/*
 * 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 javax.xml.bind.annotation.XmlType;
import javax.xml.bind.annotation.XmlSchemaType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlSeeAlso;
import org.opengis.util.GenericName;
import org.opengis.util.InternationalString;
import org.opengis.metadata.extent.Extent;
import org.opengis.metadata.citation.Citation;
import org.opengis.referencing.datum.Datum;
import org.opengis.referencing.ReferenceIdentifier;
import org.apache.sis.referencing.AbstractIdentifiedObject;
import org.apache.sis.referencing.IdentifiedObjects;
import org.apache.sis.util.iso.Types;
import org.apache.sis.util.CharSequences;
import org.apache.sis.util.ComparisonMode;
import org.apache.sis.internal.metadata.Identifiers;
import org.apache.sis.internal.metadata.NameToIdentifier;
import org.apache.sis.internal.metadata.MetadataUtilities;
import org.apache.sis.metadata.iso.citation.Citations;
import org.apache.sis.io.wkt.ElementKind;
import org.apache.sis.io.wkt.Formatter;

import static org.apache.sis.util.Utilities.deepEquals;
import static org.apache.sis.util.collection.Containers.property;

// Branch-dependent imports
import java.util.Objects;


/**
 * Specifies the relationship of a {@linkplain org.apache.sis.referencing.cs.AbstractCS Coordinate System} to the earth.
 * A datum can be defined as a set of real points on the earth that have coordinates.
 * Each datum subtype can be associated with only specific types of
 * {@linkplain org.apache.sis.referencing.cs.AbstractCS coordinate systems}, thus creating specific types of
 * {@linkplain org.apache.sis.referencing.crs.AbstractCRS coordinate reference system}.
 *
 * <div class="section">Instantiation</div>
 * This class is conceptually <cite>abstract</cite>, even if it is technically possible to instantiate it.
 * Typical applications should create instances of the most specific subclass prefixed by {@code Default} instead.
 *
 * <div class="section">Immutability and thread safety</div>
 * This base class is immutable if the property <em>values</em> (not necessarily the map itself) given to the
 * constructor are also immutable. Most SIS subclasses and related classes are immutable under similar conditions.
 * This means that unless otherwise noted in the javadoc, {@code Datum} instances created using only SIS factories
 * and static constants can be shared by many objects and passed between threads without synchronization.
 *
 * @author  Martin Desruisseaux (IRD, Geomatys)
 * @version 0.7
 *
 * @see org.apache.sis.referencing.cs.AbstractCS
 * @see org.apache.sis.referencing.crs.AbstractCRS
 *
 * @since 0.4
 * @module
 */
@XmlType(name = "AbstractDatumType", propOrder = {
    "domainOfValidity",
    "scope",
    "anchorPoint",
    "realizationEpoch"
})
@XmlRootElement(name = "AbstractDatum")
@XmlSeeAlso({
    DefaultGeodeticDatum.class,
    DefaultVerticalDatum.class,
    DefaultTemporalDatum.class,
    DefaultParametricDatum.class,
    DefaultEngineeringDatum.class,
    DefaultImageDatum.class
})
public class AbstractDatum extends AbstractIdentifiedObject implements Datum {
    /**
     * Serial number for inter-operability with different versions.
     */
    private static final long serialVersionUID = -4894180465652474930L;

    /**
     * Description, possibly including coordinates, of the point or points used to anchor the datum
     * to the Earth. Also known as the "origin", especially for Engineering and Image Datums.
     *
     * <p><b>Consider this field as final!</b>
     * This field is modified only at unmarshalling time by {@link #setAnchorPoint(InternationalString)}</p>
     *
     * @see #getAnchorPoint()
     */
    private InternationalString anchorDefinition;

    /**
     * The time after which this datum definition is valid. This time may be precise
     * (e.g. 1997 for IRTF97) or merely a year (e.g. 1983 for NAD83). If the time is
     * not defined, then the value is {@link Long#MIN_VALUE}.
     *
     * <p><b>Consider this field as final!</b>
     * This field is modified only at unmarshalling time by {@link #setRealizationEpoch(Date)}</p>
     */
    private long realizationEpoch;

