/* Copyright 2025-2026 Hawkeye 360 (HE360)
    * 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;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  
  import org.hipparchus.Field;
  import org.hipparchus.analysis.differentiation.Gradient;
  import org.hipparchus.util.FastMath;
  import org.orekit.orbits.CartesianOrbit;
  import org.orekit.orbits.FieldCartesianOrbit;
  import org.orekit.propagation.SpacecraftState;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.time.clocks.ClockModel;
  import org.orekit.time.clocks.PolynomialClockModel;
  import org.orekit.utils.AbsolutePVCoordinates;
  import org.orekit.utils.FieldAbsolutePVCoordinates;
  import org.orekit.utils.FieldPVCoordinatesProvider;
  import org.orekit.utils.PVCoordinatesProvider;
  import org.orekit.utils.ParameterDriver;
  import org.orekit.utils.TimeStampedFieldPVCoordinates;
  import org.orekit.utils.TimeStampedPVCoordinates;
  
  /** Abstract class underlying both observed and observing measurement
   * objects.  Contains the ClockModel and the ability to store a
   * master list of all parameter drivers associated with the object.
   *
   * @author Brianna Aubin
   * @since 14.0
   */
  public abstract class AbstractParticipant implements MeasurementParticipant {
  
      /** Checkstyle is annoying sometimes. */
      private static final String CLOCK_STRING = "-clock";
  
      /** Clock offset scaling factor.
       * <p>
       * We use a power of 2 to avoid numeric noise introduction
       * in the multiplications/divisions sequences.
       * </p>
       */
      private static final double CLOCK_OFFSET_SCALE = FastMath.scalb(1.0, -10);
  
      /** Stores clock model. */
      private final ClockModel clockModel;
  
      /** Stores list of all ParameterDriver values. */
      private final List<ParameterDriver> parameterDrivers = new ArrayList<>();
  
      /** Name of the satellite. */
      private final String name;
  
      /** Simple constructor.
       * @param name name of MeasurementObject
       */
      protected AbstractParticipant(final String name) {
          this(name, createEmptyPolynomialClock(name));
      }
  
      /** Simple constructor.
       * @param name name of MeasurementObject
       * @param clock clock belonging to MeasurementObject
       */
      protected AbstractParticipant(final String name, final ClockModel clock) {
  
          // Initialize member variables
          this.name = name;
          this.clockModel = clock;
  
          for (ParameterDriver parameter: clock.getParametersDrivers()) {
              parameterDrivers.add(parameter);
          }
      }
  
      /** Get the MeasurementObject name.
       * @return name for the object
       */
      @Override
      public final String getName() {
          return name;
      }
  
     /** Creates a polynomial clock with zero displacement.
      * @param name name of object that is holding the clock
      * @return new polynomial clock model
      */
     protected static PolynomialClockModel createEmptyPolynomialClock(final String name) {
         return new PolynomialClockModel(new ParameterDriver(name + CLOCK_STRING + BIAS_SUFFIX,
                                                     0.0, CLOCK_OFFSET_SCALE,
                                                     Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY),
                                            new ParameterDriver(name + CLOCK_STRING + DRIFT_SUFFIX,
                                                     0.0, CLOCK_OFFSET_SCALE,
                                                     Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY),
                                            new ParameterDriver(name + CLOCK_STRING + ACCELERATION_SUFFIX,
                                                     0.0, CLOCK_OFFSET_SCALE,
                                                     Double.NEGATIVE_INFINITY, Double.POSITIVE_INFINITY));
     }
 
     /** Get the clock model valid at some date.
      * @return clock model
      */
     @Override
     public final ClockModel getClockModel() {
         return clockModel;
     }
 
     /** Get model parameters.
      * @return model parameters, will throw an
      * exception if one PDriver has several values driven. If
      * it's the case (if at least 1 PDriver of the model has several values
      * driven) the method {@link org.orekit.utils.ParameterDriversProvider#getParameters(AbsoluteDate)} must be used.
      */
     @Override
     public List<ParameterDriver> getParametersDrivers() {
         return Collections.unmodifiableList(parameterDrivers);
     }
 
     /**
      * Add a single parameter.
      * @param parameterDriver parameter being added to the MeasurementObject
      */
     protected final void addParameterDriver(final ParameterDriver parameterDriver) {
         parameterDrivers.add(parameterDriver);
     }
 
     /**
      * Create PV provider from position-velocity-acceleration vector and template state.
      * @param templateState template state
      * @param pvCoordinates position-velocity-acceleration
      * @return position-velocity-acceleration provider
      */
     public static PVCoordinatesProvider extractPVCoordinatesProvider(final SpacecraftState templateState,
                                                                      final TimeStampedPVCoordinates pvCoordinates) {
         if (templateState.isOrbitDefined()) {
             final CartesianOrbit cartesianOrbit = new CartesianOrbit(pvCoordinates, templateState.getFrame(),
                     templateState.getOrbit().getMu());
             return templateState.getOrbit().getType().convertType(cartesianOrbit);
         } else {
             return new AbsolutePVCoordinates(templateState.getFrame(), pvCoordinates);
         }
     }
 
     /**
      * Create PV provider from position-velocity-acceleration vector and template state.
      *
      * @param templateState template state
      * @param pvCoordinates position-velocity-acceleration
      * @return position-velocity-acceleration provider
      */
     public static FieldPVCoordinatesProvider<Gradient> extractFieldPVCoordinatesProvider(final SpacecraftState templateState,
                                                                                          final TimeStampedFieldPVCoordinates<Gradient> pvCoordinates) {
         final Field<Gradient> field = pvCoordinates.getDate().getField();
         if (templateState.isOrbitDefined()) {
             final FieldCartesianOrbit<Gradient> cartesianOrbit = new FieldCartesianOrbit<>(pvCoordinates, templateState.getFrame(),
                     field.getZero().newInstance(templateState.getOrbit().getMu()));
             return templateState.getOrbit().getType().convertType(cartesianOrbit);
         } else {
             return new FieldAbsolutePVCoordinates<>(templateState.getFrame(), pvCoordinates);
         }
     }
 }