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com.hfg xml, html, svg, and bioinformatics utility library
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package com.hfg.units;


import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.hfg.util.StringUtil;

//------------------------------------------------------------------------------
/**
 Enumeration of standard sound intensity units.
 
 Sound intensity in decibels = (10dB)log(sound intensity in W/m² / reference intensity)
 where the reference intensity is 10^-12 W/m².
 
 
 @author J. Alex Taylor, hairyfatguy.com
 
 */
//------------------------------------------------------------------------------
// com.hfg XML/HTML Coding Library
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// J. Alex Taylor, President, Founder, CEO, COO, CFO, OOPS hairyfatguy.com
// [email protected]
//------------------------------------------------------------------------------

public class SoundIntensityUnit extends Unit
{
   private static Map sInstanceMap = new HashMap<>(3);

   public static final SoundIntensityUnit decibel = new SoundIntensityUnit(MeasurementSystem.SI, "decibel", "dB");
   public static final SoundIntensityUnit watts_per_sq_meter = new SoundIntensityUnit(MeasurementSystem.SI, "W m⁻²", "W m⁻²",
                                                                                      SoundIntensityUnit.decibel.new WattsPerSqMeterConverter(),
                                                                                      new SubUnit(PowerUnit.watt),
                                                                                      new SubUnit(LengthUnit.meter,-2));


   //###########################################################################
   // CONSTRUCTORS
   //###########################################################################

   //---------------------------------------------------------------------------
   private SoundIntensityUnit(MeasurementSystem inSystem, String inName, String inAbbrev)
   {
      super(inSystem, QuantityType.SOUND_INTENSITY, inName, inAbbrev);

      sInstanceMap.put(name(), this);
      sInstanceMap.put(getAbbrev(), this);
   }

   //---------------------------------------------------------------------------
   private SoundIntensityUnit(MeasurementSystem inSystem, String inName, String inAbbrev, BaseSIUnitConverter inConversionToBaseSIUnit, SubUnit... inSubUnits)
   {
      super(inSystem, QuantityType.SOUND_INTENSITY, inName, inAbbrev, inSubUnits);
      setBaseSIUnitConverter(inConversionToBaseSIUnit);
   }

   //---------------------------------------------------------------------------
   private SoundIntensityUnit(MeasurementSystem inSystem, String inName, String inAbbrev, BaseSIUnitConverter inConversionToBaseSIUnit)
   {
      super(inSystem, QuantityType.SOUND_INTENSITY, inName, inAbbrev, null, inConversionToBaseSIUnit);

      sInstanceMap.put(name(), this);
      sInstanceMap.put(getAbbrev(), this);
   }

   //---------------------------------------------------------------------------
   protected SoundIntensityUnit(List inSubUnits)
   {
      super(inSubUnits);

      // Sanity check that we were give subunits of type 'sound intensity'.
      for (SubUnit subUnit : inSubUnits)
      {
         if (! subUnit.getUnit().getQuantityType().equals(QuantityType.SOUND_INTENSITY))
         {
            throw new RuntimeException("Cannot construct a " + getClass().getSimpleName() + " for a subunit of type " + subUnit.getUnit().getQuantityType() + "!");
         }
      }
   }

   //###########################################################################
   // PUBLIC METHODS
   //###########################################################################

   //---------------------------------------------------------------------------
   public static SoundIntensityUnit valueOf(String inString)
   {
      return StringUtil.isSet(inString) ? sInstanceMap.get(inString) : null;
   }

   private class WattsPerSqMeterConverter extends BaseSIUnitConverter
   {
      private final double REF_SOUND_INTENSITY  = 1E-12; // human hearing threshold in the air

      //---------------------------------------------------------------------------
      public WattsPerSqMeterConverter()
      {
         super(0);
      }


      //---------------------------------------------------------------------------
      @Override
      public Double apply(Double inValue)
      {
         // Convert the inbound W/m² value into dB

         return 10 * Math.log10(inValue / REF_SOUND_INTENSITY);
      }

      //---------------------------------------------------------------------------
      @Override
      public Double reverse(Double inValue)
      {
         return REF_SOUND_INTENSITY * Math.pow(10, inValue/10f);
      }

   }
}