    /**
     * Area or region in which this datum object is valid.
     *
     * <p><b>Consider this field as final!</b>
     * This field is modified only at unmarshalling time by {@link #setDomainOfValidity(Extent)}</p>
     *
     * @see #getDomainOfValidity()
     */
    private Extent domainOfValidity;

    /**
     * Description of domain of usage, or limitations of usage, for which this datum object is valid.
     *
     * <p><b>Consider this field as final!</b>
     * This field is modified only at unmarshalling time by {@link #setScope(InternationalString)}</p>
     *
     * @see #getScope()
     */
    private InternationalString scope;

    /**
     * Creates a datum from the given properties.
     * The properties given in argument follow the same rules than for the
     * {@linkplain AbstractIdentifiedObject#AbstractIdentifiedObject(Map) super-class constructor}.
     * Additionally, the following properties are understood by this constructor:
     *
     * <table class="sis">
     *   <caption>Recognized properties (non exhaustive list)</caption>
     *   <tr>
     *     <th>Property name</th>
     *     <th>Value type</th>
     *     <th>Returned by</th>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.datum.Datum#ANCHOR_POINT_KEY}</td>
     *     <td>{@link InternationalString} or {@link String}</td>
     *     <td>{@link #getAnchorPoint()}</td>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.datum.Datum#REALIZATION_EPOCH_KEY}</td>
     *     <td>{@link Date}</td>
     *     <td>{@link #getRealizationEpoch()}</td>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.datum.Datum#DOMAIN_OF_VALIDITY_KEY}</td>
     *     <td>{@link Extent}</td>
     *     <td>{@link #getDomainOfValidity()}</td>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.datum.Datum#SCOPE_KEY}</td>
     *     <td>{@link InternationalString} or {@link String}</td>
     *     <td>{@link #getScope()}</td>
     *   </tr>
     *   <tr>
     *     <th colspan="3" class="hsep">Defined in parent class (reminder)</th>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.IdentifiedObject#NAME_KEY}</td>
     *     <td>{@link ReferenceIdentifier} or {@link String}</td>
     *     <td>{@link #getName()}</td>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.IdentifiedObject#ALIAS_KEY}</td>
     *     <td>{@link GenericName} or {@link CharSequence} (optionally as array)</td>
     *     <td>{@link #getAlias()}</td>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.IdentifiedObject#IDENTIFIERS_KEY}</td>
     *     <td>{@link ReferenceIdentifier} (optionally as array)</td>
     *     <td>{@link #getIdentifiers()}</td>
     *   </tr>
     *   <tr>
     *     <td>{@value org.opengis.referencing.IdentifiedObject#REMARKS_KEY}</td>
     *     <td>{@link InternationalString} or {@link String}</td>
     *     <td>{@link #getRemarks()}</td>
     *   </tr>
     * </table>
     *
     * @param  properties  the properties to be given to the identified object.
     */
    public AbstractDatum(final Map<String,?> properties) {
        super(properties);
        realizationEpoch = MetadataUtilities.toMilliseconds(property(properties, REALIZATION_EPOCH_KEY, Date.class));
        domainOfValidity = property(properties, DOMAIN_OF_VALIDITY_KEY, Extent.class);
        anchorDefinition = Types.toInternationalString(properties, ANCHOR_POINT_KEY);
        scope            = Types.toInternationalString(properties, SCOPE_KEY);
    }

    /**
     * Creates a new datum with the same values than the specified one.
     * This copy constructor provides a way to convert an arbitrary implementation into a SIS one
     * or a user-defined one (as a subclass), usually in order to leverage some implementation-specific API.
     *
     * <p>This constructor performs a shallow copy, i.e. the properties are not cloned.</p>
     *
     * @param  datum  the datum to copy.
     */
    protected AbstractDatum(final Datum datum) {
        super(datum);
        realizationEpoch = MetadataUtilities.toMilliseconds(datum.getRealizationEpoch());
        domainOfValidity = datum.getDomainOfValidity();
        scope            = datum.getScope();
        anchorDefinition = datum.getAnchorPoint();
    }

