/*
    * 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.fitting;
  
  import org.hipparchus.exception.MathIllegalArgumentException;
  import org.hipparchus.exception.MathIllegalStateException;
  import org.junit.jupiter.api.Test;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  /**
   * Tests {@link GaussianCurveFitter}.
   *
   */
  class GaussianCurveFitterTest {
      /** Good data. */
      protected static final double[][] DATASET1 = new double[][] {
          {4.0254623,  531026.0},
          {4.02804905, 664002.0},
          {4.02934242, 787079.0},
          {4.03128248, 984167.0},
          {4.03386923, 1294546.0},
          {4.03580929, 1560230.0},
          {4.03839603, 1887233.0},
          {4.0396894,  2113240.0},
          {4.04162946, 2375211.0},
          {4.04421621, 2687152.0},
          {4.04550958, 2862644.0},
          {4.04744964, 3078898.0},
          {4.05003639, 3327238.0},
          {4.05132976, 3461228.0},
          {4.05326982, 3580526.0},
          {4.05585657, 3576946.0},
          {4.05779662, 3439750.0},
          {4.06038337, 3220296.0},
          {4.06167674, 3070073.0},
          {4.0636168,  2877648.0},
          {4.06620355, 2595848.0},
          {4.06749692, 2390157.0},
          {4.06943698, 2175960.0},
          {4.07202373, 1895104.0},
          {4.0733171,  1687576.0},
          {4.07525716, 1447024.0},
          {4.0778439,  1130879.0},
          {4.07978396, 904900.0},
          {4.08237071, 717104.0},
          {4.08366408, 620014.0}
      };
      /** Poor data: right of peak not symmetric with left of peak. */
      protected static final double[][] DATASET2 = new double[][] {
          {-20.15,   1523.0},
          {-19.65,   1566.0},
          {-19.15,   1592.0},
          {-18.65,   1927.0},
          {-18.15,   3089.0},
          {-17.65,   6068.0},
          {-17.15,  14239.0},
          {-16.65,  34124.0},
          {-16.15,  64097.0},
          {-15.65, 110352.0},
          {-15.15, 164742.0},
          {-14.65, 209499.0},
          {-14.15, 267274.0},
          {-13.65, 283290.0},
          {-13.15, 275363.0},
          {-12.65, 258014.0},
          {-12.15, 225000.0},
          {-11.65, 200000.0},
          {-11.15, 190000.0},
          {-10.65, 185000.0},
          {-10.15, 180000.0},
          { -9.65, 179000.0},
          { -9.15, 178000.0},
          { -8.65, 177000.0},
          { -8.15, 176000.0},
          { -7.65, 175000.0},
          { -7.15, 174000.0},
          { -6.65, 173000.0},
          { -6.15, 172000.0},
         { -5.65, 171000.0},
         { -5.15, 170000.0}
     };
     /** Poor data: long tails. */
     protected static final double[][] DATASET3 = new double[][] {
         {-90.15,   1513.0},
         {-80.15,   1514.0},
         {-70.15,   1513.0},
         {-60.15,   1514.0},
         {-50.15,   1513.0},
         {-40.15,   1514.0},
         {-30.15,   1513.0},
         {-20.15,   1523.0},
         {-19.65,   1566.0},
         {-19.15,   1592.0},
         {-18.65,   1927.0},
         {-18.15,   3089.0},
         {-17.65,   6068.0},
         {-17.15,  14239.0},
         {-16.65,  34124.0},
         {-16.15,  64097.0},
         {-15.65, 110352.0},
         {-15.15, 164742.0},
         {-14.65, 209499.0},
         {-14.15, 267274.0},
         {-13.65, 283290.0},
         {-13.15, 275363.0},
         {-12.65, 258014.0},
         {-12.15, 214073.0},
         {-11.65, 182244.0},
         {-11.15, 136419.0},
         {-10.65,  97823.0},
         {-10.15,  58930.0},
         { -9.65,  35404.0},
         { -9.15,  16120.0},
         { -8.65,   9823.0},
         { -8.15,   5064.0},
         { -7.65,   2575.0},
         { -7.15,   1642.0},
         { -6.65,   1101.0},
         { -6.15,    812.0},
         { -5.65,    690.0},
         { -5.15,    565.0},
         {  5.15,    564.0},
         { 15.15,    565.0},
         { 25.15,    564.0},
         { 35.15,    565.0},
         { 45.15,    564.0},
         { 55.15,    565.0},
         { 65.15,    564.0},
         { 75.15,    565.0}
     };
     /** Poor data: right of peak is missing. */
     protected static final double[][] DATASET4 = new double[][] {
         {-20.15,   1523.0},
         {-19.65,   1566.0},
         {-19.15,   1592.0},
         {-18.65,   1927.0},
         {-18.15,   3089.0},
         {-17.65,   6068.0},
         {-17.15,  14239.0},
         {-16.65,  34124.0},
         {-16.15,  64097.0},
         {-15.65, 110352.0},
         {-15.15, 164742.0},
         {-14.65, 209499.0},
         {-14.15, 267274.0},
         {-13.65, 283290.0}
     };
     /** Good data, but few points. */
     protected static final double[][] DATASET5 = new double[][] {
         {4.0254623,  531026.0},
         {4.03128248, 984167.0},
         {4.03839603, 1887233.0},
         {4.04421621, 2687152.0},
         {4.05132976, 3461228.0},
         {4.05326982, 3580526.0},
         {4.05779662, 3439750.0},
         {4.0636168,  2877648.0},
         {4.06943698, 2175960.0},
         {4.07525716, 1447024.0},
         {4.08237071, 717104.0},
         {4.08366408, 620014.0}
     };
 
