/*
 * 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.util.iso;

import java.util.List;
import java.util.Collections;
import java.util.Locale;
import java.util.Objects;
import java.io.ObjectStreamException;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlSeeAlso;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import org.opengis.util.NameSpace;
import org.opengis.util.LocalName;
import org.opengis.util.TypeName;
import org.opengis.util.MemberName;
import org.opengis.util.GenericName;
import org.opengis.util.InternationalString;
import org.apache.sis.xml.Namespaces;
import org.apache.sis.util.ArgumentChecks;
import org.apache.sis.internal.jaxb.gco.CharSequenceAdapter;


/**
 * Identifier within a {@linkplain DefaultNameSpace name space} for a local object.
 * Local names are names which are directly accessible to and maintained by a name space.
 * Names are local to one and only one name space.
 * The name space within which they are local is indicated by the {@linkplain #scope() scope}.
 *
 * <p>{@code DefaultLocalName} can be instantiated by any of the following methods:</p>
 * <ul>
 *   <li>{@link DefaultNameFactory#createLocalName(NameSpace, CharSequence)}.</li>
 *   <li>{@link DefaultNameFactory#createGenericName(NameSpace, CharSequence[])} with an array of length 1.</li>
 *   <li>{@link DefaultNameFactory#parseGenericName(NameSpace, CharSequence)} with no occurrence of the separator in the path.</li>
 *   <li>Similar static convenience methods in {@link Names}.</li>
 * </ul>
 *
 * <div class="section">Immutability and thread safety</div>
 * This class is immutable and thus inherently thread-safe if the {@link NameSpace} and {@link CharSequence}
 * arguments given to the constructor are also immutable. Subclasses shall make sure that any overridden methods
 * remain safe to call from multiple threads and do not change any public {@code LocalName} state.
 *
 * @author  Martin Desruisseaux (IRD, Geomatys)
 * @version 1.0
 *
 * @see DefaultNameSpace
 * @see DefaultScopedName
 *
 * @since 0.3
 * @module
 */

/*
 * JAXB annotation would be @XmlType(name ="CodeType"), but this can not be used here
 * since "CodeType" is used for various classes (including GenericName and ScopedName).
 * (Un)marhalling of this class needs to be handled by a JAXB adapter.
 */
@XmlSeeAlso({
    DefaultTypeName.class,
    DefaultMemberName.class
})
public class DefaultLocalName extends AbstractName implements LocalName {
    /**
     * Serial number for inter-operability with different versions.
     */
    private static final long serialVersionUID = -697839568997068872L;

    /**
     * The scope of this name, or {@code null} if the scope is the unique {@code GLOBAL} instance.
     * We don't use direct reference to {@code GLOBAL} because {@code null} is used as a sentinel
     * value for stopping iterative searches (using GLOBAL would have higher risk of never-ending
     * loops in case of bug), and in order to reduce the stream size during serialization.
     */
    final NameSpace scope;

    /**
     * The name, either as a {@link String} or an {@link InternationalString}.
     *
     * <div class="section">Note on JAXB annotation</div>
     * The {@link XmlElement} annotation applied here is appropriate for {@code TypeName} and {@code MemberName}
     * subtypes only. It is <strong>not</strong> appropriate when (un)marshalling directly a {@code LocalName}.
     * The distinction between the two cases is done by {@link org.apache.sis.internal.jaxb.gco.GO_GenericName},
     * which replace the {@code LocalName} instance by an internal {@code NameValue} object (so the XML element
     * declared here is never marshalled). Example:
     *
     * {@preformat xml
     *   <gco:LocalName codeSpace=\"A code space\">A name in a scope</gco:LocalName>
     * }
     *
     * versus
     *
     * {@preformat xml
     *   <gco:TypeName>
     *     <gco:aName>
     *       <gco:CharacterString>An other local name</gco:CharacterString>
     *     </gco:aName>
     *   </gco:TypeName>
     * }
     */
    @XmlJavaTypeAdapter(CharSequenceAdapter.class)
    @XmlElement(name = "aName", namespace = Namespaces.GCO)
    final CharSequence name;

