/*
 * 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
 *
 *     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.apache.sis.referencing.operation.transform;

import java.util.Arrays;
import org.opengis.util.FactoryException;
import org.opengis.referencing.datum.Ellipsoid;
import org.opengis.referencing.operation.MathTransformFactory;
import org.opengis.referencing.operation.TransformException;
import org.opengis.parameter.ParameterValueGroup;
import org.apache.sis.referencing.CommonCRS;
import org.apache.sis.referencing.operation.provider.FranceGeocentricInterpolation;
import org.apache.sis.referencing.operation.provider.Molodensky;
import org.apache.sis.referencing.operation.provider.FranceGeocentricInterpolationTest;
import org.apache.sis.referencing.operation.provider.GeocentricTranslationTest;
import org.apache.sis.referencing.util.Formulas;
import org.apache.sis.referencing.datum.HardCodedDatum;

// Test dependencies
import org.junit.Test;
import org.apache.sis.test.DependsOnMethod;
import org.apache.sis.test.DependsOn;
import org.apache.sis.test.TestUtilities;

import static java.lang.StrictMath.*;
import static org.junit.Assert.*;
import static org.opengis.test.Assert.assertInstanceOf;


/**
 * Tests {@link MolodenskyTransform}. The {@code compareWithGeocentricTranslation()}
 * method uses {@link EllipsoidToCentricTransform} as a reference implementation.
 * The errors compared to geocentric translations should not be greater than
 * approximately 1 centimetre.
 *
 * @author  Tara Athan
 * @author  Martin Desruisseaux (Geomatys)
 * @author  Rémi Maréchal (Geomatys)
 */
@DependsOn({
    CoordinateDomainTest.class,
    ContextualParametersTest.class,
    EllipsoidToCentricTransformTest.class   // Used as a reference implementation
})
public final class MolodenskyTransformTest extends MathTransformTestCase {
    /**
     * Creates a new test case.
     */
    public MolodenskyTransformTest() {
        final double delta = toRadians(100.0 / 60) / 1852;      // Approximately 100 metres
        derivativeDeltas   = new double[] {delta, delta, 100};  // (Δλ, Δφ, Δh)
        λDimension         = new int[] {0};                     // Dimension for which to ignore ±360° differences.
        zDimension         = new int[] {2};                     // Dimension of h where to apply zTolerance
        zTolerance         = Formulas.LINEAR_TOLERANCE;         // Tolerance for ellipsoidal heights (h)
        tolerance          = Formulas.ANGULAR_TOLERANCE;        // Tolerance for longitude and latitude in degrees
    }

    /**
     * Creates a Molodensky transform for a datum shift from WGS84 to ED50.
     * Tolerance thresholds are also initialized.
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     */
    private void create(final boolean abridged) throws FactoryException {
        final Ellipsoid source = CommonCRS.WGS84.ellipsoid();
        final Ellipsoid target = CommonCRS.ED50.ellipsoid();
        transform = MolodenskyTransform.createGeodeticTransformation(
                DefaultMathTransformFactory.provider(),
                source, true, target, true,
                GeocentricTranslationTest.TX,
                GeocentricTranslationTest.TY,
                GeocentricTranslationTest.TZ,
                abridged);

        tolerance  = GeocentricTranslationTest.precision(1);        // Half the precision of target sample point
        zTolerance = GeocentricTranslationTest.precision(3);        // Required precision for h
        assertFalse(transform.isIdentity());
        validate();
    }

    /**
     * Tests the derivative of the Abridged Molodensky transformation.
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     * @throws TransformException if the transformation failed.
     */
    @Test
    public void testAbridgedMolodenskyDerivative() throws FactoryException, TransformException {
        create(true);
        verifyDerivative( 0,  0,  0);
        verifyDerivative(-3, 30,  7);
        verifyDerivative(+6, 60, 20);
    }

