/* Copyright 2002-2024 Thales Alenia Space
    * Licensed to CS GROUP (CS) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * CS licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.orekit.models.earth.troposphere;
  
  import org.hipparchus.CalculusFieldElement;
  import org.hipparchus.util.FastMath;
  import org.hipparchus.util.MathArrays;
  import org.orekit.bodies.FieldGeodeticPoint;
  import org.orekit.bodies.GeodeticPoint;
  import org.orekit.models.earth.weather.FieldPressureTemperatureHumidity;
  import org.orekit.models.earth.weather.PressureTemperatureHumidity;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.time.FieldAbsoluteDate;
  import org.orekit.utils.FieldTrackingCoordinates;
  import org.orekit.utils.TrackingCoordinates;
  
  /** Chao mapping function for radio wavelengths.
   *
   * @see "C. C. Chao, A model for tropospheric calibration from delay surface and radiosonde ballon measurements, 1972"
   *
   * @author Luc Maisonobe
   * @since 12.1
   */
  public class AbstractChaoMappingFunction implements TroposphereMappingFunction {
  
      /** First coefficient for hydrostatic (dry) component. */
      private final double ad;
  
      /** Second coefficient for hydrostatic (dry) component. */
      private final double bd;
  
      /** First coefficient for wet component. */
      private final double aw;
  
      /** Second coefficient for wet component. */
      private final double bw;
  
      /** Builds a new instance.
       * @param ad first coefficient for hydrostatic (dry) component
       * @param bd second coefficient for hydrostatic (dry) component
       * @param aw first coefficient for wet component
       * @param bw second coefficient for wet component
       */
      protected AbstractChaoMappingFunction(final double ad, final double bd, final double aw, final double bw) {
          this.ad = ad;
          this.bd = bd;
          this.aw = aw;
          this.bw = bw;
      }
  
      /** {@inheritDoc} */
      @Override
      public double[] mappingFactors(final TrackingCoordinates trackingCoordinates, final GeodeticPoint point,
                                     final PressureTemperatureHumidity weather,
                                     final AbsoluteDate date) {
          final double sinE = FastMath.sin(trackingCoordinates.getElevation());
          final double tanE = FastMath.tan(trackingCoordinates.getElevation());
          return new double[] {
              1 / (sinE + ad / (tanE + bd)),
              1 / (sinE + aw / (tanE + bw))
          };
      }
  
      /** {@inheritDoc} */
      @Override
      public <T extends CalculusFieldElement<T>> T[] mappingFactors(final FieldTrackingCoordinates<T> trackingCoordinates,
                                                                    final FieldGeodeticPoint<T> point,
                                                                    final FieldPressureTemperatureHumidity<T> weather,
                                                                    final FieldAbsoluteDate<T> date) {
          final T sinE = FastMath.sin(trackingCoordinates.getElevation());
          final T tanE = FastMath.tan(trackingCoordinates.getElevation());
          final T[] mapping = MathArrays.buildArray(date.getField(), 2);
          mapping[0] = sinE.add(tanE.add(bd).reciprocal().multiply(ad)).reciprocal();
          mapping[1] = sinE.add(tanE.add(bw).reciprocal().multiply(aw)).reciprocal();
          return mapping;
      }
  
  }