/*

* Copyright (c) 2007 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:

*

* Output stream which compares the data to existing file before writing

*

*/

package com.nokia.tracecompiler.file;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.OutputStream;

/**

 * Output stream which writes to a byte array. When writing is complete, the

 * array contents are compared to existing file and the file is written only if

 * there are changes

 * 

 */

public class FileCompareOutputStream extends ByteArrayOutputStream {

	/**

	 * The header file

	 */

	private File file;

	/**

	 * Creates a new stream

	 * 

	 * @param file

	 *            the header file

	 */

	public FileCompareOutputStream(File file) {

		this.file = file;

	}

	/**

	 * Writes the buffer to file if it has changed

	 * 

	 * @return true if header was written, false if it matched the existing

	 *         header

	 * @throws IOException

	 *             if writing fails

	 */

	public boolean writeFile() throws IOException {

		// Compares the file length to number of bytes in array

		boolean writeHeader = true;

		if (file.length() == count) {

			FileInputStream fis = new FileInputStream(file);

			byte[] temp = new byte[count];

			fis.read(temp);

			fis.close();

			writeHeader = false;

			// Compares the file content

			for (int i = 0; i < count; i++) {

				if (temp[i] != buf[i]) {

					writeHeader = true;

					i = count;

				}

			}

		}

		if (writeHeader) {

			OutputStream fos = FileUtils.createOutputStream(file);

			writeTo(fos);

			fos.close();

		}

		return writeHeader;

	}

}