/*

  * #%L

  * BufferingWriteVisitor.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.io;

 import java.io.IOException;

 import java.io.OutputStream;

 import java.util.List;

 import com.allanbank.mongodb.bson.Document;

 import com.allanbank.mongodb.bson.Element;

 import com.allanbank.mongodb.bson.ElementType;

 import com.allanbank.mongodb.bson.Visitor;

 import com.allanbank.mongodb.bson.element.ObjectId;

 /**

  * A visitor to write the BSON document to a {@link RandomAccessOutputStream}.

  * The BSON specification uses prefixed length integers in several locations.

  * The {@link RandomAccessOutputStream} allows those values to be re-written

  * with a single serialization pass.

  * 

  * @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

  */

 /* package */class BufferingWriteVisitor implements Visitor {

     /** Output buffer for spooling the written document. */

     protected final RandomAccessOutputStream myOutputBuffer;

     /**

      * Creates a new {@link BufferingWriteVisitor}.

      */

     public BufferingWriteVisitor() {

         this(new StringEncoderCache());

     }

     /**

      * Creates a new {@link BufferingWriteVisitor}.

      * 

      * @param output

      *            The output buffer to use.

      */

     public BufferingWriteVisitor(final RandomAccessOutputStream output) {

         myOutputBuffer = output;

     }

     /**

      * Creates a new {@link BufferingWriteVisitor}.

      * 

      * @param cache

      *            The cache for encoding strings

      */

     public BufferingWriteVisitor(final StringEncoderCache cache) {

         this(new RandomAccessOutputStream(cache));

     }

     /**

      * Returns the maximum number of strings that may have their encoded form

      * cached.

      * 

      * @return The maximum number of strings that may have their encoded form

      *         cached.

      * @deprecated The cache {@link StringEncoderCache} should be controlled

      *             directory. This method will be removed after the 2.1.0

      *             release.

      */

     @Deprecated

     public int getMaxCachedStringEntries() {

         return myOutputBuffer.getMaxCachedStringEntries();

     }

     /**

      * Returns the maximum length for a string that the stream is allowed to

      * cache.

      * 

      * @return The maximum length for a string that the stream is allowed to

      *         cache.

      * @deprecated The cache {@link StringEncoderCache} should be controlled

      *             directory. This method will be removed after the 2.1.0

      *             release.

      */

     @Deprecated

     public int getMaxCachedStringLength() {

         return myOutputBuffer.getMaxCachedStringLength();

     }

     /**

      * Return the current Size of the written document.

      * 

      * @return The current size of the encoded document.

      */

     public long getSize() {

         return myOutputBuffer.getPosition();

     }

     /**

      * Clears the internal buffer and prepares to write another document.

      */

     public void reset() {

         myOutputBuffer.reset();

     }

     /**

      * Sets the value of maximum number of strings that may have their encoded

      * form cached.

      * 

      * @param maxCacheEntries

      *            The new value for the maximum number of strings that may have

      *            their encoded form cached.

      * @deprecated The cache {@link StringEncoderCache} should be controlled

      *             directory. This method will be removed after the 2.1.0

      *             release.

      */

     @Deprecated

     public void setMaxCachedStringEntries(final int maxCacheEntries) {

         myOutputBuffer.setMaxCachedStringEntries(maxCacheEntries);

     }

     /**

      * Sets the value of length for a string that the stream is allowed to cache

      * to the new value. This can be used to stop a single long string from

      * pushing useful values out of the cache.

      * 

      * @param maxlength

      *            The new value for the length for a string that the encoder is

      *            allowed to cache.

      * @deprecated The cache {@link StringEncoderCache} should be controlled

      *             directory. This method will be removed after the 2.1.0

      *             release.

      */

     @Deprecated

     public void setMaxCachedStringLength(final int maxlength) {

         myOutputBuffer.setMaxCachedStringLength(maxlength);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visit(final List<Element> elements) {

         final long position = myOutputBuffer.getPosition();

         myOutputBuffer.writeInt(0);

         for (final Element element : elements) {

             element.accept(this);

         }

         myOutputBuffer.writeByte((byte) 0);

         final int size = (int) (myOutputBuffer.getPosition() - position);

         myOutputBuffer.writeIntAt(position, size);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitArray(final String name, final List<Element> elements) {

         myOutputBuffer.writeByte(ElementType.ARRAY.getToken());

         myOutputBuffer.writeCString(name);

         visit(elements);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitBinary(final String name, final byte subType,

             final byte[] data) {

         myOutputBuffer.writeByte(ElementType.BINARY.getToken());

         myOutputBuffer.writeCString(name);

         switch (subType) {

         case 2: {

             myOutputBuffer.writeInt(data.length + 4);

             myOutputBuffer.writeByte(subType);

             myOutputBuffer.writeInt(data.length);

             myOutputBuffer.writeBytes(data);

             break;

