//
//  ========================================================================
//  Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
//  ------------------------------------------------------------------------
//  All rights reserved. This program and the accompanying materials
//  are made available under the terms of the Eclipse Public License v1.0
//  and Apache License v2.0 which accompanies this distribution.
//
//      The Eclipse Public License is available at
//      http://www.eclipse.org/legal/epl-v10.html
//
//      The Apache License v2.0 is available at
//      http://www.opensource.org/licenses/apache2.0.php
//
//  You may elect to redistribute this code under either of these licenses.
//  ========================================================================
//

package org.eclipse.jetty.server.session;

import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Random;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/* ------------------------------------------------------------ */
/**
 * HashSessionIdManager. An in-memory implementation of the session ID manager.
 */
public class HashSessionIdManager extends AbstractSessionIdManager
{
    private final Map<String, Set<WeakReference<HttpSession>>> _sessions = new HashMap<String, Set<WeakReference<HttpSession>>>();

    /* ------------------------------------------------------------ */
    public HashSessionIdManager()
    {
    }

    /* ------------------------------------------------------------ */
    public HashSessionIdManager(Random random)
    {
        super(random);
    }

    /* ------------------------------------------------------------ */
    /**
     * @return Collection of String session IDs
     */
    public Collection<String> getSessions()
    {
        return Collections.unmodifiableCollection(_sessions.keySet());
    }

    /* ------------------------------------------------------------ */
    /**
     * @return Collection of Sessions for the passed session ID
     */
    public Collection<HttpSession> getSession(String id)
    {
        ArrayList<HttpSession> sessions = new ArrayList<HttpSession>();
        Set<WeakReference<HttpSession>> refs =_sessions.get(id);
        if (refs!=null)
        {
            for (WeakReference<HttpSession> ref: refs)
            {
                HttpSession session = ref.get();
                if (session!=null)
                    sessions.add(session);
            }
        }
        return sessions;
    }
    
    /* ------------------------------------------------------------ */
    @Override
    protected void doStart() throws Exception
    {
        super.doStart();
    }

    /* ------------------------------------------------------------ */
    @Override
    protected void doStop() throws Exception
    {
        _sessions.clear();
        super.doStop();
    }

    /* ------------------------------------------------------------ */
    /**
     * @see SessionIdManager#idInUse(String)
     */
    @Override
    public boolean idInUse(String id)
    {
        synchronized (this)
        {
            return _sessions.containsKey(id);
        }
    }

    /* ------------------------------------------------------------ */
    /**
     * @see SessionIdManager#addSession(HttpSession)
     */
    @Override
    public void addSession(HttpSession session)
    {
        String id = getClusterId(session.getId());
        WeakReference<HttpSession> ref = new WeakReference<HttpSession>(session);

        synchronized (this)
        {
            Set<WeakReference<HttpSession>> sessions = _sessions.get(id);
            if (sessions==null)
            {
                sessions=new HashSet<WeakReference<HttpSession>>();
                _sessions.put(id,sessions);
            }
            sessions.add(ref);
        }
    }

    /* ------------------------------------------------------------ */
    /**
     * @see SessionIdManager#removeSession(HttpSession)
     */
    @Override
    public void removeSession(HttpSession session)
    {
        String id = getClusterId(session.getId());

        synchronized (this)
        {
            Collection<WeakReference<HttpSession>> sessions = _sessions.get(id);
            if (sessions!=null)
            {
                for (Iterator<WeakReference<HttpSession>> iter = sessions.iterator(); iter.hasNext();)
                {
                    WeakReference<HttpSession> ref = iter.next();
                    HttpSession s=ref.get();
                    if (s==null)
                    {
                        iter.remove();
                        continue;
                    }
                    if (s==session)
                    {
                        iter.remove();
                        break;
                    }
                }
                if (sessions.isEmpty())
                    _sessions.remove(id);
            }
        }
    }

    /* ------------------------------------------------------------ */
    /**
     * @see SessionIdManager#invalidateAll(String)
     */
    @Override
    public void invalidateAll(String id)
    {
        Collection<WeakReference<HttpSession>> sessions;
        synchronized (this)
        {
            sessions = _sessions.remove(id);
        }

        if (sessions!=null)
        {
            for (WeakReference<HttpSession> ref: sessions)
            {
                AbstractSession session=(AbstractSession)ref.get();
                if (session!=null && session.isValid())
                    session.invalidate();
            }
            sessions.clear();
        }
    }
    
    
    /* ------------------------------------------------------------ */
    @Override
    public void renewSessionId (String oldClusterId, String oldNodeId, HttpServletRequest request)
    {
        //generate a new id
        String newClusterId = newSessionId(request.hashCode());


        synchronized (this)
        {
            Set<WeakReference<HttpSession>> sessions = _sessions.remove(oldClusterId); //get the list of sessions with same id from other contexts
            if (sessions!=null)
            {
                for (Iterator<WeakReference<HttpSession>> iter = sessions.iterator(); iter.hasNext();)
                {
                    WeakReference<HttpSession> ref = iter.next();
                    HttpSession s = ref.get();
                    if (s == null)
                    {
                        continue;
                    }
                    else
                    {
                        if (s instanceof AbstractSession)
                        {
                            AbstractSession abstractSession = (AbstractSession)s;
                            abstractSession.getSessionManager().renewSessionId(oldClusterId, oldNodeId, newClusterId, getNodeId(newClusterId, request));
                        }
                    }
                }
                _sessions.put(newClusterId, sessions);
            }
        }
    }

}
