/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF 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
    *
    *      https://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.
   */
  
  /*
   * This is not the original file distributed by the Apache Software Foundation
   * It has been modified by the Hipparchus project
   */
  package org.hipparchus.analysis.interpolation;
  
  import org.hipparchus.analysis.TrivariateFunction;
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.util.FastMath;
  import org.junit.jupiter.api.Test;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assertions.fail;
  
  /**
   * Test case for the {@link TricubicInterpolator tricubic interpolator}.
   */
  public final class TricubicInterpolatorTest {
      /**
       * Test preconditions.
       */
      @Test
      void testPreconditions() {
          double[] xval = new double[] {3, 4, 5, 6.5};
          double[] yval = new double[] {-4, -3, -1, 2.5};
          double[] zval = new double[] {-12, -8, -5.5, -3, 0, 2.5};
          double[][][] fval = new double[xval.length][yval.length][zval.length];
  
          @SuppressWarnings("unused")
          TrivariateFunction tcf = new TricubicInterpolator().interpolate(xval, yval, zval, fval);
  
          double[] wxval = new double[] {3, 2, 5, 6.5};
          try {
              tcf = new TricubicInterpolator().interpolate(wxval, yval, zval, fval);
              fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              // Expected
          }
          double[] wyval = new double[] {-4, -1, -1, 2.5};
          try {
              tcf = new TricubicInterpolator().interpolate(xval, wyval, zval, fval);
              fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              // Expected
          }
          double[] wzval = new double[] {-12, -8, -9, -3, 0, 2.5};
          try {
              tcf = new TricubicInterpolator().interpolate(xval, yval, wzval, fval);
              fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              // Expected
          }
          double[][][] wfval = new double[xval.length - 1][yval.length][zval.length];
          try {
              tcf = new TricubicInterpolator().interpolate(xval, yval, zval, wfval);
              fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              // Expected
          }
          wfval = new double[xval.length][yval.length - 1][zval.length];
          try {
              tcf = new TricubicInterpolator().interpolate(xval, yval, zval, wfval);
              fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              // Expected
          }
          wfval = new double[xval.length][yval.length][zval.length - 1];
          try {
              tcf = new TricubicInterpolator().interpolate(xval, yval, zval, wfval);
              fail("an exception should have been thrown");
          } catch (MathIllegalArgumentException e) {
              // Expected
          }
      }
  
      public void testIsValid() {
          double[] xval = new double[] {3, 4, 5, 6.5};
          double[] yval = new double[] {-4, -3, -1, 2.5};
          double[] zval = new double[] {-12, -8, -5.5, -3, 0, 2.5};
          double[][][] fval = new double[xval.length][yval.length][zval.length];
 
         TricubicInterpolatingFunction tcf = new TricubicInterpolator().interpolate(xval, yval, zval, fval);
 
         // Valid.
         assertTrue(tcf.isValidPoint(4, -3, -8));
         assertTrue(tcf.isValidPoint(5, -3, -8));
         assertTrue(tcf.isValidPoint(4, -1, -8));
         assertTrue(tcf.isValidPoint(5, -1, -8));
         assertTrue(tcf.isValidPoint(4, -3, 0));
         assertTrue(tcf.isValidPoint(5, -3, 0));
         assertTrue(tcf.isValidPoint(4, -1, 0));
         assertTrue(tcf.isValidPoint(5, -1, 0));
 
         // Invalid.
         assertFalse(tcf.isValidPoint(3.5, -3, -8));
         assertFalse(tcf.isValidPoint(4.5, -3.1, -8));
         assertFalse(tcf.isValidPoint(4.5, -2, 0));
         assertFalse(tcf.isValidPoint(4.5, 0, -3.5));
         assertFalse(tcf.isValidPoint(-10, 4.1, -1));
     }
 
     /**
      * Test for a plane.
      * <p>
      *  f(x, y, z) = 2 x - 3 y - 4 z + 5
      * </p>
      */
     @Test
     void testPlane() {
         double[] xval = new double[] {3, 4, 5, 6.5};
         double[] yval = new double[] {-4, -3, -1, 2, 2.5};
         double[] zval = new double[] {-12, -8, -5.5, -3, 0, 2.5};
 
         // Function values
         TrivariateFunction f = new TrivariateFunction() {
                 @Override
                 public double value(double x, double y, double z) {
                     return 2 * x - 3 * y - 4 * z + 5;
                 }
             };
 
         double[][][] fval = new double[xval.length][yval.length][zval.length];
 
         for (int i = 0; i < xval.length; i++) {
             for (int j = 0; j < yval.length; j++) {
                 for (int k = 0; k < zval.length; k++) {
                     fval[i][j][k] = f.value(xval[i], yval[j], zval[k]);
                 }
             }
         }
 
         TrivariateFunction tcf = new TricubicInterpolator().interpolate(xval,
                                                                         yval,
                                                                         zval,
                                                                         fval);
         double x, y, z;
         double expected, result;
 
         x = 4;
         y = -3;
         z = 0;
         expected = f.value(x, y, z);
         result = tcf.value(x, y, z);
         assertEquals(expected, result, 1e-15, "On sample point");
 
         x = 4.5;
         y = -1.5;
         z = -4.25;
         expected = f.value(x, y, z);
         result = tcf.value(x, y, z);
         assertEquals(expected, result, 1e-14, "Half-way between sample points (middle of the patch)");
     }
 
     /**
      * Sine wave.
      * <p>
      *  f(x, y, z) = a cos [&omega; z - k<sub>y</sub> x - k<sub>y</sub> y]
      * </p>
      * with A = 0.2, &omega; = 0.5, k<sub>x</sub> = 2, k<sub>y</sub> = 1.
      */
     @Test
     void testWave() {
         double[] xval = new double[] {3, 4, 5, 6.5};
         double[] yval = new double[] {-4, -3, -1, 2, 2.5};
         double[] zval = new double[] {-12, -8, -5.5, -3, 0, 4};
 
         final double a = 0.2;
         final double omega = 0.5;
         final double kx = 2;
         final double ky = 1;
 
         // Function values
         TrivariateFunction f = new TrivariateFunction() {
                 @Override
                 public double value(double x, double y, double z) {
                     return a * FastMath.cos(omega * z - kx * x - ky * y);
                 }
             };
 
         double[][][] fval = new double[xval.length][yval.length][zval.length];
         for (int i = 0; i < xval.length; i++) {
             for (int j = 0; j < yval.length; j++) {
                 for (int k = 0; k < zval.length; k++) {
                     fval[i][j][k] = f.value(xval[i], yval[j], zval[k]);
                 }
             }
         }
 
         TrivariateFunction tcf = new TricubicInterpolator().interpolate(xval,
                                                                         yval,
                                                                         zval,
                                                                         fval);
 
         double x, y, z;
         double expected, result;
 
         x = 4;
         y = -3;
         z = 0;
         expected = f.value(x, y, z);
         result = tcf.value(x, y, z);
         assertEquals(expected, result, 1e-14, "On sample point");
 
         x = 4.5;
         y = -1.5;
         z = -4.25;
         expected = f.value(x, y, z);
         result = tcf.value(x, y, z);
         assertEquals(expected, result, 1e-1, "Half-way between sample points (middle of the patch)"); // XXX Too high tolerance!
     }
 }