     /**
      * Basic.
      */
     @Test
     void testFit01() {
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter.fit(createDataset(DATASET1).toList());
 
         assertEquals(3496978.1837704973, parameters[0], 1e-4);
         assertEquals(4.054933085999146, parameters[1], 1e-4);
         assertEquals(0.015039355620304326, parameters[2], 1e-4);
     }
 
     @Test
     void testWithMaxIterations1() {
         final int maxIter = 20;
         final double[] init = { 3.5e6, 4.2, 0.1 };
 
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter
             .withMaxIterations(maxIter)
             .withStartPoint(init)
             .fit(createDataset(DATASET1).toList());
 
         assertEquals(3496978.1837704973, parameters[0], 1e-2);
         assertEquals(4.054933085999146, parameters[1], 1e-4);
         assertEquals(0.015039355620304326, parameters[2], 1e-4);
     }
 
     @Test
     void testWithMaxIterations2() {
         assertThrows(MathIllegalStateException.class, () -> {
             final int maxIter = 1; // Too few iterations.
             final double[] init = {3.5e6, 4.2, 0.1};
 
             GaussianCurveFitter fitter = GaussianCurveFitter.create();
             fitter.withMaxIterations(maxIter)
                 .withStartPoint(init)
                 .fit(createDataset(DATASET1).toList());
         });
     }
 
     @Test
     void testWithStartPoint() {
         final double[] init = { 3.5e6, 4.2, 0.1 };
 
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter
             .withStartPoint(init)
             .fit(createDataset(DATASET1).toList());
 
         assertEquals(3496978.1837704973, parameters[0], 1e-2);
         assertEquals(4.054933085999146, parameters[1], 1e-4);
         assertEquals(0.015039355620304326, parameters[2], 1e-4);
     }
 
     /**
      * Zero points is not enough observed points.
      */
     @Test
     void testFit02() {
         assertThrows(MathIllegalArgumentException.class, () -> {
             GaussianCurveFitter.create().fit(new WeightedObservedPoints().toList());
         });
     }
 
     /**
      * Two points is not enough observed points.
      */
     @Test
     void testFit03() {
         assertThrows(MathIllegalArgumentException.class, () -> {
             GaussianCurveFitter fitter = GaussianCurveFitter.create();
             fitter.fit(createDataset(new double[][]{
                 {4.0254623, 531026.0},
                 {4.02804905, 664002.0}
             }).toList());
         });
     }
 
     /**
      * Poor data: right of peak not symmetric with left of peak.
      */
     @Test
     void testFit04() {
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter.fit(createDataset(DATASET2).toList());
 
         assertEquals(233003.2967252038, parameters[0], 1e-4);
         assertEquals(-10.654887521095983, parameters[1], 1e-4);
         assertEquals(4.335937353196641, parameters[2], 1e-4);
     }
 
