//******************************************************************************
//
// File:    StreamFile.java
// Package: edu.rit.pj.io
// Unit:    Class edu.rit.pj.io.StreamFile
//
// This Java source file is copyright (C) 2006 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ 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 3 of the License, or (at your option) any later version.
//
// PJ 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.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.pj.io;

import edu.rit.pj.cluster.JobBackend;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Class StreamFile represents a file that resides in the user's account in the
 * job frontend process of a PJ cluster parallel program. Operations are
 * provided to open an input stream or an output stream to read or write the
 * file in the frontend processor.
 *
 * @author  Alan Kaminsky
 * @version 06-Nov-2006
 */
public class StreamFile
	{

// Hidden data members.

	private File myFile;

// Exported constructors.

	/**
	 * Construct a new stream file that refers to the given file in the frontend
	 * processor.
	 *
	 * @param  theFile  File.
	 *
	 * @exception  NullPointerException
	 *     (unchecked exception) Thrown if <TT>theFile</TT> is null.
	 */
	public StreamFile
		(File theFile)
		{
		if (theFile == null)
			{
			throw new NullPointerException
				("StreamFile(): theFile is null");
			}
		myFile = theFile;
		}

// Exported operations.

	/**
	 * Obtain the file in the frontend processor to which this stream file
	 * refers.
	 *
	 * @return  File.
	 */
	public File getFile()
		{
		return myFile;
		}

	/**
	 * Open an output stream for writing this stream file. If the file does not
	 * exist, it is created; if the file exists, it is overwritten.
	 * <P>
	 * When called from a job backend process in a cluster parallel program, the
	 * returned output stream communicates with the job frontend process to
	 * write the file in the frontend processor. Otherwise, the returned output
	 * stream is a normal file output stream to write the file directly.
	 * <P>
	 * <I>Note:</I> The returned output stream does not do any buffering. Each
	 * method call sends a message to and receives a message from the job
	 * frontend. Consider layering a BufferedOutputStream on top of the returned
	 * output stream.
	 *
	 * @return  Output stream.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public OutputStream getOutputStream()
		throws IOException
		{
		return getOutputStream (false);
		}

	/**
	 * Open an output stream for writing this stream file. If the file does not
	 * exist, it is created; if the file exists and the <TT>append</TT> flag is
	 * false, the file is overwritten; if the file exists and the
	 * <TT>append</TT> flag is true, data is written after the end of the file.
	 * <P>
	 * When called from a job backend process in a cluster parallel program, the
	 * returned output stream communicates with the job frontend process to
	 * write the file in the frontend processor. Otherwise, the returned output
	 * stream is a normal file output stream to write the file directly.
	 * <P>
	 * <I>Note:</I> The returned output stream does not do any buffering. Each
	 * method call sends a message to and receives a message from the job
	 * frontend. Consider layering a BufferedOutputStream on top of the returned
	 * output stream.
	 *
	 * @param  append  True to append, false to overwrite.
	 *
	 * @return  Output stream.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public OutputStream getOutputStream
		(boolean append)
		throws IOException
		{
		JobBackend backend = JobBackend.getJobBackend();
		if (backend == null)
			{
			return new FileOutputStream (myFile, append);
			}
		else
			{
			return backend.getFileWriter().open (myFile, append);
			}
		}

	/**
	 * Open an input stream for reading this stream file.
	 * <P>
	 * When called from a job backend process in a cluster parallel program, the
	 * returned input stream communicates with the job frontend process to read
	 * the file in the frontend processor. Otherwise, the returned input stream
	 * is a normal file input stream to read the file directly.
	 * <P>
	 * <I>Note:</I> The returned input stream does not do any buffering. Each
	 * method call sends a message to and receives a message from the job
	 * frontend. Consider layering a BufferedInputStream on top of the returned
	 * input stream.
	 *
	 * @return  Input stream.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public InputStream getInputStream()
		throws IOException
		{
		JobBackend backend = JobBackend.getJobBackend();
		if (backend == null)
			{
			return new FileInputStream (myFile);
			}
		else
			{
			return backend.getFileReader().open (myFile);
			}
		}

	/**
	 * Determine if this stream file is equal to the given object.
	 *
	 * @param  obj  Object to test.
	 *
	 * @return  True if this stream file is equal to <TT>obj</TT>, false
	 *          otherwise.
	 */
	public boolean equals
		(Object obj)
		{
		return
			(obj instanceof StreamFile) &&
			(this.myFile.equals (((StreamFile) obj).myFile));
		}

	/**
	 * Returns a hash code for this stream file.
	 *
	 * @return  Hash code.
	 */
	public int hashCode()
		{
		return myFile.hashCode();
		}

	/**
	 * Returns a string version of this stream file.
	 *
	 * @return  String version.
	 */
	public String toString()
		{
		return myFile.toString();
		}

	}