/*

 * Copyright (c) 2003, 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package javax.sql.rowset.serial;

import java.sql.*;

import java.io.*;

import java.util.*;

/**

 * A serialized mapping of a <code>Ref</code> object, which is the mapping in the

 * Java programming language of an SQL <code>REF</code> value.

 * <p>

 * The <code>SerialRef</code> class provides a constructor  for

 * creating a <code>SerialRef</code> instance from a <code>Ref</code>

 * object and provides methods for getting and setting the <code>Ref</code> object.

 *

 * <h3> Thread safety </h3>

 *

 * A SerialRef is not safe for use by multiple concurrent threads.  If a

 * SerialRef is to be used by more than one thread then access to the SerialRef

 * should be controlled by appropriate synchronization.

 *

 * @since 1.5

 */

public class SerialRef implements Ref, Serializable, Cloneable {

    /**

     * String containing the base type name.

     * @serial

     */

    private String baseTypeName;

    /**

     * This will store the type <code>Ref</code> as an <code>Object</code>.

     */

    private Object object;

    /**

     * Private copy of the Ref reference.

     */

    private Ref reference;

    /**

     * Constructs a <code>SerialRef</code> object from the given <code>Ref</code>

     * object.

     *

     * @param ref a Ref object; cannot be <code>null</code>

     * @throws SQLException if a database access occurs; if <code>ref</code>

     *     is <code>null</code>; or if the <code>Ref</code> object returns a

     *     <code>null</code> value base type name.

     * @throws SerialException if an error occurs serializing the <code>Ref</code>

     *     object

     */

    public SerialRef(Ref ref) throws SerialException, SQLException {

        if (ref == null) {

            throw new SQLException("Cannot instantiate a SerialRef object " +

                "with a null Ref object");

        }

        reference = ref;

        object = ref;

        if (ref.getBaseTypeName() == null) {

            throw new SQLException("Cannot instantiate a SerialRef object " +

                "that returns a null base type name");

        } else {

            baseTypeName = ref.getBaseTypeName();

        }

    }

    /**

     * Returns a string describing the base type name of the <code>Ref</code>.

     *

     * @return a string of the base type name of the Ref

     * @throws SerialException in no Ref object has been set

     */

    public String getBaseTypeName() throws SerialException {

        return baseTypeName;

    }

    /**

     * Returns an <code>Object</code> representing the SQL structured type

     * to which this <code>SerialRef</code> object refers.  The attributes

     * of the structured type are mapped according to the given type map.

     *

     * @param map a <code>java.util.Map</code> object containing zero or

     *        more entries, with each entry consisting of 1) a <code>String</code>

     *        giving the fully qualified name of a UDT and 2) the

     *        <code>Class</code> object for the <code>SQLData</code> implementation

     *        that defines how the UDT is to be mapped

     * @return an object instance resolved from the Ref reference and mapped

     *        according to the supplied type map

     * @throws SerialException if an error is encountered in the reference

     *        resolution

     */

    public Object getObject(java.util.Map<String,Class<?>> map)

        throws SerialException

    {

        map = new Hashtable<String, Class<?>>(map);

        if (object != null) {

            return map.get(object);

        } else {

            throw new SerialException("The object is not set");

        }

    }

    /**

     * Returns an <code>Object</code> representing the SQL structured type

     * to which this <code>SerialRef</code> object refers.

     *

     * @return an object instance resolved from the Ref reference

     * @throws SerialException if an error is encountered in the reference

     *         resolution

     */

    public Object getObject() throws SerialException {

        if (reference != null) {

            try {

                return reference.getObject();

            } catch (SQLException e) {

                throw new SerialException("SQLException: " + e.getMessage());

            }

        }

        if (object != null) {

            return object;

        }

        throw new SerialException("The object is not set");

    }

    /**

     * Sets the SQL structured type that this <code>SerialRef</code> object

     * references to the given <code>Object</code> object.

     *

     * @param obj an <code>Object</code> representing the SQL structured type

     *        to be referenced

     * @throws SerialException if an error is encountered generating the

     * the structured type referenced by this <code>SerialRef</code> object

     */

    public void setObject(Object obj) throws SerialException {

        try {

            reference.setObject(obj);

        } catch (SQLException e) {

            throw new SerialException("SQLException: " + e.getMessage());

        }

        object = obj;

    }

    /**

     * Compares this SerialRef to the specified object.  The result is {@code

     * true} if and only if the argument is not {@code null} and is a {@code

     * SerialRef} object that represents the same object as this

     * object.

     *

     * @param  obj The object to compare this {@code SerialRef} against

     *

     * @return  {@code true} if the given object represents a {@code SerialRef}

     *          equivalent to this SerialRef, {@code false} otherwise

     *

     */

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if(obj instanceof SerialRef) {

            SerialRef ref = (SerialRef)obj;

            return baseTypeName.equals(ref.baseTypeName) &&

                    object.equals(ref.object);

        }

        return false;

    }

    /**

     * Returns a hash code for this {@code SerialRef}.

     * @return  a hash code value for this object.

     */

    public int hashCode() {

        return (31 + object.hashCode()) * 31 + baseTypeName.hashCode();

    }

    /**

     * Returns a clone of this {@code SerialRef}.

     * The underlying {@code Ref} object will be set to null.

     *

     * @return  a clone of this SerialRef

     */

    public Object clone() {

        try {

            SerialRef ref = (SerialRef) super.clone();

            ref.reference = null;

            return ref;

        } catch (CloneNotSupportedException ex) {

            // this shouldn't happen, since we are Cloneable

            throw new InternalError();

        }

    }

    /**

     * readObject is called to restore the state of the SerialRef from

     * a stream.

     */

    private void readObject(ObjectInputStream s)

            throws IOException, ClassNotFoundException {

        ObjectInputStream.GetField fields = s.readFields();

        object = fields.get("object", null);

        baseTypeName = (String) fields.get("baseTypeName", null);

        reference = (Ref) fields.get("reference", null);

    }

    /**

     * writeObject is called to save the state of the SerialRef

     * to a stream.

     */

    private void writeObject(ObjectOutputStream s)

            throws IOException {

        ObjectOutputStream.PutField fields = s.putFields();

        fields.put("baseTypeName", baseTypeName);

        fields.put("object", object);

        // Note: this check to see if it is an instance of Serializable

        // is for backwards compatibility

        fields.put("reference", reference instanceof Serializable ? reference : null);

        s.writeFields();

    }

    /**

     * The identifier that assists in the serialization of this <code>SerialRef</code>

     * object.

     */

    static final long serialVersionUID = -4727123500609662274L;

}