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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2009-2015 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
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 * and therefore, elected the GPL Version 2 license, then the option applies
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 */

package com.pdd.pop.ext.glassfish.grizzly.utils;

import com.pdd.pop.ext.glassfish.grizzly.attributes.AttributeStorage;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import com.pdd.pop.ext.glassfish.grizzly.AbstractTransformer;
import com.pdd.pop.ext.glassfish.grizzly.Buffer;
import com.pdd.pop.ext.glassfish.grizzly.Grizzly;
import com.pdd.pop.ext.glassfish.grizzly.TransformationException;
import com.pdd.pop.ext.glassfish.grizzly.TransformationResult;
import com.pdd.pop.ext.glassfish.grizzly.attributes.Attribute;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * String decoder, which decodes {@link Buffer} to {@link String}
 * 
 * @author Alexey Stashok
 */
public class StringDecoder extends AbstractTransformer {
    private static final Logger logger = Grizzly.logger(StringDecoder.class);
    
    protected Charset charset;
    
    protected final Attribute lengthAttribute;

    protected byte[] stringTerminateBytes;

    @SuppressWarnings("unused")
    public StringDecoder() {
        this(null, null);
    }

    @SuppressWarnings("unused")
    public StringDecoder(final String stringTerminator) {
        this(Charset.forName("UTF-8"), stringTerminator);
    }

    public StringDecoder(final Charset charset) {
        this(charset, null);
    }

    public StringDecoder(final Charset charset, final String stringTerminator) {
        this.charset = charset != null ? charset : Charset.defaultCharset();
        
        if (stringTerminator != null) {
            try {
                this.stringTerminateBytes = stringTerminator.getBytes(
                        this.charset.name());
            } catch (final UnsupportedEncodingException ignored) {
                // should never happen as we are getting charset name from Charset
            }
        }

        lengthAttribute = attributeBuilder.createAttribute(
                "StringDecoder.StringSize");
    }

    @Override
    public String getName() {
        return "StringDecoder";
    }

    @Override
    protected TransformationResult transformImpl(
            final AttributeStorage storage, final Buffer input)
            throws TransformationException {

        if (input == null) {
            throw new TransformationException("Input could not be null");
        }

        final TransformationResult result;

        result = stringTerminateBytes == null
                ? parseWithLengthPrefix(storage, input)
                : parseWithTerminatingSeq(storage, input);

        return result;
    }

    protected TransformationResult parseWithLengthPrefix(
            final AttributeStorage storage, final Buffer input) {
        Integer stringSize = lengthAttribute.get(storage);

        if (logger.isLoggable(Level.FINE)) {
            logger.log(Level.FINE, "StringDecoder decode stringSize={0} buffer={1} content={2}",
                    new Object[]{stringSize, input, input.toStringContent()});
        }

        if (stringSize == null) {
            if (input.remaining() < 4) {
                return TransformationResult.createIncompletedResult(input);
            }

            stringSize = input.getInt();
            lengthAttribute.set(storage, stringSize);
        }
        
        if (input.remaining() < stringSize) {
            return TransformationResult.createIncompletedResult(input);
        }

        final int tmpLimit = input.limit();
        input.limit(input.position() + stringSize);
        final String stringMessage = input.toStringContent(charset);
        input.position(input.limit());
        input.limit(tmpLimit);

        return TransformationResult.createCompletedResult(
                stringMessage, input);
    }

    protected TransformationResult parseWithTerminatingSeq(
            final AttributeStorage storage, final Buffer input) {
        final int terminationBytesLength = stringTerminateBytes.length;
        int checkIndex = 0;
        
        int termIndex = -1;

        final Integer offsetInt = lengthAttribute.get(storage);
        int offset = 0;
        if (offsetInt != null) {
            offset = offsetInt;
        }

        for (int i = input.position() + offset, lim = input.limit(); i < lim; i++) {
            if (input.get(i) == stringTerminateBytes[checkIndex]) {
                checkIndex++;
                if (checkIndex >= terminationBytesLength) {
                    termIndex = i - terminationBytesLength + 1;
                    break;
                }
            }
        }

        if (termIndex >= 0) {
            // Terminating sequence was found
            final int tmpLimit = input.limit();
            input.limit(termIndex);
            final String stringMessage = input.toStringContent(charset);
            input.limit(tmpLimit);
            input.position(termIndex + terminationBytesLength);
            return TransformationResult.createCompletedResult(
                    stringMessage, input);
        } else {
            offset = input.remaining() - terminationBytesLength;
            if (offset < 0) {
                offset = 0;
            }

            lengthAttribute.set(storage, offset);            
            return TransformationResult.createIncompletedResult(
                    input);
        }
    }

    @Override
    public void release(final AttributeStorage storage) {
        lengthAttribute.remove(storage);
        super.release(storage);
    }

    @Override
    public boolean hasInputRemaining(final AttributeStorage storage,
                                     final Buffer input) {
        return input != null && input.hasRemaining();
    }

    public Charset getCharset() {
        return charset;
    }

    public void setCharset(final Charset charset) {
        this.charset = charset;
    }
}




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