    /**
     * Constructs a local name from the given character sequence.
     * If the character sequence is an instance of {@link InternationalString},
     * then its {@link InternationalString#toString(java.util.Locale) toString(Locale.ROOT)}
     * method will be invoked for fetching an unlocalized name.
     * Otherwise the {@link CharSequence#toString()} method will be used.
     *
     * @param scope  the scope of this name, or {@code null} for a global scope.
     * @param name   the local name (never {@code null}).
     */
    protected DefaultLocalName(NameSpace scope, final CharSequence name) {
        ArgumentChecks.ensureNonNull("name", name);
        if (scope == GlobalNameSpace.GLOBAL) {
            scope = null;                                       // Handled specially by scope().
        }
        this.scope = scope;
        if (name instanceof InternationalString) {
            if (name.getClass() == SimpleInternationalString.class) {
                /*
                 * In the special case of SimpleInternationalString, we will retain the String
                 * flavor instead than InternationalString (this is done by name.toString() at
                 * the end of this constructor). It will not cause any lost of information since
                 * SimpleInternationalString contains only one String. This simplification allows
                 * the equals(Object) method to return "true" for DefaultLocalName that would
                 * otherwise be considered different.
                 *
                 * In order to reduce the amount of objects created, we retain the full
                 * InternationalString in the "asString" field, which is NOT considered
                 * by equals(Object). This is the value returned by toInternationalString().
                 */
                asString = name;
            } else {
                /*
                 * For any InternationalString that are not SimpleInternationalString, we retain
                 * the given name and we do NOT set the "asString" field. It will be computed on
                 * the fly when first needed.
                 */
                this.name = name;
                return;
            }
        }
        this.name = name.toString();
    }

    /**
     * Returns a SIS local name 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 MemberName} or {@link TypeName},
     *       then this method delegates to {@code castOrCopy(…)} method of the corresponding subclass.</li>
     *   <li>Otherwise if the given object is already an instance of {@code DefaultLocalName},
     *       then it is returned unchanged.</li>
     *   <li>Otherwise a new {@code DefaultLocalName} instance is created
     *       with the same values than the given name.</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 DefaultLocalName castOrCopy(final LocalName object) {
        if (object instanceof MemberName) {
            return DefaultMemberName.castOrCopy((MemberName) object);
        }
        if (object instanceof TypeName) {
            return DefaultTypeName.castOrCopy((TypeName) object);
        }
        if (object == null || object instanceof DefaultLocalName) {
            return (DefaultLocalName) object;
        }
        final NameSpace scope = object.scope();
        final InternationalString name = object.toInternationalString();
        if (scope instanceof DefaultNameSpace) {
            return ((DefaultNameSpace) scope).local(name, null);        // May return a cached instance.
        } else {
            return new DefaultLocalName(scope, name);
        }
    }

    /**
     * Returns the scope (name space) in which this name is local. This method returns a
     * non-null value in all cases, even when the scope given to the constructor was null.
     */
    @Override
    public NameSpace scope() {
        return (scope != null) ? scope : GlobalNameSpace.GLOBAL;
    }

    /**
     * Returns the depth, which is always 1 for a local name.
     */
    @Override
    public final int depth() {
        return 1;
    }

    /**
     * Returns the sequence of local name for this name.
     * Since this object is itself a local name, this method always returns a singleton
     * containing only {@code this}.
     */
    @Override
    public final List<DefaultLocalName> getParsedNames() {
        return Collections.singletonList(this);
    }

    /**
     * Returns {@code this} since this object is already a local name.
     *
     * @return {@code this}.
     */
    @Override
    public final LocalName head() {
        return this;
    }

