/* Copyright 2002-2022 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.models.earth.troposphere;
  
  import org.hipparchus.util.FastMath;
  import org.hipparchus.util.Precision;
  import org.junit.Assert;
  import org.junit.Before;
  import org.junit.BeforeClass;
  import org.junit.Test;
  import org.orekit.Utils;
  import org.orekit.bodies.GeodeticPoint;
  import org.orekit.errors.OrekitException;
  import org.orekit.time.AbsoluteDate;
  import org.orekit.time.TimeScalesFactory;
  
  public class ViennaOneModelTest {
   
      private static double epsilon = 1e-6;
  
      @BeforeClass
      public static void setUpGlobal() {
          Utils.setDataRoot("atmosphere");
      }
  
      @Before
      public void setUp() throws OrekitException {
          Utils.setDataRoot("regular-data:potential/shm-format");
      }
  
      @Test
      public void testMappingFactors() {
          
          // Site (NRAO, Green Bank, WV): latitude:  38°
          //                              longitude: 280°
          //                              height:    824.17 m
          //
          // Date: MJD 55055 -> 12 August 2009 at 0h UT
          //
          // Ref for the inputs:    Petit, G. and Luzum, B. (eds.), IERS Conventions (2010),
          //                        IERS Technical Note No. 36, BKG (2010)
          //
          // Values: ah  = 0.00127683
          //         aw  = 0.00060955
          //         zhd = 2.0966 m
          //         zwd = 0.2140 m
          //
          // Values taken from: http://vmf.geo.tuwien.ac.at/trop_products/GRID/2.5x2/VMF1/VMF1_OP/2009/VMFG_20090812.H00
          //
          // Expected mapping factors : hydrostatic -> 3.425088
          //                                    wet -> 3.448300
          //
          // Expected outputs are obtained by performing the Matlab script vmf1_ht.m provided by TU WIEN:
          // http://vmf.geo.tuwien.ac.at/codes/
          //
  
          final AbsoluteDate date = AbsoluteDate.createMJDDate(55055, 0, TimeScalesFactory.getUTC());
          
          final double latitude     = FastMath.toRadians(38.0);
          final double longitude    = FastMath.toRadians(280.0);
          final double height       = 824.17;
          final GeodeticPoint point = new GeodeticPoint(latitude, longitude, height);
  
          final double elevation     = 0.5 * FastMath.PI - 1.278564131;
          final double expectedHydro = 3.425088;
          final double expectedWet   = 3.448300;
          
          final double[] a = { 0.00127683, 0.00060955 };
          final double[] z = {2.0966, 0.2140};
          
          final ViennaOneModel model = new ViennaOneModel(a, z);
          
          final double[] computedMapping = model.mappingFactors(elevation, point, date);
          
          Assert.assertEquals(expectedHydro, computedMapping[0], 4.1e-6);
          Assert.assertEquals(expectedWet,   computedMapping[1], 1.0e-6);
      }
  
      @Test
      public void testDelay() {
          final double elevation = 10d;
          final double height = 100d;
          final AbsoluteDate date = new AbsoluteDate();
          final double[] a = { 0.00127683, 0.00060955 };
          final double[] z = {2.0966, 0.2140};
         final GeodeticPoint point = new GeodeticPoint(FastMath.toRadians(45.0), FastMath.toRadians(45.0), height);
         ViennaOneModel model = new ViennaOneModel(a, z);
         final double path = model.pathDelay(FastMath.toRadians(elevation), point, model.getParameters(), date);
         Assert.assertTrue(Precision.compareTo(path, 20d, epsilon) < 0);
         Assert.assertTrue(Precision.compareTo(path, 0d, epsilon) > 0);
     }
 
     @Test
     public void testFixedHeight() {
         final AbsoluteDate date = new AbsoluteDate();
         final double[] a = { 0.00127683, 0.00060955 };
         final double[] z = {2.0966, 0.2140};
         final GeodeticPoint point = new GeodeticPoint(FastMath.toRadians(45.0), FastMath.toRadians(45.0), 350.0);
         ViennaOneModel model = new ViennaOneModel(a, z);
         double lastDelay = Double.MAX_VALUE;
         // delay shall decline with increasing elevation angle
         for (double elev = 10d; elev < 90d; elev += 8d) {
             final double delay = model.pathDelay(FastMath.toRadians(elev), point, model.getParameters(), date);
             Assert.assertTrue(Precision.compareTo(delay, lastDelay, epsilon) < 0);
             lastDelay = delay;
         }
     }
 
 }