/* ====================================================================
 * Trove - Copyright (c) 1999-2000 Walt Disney Internet Group
 * ====================================================================
 * The Tea Software License, Version 1.1
 *
 * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Walt Disney Internet Group (http://opensource.go.com/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact opensource@dig.com.
 *
 * 5. Products derived from this software may not be called "Tea",
 *    "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet",
 *    "Kettle", "Trove" or "BeanDoc" appear in their name, without prior
 *    written permission of the Walt Disney Internet Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * For more information about Tea, please see http://opensource.go.com/.
 */

package com.go.trove.io;

import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.io.IOException;
import java.util.List;
import java.util.ArrayList;

/******************************************************************************
 * A ByteBuffer implementation that can read from an open file or can write
 * to it. This implementation is best suited for temporary byte data that is
 * too large to hold in memory.
 *
 * @author Brian S O'Neill
 * @version
 * <!--$$Revision: 1.1 $--> 5 <!-- $$JustDate:--> 00/12/05 <!-- $-->
 */
public class FileByteBuffer implements ByteBuffer {
    private RandomAccessFile mFile;
    private List mSurrogates;
    private List mCaptureBuffers;

    /**
     * Creates a FileByteBuffer on a RandomAccessFile. If the file is opened
     * read-only, then the append operations will fail.
     *
     * @param file The file to use as a buffer.
     */
    public FileByteBuffer(RandomAccessFile file) throws IOException {
        mFile = file;
        file.seek(0);
    }

    public long getBaseByteCount() throws IOException {
        return mFile.length();
    }

    public long getByteCount() throws IOException {
        long count = getBaseByteCount();
        if (mSurrogates == null) {
            return count;
        }
        
        int size = mSurrogates.size();
        for (int i=0; i<size; i++) {
            count += ((Surrogate)mSurrogates.get(i)).mByteData.getByteCount();
        }

        return count;
    }

    public void writeTo(OutputStream out) throws IOException {
        long length = mFile.length();
        int bufSize;
        if (length > 4000) {
            bufSize = 4000;
        }
        else {
            bufSize = (int)length;
        }
        
        byte[] inputBuffer = new byte[bufSize];
        
        mFile.seek(0);

        if (mSurrogates != null) {
            long currentPos = 0;
            
            int size = mSurrogates.size();
            for (int i=0; i<size; i++) {
                Surrogate s = (Surrogate)mSurrogates.get(i);
                currentPos = writeTo(inputBuffer, out, currentPos, s.mPos);
                s.mByteData.writeTo(out);
            }
        }

        // Write out the rest of the file.
        int readAmount;
        while ((readAmount = mFile.read(inputBuffer, 0, bufSize)) > 0) {
            out.write(inputBuffer, 0, readAmount);
        }
    }

    private long writeTo(byte[] inputBuffer, OutputStream out, 
                         long fromPos, long toPos) throws IOException {
        if (toPos == fromPos) {
            return fromPos;
        }

        int bufSize = inputBuffer.length;
        int readAmount;

        while (toPos > fromPos) {
            int amount;
            if (bufSize <= (toPos - fromPos)) {
                amount = bufSize;
            }
            else {
                amount = (int)(toPos - fromPos);
            }

            while ((readAmount = mFile.read(inputBuffer, 0, amount)) > 0) {
                out.write(inputBuffer, 0, readAmount);
                fromPos += readAmount;
                amount -= readAmount;
                if (amount <= 0) {
                    break;
                }
            }

            if (readAmount <= 0) {
                break;
            }
        }

        return fromPos;
    }

    public void append(byte b) throws IOException {
        List captureBuffers;
        if ((captureBuffers = mCaptureBuffers) != null) {
            int size = captureBuffers.size();
            for (int i=0; i<size; i++) {
                ((ByteBuffer)captureBuffers.get(i)).append(b);
            }
        }

        mFile.write(b);
    }

    public void append(byte[] bytes) throws IOException {
        mFile.write(bytes);
    }

    public void append(byte[] bytes, int offset, int length) 
        throws IOException 
    {
        List captureBuffers;
        if ((captureBuffers = mCaptureBuffers) != null) {
            int size = captureBuffers.size();
            for (int i=0; i<size; i++) {
                ((ByteBuffer)captureBuffers.get(i)).append
                    (bytes, offset, length);
            }
        }

        mFile.write(bytes, offset, length); 
    }

    public void appendSurrogate(ByteData s) throws IOException {
        if (s == null) {
            return;
        }

        List captureBuffers;
        if ((captureBuffers = mCaptureBuffers) != null) {
            int size = captureBuffers.size();
            for (int i=0; i<size; i++) {
                ((ByteBuffer)captureBuffers.get(i)).appendSurrogate(s);
            }
        }

        if (mSurrogates == null) {
            mSurrogates = new ArrayList();
        }

        mSurrogates.add(new Surrogate(s));
    }

    public void addCaptureBuffer(ByteBuffer buffer) {
        List captureBuffers;
        if ((captureBuffers = mCaptureBuffers) == null) {
            captureBuffers = mCaptureBuffers = new ArrayList();
        }
        captureBuffers.add(buffer);
    }

    public void removeCaptureBuffer(ByteBuffer buffer) {
        List captureBuffers;
        if ((captureBuffers = mCaptureBuffers) != null) {
            captureBuffers.remove(buffer);
        }
    }

    public void reset() throws IOException {
        List byteDatas;
        int i, size;

        if ((byteDatas = mSurrogates) != null) {
            size = byteDatas.size();
            for (i=0; i<size; i++) {
                ((ByteData)byteDatas.get(i)).reset();
            }
        }

        if ((byteDatas = mCaptureBuffers) != null) {
            size = byteDatas.size();
            for (i=0; i<size; i++) {
                ((ByteData)byteDatas.get(i)).reset();
            }
        }
    }

    private class Surrogate {
        public final ByteData mByteData;
        public final long mPos;

        public Surrogate(ByteData data) throws IOException {
            mByteData = data;
            mPos = mFile.getFilePointer();
        }
    }
}