/*
 *  Copyright 2011 BetaSteward_at_googlemail.com. All rights reserved.
 * 
 *  Redistribution and use in source and binary forms, with or without modification, are
 *  permitted provided that the following conditions are met:
 * 
 *     1. Redistributions of source code must retain the above copyright notice, this list of
 *        conditions and the following disclaimer.
 * 
 *     2. Redistributions in binary form must reproduce the above copyright notice, this list
 *        of conditions and the following disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 * 
 *  THIS SOFTWARE IS PROVIDED BY BetaSteward_at_googlemail.com ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 *  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BetaSteward_at_googlemail.com OR
 *  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 *  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 *  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 *  The views and conclusions contained in the software and documentation are those of the
 *  authors and should not be interpreted as representing official policies, either expressed
 *  or implied, of BetaSteward_at_googlemail.com.
 */
package mage.server;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import mage.server.User.UserState;
import mage.server.util.ThreadExecutor;
import org.apache.log4j.Logger;

/**
 *
 * manages users - if a user is disconnected and 10 minutes have passed with no
 * activity the user is removed
 * 
 * @author BetaSteward_at_googlemail.com
 */
public class UserManager {

    protected static ScheduledExecutorService expireExecutor = Executors.newSingleThreadScheduledExecutor();

    private static final Logger logger = Logger.getLogger(UserManager.class);

    private final ConcurrentHashMap<UUID, User> users = new ConcurrentHashMap<>();
    
    private static final ExecutorService callExecutor = ThreadExecutor.getInstance().getCallExecutor();

    private static final UserManager INSTANCE = new UserManager();

    public static UserManager getInstance() {
        return INSTANCE;
    }
    
    private UserManager()  {
        expireExecutor.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                checkExpired();
            }
        }, 60, 60, TimeUnit.SECONDS);
    }

    public User createUser(String userName, String host) {
        if (findUser(userName) != null) {
            return null; //user already exists
        }
        User user = new User(userName, host);
        users.put(user.getId(), user);
        return user;
    }

    public User getUser(UUID userId) {
        if (userId != null) {
            return users.get(userId);
        }
        return null;
    }

    public User findUser(String userName) {
        for (User user: users.values()) {
            if (user.getName().equals(userName)) {
                return user;
            }
        }
        return null;
    }

    public Collection<User> getUsers() {
        return users.values();
    }

    public boolean connectToSession(String sessionId, UUID userId) {
        if (userId != null) {
            User user = users.get(userId);
            if (user != null) {
                user.setSessionId(sessionId);
                return true;
            }
        }
        return false;
    }

    public void disconnect(UUID userId, DisconnectReason reason) {
        if (userId != null) {
            User user = users.get(userId);
            if (user != null) {                
                user.setSessionId(""); // Session will be set again with new id if user reconnects
            }
            ChatManager.getInstance().removeUser(userId, reason);
        }
    }

    public boolean isAdmin(UUID userId) {
        if (userId != null) {
            User user = users.get(userId);
            if (user != null) {                
                return user.getName().equals("Admin");
            }
        }
        return false;
    }

    public void removeUser(final UUID userId, final DisconnectReason reason) {        
        if (userId != null) {
            final User user = users.get(userId);
            if (user != null) {
                callExecutor.execute(
                    new Runnable() {
                        @Override
                        public void run() {
                            try {
                                logger.info("USER REMOVE - " + user.getName() + " (" + reason.toString() + ")  userId: " + userId);
                                user.remove(reason);
                                logger.debug("USER REMOVE END - " + user.getName());
                            } catch (Exception ex) {
                                handleException(ex);
                            } finally {
                                users.remove(userId);
                            }
                        }
                    }
                );
            } else {
                logger.warn("Trying to remove userId: " + userId + " - but it does not exist.");
            }
        }        
    }

    public boolean extendUserSession(UUID userId, String pingInfo) {
        if (userId != null) {
            User user = users.get(userId);
            if (user != null) {  
                user.updateLastActivity(pingInfo);
                return true;
            }
        }
        return false;
    }

    /**
     * Is the connection lost for more than 3 minutes, the user will be removed (within 3 minutes the user can reconnect)
     */
    private void checkExpired() {
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.MINUTE, -3);
        List<User> usersToCheck = new ArrayList<>();
        usersToCheck.addAll(users.values());
        for (User user : usersToCheck) {
            if (!user.getUserState().equals(UserState.Expired) && user.isExpired(calendar.getTime())) {
                removeUser(user.getId(), DisconnectReason.SessionExpired);
            }
        }
    }

    public void handleException(Exception ex) {
        if (ex != null) {
            logger.fatal("User manager exception " + (ex.getMessage() == null ? "null":ex.getMessage()));
            if (ex.getCause() != null) {
                logger.debug("- Cause: " + (ex.getCause().getMessage() == null ? "null":ex.getCause().getMessage()));
            }
            ex.printStackTrace();
        }else {
            logger.fatal("User manager exception - null");
        }
    }
}