    /**
     * Returns {@code this} since this object is already a local name.
     *
     * @return {@code this}.
     */
    @Override
    public final LocalName tip() {
        return this;
    }

    /**
     * Returns a locale-independent string representation of this local name.
     * This string does not include the scope, which is consistent with the
     * {@linkplain #getParsedNames() parsed names} definition.
     *
     * @return a local-independent string representation of this name.
     */
    @Override
    public synchronized String toString() {
        if (asString == null) {
            if (name instanceof InternationalString) {
                asString = ((InternationalString) name).toString(Locale.ROOT);
            } else {
                asString = name.toString();
            }
        } else if (asString instanceof InternationalString) {
            return ((InternationalString) asString).toString(Locale.ROOT);
        }
        return asString.toString();
    }

    /**
     * Returns a local-dependent string representation of this local name.
     */
    @Override
    public synchronized InternationalString toInternationalString() {
        if (!(asString instanceof InternationalString)) {
            asString = Types.toInternationalString(name);
        }
        return (InternationalString) asString;
    }

    /**
     * Compares this name with the specified object for order. Returns a negative integer,
     * zero, or a positive integer as this name lexicographically precedes, is equal to,
     * or follows the specified object.
     *
     * @param  name  the other name to compare with this name.
     * @return -1 if this name precedes the given one, +1 if it follows, 0 if equals.
     */
    @Override
    public int compareTo(final GenericName name) {
        if (name instanceof LocalName) {
            /*
             * Note: a previous version was using String.compareToIgnoreCase(String).
             * However it is slightly slower than String.compareTo(String), increase
             * the inconsistency with equals(Object), may be more suprising to the
             * developer and result in unsatisfactory ordering for certain locales
             * anyway (we are supposed to use Collator instead).
             */
            return toString().compareTo(name.toString());
        } else {
            return super.compareTo(name);
        }
    }

    /**
     * Compares this local name with the specified object for equality.
     *
     * @param  object  the object to compare with this name for equality.
     * @return {@code true} if the given object is equal to this name.
     */
    @Override
    public boolean equals(final Object object) {
        if (object == this) {
            return true;
        }
        if (object != null && object.getClass() == getClass()) {
            final DefaultLocalName that = (DefaultLocalName) object;
            return Objects.equals(this.scope, that.scope) &&
                   Objects.equals(this.name,  that.name);
        }
        return false;
    }

    /**
     * Invoked by {@link #hashCode()} for computing the hash code value when first needed.
     */
    @Override
    int computeHashCode() {
        return Objects.hash(scope, name) ^ (int) serialVersionUID;
    }

    /**
     * If an instance already exists for the deserialized name, returns that instance.
     *
     * <p>Because of its private access, this method is <strong>not</strong> invoked if the
     * deserialized class is a subclass. This is the intended behavior since we don't want
     * to replace an instance of a user-defined class.</p>
     *
     * @return the unique instance.
     * @throws ObjectStreamException required by specification but should never be thrown.
     */
    private Object readResolve() throws ObjectStreamException {
        final DefaultNameSpace ns;
        if (scope == null) {                    // Not a bug: readResolve() is intentionally private.
            ns = GlobalNameSpace.GLOBAL;
        } else if (scope instanceof DefaultNameSpace) {
            ns = (DefaultNameSpace) scope;
        } else {
            return this;
        }
        return ns.local(name, this);
    }




    //////////////////////////////////////////////////////////////////////////////////////////////////
    ////////                                                                                  ////////
    ////////                               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.                                              ////////
    ////////                                                                                  ////////
    //////////////////////////////////////////////////////////////////////////////////////////////////

    /**
     * Empty constructor to be used by JAXB only, or by sub-classes empty constructors
     * themselves used only by JAXB. Despite its "final" declaration, the {@link #name}
     * field will be set by JAXB during unmarshalling.
     */
    DefaultLocalName() {
        scope = null;
        name  = null;
    }
}
