package org.djunits.unit;
   
   import static org.djunits.unit.unitsystem.UnitSystem.OTHER;
   import static org.djunits.unit.unitsystem.UnitSystem.SI_ACCEPTED;
   import static org.djunits.unit.unitsystem.UnitSystem.SI_DERIVED;
   
   import org.djunits.unit.scale.GradeScale;
   import org.djunits.unit.scale.LinearScale;
   import org.djunits.unit.scale.Scale;
  import org.djunits.unit.unitsystem.UnitSystem;
  
  /**
   * Standard angle unit. Several conversion factors have been taken from
   * <a href="http://en.wikipedia.org/wiki/Conversion_of_units">http://en.wikipedia.org/wiki/Conversion_of_units</a>.
   * <p>
   * Note that the Angle is <b>counter</b>clockwise.
   * <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 AngleUnit extends Unit<AngleUnit>
  {
      /** */
      private static final long serialVersionUID = 20140607L;
  
      /** The SI unit for angle is radian. */
      public static final AngleUnit SI;
  
      /** radian. */
      public static final AngleUnit RADIAN;
  
      /** percent (non-linear, 100% is 45 degrees; 90 degrees is infinite). */
      public static final AngleUnit PERCENT;
  
      /** degree. */
      public static final AngleUnit DEGREE;
  
      /** arcminute. */
      public static final AngleUnit ARCMINUTE;
  
      /** arcsecond. */
      public static final AngleUnit ARCSECOND;
  
      /** grad. */
      public static final AngleUnit GRAD;
  
      /** centesimal arcminute. */
      public static final AngleUnit CENTESIMAL_ARCMINUTE;
  
      /** centesimal arcsecond. */
      public static final AngleUnit CENTESIMAL_ARCSECOND;
  
      static
      {
          SI = new AngleUnit("AngleUnit.rad", SI_DERIVED);
          RADIAN = SI;
          DEGREE = new AngleUnit("AngleUnit.deg", SI_ACCEPTED, RADIAN, Math.PI / 180.0);
          ARCMINUTE = new AngleUnit("AngleUnit.arcmin", SI_ACCEPTED, DEGREE, 1.0 / 60.0);
          ARCSECOND = new AngleUnit("AngleUnit.arcsec", SI_ACCEPTED, DEGREE, 1.0 / 3600.0);
          GRAD = new AngleUnit("AngleUnit.grad", OTHER, RADIAN, 2.0 * Math.PI / 400.0);
          CENTESIMAL_ARCMINUTE = new AngleUnit("AngleUnit.centesimal_arcmin", OTHER, GRAD, 1.0 / 100.0);
          CENTESIMAL_ARCSECOND = new AngleUnit("AngleUnit.centesimal_arcsec", OTHER, GRAD, 1.0 / 10000.0);
          PERCENT = new AngleUnit("AngleUnit.perc", OTHER, new GradeScale(0.01));
  
      }
  
      /**
       * Build a standard 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
       */
      private AngleUnit(final String abbreviationKey, final UnitSystem unitSystem)
      {
          super(abbreviationKey, unitSystem);
      }
  
      /**
       * Build a unit by converting it from another 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 AngleUnit; 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 AngleUnit(final String abbreviationKey, final UnitSystem unitSystem, final AngleUnit referenceUnit,
              final double scaleFactorToReferenceUnit)
      {
          super(abbreviationKey, unitSystem, new LinearScale(
                  ((LinearScale) referenceUnit.getScale()).getConversionFactorToStandardUnit() * scaleFactorToReferenceUnit));
      }
  
      /**
       * 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 AngleUnit; 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 AngleUnit(final String name, final String abbreviation, final UnitSystem unitSystem, final AngleUnit referenceUnit,
             final double scaleFactorToReferenceUnit)
     {
         super(name, abbreviation, unitSystem, new LinearScale(
                 ((LinearScale) referenceUnit.getScale()).getConversionFactorToStandardUnit() * scaleFactorToReferenceUnit));
     }
 
     /**
      * Build an angle-slope unit with its own scale.
      * @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 scale Scale; the scale to use
      */
     private AngleUnit(final String abbreviationKey, final UnitSystem unitSystem, final Scale scale)
     {
         super(abbreviationKey, unitSystem, scale);
     }
 
     /** {@inheritDoc} */
     @Override
     public final AngleUnit getStandardUnit()
     {
         return RADIAN;
     }
 
     /** {@inheritDoc} */
     @Override
     public final String getSICoefficientsString()
     {
         return "1";
     }
 
     /** {@inheritDoc} */
     @Override
     public int hashCode()
     {
         final int prime = 31;
         int result = super.hashCode();
         result = prime * result + ((getScale() == null) ? 0 : getScale().hashCode());
         return result;
     }
 
     /** {@inheritDoc} */
     @SuppressWarnings("checkstyle:needbraces")
     @Override
     public boolean equals(final Object obj)
     {
         if (this == obj)
             return true;
         if (!super.equals(obj))
             return false;
         if (getClass() != obj.getClass())
             return false;
         AngleUnit other = (AngleUnit) obj;
         if (getScale() == null)
         {
             if (other.getScale() != null)
                 return false;
         }
         else if (!getScale().equals(other.getScale()))
             return false;
         return true;
     }
 
     /** {@inheritDoc} */
     @SuppressWarnings("checkstyle:needbraces")
     @Override
     public boolean equalsIgnoreNaming(final Object obj)
     {
         if (this == obj)
             return true;
         if (getClass() != obj.getClass())
             return false;
         AngleUnit other = (AngleUnit) obj;
         if (getScale() == null)
         {
             if (other.getScale() != null)
                 return false;
         }
         else if (!getScale().equals(other.getScale()))
             return false;
         return true;
     }
 
 }