    /**
     * Tests the derivative of the Molodensky transformation.
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     * @throws TransformException if the transformation failed.
     */
    @Test
    @DependsOnMethod("testAbridgedMolodenskyDerivative")
    public void testMolodenskyDerivative() throws FactoryException, TransformException {
        create(false);
        verifyDerivative( 0,  0,  0);
        verifyDerivative(-3, 30,  7);
        verifyDerivative(+6, 60, 20);
    }

    /**
     * Tests using the sample point given by the EPSG guide.
     *
     * <ul>
     *   <li>Source point in WGS84: 53°48'33.820"N, 02°07'46.380"E, 73.00 metres.</li>
     *   <li>Target point in ED50:  53°48'36.565"N, 02'07"51.477"E, 28.02 metres.</li>
     *   <li>Datum shift: dX = +84.87m, dY = +96.49m, dZ = +116.95m.</li>
     * </ul>
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     * @throws TransformException if the transformation failed.
     */
    @Test
    @DependsOnMethod("testAbridgedMolodenskyDerivative")
    public void testAbridgedMolodensky() throws FactoryException, TransformException {
        create(true);
        final double[] sample   = GeocentricTranslationTest.samplePoint(1);
        final double[] expected = GeocentricTranslationTest.samplePoint(5);
        isInverseTransformSupported = false;
        tolerance = Formulas.LINEAR_TOLERANCE;  // Other SIS branches use a stricter threshold.
        verifyTransform(sample, expected);
        /*
         * When testing the inverse transformation, we need to relax slightly
         * the tolerance for the 'h' value.
         */
        zTolerance = Formulas.LINEAR_TOLERANCE;
        isInverseTransformSupported = true;
        verifyTransform(sample, expected);
    }

    /**
     * Tests using the same EPSG example than the one provided in {@link EllipsoidToCentricTransformTest}.
     *
     * <ul>
     *   <li>Source point in WGS84: 53°48'33.820"N, 02°07'46.380"E, 73.00 metres.</li>
     *   <li>Target point in ED50:  53°48'36.565"N, 02'07"51.477"E, 28.02 metres.</li>
     *   <li>Datum shift: dX = +84.87m, dY = +96.49m, dZ = +116.95m.</li>
     * </ul>
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     * @throws TransformException if the transformation failed.
     */
    @Test
    @DependsOnMethod({"testAbridgedMolodensky", "testMolodenskyDerivative"})
    public void testMolodensky() throws FactoryException, TransformException {
        create(false);
        final double[] sample   = GeocentricTranslationTest.samplePoint(1);
        final double[] expected = GeocentricTranslationTest.samplePoint(4);
        isInverseTransformSupported = false;
        tolerance = Formulas.LINEAR_TOLERANCE;  // Other SIS branches use a stricter threshold.
        verifyTransform(sample, expected);
        /*
         * When testing the inverse transformation, we need to relax slightly
         * the tolerance for the 'h' value.
         */
        zTolerance = Formulas.LINEAR_TOLERANCE;
        isInverseTransformSupported = true;
        verifyTransform(sample, expected);
    }

    /**
     * Tests the point used in {@link FranceGeocentricInterpolationTest}. We use this test for measuring the
     * errors induced by the use of the Molodensky approximation instead of a real geocentric translation.
     * The error is approximately 1 centimetre, which is about 6 times more than the accuracy of the point
     * given in {@code FranceGeocentricInterpolationTest}.
     *
     * @throws FactoryException if an error occurred while creating the transform.
     * @throws TransformException if transformation of a point failed.
     */
    @Test
    @DependsOnMethod("testMolodensky")
    public void testFranceGeocentricInterpolationPoint() throws FactoryException, TransformException {
        transform = MolodenskyTransform.createGeodeticTransformation(
                DefaultMathTransformFactory.provider(),
                HardCodedDatum.NTF.getEllipsoid(), true,        // Clarke 1880 (IGN)
                CommonCRS.ETRS89.ellipsoid(), true,             // GRS 1980 ellipsoid
               -FranceGeocentricInterpolation.TX,
               -FranceGeocentricInterpolation.TY,
               -FranceGeocentricInterpolation.TZ,
                false);
        /*
         * Code below is a copy-and-paste of GeocentricTranslationTest.testFranceGeocentricInterpolationPoint(),
         * but with the tolerance threshold increased. We do not let the error goes beyond 1 cm however.
         */
        tolerance = Formulas.LINEAR_TOLERANCE;  // Other SIS branches use a stricter threshold.
        final double[] source   = Arrays.copyOf(FranceGeocentricInterpolationTest.samplePoint(1), 3);
        final double[] expected = Arrays.copyOf(FranceGeocentricInterpolationTest.samplePoint(2), 3);
        expected[2] = 43.15;  // Anti-regression (this value is not provided in NTG_88 guidance note).
        verifyTransform(source, expected);
        validate();
    }