     /**
      * Poor data: long tails.
      */
     @Test
     void testFit05() {
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter.fit(createDataset(DATASET3).toList());
 
         assertEquals(283863.81929180305, parameters[0], 1e-4);
         assertEquals(-13.29641995105174, parameters[1], 1e-4);
         assertEquals(1.7297330293549908, parameters[2], 1e-4);
     }
 
     /**
      * Poor data: right of peak is missing.
      */
     @Test
     void testFit06() {
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter.fit(createDataset(DATASET4).toList());
 
         assertEquals(285250.66754309234, parameters[0], 1e-4);
         assertEquals(-13.528375695228455, parameters[1], 1e-4);
         assertEquals(1.5204344894331614, parameters[2], 1e-4);
     }
 
     /**
      * Basic with smaller dataset.
      */
     @Test
     void testFit07() {
         GaussianCurveFitter fitter = GaussianCurveFitter.create();
         double[] parameters = fitter.fit(createDataset(DATASET5).toList());
 
         assertEquals(3514384.729342235, parameters[0], 1e-4);
         assertEquals(4.054970307455625, parameters[1], 1e-4);
         assertEquals(0.015029412832160017, parameters[2], 1e-4);
     }
 
     @Test
     void testMath519() {
         // The optimizer will try negative sigma values but "GaussianCurveFitter"
         // will catch the raised exceptions and return NaN values instead.
 
         final double[] data = {
             1.1143831578403364E-29,
             4.95281403484594E-28,
             1.1171347211930288E-26,
             1.7044813962636277E-25,
             1.9784716574832164E-24,
             1.8630236407866774E-23,
             1.4820532905097742E-22,
             1.0241963854632831E-21,
             6.275077366673128E-21,
             3.461808994532493E-20,
             1.7407124684715706E-19,
             8.056687953553974E-19,
             3.460193945992071E-18,
             1.3883326374011525E-17,
             5.233894983671116E-17,
             1.8630791465263745E-16,
             6.288759227922111E-16,
             2.0204433920597856E-15,
             6.198768938576155E-15,
             1.821419346860626E-14,
             5.139176445538471E-14,
             1.3956427429045787E-13,
             3.655705706448139E-13,
             9.253753324779779E-13,
             2.267636001476696E-12,
             5.3880460095836855E-12,
             1.2431632654852931E-11
         };
 
         final WeightedObservedPoints obs = new WeightedObservedPoints();
         for (int i = 0; i < data.length; i++) {
             obs.add(i, data[i]);
         }
         final double[] p = GaussianCurveFitter.create().fit(obs.toList());
 
         assertEquals(53.1572792, p[1], 1e-7);
         assertEquals(5.75214622, p[2], 1e-8);
     }
 
     @Test
     void testMath798() {
         // When the data points are not commented out below, the fit stalls.
         // This is expected however, since the whole dataset hardly looks like
         // a Gaussian.
         // When commented out, the fit proceeds fine.
 
         final WeightedObservedPoints obs = new WeightedObservedPoints();
 
         obs.add(0.23, 395.0);
         //obs.add(0.68, 0.0);
         obs.add(1.14, 376.0);
         //obs.add(1.59, 0.0);
         obs.add(2.05, 163.0);
         //obs.add(2.50, 0.0);
         obs.add(2.95, 49.0);
         //obs.add(3.41, 0.0);
         obs.add(3.86, 16.0);
         //obs.add(4.32, 0.0);
         obs.add(4.77, 1.0);
 
         final double[] p = GaussianCurveFitter.create().fit(obs.toList());
 
         // Values are copied from a previous run of this test.
         assertEquals(420.8397296167364, p[0], 1e-12);
         assertEquals(0.603770729862231, p[1], 1e-15);
         assertEquals(1.0786447936766612, p[2], 1e-14);
     }
 
     /**
      * Adds the specified points to specified <code>GaussianCurveFitter</code>
      * instance.
      *
      * @param points Data points where first dimension is a point index and
      *        second dimension is an array of length two representing the point
      *        with the first value corresponding to X and the second value
      *        corresponding to Y.
      * @return the collection of observed points.
      */
     private static WeightedObservedPoints createDataset(double[][] points) {
         final WeightedObservedPoints obs = new WeightedObservedPoints();
         for (int i = 0; i < points.length; i++) {
             obs.add(points[i][0], points[i][1]);
         }
         return obs;
     }
 }