/* Copyright 2022-2025 Romain Serra
    * 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.control.indirect.adjoint;
  
  import org.hipparchus.CalculusFieldElement;
  import org.hipparchus.analysis.differentiation.FieldGradient;
  import org.hipparchus.analysis.differentiation.Gradient;
  import org.hipparchus.complex.Complex;
  import org.hipparchus.complex.ComplexField;
  import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
  import org.hipparchus.geometry.euclidean.threed.Vector3D;
  import org.hipparchus.util.MathArrays;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  import org.mockito.Mockito;
  import org.orekit.frames.Frame;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.time.FieldAbsoluteDate;
  
  class AbstractCartesianAdjointEquationTermTest {
  
      @Test
      void testBuildGradientCartesianVector() {
          // GIVEN
          final double[] variables = {1, 2, 3, 4, 5, 6};
          // WHEN
          final Gradient[] gradients = AbstractCartesianAdjointEquationTerm.buildGradientCartesianVector(variables);
          // THEN
          for (int i = 0; i < gradients.length; i++) {
              Assertions.assertEquals(6, gradients[i].getFreeParameters());
              Assertions.assertEquals(gradients[i].getValue(), variables[i]);
              Assertions.assertEquals(1, gradients[i].getGradient()[i]);
          }
      }
  
      @Test
      void testBuildFieldGradientCartesianVector() {
          // GIVEN
          final Complex[] variables = MathArrays.buildArray(ComplexField.getInstance(), 6);
          for (int i = 0; i < variables.length; i++) {
              variables[i] = Complex.ONE.multiply(i);
          }
          // WHEN
          final FieldGradient<Complex>[] gradients = AbstractCartesianAdjointEquationTerm.buildFieldGradientCartesianVector(variables);
          // THEN
          for (int i = 0; i < gradients.length; i++) {
              Assertions.assertEquals(6, gradients[i].getFreeParameters());
              Assertions.assertEquals(gradients[i].getValue(), variables[i]);
              Assertions.assertEquals(Complex.ONE, gradients[i].getGradient()[i]);
          }
      }
  
      @Test
      void testGetFieldRatesContribution() {
          // GIVEN
          final Complex[] fieldState = MathArrays.buildArray(ComplexField.getInstance(), 6);
          final Complex[] fieldAdjoint = MathArrays.buildArray(ComplexField.getInstance(), 6);
          for (int i = 0; i < fieldAdjoint.length; i++) {
              fieldState[i] = Complex.MINUS_ONE;
              fieldAdjoint[i] = Complex.ONE.multiply(i);
          }
          final TestAdjointTerm adjointTerm = new TestAdjointTerm();
          final FieldAbsoluteDate<Complex> fieldDate = FieldAbsoluteDate.getArbitraryEpoch(ComplexField.getInstance());
          final Frame frame = Mockito.mock(Frame.class);
          // WHEN
          final Complex[] fieldRatesContribution = adjointTerm.getFieldRatesContribution(fieldDate, fieldState, fieldAdjoint, frame);
          // THEN
          final double[] states = new double[fieldAdjoint.length];
          final double[] adjoint = new double[fieldAdjoint.length];
          for (int i = 0; i < adjoint.length; i++) {
              states[i] = fieldState[i].getReal();
              adjoint[i] = fieldAdjoint[i].getReal();
          }
          final double[] ratesContribution = adjointTerm.getRatesContribution(fieldDate.toAbsoluteDate(), states, adjoint, frame);
          for (int i = 0; i < fieldRatesContribution.length; i++) {
              Assertions.assertEquals(fieldRatesContribution[i].getReal(), ratesContribution[i]);
          }
      }
  
      private static class TestAdjointTerm extends AbstractCartesianAdjointEquationTerm {
          public TestAdjointTerm() {}
  
          @Override
          protected Vector3D getAcceleration(AbsoluteDate date, double[] stateVariables, Frame frame) {
              return new Vector3D(stateVariables[0], stateVariables[1], stateVariables[5]);
         }
 
         @Override
         protected <T extends CalculusFieldElement<T>> FieldVector3D<T> getFieldAcceleration(FieldAbsoluteDate<T> date, T[] stateVariables, Frame frame) {
             return new FieldVector3D<>(date.getField(),
                     new Vector3D(stateVariables[0].getReal(), stateVariables[1].getReal(), stateVariables[5].getReal()));
         }
     }
 }