package org.djunits.unit;
   
   import org.djunits.quantity.Quantity;
   import org.djunits.unit.scale.IdentityScale;
   import org.djunits.unit.si.SIPrefixes;
   import org.djunits.unit.unitsystem.UnitSystem;
   
   /**
    * Standard acceleration unit based on distance and time.
   * <p>
   * Copyright (c) 2015-2024 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>
   */
  public class AccelerationUnit extends Unit<AccelerationUnit>
  {
      /** */
      private static final long serialVersionUID = 20140607L;
  
      /** The base, with "m/s2" as the SI signature. */
      public static final Quantity<AccelerationUnit> BASE = new Quantity<>("Acceleration", "m/s2");
  
      /** The SI unit for acceleration is m/s^2. */
      public static final AccelerationUnit SI = new AccelerationUnit().build(new Unit.Builder<AccelerationUnit>()
              .setQuantity(BASE).setId("m/s2").setName("meter per second squared").setUnitSystem(UnitSystem.SI_DERIVED)
              .setSiPrefixes(SIPrefixes.NONE, 1.0).setScale(IdentityScale.SCALE).setAdditionalAbbreviations("m/sec^2"));
  
      /** m/s2. */
      public static final AccelerationUnit METER_PER_SECOND_2 = SI;
  
      /** km/h2. */
      public static final AccelerationUnit KM_PER_HOUR_2 = SI.deriveLinear(factorLD("km", "h"), "km/h2",
              "kilometer per hour squared", UnitSystem.SI_ACCEPTED, "km/h2", "km/h2", "km/hr^2", "km/hour^2");
  
      /** ft/s2. */
      public static final AccelerationUnit FOOT_PER_SECOND_2 = SI.deriveLinear(factorLD("ft", "s"), "ft/s2",
              "foot per second squared", UnitSystem.IMPERIAL, "ft/s2", "ft/s2", "ft/sec^2");
  
      /** in/s2. */
      public static final AccelerationUnit INCH_PER_SECOND_2 = SI.deriveLinear(factorLD("in", "s"), "in/s2",
              "inch per second squared", UnitSystem.IMPERIAL, "in/s2", "in/s2", "in/sec^2");
  
      /** mi/h2. */
      public static final AccelerationUnit MILE_PER_HOUR_2 = SI.deriveLinear(factorLD("mi", "h"), "mi/h2",
              "mile per hour squared", UnitSystem.IMPERIAL, "mi/h2", "mi/h2", "mi/hr^2", "mi/hour^2");
  
      /** mi/s2. */
      public static final AccelerationUnit MILE_PER_SECOND_2 = SI.deriveLinear(factorLD("mi", "s"), "mi/s2",
              "mile per second squared", UnitSystem.IMPERIAL, "mi/s2", "mi/s2", "mi/sec^2");
  
      /** kt/s. */
      public static final AccelerationUnit KNOT_PER_SECOND =
              SI.deriveLinear(factorSD("kt", "s"), "kt/s", "knot per second", UnitSystem.OTHER, "kt/s", "kt/s", "kt/sec");
  
      /** mi/h/s. */
      public static final AccelerationUnit MILE_PER_HOUR_PER_SECOND =
              SI.deriveLinear(factorSD("mi/h", "s"), "mi/h/s", "mile per hour per second", UnitSystem.IMPERIAL, "mi/h/s",
                      "mi/h/s", "mi/hr/s", "mi/hour/s", "mi/h/sec", "mi/hr/sec", "mi/hour/sec");
  
      /** The standard gravity. */
      public static final AccelerationUnit STANDARD_GRAVITY = SI.deriveLinear(9.80665, "g", "standard gravity", UnitSystem.OTHER);
  
      /** cm/s. */
      public static final AccelerationUnit GAL = SI.deriveLinear(factorLD("cm", "s"), "Gal", "gal", UnitSystem.CGS);
  
      /**
       * Determine the conversion factor to the base acceleration unit, given a length unit and a duration unit.
       * @param length String; a length unit, e.g. km
       * @param duration String; a duration unit, e.g. h
       * @return double; the conversion factor from the provided units (e.g. km/h2) to the standard unit (m/s2)
       */
      private static double factorLD(final String length, final String duration)
      {
          double l = LengthUnit.BASE.of(length).getScale().toStandardUnit(1.0);
          double d = DurationUnit.BASE.of(duration).getScale().toStandardUnit(1.0);
          return l / (d * d);
      }
  
      /**
       * Determine the conversion factor to the base acceleration unit, given a speed unit and a duration unit.
       * @param speed String; a speed unit, e.g. km/h
       * @param duration String; a duration unit, e.g. s
       * @return the conversion factor from the provided units (e.g. km/h/s) to the standard unit (m/s2)
       */
      private static double factorSD(final String speed, final String duration)
      {
          return SpeedUnit.BASE.of(speed).getScale().toStandardUnit(1.0)
                  / DurationUnit.BASE.of(duration).getScale().toStandardUnit(1.0);
      }
  
  }