/*******************************************************************************
 * Copyright (c) 2001, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Jens Lukowski/Innoopract - initial renaming/restructuring
 *     
 *******************************************************************************/
package org.eclipse.wst.sse.core.internal.util;

import java.io.IOException;
import java.io.InputStream;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;

public class DocumentInputStream extends InputStream {
	private IDocument fDocument;
	private int fMark = -1;
	private int fPosition = 0;

	public DocumentInputStream(IDocument source) {
		super();
		fDocument = source;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#available()
	 */
	public int available() throws IOException {
		return fDocument.getLength() - fPosition;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#close()
	 */
	public void close() throws IOException {
		this.fDocument = null;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#mark(int)
	 */
	public synchronized void mark(int readlimit) {
		fMark = fPosition;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#markSupported()
	 */
	public boolean markSupported() {
		return true;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#read()
	 */
	public int read() throws IOException {
		try {
			if (fPosition < fDocument.getLength())
				return fDocument.getChar(fPosition++);
			else
				return -1;
		} catch (BadLocationException e) {
			throw new IOException(e.getMessage());
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#reset()
	 */
	public synchronized void reset() throws IOException {
		fPosition = fMark;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see java.io.InputStream#skip(long)
	 */
	public long skip(long n) throws IOException {
		long skipped = n;
		if (n < fDocument.getLength() - fPosition) {
			skipped = n;
			fPosition += skipped;
		} else {
			skipped = fDocument.getLength() - fPosition;
			fPosition = fDocument.getLength();
		}
		return skipped;
	}
}