package org.djunits.unit.scale;
   
   import org.djunits.unit.util.UnitRuntimeException;
   import org.djutils.exceptions.Throw;
   
   /**
    * A Scale for linear transformations not involving a zero-offset, e.g. for Length, Time, Area. <br>
    * A linear scale is a scale that is linearly relates a unit to the underlying SI standard unit. E.g. Mile is linearly related
    * to meter (the SI unit for length) and the conversion is zero-based (0 miles equals 0 meter). Unlike temperature in degrees
   * Celsius which is <strong>not</strong> linearly related to the Kelvin (the SI unit for temperature) because the conversion is
   * not zero-based (0&deg;C is 273.15K).
   * <p>
   * Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="https://djunits.org/docs/license.html">DJUNITS License</a>.
   * </p>
   * @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="https://www.tudelft.nl/staff/p.knoppers/">Peter Knoppers</a>
   */
  public class LinearScale implements Scale
  {
      /** */
      private static final long serialVersionUID = 20151011L;
  
      /** multiply by this number to convert to the standard (e.g., SI) unit. */
      private final double conversionFactorToStandardUnit;
  
      /**
       * Construct a Scale for linear transformations.
       * @param conversionFactorToStandardUnit double; the conversion factor by which this number has to be multiplied to convert
       *            it to the standard (e.g., SI) unit.
       */
      public LinearScale(final double conversionFactorToStandardUnit)
      {
          Throw.when(conversionFactorToStandardUnit == 0.0, UnitRuntimeException.class,
                  "conversion factor for linear scale cannnot be 0");
          this.conversionFactorToStandardUnit = conversionFactorToStandardUnit;
      }
  
      @SuppressWarnings("checkstyle:designforextension")
      @Override
      public double toStandardUnit(final double value)
      {
          return value * this.conversionFactorToStandardUnit;
      }
  
      @SuppressWarnings("checkstyle:designforextension")
      @Override
      public double fromStandardUnit(final double value)
      {
          return value / this.conversionFactorToStandardUnit;
      }
  
      /**
       * Retrieve the factor for conversion to the standard unit.
       * @return double; the factor for conversion to the standard unit
       */
      public final double getConversionFactorToStandardUnit()
      {
          return this.conversionFactorToStandardUnit;
      }
  
      @Override
      public boolean isBaseSIScale()
      {
          return this.conversionFactorToStandardUnit == 1.0;
      }
  
      @Override
      public int hashCode()
      {
          final int prime = 31;
          int result = 1;
          long temp;
          temp = Double.doubleToLongBits(this.conversionFactorToStandardUnit);
          result = prime * result + (int) (temp ^ (temp >>> 32));
          return result;
      }
  
      @SuppressWarnings("checkstyle:needbraces")
      @Override
      public boolean equals(final Object obj)
      {
          if (this == obj)
              return true;
          if (obj == null)
              return false;
          if (getClass() != obj.getClass())
              return false;
          LinearScale other = (LinearScale) obj;
          if (Double.doubleToLongBits(this.conversionFactorToStandardUnit) != Double
                  .doubleToLongBits(other.conversionFactorToStandardUnit))
              return false;
          return true;
      }
  
      @Override
      public String toString()
      {
          return "LinearScale [conversionFactorToStandardUnit=" + this.conversionFactorToStandardUnit + "]";
     }
 
 }