/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2014 by RapidMiner and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapidminer.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.nio.file;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectStreamException;
import java.io.WriteAbortedException;

import com.rapidminer.operator.Annotations;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.ResultObjectAdapter;
import com.rapidminer.tools.Tools;

/**
 * 
 * This class represents buffers, files or streams that can be parsed by Operators.
 * 
 * @author Nils Woehler, Marius Helf
 *
 */
public abstract class FileObject extends ResultObjectAdapter {

	private static final long serialVersionUID = 1L;

	/**
	 * Open Stream to read data in this Object.
	 * @throws OperatorException 
	 * 
	 */
	public abstract InputStream openStream() throws OperatorException;

	/**
	 * Returns the data as a file. Maybe slow if underlying implementation needs to copy the data into the file first.
	 * This file should be used only for reading. Writing to this file has an undefined effect.
	 */
	public abstract File getFile() throws OperatorException;

	@Override
	public String getName() {
		return "File";
	}

	/**
	 * Returns the filename of this file object.<br/>
	 * <br/>
	 * If the {@link Annotations#KEY_FILENAME} annotation is defined, returns it.
	 * Otherwise, tries to retrieve the {@link Annotations#KEY_SOURCE} annotation
	 * and extract a filename from it.<br/>
	 * <br/>
	 * Returns null if none of the above works.
	 */
	public String getFilename() {
		String filename = getAnnotations().getAnnotation(Annotations.KEY_FILENAME);
		if (filename == null) {
			filename = getAnnotations().getAnnotation(Annotations.KEY_SOURCE);
			if (filename != null) {
				filename = filename.replaceAll(".*[/\\\\]([^/\\\\\\?]*).*", "$1");
			}
		}
		return filename;
	}

	protected Object writeReplace() throws ObjectStreamException {
		if (this instanceof BufferedFileObject) {
			return this;
		}
		InputStream fileInputStream = null;
		try {
			fileInputStream = openStream();
			return new BufferedFileObject(Tools.readInputStream(fileInputStream));
		} catch (OperatorException e) {
			throw new WriteAbortedException("Could not write FileObject", e);
		} catch (IOException e) {
			throw new WriteAbortedException("Could not write FileObject", e);
		} finally {
			if (fileInputStream != null) {
				try {
					fileInputStream.close();
				} catch (IOException e) {}
			}
		}
	}
}