    /**
     * Tests conversion of random points. The test is performed with the Molodensky transform,
     * not the abridged one, because the errors caused by the abridged Molodensky method are
     * too high for this test.
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     * @throws TransformException if a transformation failed.
     */
    @Test
    @DependsOnMethod("testMolodensky")
    public void testRandomPoints() throws FactoryException, TransformException {
        create(false);
        tolerance  = Formulas.LINEAR_TOLERANCE * 3;     // To be converted in degrees by ToleranceModifier.GEOGRAPHIC
        zTolerance = Formulas.LINEAR_TOLERANCE * 2;
//      toleranceModifier = ToleranceModifiers.concatenate(ToleranceModifier.GEOGRAPHIC, toleranceModifier);
        verifyInDomain(new double[] {-179, -85, -500},
                       new double[] {+179, +85, +500},
                       new int[]    {   8,   8,    8},
                       TestUtilities.createRandomNumberGenerator(208129394));
    }

    /**
     * Tests the creation through the provider.
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     * @throws TransformException if a transformation failed.
     */
    @Test
    @DependsOnMethod("testRandomPoints")
    public void testProvider() throws FactoryException, TransformException {
        final MathTransformFactory factory = new MathTransformFactoryMock(new Molodensky());
        final ParameterValueGroup parameters = factory.getDefaultParameters("Molodenski");
        parameters.parameter("dim").setValue(3);
        parameters.parameter("dx").setValue(-3.0);
        parameters.parameter("dy").setValue(142.0);
        parameters.parameter("dz").setValue(183.0);
        parameters.parameter("src_semi_major").setValue(6378206.4);
        parameters.parameter("src_semi_minor").setValue(6356583.8);
        parameters.parameter("tgt_semi_major").setValue(6378137.0);
        parameters.parameter("tgt_semi_minor").setValue(6356752.31414036);
        transform = factory.createParameterizedTransform(parameters);
        assertEquals(3, transform.getSourceDimensions());
        assertEquals(3, transform.getTargetDimensions());
        tolerance  = Formulas.ANGULAR_TOLERANCE * 5;
        zTolerance = Formulas.LINEAR_TOLERANCE  * 5;
        verifyInDomain(CoordinateDomain.RANGE_10, ORDINATE_COUNT);
    }

    /**
     * Verifies that creating a Molodensky operation with same source and target ellipsoid and zero translation
     * results in an identity affine transform.
     *
     * @throws FactoryException if an error occurred while creating a transform step.
     */
    @Test
    public void testIdentity() throws FactoryException {
        final Ellipsoid source = CommonCRS.WGS84.ellipsoid();
        transform = MolodenskyTransform.createGeodeticTransformation(
                DefaultMathTransformFactory.provider(), source, false, source, false, 0, 0, 0, false);
        assertInstanceOf("Expected optimized type.", LinearTransform.class, transform);
        assertTrue(transform.isIdentity());
        validate();
    }