    /**
     * Returns a SIS datum implementation with the values of the given arbitrary implementation.
     * This method performs the first applicable action in the following choices:
     *
     * <ul>
     *   <li>If the given object is {@code null}, then this method returns {@code null}.</li>
     *   <li>Otherwise if the given object is an instance of
     *       {@link org.opengis.referencing.datum.GeodeticDatum},
     *       {@link org.opengis.referencing.datum.VerticalDatum},
     *       {@link org.opengis.referencing.datum.TemporalDatum},
     *       {@link org.opengis.referencing.datum.EngineeringDatum} or
     *       {@link org.opengis.referencing.datum.ImageDatum},
     *       then this method delegates to the {@code castOrCopy(…)} method of the corresponding SIS subclass.
     *       Note that if the given object implements more than one of the above-cited interfaces,
     *       then the {@code castOrCopy(…)} method to be used is unspecified.</li>
     *   <li>Otherwise if the given object is already an instance of
     *       {@code AbstractDatum}, then it is returned unchanged.</li>
     *   <li>Otherwise a new {@code AbstractDatum} instance is created using the
     *       {@linkplain #AbstractDatum(Datum) copy constructor}
     *       and returned. Note that this is a <cite>shallow</cite> copy operation, since the other
     *       properties contained in the given object are not recursively copied.</li>
     * </ul>
     *
     * @param  object  the object to get as a SIS implementation, or {@code null} if none.
     * @return a SIS implementation containing the values of the given object (may be the
     *         given object itself), or {@code null} if the argument was null.
     */
    public static AbstractDatum castOrCopy(final Datum object) {
        return SubTypes.castOrCopy(object);
    }

    /**
     * Returns the GeoAPI interface implemented by this class.
     * The default implementation returns {@code Datum.class}.
     * Subclasses implementing a more specific GeoAPI interface shall override this method.
     *
     * @return the datum interface implemented by this class.
     */
    @Override
    public Class<? extends Datum> getInterface() {
        return Datum.class;
    }

    /**
     * Returns a description of the point(s) used to anchor the datum to the Earth.
     * Also known as the "origin", especially for Engineering and Image Datums.
     *
     * <ul>
     *   <li>For a {@linkplain DefaultGeodeticDatum geodetic datum}, the anchor may be the point(s) where the
     *       relationship between geoid and ellipsoid is defined.</li>
     *
     *   <li>For an {@linkplain DefaultEngineeringDatum engineering datum}, the anchor may be an identified
     *       physical point with the orientation defined relative to the object.</li>
     *
     *   <li>For an {@linkplain DefaultImageDatum image datum}, the anchor point may be the centre or the corner
     *       of the image.</li>
     *
     *   <li>For a {@linkplain DefaultTemporalDatum temporal datum}, see their
     *       {@linkplain DefaultTemporalDatum#getOrigin() origin} instead.</li>
     * </ul>
     *
     * @return description, possibly including coordinates, of the point or points used to anchor the datum to the Earth.
     */
    @Override
    @XmlElement(name = "anchorDefinition")
    public InternationalString getAnchorPoint() {
        return anchorDefinition;
    }

    /**
     * The time after which this datum definition is valid.
     * This time may be precise or merely a year.
     *
     * <p>If an old datum is superseded by a new datum, then the realization epoch for the new datum
     * defines the upper limit for the validity of the old datum.</p>
     *
     * @return the time after which this datum definition is valid, or {@code null} if none.
     */
    @Override
    @XmlSchemaType(name = "date")
    @XmlElement(name = "realizationEpoch")
    public Date getRealizationEpoch() {
        return MetadataUtilities.toDate(realizationEpoch);
    }

    /**
     * Returns the region or timeframe in which this datum is valid, or {@code null} if unspecified.
     *
     * @return area or region or timeframe in which this datum is valid, or {@code null}.
     *
     * @see org.apache.sis.metadata.iso.extent.DefaultExtent
     */
    @Override
    @XmlElement(name = "domainOfValidity")
    public Extent getDomainOfValidity() {
        return domainOfValidity;
    }

    /**
     * Returns the domain or limitations of usage, or {@code null} if unspecified.
     *
     * @return description of domain of usage, or limitations of usage, for which this datum object is valid.
     */
    @Override
    @XmlElement(name = "scope", required = true)
    public InternationalString getScope() {
        return scope;
    }

