/*

  * #%L

  * Delete.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.client.message;

 import java.io.IOException;

 import com.allanbank.mongodb.ReadPreference;

 import com.allanbank.mongodb.bson.Document;

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

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

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

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

 import com.allanbank.mongodb.client.Message;

 import com.allanbank.mongodb.client.Operation;

 import com.allanbank.mongodb.error.DocumentToLargeException;

 /**

  * Message to <a href=

  * "http://www.mongodb.org/display/DOCS/Mongo+Wire+Protocol#MongoWireProtocol-OPDELETE"

  * >delete</a> documents from a collection. The format of the message is:

  * 

  * <pre>

  * <code>

  * struct {

  *     MsgHeader header;             // standard message header

  *     int32     ZERO;               // 0 - reserved for future use

  *     cstring   fullCollectionName; // "dbname.collectionname"

  *     int32     flags;              // bit vector - see below for details.

  *     document  selector;           // query object.  See below for details.

  * }

  * </code>

  * </pre>

  * 

  * @api.no This class is <b>NOT</b> part of the drivers API. This class may be

  *         mutated in incompatible ways between any two releases of the driver.

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

  */

 public class Delete extends AbstractMessage {

     /** The flag bit for performing a single delete only. */

     public static final int SINGLE_DELETE_BIT = 1;

     /** The query for selecting the documents to delete. */

     private final Document myQuery;

     /**

      * If true, only the first document found should be deleted, otherwise all

      * matching documents should be deleted.

      */

     private final boolean mySingleDelete;

     /**

      * Create a new Delete message.

      * 

      * @param in

      *            The stream to read the delete message from.

      * @throws IOException

      *             On a failure reading the delete message.

      */

     public Delete(final BsonInputStream in) throws IOException {

         in.readInt(); // reserved - 0.

         init(in.readCString());

         final int flags = in.readInt();

         myQuery = in.readDocument();

         mySingleDelete = (flags & SINGLE_DELETE_BIT) == SINGLE_DELETE_BIT;

     }

     /**

      * Create a new Delete message.

      * 

      * @param databaseName

      *            The name of the database.

      * @param collectionName

      *            The name of the collection.

      * @param query

      *            The query document for selecting documents to delete.

      * @param singleDelete

      *            If true, only the first document found should be deleted,

      *            otherwise all matching documents should be deleted.

      */

     public Delete(final String databaseName, final String collectionName,

             final Document query, final boolean singleDelete) {

         super(databaseName, collectionName, ReadPreference.PRIMARY);

         myQuery = query;

         mySingleDelete = singleDelete;

     }

     /**

      * 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 Delete other = (Delete) object;

             result = super.equals(object)

                     && (mySingleDelete == other.mySingleDelete)

                     && myQuery.equals(other.myQuery);

         }

         return result;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to return the name of the operation: "DELETE".

      * </p>

      */

     @Override

     public String getOperationName() {

         return Operation.DELETE.name();

     }

     /**

      * Returns the query {@link Document}.

      * 

      * @return The query {@link Document}.

      */

     public Document getQuery() {

         return myQuery;

     }

     /**

      * 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) + (mySingleDelete ? 1 : 3);

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

         return result;

     }

     /**

      * Returns if only a single or all matching documents should be deleted.

      * 

      * @return True if only the first document found will be deleted, otherwise

      *         all matching documents will be deleted.

      */

     public boolean isSingleDelete() {

         return mySingleDelete;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to return the size of the {@link Delete}.

      * </p>

      */

     @Override

     public int size() {

         int size = HEADER_SIZE + 10; // See below.

         // size += 4; // reserved - 0;

         size += StringEncoder.utf8Size(myDatabaseName);

         // size += 1; // StringEncoder.utf8Size(".");

         size += StringEncoder.utf8Size(myCollectionName);

         // size += 1; // \0 on the CString.

         // size += 4; // flags

         size += myQuery.size();

         return size;

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to ensure the query document is not too large.

      * </p>

      */

     @Override

     public void validateSize(final int maxDocumentSize)

             throws DocumentToLargeException {

         final long size = myQuery.size();

         if (maxDocumentSize < size) {

             throw new DocumentToLargeException((int) size, maxDocumentSize,

                     myQuery);

         }

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to write a delete message.

      * </p>

      * 

      * @see Message#write

      */

     @Override

     public void write(final int messageId, final BsonOutputStream out)

             throws IOException {

         final int flags = computeFlags();

         int size = HEADER_SIZE;

         size += 4; // reserved - 0;

         size += out.sizeOfCString(myDatabaseName, ".", myCollectionName);

         size += 4; // flags

         size += myQuery.size();

         writeHeader(out, messageId, 0, Operation.DELETE, size);

         out.writeInt(0);

         out.writeCString(myDatabaseName, ".", myCollectionName);

         out.writeInt(flags);

         out.writeDocument(myQuery);

     }

     /**

      * {@inheritDoc}

      * <p>

      * Overridden to write a delete message.

      * </p>

      * 

      * @see Message#write

      */

     @Override

     public void write(final int messageId, final BufferingBsonOutputStream out)

             throws IOException {

         final int flags = computeFlags();

         final long start = writeHeader(out, messageId, 0, Operation.DELETE);

         out.writeInt(0);

         out.writeCString(myDatabaseName, ".", myCollectionName);

         out.writeInt(flags);

         out.writeDocument(myQuery);

         finishHeader(out, start);

         out.flushBuffer();

     }

     /**

      * Computes the message flags bit field.

      * 

      * @return The message flags bit field.

      */

     private int computeFlags() {

         int flags = 0;

         if (mySingleDelete) {

             flags += SINGLE_DELETE_BIT;

         }

         return flags;

     }

 }