/*
 * Copyright 2012, 2013 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */


package com.redhat.thermostat.web.server;

import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;

class TokenManager {

    private static final int TOKEN_LENGTH = 256;

    private SecureRandom random = new SecureRandom();

    private Map<String,byte[]> tokens = Collections.synchronizedMap(new HashMap<String,byte[]>());

    // Maybe use a ScheduledExecutorService if this turns out to not scale well enough.
    private Timer timer = new Timer();

    private int timeout = 30 * 1000;

    void setTimeout(int timeout) {
        this.timeout = timeout;
    }

    byte[] generateToken(String clientToken) {
        byte[] token = new byte[TOKEN_LENGTH];
        random.nextBytes(token);
        tokens.put(clientToken, token);
        scheduleRemoval(clientToken);
        return token;
    }

    private void scheduleRemoval(final String clientToken) {
        TimerTask task = new TimerTask() {
            
            @Override
            public void run() {
                tokens.remove(clientToken);
            }
        };
        timer.schedule(task, timeout);
    }

    boolean verifyToken(String clientToken, byte[] token) {
        if (tokens.containsKey(clientToken)) {
            byte[] storedToken = tokens.get(clientToken);
            boolean verified = Arrays.equals(token, storedToken);
            if (verified) {
                tokens.remove(clientToken);
            }
            return verified;
        }
        return false;
    }

}