    /**
     * Returns {@code true} if either the {@linkplain #getName() primary name} or at least
     * one {@linkplain #getAlias() alias} matches the given string according heuristic rules.
     * This method performs the comparison documented in the
     * {@linkplain AbstractIdentifiedObject#isHeuristicMatchForName(String) super-class},
     * with the following additional flexibility:
     *
     * <ul>
     *   <li>The {@code "D_"} prefix (used in ESRI datum names), if presents in the given name or in this datum name,
     *       is ignored.</li>
     *   <li>If this datum is an instance of {@link DefaultGeodeticDatum}, then the prime meridian name may also
     *       be ignored.</li>
     * </ul>
     *
     * <div class="section">Future evolutions</div>
     * This method implements heuristic rules learned from experience while trying to provide inter-operability
     * with different data producers. Those rules may be adjusted in any future SIS version according experience
     * gained while working with more data producers.
     *
     * @param  name  the name to compare.
     * @return {@code true} if the primary name or at least one alias matches the specified {@code name}.
     */
    @Override
    public boolean isHeuristicMatchForName(final String name) {
        return NameToIdentifier.isHeuristicMatchForName(super.getName(), super.getAlias(), name, Simplifier.INSTANCE);
    }

    /**
     * A function for simplifying a {@link Datum} name before comparison.
     *
     * <p>Note: if heuristic rules are modified, consider updating {@code EPSGDataAccess} accordingly.</p>
     *
     * @see org.apache.sis.referencing.factory.sql.EPSGCodeFinder#toDatumPattern(String, StringBuilder)
     *
     * @since 0.7
     */
    static class Simplifier extends NameToIdentifier.Simplifier {
        /** The singleton simplifier for non-geodetic datum. */
        static final Simplifier INSTANCE = new Simplifier();

        /** For subclasses and default instance only. */
        Simplifier() {}

        /** Simplify the given datum name. */
        @Override protected CharSequence apply(CharSequence name) {
            name = super.apply(name);
            if (CharSequences.startsWith(name, ESRI_DATUM_PREFIX, false)) {
                name = name.subSequence(ESRI_DATUM_PREFIX.length(), name.length());
            }
            return name;
        }
    }

    /**
     * Compares the specified object with this datum for equality.
     * If the {@code mode} argument value is {@link ComparisonMode#STRICT STRICT} or
     * {@link ComparisonMode#BY_CONTRACT BY_CONTRACT}, then all available properties are compared including the
     * {@linkplain #getAnchorPoint() anchor point}, {@linkplain #getRealizationEpoch() realization epoch},
     * {@linkplain #getDomainOfValidity() domain of validity} and the {@linkplain #getScope() scope}.
     *
     * @param  object  the object to compare to {@code this}.
     * @param  mode    {@link ComparisonMode#STRICT STRICT} for performing a strict comparison, or
     *                 {@link ComparisonMode#IGNORE_METADATA IGNORE_METADATA} for comparing only
     *                 properties relevant to coordinate transformations.
     * @return {@code true} if both objects are equal.
     */
    @Override
    public boolean equals(final Object object, final ComparisonMode mode) {
        if (!super.equals(object, mode)) {
            return false;
        }
        switch (mode) {
            case STRICT: {
                final AbstractDatum that = (AbstractDatum) object;
                return this.realizationEpoch == that.realizationEpoch &&
                       Objects.equals(this.domainOfValidity, that.domainOfValidity) &&
                       Objects.equals(this.anchorDefinition, that.anchorDefinition) &&
                       Objects.equals(this.scope,            that.scope);
            }
            case BY_CONTRACT: {
                final Datum that = (Datum) object;
                return deepEquals(getRealizationEpoch(), that.getRealizationEpoch(), mode) &&
                       deepEquals(getDomainOfValidity(), that.getDomainOfValidity(), mode) &&
                       deepEquals(getAnchorPoint(),      that.getAnchorPoint(),      mode) &&
                       deepEquals(getScope(),            that.getScope(),            mode);
            }
            default: {
                /*
                 * Tests for identifiers or name since datum with different identification may have completely
                 * different meaning. We do not perform this check if the user asked for metadata comparison,
                 * because in such case the name and identifiers have already been compared by the subclass.
                 *
                 * According ISO 19162 (Well Known Text representation of Coordinate Reference Systems),
                 * identifiers shall have precedence over name at least in the case of operation methods
                 * and parameters. We extend this rule to datum as well.
                 */
                final Datum that = (Datum) object;
                final Boolean match = Identifiers.hasCommonIdentifier(getIdentifiers(), that.getIdentifiers());
                if (match != null) {
                    return match;
                }
                return isHeuristicMatchForName(that.getName().getCode())
                        || IdentifiedObjects.isHeuristicMatchForName(that, getName().getCode());
            }
        }
    }

