/*******************************************************************************
 *  Copyright (c) 2012 Google, Inc.
 *  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:
 *  Google, Inc. - initial API and implementation
 *******************************************************************************/
package com.windowtester.runtime.swt.internal.util;

import java.util.ArrayList;
import java.util.List;

/**
 * A utility class for tokenizing path Strings.
 */
public class PathStringTokenizerUtil {

	/**
	 * Take a path string (elements delimited by the '\' character) and break it
	 * into tokens. If an element contains the delimeter, it must be escaped.
	 * <p>
	 * <p>
	 * For example: "Edit/Find\\/Replace" tokenizes to "Edit", "Find/Replace".
	 * 
	 * @param pathString -
	 *            the path string to tokenize
	 * @return an array of string tokens.
	 */
	public static String[] tokenize(String pathString) {
		if (pathString == null)
			throw new IllegalArgumentException("path string must be non-null");
		return new PathTokenizer(pathString).tokenize();		
	}

	/**
	 * A helper class for tokenizing.
	 */
	public static class PathTokenizer {
		
		private final String _pathString;
		private final char _delimeter;
		private final char _escape;
		private StringBuffer _sb = new StringBuffer();
		private final List _items = new ArrayList();

		public PathTokenizer(String pathString, char delimeter, char escape) {
			_pathString = pathString;
			_delimeter = delimeter;
			_escape = escape;
		}

		public PathTokenizer(String pathString) {
			this(pathString, '/', '\\');
		}

		boolean isDelimeter(char c) {
			return c == _delimeter;
		}

		boolean isEscape(char c) {
			return c == _escape;
		}

		public String[] tokenize() {
			for (int i = 0; inBounds(i); ++i) {
				//System.out.println(getChar(i));
				if (isDelimeter(getChar(i))) {
					addItem();
				//removed 
				//}else if (isDoubleEscapeCase(i)) {
					//ignore
				} else if (isEscapeCase(i)) {
					addChar(++i); //advance and add escaped char
				} else {
					addChar(i);    //just add
				}
			}
			//add last item
			addItem();
			
			return getItems();
		}

		private String[] getItems() {
			return (String[]) _items.toArray(new String[]{});
		}

		private void addChar(int i) {
			_sb.append(getChar(i));
		}
		
		private boolean isEscapeCase(int i) {
			return inBounds(i + 1) && isEscape(getChar(i))
					&& isDelimeter(getChar(i + 1));
		}

		private void addItem() {
			if (_sb.length() == 0)
				return;
			_items.add(_sb.toString());
			_sb = new StringBuffer(); // would be nice if we could just clear it...
		}

		private char getChar(int i) {
			return _pathString.charAt(i);
		}

		private boolean inBounds(int i) {
			return i < _pathString.length();
		}

	}

}