         }

         case 0:

         default:

             myOutputBuffer.writeInt(data.length);

             myOutputBuffer.writeByte(subType);

             myOutputBuffer.writeBytes(data);

             break;

         }

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitBoolean(final String name, final boolean value) {

         myOutputBuffer.writeByte(ElementType.BOOLEAN.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeByte(value ? (byte) 0x01 : 0x00);

     }

     /**

      * {@inheritDoc}

      */

     @SuppressWarnings("deprecation")

     @Override

     public void visitDBPointer(final String name, final String databaseName,

             final String collectionName, final ObjectId id) {

         myOutputBuffer.writeByte(ElementType.DB_POINTER.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeString(databaseName + "." + collectionName);

         // Just to be complicated the Object ID is big endian.

         myOutputBuffer.writeInt(EndianUtils.swap(id.getTimestamp()));

         myOutputBuffer.writeLong(EndianUtils.swap(id.getMachineId()));

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitDocument(final String name, final List<Element> elements) {

         myOutputBuffer.writeByte(ElementType.DOCUMENT.getToken());

         myOutputBuffer.writeCString(name);

         visit(elements);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitDouble(final String name, final double value) {

         myOutputBuffer.writeByte(ElementType.DOUBLE.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeLong(Double.doubleToLongBits(value));

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitInteger(final String name, final int value) {

         myOutputBuffer.writeByte(ElementType.INTEGER.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeInt(value);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitJavaScript(final String name, final String code) {

         myOutputBuffer.writeByte(ElementType.JAVA_SCRIPT.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeString(code);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitJavaScript(final String name, final String code,

             final Document scope) {

         myOutputBuffer.writeByte(ElementType.JAVA_SCRIPT_WITH_SCOPE.getToken());

         myOutputBuffer.writeCString(name);

         final long start = myOutputBuffer.getPosition();

         myOutputBuffer.writeInt(0);

         myOutputBuffer.writeString(code);

         scope.accept(this);

         final int size = (int) (myOutputBuffer.getPosition() - start);

         myOutputBuffer.writeIntAt(start, size);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitLong(final String name, final long value) {

         myOutputBuffer.writeByte(ElementType.LONG.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeLong(value);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitMaxKey(final String name) {

         myOutputBuffer.writeByte(ElementType.MAX_KEY.getToken());

         myOutputBuffer.writeCString(name);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitMinKey(final String name) {

         myOutputBuffer.writeByte(ElementType.MIN_KEY.getToken());

         myOutputBuffer.writeCString(name);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitMongoTimestamp(final String name, final long value) {

         myOutputBuffer.writeByte(ElementType.MONGO_TIMESTAMP.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeLong(value);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitNull(final String name) {

         myOutputBuffer.writeByte(ElementType.NULL.getToken());

         myOutputBuffer.writeCString(name);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitObjectId(final String name, final ObjectId id) {

         myOutputBuffer.writeByte(ElementType.OBJECT_ID.getToken());

         myOutputBuffer.writeCString(name);

         // Just to be complicated the Object ID is big endian.

         myOutputBuffer.writeInt(EndianUtils.swap(id.getTimestamp()));

         myOutputBuffer.writeLong(EndianUtils.swap(id.getMachineId()));

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitRegularExpression(final String name, final String pattern,

             final String options) {

         myOutputBuffer.writeByte(ElementType.REGEX.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeCString(pattern);

         myOutputBuffer.writeCString(options);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitString(final String name, final String value) {

         myOutputBuffer.writeByte(ElementType.STRING.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeString(value);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitSymbol(final String name, final String symbol) {

         myOutputBuffer.writeByte(ElementType.SYMBOL.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeString(symbol);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitTimestamp(final String name, final long timestamp) {

         myOutputBuffer.writeByte(ElementType.UTC_TIMESTAMP.getToken());

         myOutputBuffer.writeCString(name);

         myOutputBuffer.writeLong(timestamp);

     }

     /**

      * Writes the internal buffer to the provided stream.

      * 

      * @param out

      *            The stream to write the internal buffer to.

      * @throws IOException

      *             On a failure writing the buffer to the <tt>out</tt> stream.

      */

     public void writeTo(final OutputStream out) throws IOException {

         myOutputBuffer.writeTo(out);

     }

     /**

      * Returns the visitor's output buffer.

      * 

      * @return The visitor's output buffer.

      */

     protected RandomAccessOutputStream getOutputBuffer() {

         return myOutputBuffer;

     }

 }