package org.djunits.unit;
   
   import org.djunits.unit.quantity.Quantity;
   import org.djunits.unit.scale.IdentityScale;
   import org.djunits.unit.si.SIPrefixes;
   import org.djunits.unit.unitsystem.UnitSystem;
   
   /**
    * According to <a href="http://en.wikipedia.org/wiki/Velocity">Wikipedia</a>: Speed describes only how fast an object is
   * moving, whereas speed gives both how fast and in what direction the object is moving.
   * <p>
   * Copyright (c) 2015-2023 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>
   */
  public class SpeedUnit extends Unit<SpeedUnit>
  {
      /** */
      private static final long serialVersionUID = 20140607L;
  
      /** The base, with "m/s" as the SI signature. */
      public static final Quantity<SpeedUnit> BASE = new Quantity<>("Speed", "m/s");
  
      /** The SI unit for speed is m/s. */
      public static final SpeedUnit SI = new SpeedUnit().build(new Unit.Builder<SpeedUnit>().setQuantity(BASE).setId("m/s")
              .setName("meter per second").setUnitSystem(UnitSystem.SI_DERIVED).setSiPrefixes(SIPrefixes.NONE, 1.0)
              .setScale(IdentityScale.SCALE).setAdditionalAbbreviations("m/sec"));
  
      /** m/s. */
      public static final SpeedUnit METER_PER_SECOND = SI;
  
      /** m/h. */
      public static final SpeedUnit METER_PER_HOUR = SI.deriveLinear(factorLD(LengthUnit.METER, DurationUnit.HOUR), "m/h",
              "meter per hour", UnitSystem.SI_ACCEPTED, "m/h", "m/h", "m/hr", "m/hour");
  
      /** km/s. */
      public static final SpeedUnit KM_PER_SECOND = SI.deriveLinear(factorLD(LengthUnit.KILOMETER, DurationUnit.SECOND), "km/s",
              "kilometer per second", UnitSystem.SI_DERIVED, "km/s", "km/s", "km/sec");
  
      /** km/h. */
      public static final SpeedUnit KM_PER_HOUR = SI.deriveLinear(factorLD(LengthUnit.KILOMETER, DurationUnit.HOUR), "km/h",
              "kilometer per hour", UnitSystem.SI_ACCEPTED, "km/h", "km/h", "km/hr", "km/hour");
  
      /** in/s. */
      public static final SpeedUnit INCH_PER_SECOND = SI.deriveLinear(factorLD(LengthUnit.INCH, DurationUnit.SECOND), "in/s",
              "inch per second", UnitSystem.IMPERIAL, "in/s", "in/s", "in/sec");
  
      /** in/min. */
      public static final SpeedUnit INCH_PER_MINUTE =
              SI.deriveLinear(factorLD(LengthUnit.INCH, DurationUnit.MINUTE), "in/min", "inch per minute", UnitSystem.IMPERIAL);
  
      /** in/h. */
      public static final SpeedUnit INCH_PER_HOUR = SI.deriveLinear(factorLD(LengthUnit.INCH, DurationUnit.HOUR), "in/h",
              "inch per hour", UnitSystem.IMPERIAL, "in/h", "in/h", "in/hr", "in/hour");
  
      /** ft/s. */
      public static final SpeedUnit FOOT_PER_SECOND = SI.deriveLinear(factorLD(LengthUnit.FOOT, DurationUnit.SECOND), "ft/s",
              "foot per second", UnitSystem.IMPERIAL, "ft/s", "ft/s", "ft/sec");
  
      /** ft/min. */
      public static final SpeedUnit FOOT_PER_MINUTE =
              SI.deriveLinear(factorLD(LengthUnit.FOOT, DurationUnit.MINUTE), "ft/min", "inch per minute", UnitSystem.IMPERIAL);
  
      /** ft/h. */
      public static final SpeedUnit FOOT_PER_HOUR = SI.deriveLinear(factorLD(LengthUnit.FOOT, DurationUnit.HOUR), "ft/h",
              "foot per hour", UnitSystem.IMPERIAL, "ft/h", "ft/h", "ft/hr", "ft/hour");
  
      /** mile/s. */
      public static final SpeedUnit MILE_PER_SECOND = SI.deriveLinear(factorLD(LengthUnit.MILE, DurationUnit.SECOND), "mi/s",
              "mile per second", UnitSystem.IMPERIAL, "mi/s", "mi/s", "mi/sec");
  
      /** mile/min. */
      public static final SpeedUnit MILE_PER_MINUTE =
              SI.deriveLinear(factorLD(LengthUnit.MILE, DurationUnit.MINUTE), "mi/min", "mile per minute", UnitSystem.IMPERIAL);
  
      /** mile/h. */
      public static final SpeedUnit MILE_PER_HOUR = SI.deriveLinear(factorLD(LengthUnit.MILE, DurationUnit.HOUR), "mi/h",
              "mile per hour", UnitSystem.IMPERIAL, "mi/h", "mi/h", "mi/hr", "mi/hour");
  
      /** knot = Nautical Mile per hour. */
      public static final SpeedUnit KNOT =
              SI.deriveLinear(factorLD(LengthUnit.NAUTICAL_MILE, DurationUnit.HOUR), "kt", "knot", UnitSystem.OTHER);
  
      /**
       * Determine the conversion factor to the base speed unit, given a length unit and a duration unit.
       * @param length LengthUnit; the used length unit, e.g. km
       * @param duration DurationUnit; the used duration unit, e.g. h
       * @return double; the conversion factor from the provided units (e.g. km/h) to the standard unit (e.g., m/s)
       */
      private static double factorLD(final LengthUnit length, final DurationUnit duration)
      {
          return length.getScale().toStandardUnit(1.0) / duration.getScale().toStandardUnit(1.0);
      }
  
  }