/*

  * #%L

  * TimestampElement.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 java.util.Date;

 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 timestamp as the milliseconds since the epoch.

  * 

  * @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 TimestampElement extends AbstractElement {

     /** The BSON type for a long. */

     public static final ElementType TYPE = ElementType.UTC_TIMESTAMP;

     /** Serialization version for the class. */

     private static final long serialVersionUID = 949598909338399091L;

     /**

      * 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 = 10; // type (1) + name null byte (1) + value (8).

         result += StringEncoder.utf8Size(name);

         return result;

     }

     /** The BSON timestamp value as the milliseconds since the epoch. */

     private final long myTimestamp;

     /**

      * Constructs a new {@link TimestampElement}.

      * 

      * @param name

      *            The name for the BSON long.

      * @param value

      *            The BSON timestamp value as the milliseconds since the epoch.

      * @throws IllegalArgumentException

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

      */

     public TimestampElement(final String name, final long value) {

         this(name, value, computeSize(name));

     }

     /**

      * Constructs a new {@link TimestampElement}.

      * 

      * @param name

      *            The name for the BSON long.

      * @param value

      *            The BSON timestamp value as the milliseconds since the epoch.

      * @param size

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

      *            then use the

      *            {@link TimestampElement#TimestampElement(String, long)}

      *            constructor instead.

      * @throws IllegalArgumentException

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

      */

     public TimestampElement(final String name, final long value, final long size) {

         super(name, size);

         myTimestamp = value;

     }

     /**

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

      * 

      * @see Element#accept(Visitor)

      */

     @Override

     public void accept(final Visitor visitor) {

         visitor.visitTimestamp(getName(), getTime());

     }

     /**

      * {@inheritDoc}

      * <p>

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

      * </p>

      * <p>

      * Note that for MongoDB {@link MongoTimestampElement} and

      * {@link TimestampElement} will return equal based on the type. Care is

      * taken here to make sure that the values return the same value regardless

      * of comparison order.

      * </p>

      */

     @Override

     public int compareTo(final Element otherElement) {

         int result = super.compareTo(otherElement);

         if (result == 0) {

             // Might be a MongoTimestampElement or TimestampElement.

             final ElementType otherType = otherElement.getType();

             if (otherType == ElementType.UTC_TIMESTAMP) {

                 result = compare(getTime(),

                         ((TimestampElement) otherElement).getTime());

             }

             else {

                 result = compare(getTime(),

                         ((MongoTimestampElement) otherElement).getTime());

             }

         }

         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 TimestampElement other = (TimestampElement) object;

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

         }

         return result;

     }

     /**

      * Returns the BSON timestamp value as the milliseconds since the epoch.

      * 

      * @return The BSON timestamp value as the milliseconds since the epoch.

      */

     public long getTime() {

         return myTimestamp;

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public ElementType getType() {

         return TYPE;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Returns the {@link Date}.

      * </p>

      */

     @Override

     public Date getValueAsObject() {

         return new Date(getTime());

     }

     /**

      * 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) + (int) (myTimestamp & 0xFFFFFFFF);

         result = (31 * result) + (int) ((myTimestamp >> 32) & 0xFFFFFFFF);

         return result;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Returns a new {@link TimestampElement}.

      * </p>

      */

     @Override

     public TimestampElement withName(final String name) {

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

             return this;

         }

         return new TimestampElement(name, myTimestamp);

     }

 }