/*

  * #%L

  * ObjectIdElement.java - mongodb-async-driver - Allanbank Consulting, Inc.

  * %%

  * Copyright (C) 2011 - 2014 Allanbank Consulting, Inc.

  * %%

  * Licensed 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.

  * #L%

  */

 package com.allanbank.mongodb.bson.element;

 import static com.allanbank.mongodb.util.Assertions.assertNotNull;

 import com.allanbank.mongodb.bson.Element;

 import com.allanbank.mongodb.bson.ElementType;

 import com.allanbank.mongodb.bson.Visitor;

 import com.allanbank.mongodb.bson.io.StringEncoder;

 /**

  * A wrapper for a BSON Object Id.

  * 

  * @api.yes This class is part of the driver's API. Public and protected members

  *          will be deprecated for at least 1 non-bugfix release (version

  *          numbers are <major>.<minor>.<bugfix>) before being

  *          removed or modified.

  * @copyright 2011-2013, Allanbank Consulting, Inc., All Rights Reserved

  */

 public class ObjectIdElement extends AbstractElement {

     /** The BSON type for a Object Id. */

     public static final String DEFAULT_NAME = "_id";

     /** The BSON type for a Object Id. */

     public static final ElementType TYPE = ElementType.OBJECT_ID;

     /** Serialization version for the class. */

     private static final long serialVersionUID = -3563737127052573642L;

     /**

      * Computes and returns the number of bytes that are used to encode the

      * element.

      * 

      * @param name

      *            The name for the element.

      * @return The size of the element when encoded in bytes.

      */

     private static long computeSize(final String name) {

         long result = 14; // type (1) + name null byte (1) + id value 12

         result += StringEncoder.utf8Size(name);

         return result;

     }

     /** The BSON Object id. */

     private final ObjectId myId;

     /**

      * Constructs a new {@link ObjectIdElement}.

      * 

      * @param name

      *            The name for the BSON Object Id.

      * @param id

      *            The object id.

      * @throws IllegalArgumentException

      *             If the {@code name} or {@code id} is <code>null</code>.

      */

     public ObjectIdElement(final String name, final ObjectId id) {

         this(name, id, computeSize(name));

     }

     /**

      * Constructs a new {@link ObjectIdElement}.

      * 

      * @param name

      *            The name for the BSON Object Id.

      * @param id

      *            The object id.

      * @param size

      *            The size of the element when encoded in bytes. If not known

      *            then use the

      *            {@link ObjectIdElement#ObjectIdElement(String, ObjectId)}

      *            constructor instead.

      * @throws IllegalArgumentException

      *             If the {@code name} or {@code id} is <code>null</code>.

      */

     public ObjectIdElement(final String name, final ObjectId id, final long size) {

         super(name, size);

         assertNotNull(id, "ObjectId element's id cannot be null.");

         myId = id;

     }

     /**

      * Accepts the visitor and calls the {@link Visitor#visitObjectId} method.

      * 

      * @see Element#accept(Visitor)

      */

     @Override

     public void accept(final Visitor visitor) {

         visitor.visitObjectId(getName(), myId);

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to compare the values if the base class comparison is equals.

      * </p>

      */

     @Override

     public int compareTo(final Element otherElement) {

         int result = super.compareTo(otherElement);

         if (result == 0) {

             final ObjectIdElement other = (ObjectIdElement) otherElement;

             result = myId.compareTo(other.myId);

         }

         return result;

     }

     /**

      * Determines if the passed object is of this same type as this object and

      * if so that its fields are equal.

      * 

      * @param object

      *            The object to compare to.

      * 

      * @see java.lang.Object#equals(java.lang.Object)

      */

     @Override

     public boolean equals(final Object object) {

         boolean result = false;

         if (this == object) {

             result = true;

         }

         else if ((object != null) && (getClass() == object.getClass())) {

             final ObjectIdElement other = (ObjectIdElement) object;

             result = super.equals(object) && myId.equals(other.myId);

         }

         return result;

     }

     /**

      * Returns the id value.

      * 

      * @return The id value.

      */

     public ObjectId getId() {

         return myId;

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public ElementType getType() {

         return TYPE;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Returns the {@link ObjectId}.

      * </p>

      */

     @Override

     public ObjectId getValueAsObject() {

         return myId;

     }

     /**

      * Computes a reasonable hash code.

      * 

      * @return The hash code value.

      */

     @Override

     public int hashCode() {

         int result = 1;

         result = (31 * result) + super.hashCode();

         result = (31 * result) + myId.hashCode();

         return result;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Returns a new {@link ObjectIdElement}.

      * </p>

      */

     @Override

     public ObjectIdElement withName(final String name) {

         if (getName().equals(name)) {

             return this;

         }

         return new ObjectIdElement(name, myId);

     }

 }