/* Copyright 2002-2025 CS GROUP
    * 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.estimation.measurements.gnss;
  
  import java.util.Collections;
  import java.util.List;
  
  import org.hipparchus.geometry.euclidean.threed.Rotation;
  import org.hipparchus.geometry.euclidean.threed.Vector3D;
  import org.hipparchus.util.FastMath;
  import org.hipparchus.util.MathUtils;
  import org.orekit.estimation.measurements.EstimatedMeasurementBase;
  import org.orekit.estimation.measurements.EstimationModifier;
  import org.orekit.estimation.measurements.ObservedMeasurement;
  import org.orekit.utils.ParameterDriver;
  import org.orekit.utils.TimeStampedPVCoordinates;
  
  /** Base class for wind-up effect computation.
   * @see <a href="https://gssc.esa.int/navipedia/index.php/Carrier_Phase_Wind-up_Effect">Carrier Phase Wind-up Effect</a>
   * @param <T> the type of the measurement
   * @author Luc Maisonobe
   * @since 12.0
   */
  public abstract class AbstractWindUp<T extends ObservedMeasurement<T>> implements EstimationModifier<T> {
  
      /** Emitter dipole. */
      private final Dipole emitter;
  
      /** Receiver dipole. */
      private final Dipole receiver;
  
      /** Cached angular value of wind-up. */
      private double angularWindUp;
  
      /** Simple constructor.
       * @param emitter emitter dipole
       * @param receiver receiver dipole
       */
      protected AbstractWindUp(final Dipole emitter, final Dipole receiver) {
          this.emitter  = emitter;
          this.receiver = receiver;
          angularWindUp = 0.0;
      }
  
      /** {@inheritDoc} */
      @Override
      public String getEffectName() {
          return "wind-up";
      }
  
      /** {@inheritDoc}
       * <p>
       * Wind-up effect has no parameters, the returned list is always empty.
       * </p>
       */
      @Override
      public List<ParameterDriver> getParametersDrivers() {
          return Collections.emptyList();
      }
  
      /** Compute rotation from emitter to inertial frame.
       * @param estimated estimated measurement to modify
       * @return rotation from emitter to inertial frame
       */
      protected abstract Rotation emitterToInert(EstimatedMeasurementBase<T> estimated);
  
      /** Compute rotation from receiver to inertial frame.
       * @param estimated estimated measurement to modify
       * @return rotation from receiver to inertial frame
       */
      protected abstract Rotation receiverToInert(EstimatedMeasurementBase<T> estimated);
  
      /** Cache angular wind-up.
       * @param participants particpants to the carrier-phase measurement
       * @param receiverToInert rotation for receiver to inertial frame
       * @param emitterToInert rotation from emitter to inertial frame
       * @since 13.0
       */
      public void cacheAngularWindUp(final TimeStampedPVCoordinates[] participants,
                                     final Rotation receiverToInert, final Rotation emitterToInert) {
  
          // signal line of sight
          final Vector3D los = participants[1].getPosition().subtract(participants[0].getPosition()).normalize();
  
          // get receiver dipole
         final Vector3D iReceiver       = receiverToInert.applyTo(receiver.getPrimary());
         final Vector3D jReceiver       = receiverToInert.applyTo(receiver.getSecondary());
         final Vector3D dReceiver       = new Vector3D(1.0, iReceiver, -Vector3D.dotProduct(iReceiver, los), los).
                                          add(Vector3D.crossProduct(los, jReceiver));
 
         // get emitter dipole
         final Vector3D iEmitter       = emitterToInert.applyTo(emitter.getPrimary());
         final Vector3D jEmitter       = emitterToInert.applyTo(emitter.getSecondary());
         final Vector3D dEmitter       = new Vector3D(1.0, iEmitter, -Vector3D.dotProduct(iEmitter, los), los).
                                         subtract(Vector3D.crossProduct(los, jEmitter));
 
         // raw correction
         final double correction = FastMath.copySign(Vector3D.angle(dEmitter, dReceiver),
                                                     Vector3D.dotProduct(los, Vector3D.crossProduct(dEmitter, dReceiver)));
 
         // ensure continuity across measurements
         // we assume the various measurements are close enough in time
         // (less the one satellite half-turn) so the angles remain close
         angularWindUp = MathUtils.normalizeAngle(correction, angularWindUp);
 
     }
 
     /** Get cached value of angular wind-up.
      * @return cached value of angular wind-up
      * @since 13.0
      */
     public double getAngularWindUp() {
         return angularWindUp;
     }
 
     /** {@inheritDoc} */
     @Override
     public void modifyWithoutDerivatives(final EstimatedMeasurementBase<T> estimated) {
 
         // cache new angular wind-up
         final TimeStampedPVCoordinates[] participants = estimated.getParticipants();
         final Rotation receiverToInert = receiverToInert(estimated);
         final Rotation emitterToInert = emitterToInert(estimated);
         cacheAngularWindUp(participants, receiverToInert, emitterToInert);
 
         // update estimate
         estimated.modifyEstimatedValue(this, estimated.getEstimatedValue()[0] + angularWindUp / MathUtils.TWO_PI);
 
     }
 
 }