/*

* Copyright (c) 2002 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  SourceStream that buffers data from another SourceStream.

*

*/

package com.nokia.microedition.media;

import java.io.IOException;

import javax.microedition.media.protocol.SourceStream;

/**

 * SourceStream that buffers data from another SourceStream.

 *

 */

public class BufferSourceStream extends InputStreamSourceStream

{

    // Deferred buffer size

    private static final int BUFFER_SIZE = 5120;

    // Stream to buffer

    SourceStream iSourceStream;

    byte[] iBuffer;

    // stream read position

    int iPos;

    /**

     * Constructor.

     * @param aInputStream An InputStream

     */

    public BufferSourceStream(SourceStream aSourceStream)

    {

        iSourceStream = aSourceStream;

    }

    /**

     * Return header data.

     * @return header data

     */

    public byte[] getHeader() throws IOException

    {

        // Read header if this method is called for the first time

        if (iBuffer == null)

        {

            byte[] tmpBuffer = new byte[ BUFFER_SIZE ];

            int bytesInBuffer = iSourceStream.read(tmpBuffer, 0, BUFFER_SIZE);

            // bytesInBuffer is the total number of bytes read into the buffer,

            // or -1 if there is no more data because the end of the stream has

            // been reached.

            if (bytesInBuffer >= 0)

            {

                iBuffer = new byte[ bytesInBuffer ];

                System.arraycopy(tmpBuffer, 0,

                                 iBuffer, 0, bytesInBuffer);

            }

            else

            {

                throw new IOException();

            }

        }

        return iBuffer;

    }

    /**

     * Read from Input Stream

     * @param buffer Input Stream

     * @param offset where reading starts

     * @param length length of read data

     * @return bytes read

     * @throws IOException

     */

    public int read(byte[] aBuffer, int aOffset, int aLength) throws IOException

    {

        // bytes read from internal buffer

        int bytesFromBuffer = 0;

        if ((iBuffer != null) &&   // read from iBuffer if getHeader is called

                (iPos < iBuffer.length))

        {

            // Need to read from buffer

            if (aLength < iBuffer.length - iPos)

            {

                // aLength bytes can be read from buffer

                bytesFromBuffer = aLength;

            }

            else

            {

                // aLength cannot be read from buffer

                // read all there is available

                bytesFromBuffer = iBuffer.length - iPos;

            }

            System.arraycopy(iBuffer, iPos,

                             aBuffer, aOffset, bytesFromBuffer);

            // move stream position

            iPos += bytesFromBuffer;

            return bytesFromBuffer;

        }

        // bytes read from iSourceStream

        int bytesFromStream = 0;

        // Check if bytes are needed from SourceStream

        if (bytesFromBuffer < aLength)

        {

            bytesFromStream = iSourceStream.read(aBuffer,

                                                 bytesFromBuffer,

                                                 aLength - bytesFromBuffer);

            if (bytesFromStream != -1)

            {

                // move stream position, if not end of stream

                iPos += bytesFromStream;

            }

        }

        return bytesFromStream;

    }

}

// End of File