    /**
     * Tests the standard Well Known Text (version 1) formatting.
     * The result is what we show to users, but may quite different than what SIS has in memory.
     *
     * @throws FactoryException if an error occurred while creating a transform.
     * @throws TransformException should never happen.
     */
    @Test
    public void testWKT() throws FactoryException, TransformException {
        create(true);
        assertWktEquals("PARAM_MT[“Abridged_Molodenski”,\n" +
                        "  PARAMETER[“dim”, 3],\n" +
                        "  PARAMETER[“src_semi_major”, 6378137.0],\n" +
                        "  PARAMETER[“src_semi_minor”, 6356752.314245179],\n" +
                        "  PARAMETER[“tgt_semi_major”, 6378388.0],\n" +
                        "  PARAMETER[“tgt_semi_minor”, 6356911.9461279465],\n" +
                        "  PARAMETER[“dx”, 84.87],\n" +
                        "  PARAMETER[“dy”, 96.49],\n" +
                        "  PARAMETER[“dz”, 116.95],\n" +
                        "  PARAMETER[“Semi-major axis length difference”, 251.0],\n" +
                        "  PARAMETER[“Flattening difference”, 1.4192702255886284E-5]]");

        transform = transform.inverse();
        assertWktEquals("PARAM_MT[“Abridged_Molodenski”,\n" +
                        "  PARAMETER[“dim”, 3],\n" +
                        "  PARAMETER[“src_semi_major”, 6378388.0],\n" +
                        "  PARAMETER[“src_semi_minor”, 6356911.9461279465],\n" +
                        "  PARAMETER[“tgt_semi_major”, 6378137.0],\n" +
                        "  PARAMETER[“tgt_semi_minor”, 6356752.314245179],\n" +
                        "  PARAMETER[“dx”, -84.87],\n" +
                        "  PARAMETER[“dy”, -96.49],\n" +
                        "  PARAMETER[“dz”, -116.95],\n" +
                        "  PARAMETER[“Semi-major axis length difference”, -251.0],\n" +
                        "  PARAMETER[“Flattening difference”, -1.4192702255886284E-5]]");
    }

    /**
     * Tests the internal Well Known Text formatting.
     * This WKT shows what SIS has in memory for debugging purpose.
     * This is normally not what we show to users.
     *
     * @throws FactoryException if an error occurred while creating a transform.
     * @throws TransformException should never happen.
     */
    @Test
    public void testInternalWKT() throws FactoryException, TransformException {
        create(true);
        assertInternalWktEquals(
                "Concat_MT[\n" +
                "  Param_MT[“Affine”,\n" +
                "    Parameter[“num_row”, 4],\n" +
                "    Parameter[“num_col”, 4],\n" +
                "    Parameter[“elt_0_0”, 0.017453292519943295],\n" +       // Degrees to radians conversion
                "    Parameter[“elt_1_1”, 0.017453292519943295]],\n" +
                "  Param_MT[“Molodensky (radians domain)”,\n" +
                "    Parameter[“src_semi_major”, 6378137.0],\n" +
                "    Parameter[“src_semi_minor”, 6356752.314245179],\n" +
                "    Parameter[“Semi-major axis length difference”, 251.0, Id[“EPSG”, 8654]],\n" +
                "    Parameter[“Flattening difference”, 1.4192702255886284E-5, Id[“EPSG”, 8655]],\n" +
                "    Parameter[“X-axis translation”, 84.87, Id[“EPSG”, 8605]],\n" +
                "    Parameter[“Y-axis translation”, 96.49, Id[“EPSG”, 8606]],\n" +
                "    Parameter[“Z-axis translation”, 116.95, Id[“EPSG”, 8607]],\n" +
                "    Parameter[“abridged”, TRUE],\n" +
                "    Parameter[“dim”, 3]],\n" +
                "  Param_MT[“Affine”,\n" +
                "    Parameter[“num_row”, 4],\n" +
                "    Parameter[“num_col”, 4],\n" +
                "    Parameter[“elt_0_0”, 57.29577951308232],\n" +          // Radians to degrees conversion
                "    Parameter[“elt_1_1”, 57.29577951308232]]]");
    }
}
