/*
 * 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.datum;

import java.util.Date;
import java.util.Map;
import java.util.HashMap;
import org.opengis.referencing.datum.PixelInCell;
import org.opengis.referencing.datum.VerticalDatumType;
import org.apache.sis.referencing.NamedIdentifier;
import org.apache.sis.referencing.internal.VerticalDatumTypes;
import org.apache.sis.metadata.iso.citation.HardCodedCitations;
import org.apache.sis.measure.Units;

import static org.opengis.referencing.datum.Datum.*;
import static org.apache.sis.util.internal.StandardDateFormat.MILLISECONDS_PER_DAY;


/**
 * Collection of datum for testing purpose.
 *
 * @author  Martin Desruisseaux (Geomatys)
 */
public final class HardCodedDatum {
    /**
     * Greenwich meridian (EPSG:8901), with angular measurements in decimal degrees.
     */
    public static final DefaultPrimeMeridian GREENWICH = new DefaultPrimeMeridian(
            properties("Greenwich", "8901", null),
            0, Units.DEGREE);

    /**
     * Paris meridian (EPSG:8903), with angular measurements in grad.
     */
    public static final DefaultPrimeMeridian PARIS = new DefaultPrimeMeridian(
            properties("Paris", "8903", null),
            2.5969213, Units.GRAD);

    /**
     * Old Paris meridian (EPSG:8914) defined as 2°20'13.95"E.
     * Equivalent to 2.596898 grad (value given by EPSG).
     *
     * <p>When used together with {@link #PARIS}, this prime meridian is useful for testing
     * two real-world prime meridians that are very close together but still different.</p>
     */
    public static final DefaultPrimeMeridian PARIS_RGS = new DefaultPrimeMeridian(
            properties("Paris RGS", "8914", null),
            2 + (20 + 13.95/60)/60, Units.DEGREE);

    /**
     * WGS 1984 datum (EPSG:6326). Prime meridian is Greenwich.
     * This datum is used in GPS systems.
     */
    public static final DefaultGeodeticDatum WGS84 = new DefaultGeodeticDatum(
            properties("World Geodetic System 1984", "6326", "Satellite navigation."),
            new DefaultEllipsoid(GeodeticDatumMock.WGS84.getEllipsoid()), GREENWICH);

    /**
     * WGS 1972 datum (EPSG:6322). Prime meridian is Greenwich.
     * This datum is used, together with {@linkplain #WGS84}, in
     * {@code org.apache.sis.referencing.operation.transform.EarthGravitationalModel}.
     */
    public static final DefaultGeodeticDatum WGS72 = new DefaultGeodeticDatum(
            properties("World Geodetic System 1972", "6322", WGS84.getScope()),
            new DefaultEllipsoid(GeodeticDatumMock.WGS84.getEllipsoid()), GREENWICH);

    /**
     * Nouvelle Triangulation Française datum (EPSG:6807). Prime meridian is Paris.
     */
    public static final DefaultGeodeticDatum NTF = new DefaultGeodeticDatum(
            properties("Nouvelle Triangulation Française", "6807", "Topographic mapping."),
            new DefaultEllipsoid(GeodeticDatumMock.NTF.getEllipsoid()), PARIS);

    /**
     * Tokyo 1918 datum (EPSG:6301). Ellipsoid is Bessel 1841 and prime meridian is Greenwich.
     * Bursa-Wolf parameters to {@link #JGD2000} are (-146.414, 507.337, 680.507).
     */
    public static final DefaultGeodeticDatum TOKYO = new DefaultGeodeticDatum(
            properties("Tokyo 1918", "6301", "Geodetic survey."),
            DefaultEllipsoid.createFlattenedSphere(properties("Bessel 1841", "7004", null),
                    6377397.155, 299.1528128, Units.METRE), GREENWICH);

    /**
     * Japanese Geodetic Datum 2000 datum (EPSG:6612). Ellipsoid is GRS 1980 and prime meridian is Greenwich.
     * This is useful for testing datum shift from {@link #TOKYO}.
     */
    public static final DefaultGeodeticDatum JGD2000 = new DefaultGeodeticDatum(
            properties("Japanese Geodetic Datum 2000", "6612", TOKYO.getScope()),
            DefaultEllipsoid.createFlattenedSphere(properties("GRS 1980", "7019", null),
                    6378137, 298.257222101, Units.METRE), GREENWICH);

    /**
     * Spherical datum based on GRS 1980 Authalic Sphere (EPSG:6047). Prime meridian is Greenwich.
     */
    public static final DefaultGeodeticDatum SPHERE = new DefaultGeodeticDatum(
            properties("Not specified (based on GRS 1980 Authalic Sphere)", "6047", "Not a valid datum."),
            new DefaultEllipsoid(GeodeticDatumMock.SPHERE.getEllipsoid()), GREENWICH);

    /**
     * Ellipsoid for measurements of height above the ellipsoid.
     * This is not a valid datum according ISO 19111, but is used by Apache SIS for internal calculation.
     */
    public static final DefaultVerticalDatum ELLIPSOID = new DefaultVerticalDatum(
            properties("Ellipsoid", null, SPHERE.getScope()),
            VerticalDatumTypes.ELLIPSOIDAL);

    /**
     * Mean sea level, which can be used as an approximation of geoid.
     */
    public static final DefaultVerticalDatum MEAN_SEA_LEVEL = new DefaultVerticalDatum(
            properties("Mean Sea Level", "5100", "Hydrography."),
            VerticalDatumType.GEOIDAL);

    /**
     * Default datum for time measured since January 1st, 1970 at 00:00 UTC.
     */
    public static final DefaultTemporalDatum UNIX = new DefaultTemporalDatum(
            properties("UNIX", null, null),
            new Date(0));

    /**
     * Default datum for time measured since November 17, 1858 at 00:00 UTC.
     */
    public static final DefaultTemporalDatum MODIFIED_JULIAN = new DefaultTemporalDatum(
            properties("Modified Julian", null, null),
            new Date(-40587L * MILLISECONDS_PER_DAY));

    /**
     * A parametric datum for day of year, without any particular year.
     */
    public static final DefaultParametricDatum DAY_OF_YEAR = new DefaultParametricDatum(
            properties("Day of year", null, null));

    /**
     * Image with {@link PixelInCell#CELL_CENTER}.
     */
    public static final DefaultImageDatum IMAGE = new DefaultImageDatum(
            properties("Image", null, null),
            PixelInCell.CELL_CENTER);

    /**
     * An engineering datum for unknown coordinate reference system. Such CRS are usually
     * assumed Cartesian, but will not have any transformation path to other CRS.
     */
    public static final DefaultEngineeringDatum UNKNOWN = new DefaultEngineeringDatum(properties("Unknown", null, null));

    /**
     * Creates a map of properties for the given name and EPSG code.
     */
    private static Map<String,?> properties(final String name, final String code, final CharSequence scope) {
        final Map<String,Object> properties = new HashMap<>(4);
        properties.put(NAME_KEY, name);
        if (code != null) {
            properties.put(IDENTIFIERS_KEY, new NamedIdentifier(HardCodedCitations.EPSG, code));
        }
        if (scope != null) {
            properties.put(SCOPE_KEY, scope);
        }
        return properties;
    }

    /**
     * Do not allow instantiation of this class.
     */
    private HardCodedDatum() {
    }
}
