package com.yanek.study.util;

/**//*
 * blog: http://hi.baidu.com/bobylou
 * $Revision: 1.1 $
 * $Date: 2007/07/18 10:02:55 $
 * $Author: bobrow$
 */

import java.util.ArrayList;

import javax.servlet.http.HttpSession;

public class Token {

	private static final String TOKEN_LIST_NAME = "tokenList";

	public static final String TOKEN_STRING_NAME = "token";

	private static ArrayList getTokenList(HttpSession session) {
		Object obj = session.getAttribute(TOKEN_LIST_NAME);
		if (obj != null) {
			return (ArrayList) obj;
		} else {
			ArrayList tokenList = new ArrayList();
			session.setAttribute(TOKEN_LIST_NAME, tokenList);
			return tokenList;
		}
	}

	private static void saveTokenString(String tokenStr, HttpSession session) {
		ArrayList tokenList = getTokenList(session);
		tokenList.add(tokenStr);
		session.setAttribute(TOKEN_LIST_NAME, tokenList);
	}

	private static String generateTokenString() {
		return new Long(System.currentTimeMillis()).toString();
	}

	/** */
	/**
	 * Generate a token string, and save the string in session, then return the
	 * token string.
	 * 
	 * @param HttpSession
	 *            session
	 * @return a token string used for enforcing a single request for a
	 *         particular transaction.
	 */
	public static String getTokenString(HttpSession session) {
		String tokenStr = generateTokenString();
		saveTokenString(tokenStr, session);
		return tokenStr;
	}

	/** */
	/**
	 * check whether token string is valid. if session contains the token
	 * string, return true. otherwise, return false.
	 * 
	 * @param String
	 *            tokenStr
	 * @param HttpSession
	 *            session
	 * @return true: session contains tokenStr; false: session is null or
	 *         tokenStr is id not in session
	 */
	public static boolean isTokenStringValid(String tokenStr,
			HttpSession session) {
		boolean valid = false;
		if (session != null) {
			ArrayList tokenList = getTokenList(session);
			if (tokenList.contains(tokenStr)) {
				valid = true;
				tokenList.remove(tokenStr);
			}
		}
		return valid;
	}
}