/*

  * #%L

  * SizeOfVisitor.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.nio.charset.Charset;

 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.BinaryElement;

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

 /**

  * A visitor to determine the size of the documents it visits.

  * 

  * @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 SizeOfVisitor implements Visitor {

     /** UTF-8 Character set for encoding strings. */

     public final static Charset UTF8 = StringDecoder.UTF8;

     /** The computed size. */

     private int mySize;

     /** The encoder for strings. */

     private final StringEncoder myStringEncoder;

     /**

      * Creates a new SizeOfVisitor.

      */

     public SizeOfVisitor() {

         this(null);

     }

     /**

      * Creates a new SizeOfVisitor.

      * 

      * @param encoder

      *            The encoder for strings.

      */

     public SizeOfVisitor(final StringEncoder encoder) {

         super();

         mySize = 0;

         myStringEncoder = encoder;

     }

     /**

      * Returns the visitor's output buffer.

      * 

      * @param string

      *            The 'C' string to determine the size of.

      * @return The visitor's output buffer.

      */

     public int computeCStringSize(final String string) {

         return utf8Size(string) + 1;

     }

     /**

      * Returns the visitor's output buffer.

      * 

      * @param string

      *            The 'UTF8' string to determine the size of.

      * @return The visitor's output buffer.

      */

     public int computeStringSize(final String string) {

         return 4 + utf8Size(string) + 1;

     }

     /**

      * Return the current Size of the written document.

      * 

      * @return The current size of the encoded document.

      */

     public int getSize() {

         return mySize;

     }

     /**

      * Resets the size to zero and clears the cached documents. Use

      * {@link #rewind()} to just set the size to zero and not clear the cached

      * documents.

      */

     public void reset() {

         mySize = 0;

     }

     /**

      * Resets the size to zero but does not clear the cached documents. Use

      * {@link #reset()} to set the size to zero and clear the cached documents.

      */

     public void rewind() {

         mySize = 0;

     }

     /**

      * Computes the size of the encoded UTF8 String based on the table below.

      * 

      * <pre>

      * #    Code Points      Bytes

      * 1    U+0000..U+007F   1

      * 

      * 2    U+0080..U+07FF   2

      * 

      * 3    U+0800..U+0FFF   3

      *      U+1000..U+FFFF

      * 

      * 4   U+10000..U+3FFFF  4

      *     U+40000..U+FFFFF  4

      *    U+100000..U10FFFF  4

      * </pre>

      * 

      * @param string

      *            The string to determine the length of.

      * @return The length of the string encoded as UTF8.

      */

     public int utf8Size(final String string) {

         if (myStringEncoder != null) {

             return myStringEncoder.encodeSize(string);

         }

         return StringEncoder.utf8Size(string);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 4;

         for (final Element element : elements) {

             // Optimization to avoid the array copy.

             if (element.getType() == ElementType.BINARY) {

                 final BinaryElement be = (BinaryElement) element;

                 doVisitBinary(be.getName(), be.getSubType(), be.length());

             }

             else {

                 element.accept(this);

             }

         }

         mySize += 1;

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         visit(elements);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

             final byte[] data) {

         final int dataLength = data.length;

         doVisitBinary(name, subType, dataLength);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 1;

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

             final String collectionName, final ObjectId id) {

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += computeStringSize(databaseName + "." + collectionName);

         mySize += (4 + 8);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         visit(elements);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 8;

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 4;

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += computeStringSize(code);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

             final Document scope) {

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 4;

         mySize += computeStringSize(code);

         scope.accept(this);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 8;

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitMaxKey(final String name) {

         mySize += 1;

         mySize += computeCStringSize(name);

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitMinKey(final String name) {

         mySize += 1;

         mySize += computeCStringSize(name);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 8;

     }

     /**

      * {@inheritDoc}

      */

     @Override

     public void visitNull(final String name) {

         mySize += 1;

         mySize += computeCStringSize(name);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += (4 + 8);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

             final String options) {

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += computeCStringSize(pattern);

         mySize += computeCStringSize(options);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += computeStringSize(value);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += computeStringSize(symbol);

     }

     /**

      * {@inheritDoc}

      */

     @Override

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

         mySize += 1;

         mySize += computeCStringSize(name);

         mySize += 8;

     }

     /**

      * Computes the size of the binary based on the name, type and length of the

      * data.

      * 

      * @param name

      *            The name of the element.

      * @param subType

      *            The sub-type of the binary element.

      * @param dataLength

      *            The length of data contained in the element.

      */

     private void doVisitBinary(final String name, final byte subType,

             final int dataLength) {

         mySize += 1;

         mySize += computeCStringSize(name);

         switch (subType) {

         case 2: {

             mySize += (4 + 1 + 4 + dataLength);

             break;

         }

         case 0:

         default:

             mySize += (4 + 1 + dataLength);

             break;

         }

     }

 }