/*
    * dpkg - Debian Package library and the Debian Package Maven plugin
    * (c) Copyright 2016 Gerrit Hohl
    *
    * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   */
  package net.sourceforge.javadpkg.io.impl;
  
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  
  import net.sourceforge.javadpkg.io.DataSource;
  import net.sourceforge.javadpkg.io.Streams;
  
  /**
   * <p>
   * A {@link DataSource} implementation based on a file.
   * </p>
   *
   * @author Gerrit Hohl (gerrit-hohl@users.sourceforge.net)
   * @version <b>1.0</b>, 26.04.2016 by Gerrit Hohl
   */
  public class DataFileSource implements DataSource {
  	
  	
  	/** The file. */
  	private File					file;
  	/** The flag if the {@link #reset()} method will be supported. */
  	private boolean					resettable;
  	/** The name of the source. */
  	private String					name;
  	/** The stream. */
  	private InputStream				in;
  	/**
  	 * <p>
  	 * The public stream which is returned by the {@link #getInputStream()}
  	 * method.
  	 * </p>
  	 */
  	private UncloseableInputStream	publicIn;
  	/** The flag if the stream is already open. */
  	private boolean					opened;
  	
  	
  	/**
  	 * <p>
  	 * Creates a source.
  	 * </p>
  	 * <p>
  	 * The stream on the file will be opened the first time the
  	 * {@link #getInputStream()} method is called.
  	 * </p>
  	 *
  	 * @param file
  	 *            The file.
  	 * @param resettable
  	 *            The flag if the {@link #reset()} method will be supported.
  	 * @throws IllegalArgumentException
  	 *             If the file is <code>null</code>.
  	 */
  	public DataFileSource(File file, boolean resettable) {
  		super();
  
  		if (file == null)
  			throw new IllegalArgumentException("Argument file is null.");
  		
  		this.file = file;
  		this.name = file.getAbsolutePath();
  		this.in = null;
  		this.publicIn = null;
  		this.opened = false;
  		this.resettable = resettable;
  	}
  
  
  	/**
  	 * <p>
  	 * Creates a source.
  	 * </p>
  	 * <p>
  	 * The stream on the file will be opened the first time the
  	 * {@link #getInputStream()} method is called.
  	 * </p>
  	 * <p>
  	 * The {@link #reset()} method will be supported.
 	 * </p>
 	 *
 	 * @param file
 	 *            The file.
 	 * @throws IllegalArgumentException
 	 *             If the file is <code>null</code>.
 	 */
 	public DataFileSource(File file) {
 		this(file, true);
 	}
 
 
 	@Override
 	public String getName() {
 		return this.name;
 	}
 	
 	
 	@Override
 	public long getLength() {
 		return this.file.length();
 	}
 	
 	
 	@Override
 	public boolean isResettable() {
 		return this.resettable;
 	}
 
 
 	@Override
 	public void reset() throws IOException {
 		if (!this.resettable)
 			throw new IOException("Source |" + this.name + "| doesn't support a reset.");
 		try {
 			if (this.in != null) {
 				this.in.close();
 			}
 		} finally {
 			this.in = null;
 			this.publicIn = null;
 			this.opened = false;
 		}
 	}
 
 
 	/**
 	 * <p>
 	 * Creates the {@link InputStream} which is returned by the
 	 * {@link #getInputStream()} method.
 	 * </p>
 	 */
 	private void createPublicInputStream() {
 		this.publicIn = new UncloseableInputStream(this.in, new DelegateCloseHandler(this));
 	}
 	
 	
 	/**
 	 * <p>
 	 * Ensures that the stream is opened.
 	 * </p>
 	 *
 	 * @throws IOException
 	 *             If an error occurs while opening the stream or if the source
 	 *             is already closed.
 	 */
 	private void ensureInputStream() throws IOException {
 		if (this.in == null) {
 			if (!this.opened) {
 				try {
 					this.in = Streams.createBufferedFileInputStream(this.file);
 				} catch (FileNotFoundException e) {
 					throw new IOException("Couldn't open stream on source |" + this.name + "|: " + e.getMessage());
 				}
 				this.createPublicInputStream();
 			} else
 				throw new IOException("The stream of source |" + this.name + "| is already closed.");
 		}
 	}
 
 
 	@Override
 	public InputStream getInputStream() throws IOException {
 		this.ensureInputStream();
 		return this.publicIn;
 	}
 	
 	
 	@Override
 	public void close() throws IOException {
 		try {
 			if (this.in != null) {
 				this.in.close();
 			}
 		} finally {
 			this.publicIn = null;
 			this.in = null;
 		}
 	}
 
 
 }