    /**
     * Invoked by {@code hashCode()} for computing the hash code when first needed.
     * See {@link org.apache.sis.referencing.AbstractIdentifiedObject#computeHashCode()}
     * for more information.
     *
     * @return the hash code value. This value may change in any future Apache SIS version.
     */
    @Override
    protected long computeHashCode() {
        return super.computeHashCode() + Objects.hash(anchorDefinition, realizationEpoch, domainOfValidity, scope);
    }

    /**
     * Formats the inner part of the <cite>Well Known Text</cite> (WKT) representation for this datum.
     * See {@link AbstractIdentifiedObject#formatTo(Formatter)} for more information.
     *
     * @param  formatter  the formatter where to format the inner content of this WKT element.
     * @return the {@linkplain org.apache.sis.io.wkt.KeywordCase#CAMEL_CASE CamelCase} keyword
     *         for the WKT element, or {@code null} if unknown.
     */
    @Override
    protected String formatTo(final Formatter formatter) {
        final Citation authority = formatter.getNameAuthority();
        String name = IdentifiedObjects.getName(this, authority);
        if (name == null) {
            name = IdentifiedObjects.getName(this, null);
            if (name == null) {                                 // Should never happen, but be safe.
                return super.formatTo(formatter);
            }
            if ("ESRI".equalsIgnoreCase(Citations.toCodeSpace(authority)) && !name.startsWith(Simplifier.ESRI_DATUM_PREFIX)) {
                name = Simplifier.ESRI_DATUM_PREFIX + name;
            }
        }
        formatter.append(name, ElementKind.DATUM);
        return null;
    }




    //////////////////////////////////////////////////////////////////////////////////////////////////
    ////////                                                                                  ////////
    ////////                               XML support with JAXB                              ////////
    ////////                                                                                  ////////
    ////////        The following methods are invoked by JAXB using reflection (even if       ////////
    ////////        they are private) or are helpers for other methods invoked by JAXB.       ////////
    ////////        Those methods can be safely removed if Geographic Markup Language         ////////
    ////////        (GML) support is not needed.                                              ////////
    ////////                                                                                  ////////
    //////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Constructs a new object in which every attributes are set to a null value.
     * <strong>This is not a valid object.</strong> This constructor is strictly
     * reserved to JAXB, which will assign values to the fields using reflexion.
     */
    AbstractDatum() {
        super(org.apache.sis.internal.referencing.NilReferencingObject.INSTANCE);
        realizationEpoch = Long.MIN_VALUE;
    }

    /**
     * Invoked by JAXB only at unmarshalling time.
     *
     * @see #getAnchorPoint()
     */
    private void setAnchorPoint(final InternationalString value) {
        if (anchorDefinition == null) {
            anchorDefinition = value;
        } else {
            MetadataUtilities.propertyAlreadySet(AbstractDatum.class, "setAnchorPoint", "anchorDefinition");
        }
    }

    /**
     * Invoked by JAXB only at unmarshalling time.
     *
     * @see #getRealizationEpoch()
     */
    private void setRealizationEpoch(final Date value) {
        if (realizationEpoch == Long.MIN_VALUE) {
            realizationEpoch = value.getTime();
        } else {
            MetadataUtilities.propertyAlreadySet(AbstractDatum.class, "setRealizationEpoch", "realizationEpoch");
        }
    }

    /**
     * Invoked by JAXB only at unmarshalling time.
     *
     * @see #getDomainOfValidity()
     */
    private void setDomainOfValidity(final Extent value) {
        if (domainOfValidity == null) {
            domainOfValidity = value;
        } else {
            MetadataUtilities.propertyAlreadySet(AbstractDatum.class, "setDomainOfValidity", "domainOfValidity");
        }
    }

    /**
     * Invoked by JAXB only at unmarshalling time.
     *
     * @see #getScope()
     */
    private void setScope(final InternationalString value) {
        if (scope == null) {
            scope = value;
        } else {
            MetadataUtilities.propertyAlreadySet(AbstractDatum.class, "setScope", "scope");
        }
    }
}
