/*******************************************************************************
 * Copyright (c) 2004, 2008 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
 *******************************************************************************/
package org.eclipse.ltk.core.refactoring.tests;

import java.io.IOException;

import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;

/**
 * Home for file system-related utility methods.
 */
public class FileSystemHelper {
	/** counter for generating unique random file system locations */
	protected static int nextLocationCounter = 0;
	private static final long MASK = 0x00000000FFFFFFFFL;

	/*
	 * Return the root directory for the temp dir.
	 */
	public static IPath getTempDir() {
		String tempPath = System.getProperty("java.io.tmpdir");
		try {
			tempPath = new java.io.File(tempPath).getCanonicalPath();
		} catch (IOException e) {
			//ignore and use non-canonical path
		}
		return new Path(tempPath);
	}

	/**
	 * Returns a unique location on disk.  It is guaranteed that no file currently
	 * exists at that location.  The returned location will be unique with respect
	 * to all other locations generated by this method in the current session.
	 * If the caller creates a folder or file at this location, they are responsible for
	 * deleting it when finished.
	 * @param parent the parent path
	 * @return returns a unique location on disk
	 */
	public static IPath getRandomLocation(IPath parent) {
		IPath path = computeRandomLocation(parent);
		while (path.toFile().exists()) {
			try {
				Thread.sleep(10);
			} catch (InterruptedException e) {
				// ignore
			}
			path = computeRandomLocation(parent);
		}
		return path;
	}

	public static IPath computeRandomLocation(IPath parent) {
		long segment = (long) ++nextLocationCounter << 32 | System.currentTimeMillis() & MASK;
		return parent.append(Long.toString(segment));
	}

}