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/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.io;

import proguard.classfile.*;

import java.io.*;
import java.nio.charset.Charset;

/**
 * This DataEntryReader writes the resource data entries that it reads to a
 * given DataEntryWriter, updating their contents based on the renamed classes
 * in the given ClassPool.
 *
 * @author Eric Lafortune
 */
public class DataEntryRewriter extends DataEntryCopier
{
    private final ClassPool classPool;
    private final Charset   charset;


    /**
     * Creates a new DataEntryRewriter.
     */
    public DataEntryRewriter(ClassPool       classPool,
                             Charset         charset,
                             DataEntryWriter dataEntryWriter)
    {
        super(dataEntryWriter);

        this.classPool = classPool;
        this.charset   = charset;
    }


    // Implementations for DataEntryCopier.

    protected void copyData(InputStream  inputStream,
                            OutputStream outputStream)
    throws IOException
    {
        Reader reader = new BufferedReader(new InputStreamReader(inputStream, charset));
        Writer writer = new BufferedWriter(new OutputStreamWriter(outputStream, charset));

        copyData(reader, writer);

        writer.flush();
    }


    /**
     * Copies all data that it can read from the given reader to the given
     * writer.
     */
    protected void copyData(Reader reader,
                            Writer writer)
    throws IOException
    {
        StringBuffer word = new StringBuffer();

        while (true)
        {
            int i = reader.read();
            if (i < 0)
            {
                break;
            }

            // Is the character part of a word?
            char c = (char)i;
            if (Character.isJavaIdentifierPart(c) ||
                c == '.' ||
                c == '-')
            {
                // Collect the characters in this word.
                word.append(c);
            }
            else
            {
                // Write out the updated word, if any.
                writeUpdatedWord(writer, word.toString());
                word.setLength(0);

                // Write out the character that terminated it.
                writer.write(c);
            }
        }

        // Write out the final word.
        writeUpdatedWord(writer, word.toString());
    }


    // Small utility methods.

    /**
     * Writes the given word to the given writer, after having adapted it,
     * based on the renamed class names.
     */
    private void writeUpdatedWord(Writer writer, String word)
    throws IOException
    {
        if (word.length() > 0)
        {
            String newWord = word;

            boolean containsDots = word.indexOf('.') >= 0;

            // Replace dots by forward slashes.
            String className = containsDots ?
                word.replace('.', ClassConstants.PACKAGE_SEPARATOR) :
                word;

            // Find the class corresponding to the word.
            Clazz clazz = classPool.getClass(className);
            if (clazz != null)
            {
                // Update the word if necessary.
                String newClassName = clazz.getName();
                if (!className.equals(newClassName))
                {
                    // Replace forward slashes by dots.
                    newWord = containsDots ?
                        newClassName.replace(ClassConstants.PACKAGE_SEPARATOR, '.') :
                        newClassName;
                }
            }

            writer.write(newWord);
        }
    }
}