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
      */
     private TorqueUnit(final ForceUnit forceUnit, final LengthUnit lengthUnit, final String abbreviationKey,
             final UnitSystem unitSystem)
     {
         super(abbreviationKey, unitSystem, NEWTON_METER, forceUnit.getScaleFactor() * lengthUnit.getScaleFactor());
         this.massUnit = forceUnit.getMassUnit();
         this.lengthUnit = forceUnit.getLengthUnit();
         this.durationUnit = forceUnit.getDurationUnit();
     }
 
     /**
      * Create a user-defined torque unit from force and length units.
      * @param forceUnit ForceUnit; the unit of force for the torque unit, e.g., Newton
      * @param lengthUnit LengthUnit; the unit of length for the torque unit, e.g., meter
      * @param name String; the long name of the unit
      * @param abbreviation String; the abbreviation of the unit
      * @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
      */
     public TorqueUnit(final ForceUnit forceUnit, final LengthUnit lengthUnit, final String name, final String abbreviation,
             final UnitSystem unitSystem)
     {
         super(name, abbreviation, unitSystem, NEWTON_METER, forceUnit.getScaleFactor() * lengthUnit.getScaleFactor());
         this.massUnit = forceUnit.getMassUnit();
         this.lengthUnit = forceUnit.getLengthUnit();
         this.durationUnit = forceUnit.getDurationUnit();
     }
 
     /**
      * Construct a torque unit based on another torque unit.
      * @param abbreviationKey String; the key to the locale file for the abbreviation of the unit
      * @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
      * @param referenceUnit TorqueUnit; the unit to convert to
      * @param scaleFactorToReferenceUnit double; multiply a value in this unit by the factor to convert to the given reference
      *            unit
      */
     private TorqueUnit(final String abbreviationKey, final UnitSystem unitSystem, final TorqueUnit referenceUnit,
             final double scaleFactorToReferenceUnit)
     {
         super(abbreviationKey, unitSystem, referenceUnit, scaleFactorToReferenceUnit);
         this.massUnit = referenceUnit.getMassUnit();
         this.lengthUnit = referenceUnit.getLengthUnit();
         this.durationUnit = referenceUnit.getDurationUnit();
     }
 
     /**
      * Build a user-defined unit with a conversion factor to another unit.
      * @param name String; the long name of the unit
      * @param abbreviation String; the abbreviation of the unit
      * @param unitSystem UnitSystem; the unit system, e.g. SI or Imperial
      * @param referenceUnit TorqueUnit; the unit to convert to
      * @param scaleFactorToReferenceUnit double; multiply a value in this unit by the factor to convert to the given reference
      *            unit
      */
     public TorqueUnit(final String name, final String abbreviation, final UnitSystem unitSystem, final TorqueUnit referenceUnit,
             final double scaleFactorToReferenceUnit)
     {
         super(name, abbreviation, unitSystem, referenceUnit, scaleFactorToReferenceUnit);
         this.massUnit = referenceUnit.getMassUnit();
         this.lengthUnit = referenceUnit.getLengthUnit();
         this.durationUnit = referenceUnit.getDurationUnit();
     }
 
     /**
      * @return massUnit
      */
     public final MassUnit getMassUnit()
     {
         return this.massUnit;
     }
 
     /**
      * @return lengthUnit
      */
     public final LengthUnit getLengthUnit()
     {
         return this.lengthUnit;
     }
 
     /**
      * @return durationUnit
      */
     public final DurationUnit getDurationUnit()
     {
         return this.durationUnit;
     }
 
     /** {@inheritDoc} */
     @Override
     public final TorqueUnit getStandardUnit()
     {
         return NEWTON_METER;
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getSICoefficientsString()
     {
         return "kgm2/s2";
     }
 
 }