package org.apache.lucene.store;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache Lucene", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.Serializable;
import java.io.IOException;
import java.util.Vector;
import java.util.Hashtable;
import java.util.Enumeration;

import org.apache.lucene.store.Directory;
import org.apache.lucene.store.InputStream;
import org.apache.lucene.store.OutputStream;

//--------------------------------------------------------------------------------------------------------------

final public class SerializableRAMDirectory extends Directory implements Serializable {

	Hashtable files = new Hashtable();

	public SerializableRAMDirectory() {
		}

	/** Returns an array of strings, one for each file in the directory. */
	public final String[] list() {
		String[] result = new String[files.size()];
		int i = 0;
		Enumeration names = files.keys();
		while (names.hasMoreElements()) {
			result[i++] = (String)names.nextElement();
			}
		return result;
		}

	/** Returns true iff the named file exists in this directory. */
	public final boolean fileExists(String name) {
		SerializableRAMFile file = (SerializableRAMFile)files.get(name);
		return file != null;
		}

	/** Returns the time the named file was last modified. */
	public final long fileModified(String name) throws IOException {
		SerializableRAMFile file = (SerializableRAMFile)files.get(name);
		return file.lastModified;
		}

	/** Returns the length in bytes of a file in the directory. */
	public final long fileLength(String name) {
		SerializableRAMFile file = (SerializableRAMFile)files.get(name);
		return file.length;
		}

	/** Removes an existing file in the directory. */
	public final void deleteFile(String name) {
		files.remove(name);
		}

	/** Removes an existing file in the directory. */
	public final void renameFile(String from, String to) {
		SerializableRAMFile file = (SerializableRAMFile)files.get(from);
		files.remove(from);
		files.put(to, file);
		}

	/** Creates a new, empty file in the directory with the given name.
		Returns a stream writing this file. */
	public final OutputStream createFile(String name) {
		SerializableRAMFile file = new SerializableRAMFile();
		files.put(name, file);
		return new SerializableRAMOutputStream(file);
		}

	/** Returns a stream reading an existing file. */
	public final InputStream openFile(String name) {
		SerializableRAMFile file = (SerializableRAMFile)files.get(name);
		return new SerializableRAMInputStream(file);
		}

	/** Construct a {@link Lock}.
	 * @param name the name of the lock file
	 */
	public final Lock makeLock(final String name) {
		return new Lock() {
			//--
			public boolean obtain() throws IOException {
				synchronized (files) {
					if (!fileExists(name)) {
						createFile(name).close();
						return true;
						}
					return false;
					}
				}
			public void release() {
				deleteFile(name);
				}
			};
		   //--
		}

	/** Closes the store to future operations. */
	public final void close() {
		}
	}

//--------------------------------------------------------------------------------------------------------------

final class SerializableRAMInputStream extends InputStream implements Cloneable {
	SerializableRAMFile file;
	int pointer = 0;

	public SerializableRAMInputStream(SerializableRAMFile f) {
		file = f;
		length = file.length;
		}

	/** InputStream methods */
	public final void readInternal(byte[] dest, int destOffset, int len) {
		int remainder = len;
		int start = pointer;
		while (remainder != 0) {
			int bufferNumber = start/InputStream.BUFFER_SIZE;
			int bufferOffset = start%InputStream.BUFFER_SIZE;
			int bytesInBuffer = InputStream.BUFFER_SIZE - bufferOffset;
			int bytesToCopy = bytesInBuffer >= remainder ? remainder : bytesInBuffer;
			byte[] buffer = (byte[])file.buffers.elementAt(bufferNumber);
			System.arraycopy(buffer, bufferOffset, dest, destOffset, bytesToCopy);
			destOffset += bytesToCopy;
			start += bytesToCopy;
			remainder -= bytesToCopy;
			}
		pointer += len;
		}

	public final void close() {
		}

	/** Random-access methods */
	public final void seekInternal(long pos) {
		pointer = (int)pos;
		}
	}

//--------------------------------------------------------------------------------------------------------------

final class SerializableRAMOutputStream extends OutputStream {
	SerializableRAMFile file;
	int pointer = 0;

	public SerializableRAMOutputStream(SerializableRAMFile f) {
		file = f;
		}

	/** output methods: */
	public final void flushBuffer(byte[] src, int len) {
		int bufferNumber = pointer/OutputStream.BUFFER_SIZE;
		int bufferOffset = pointer%OutputStream.BUFFER_SIZE;
		int bytesInBuffer = OutputStream.BUFFER_SIZE - bufferOffset;
		int bytesToCopy = bytesInBuffer >= len ? len : bytesInBuffer;

		if (bufferNumber == file.buffers.size())
			file.buffers.addElement(new byte[OutputStream.BUFFER_SIZE]);

		byte[] buffer = (byte[])file.buffers.elementAt(bufferNumber);
		System.arraycopy(src, 0, buffer, bufferOffset, bytesToCopy);

		if (bytesToCopy < len) {			  // not all in one buffer
			int srcOffset = bytesToCopy;
			bytesToCopy = len - bytesToCopy;		  // remaining bytes
			bufferNumber++;
			if (bufferNumber == file.buffers.size())
				file.buffers.addElement(new byte[OutputStream.BUFFER_SIZE]);
			buffer = (byte[])file.buffers.elementAt(bufferNumber);
			System.arraycopy(src, srcOffset, buffer, 0, bytesToCopy);
			}
		pointer += len;
		if (pointer > file.length)
			file.length = pointer;

		file.lastModified = System.currentTimeMillis();
		}

	public final void close() throws IOException {
		super.close();
		}

	/** Random-access methods */
	public final void seek(long pos) throws IOException {
		super.seek(pos);
		pointer = (int)pos;
		}
	public final long length() throws IOException {
		return file.length;
		}
	}

//--------------------------------------------------------------------------------------------------------------

final class SerializableRAMFile implements Serializable {
	Vector buffers = new Vector();
	long length;
	long lastModified = System.currentTimeMillis();
	}

//--------------------------------------------------------------------------------------------------------------