/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.valves;

import java.io.IOException;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Container;
import org.apache.catalina.Context;
import org.apache.catalina.Engine;
import org.apache.catalina.Globals;
import org.apache.catalina.Host;
import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.Store;
import org.apache.catalina.StoreManager;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;

/**
 * Valve that implements per-request session persistence. It is intended to be
 * used with non-sticky load-balancers.
 * <p>
 * <b>USAGE CONSTRAINT</b>: To work correctly it requires a  PersistentManager.
 * <p>
 * <b>USAGE CONSTRAINT</b>: To work correctly it assumes only one request exists
 *                              per session at any one time.
 *
 * @author Jean-Frederic Clere
 */
public class PersistentValve extends ValveBase {

    // Saves a couple of calls to getClassLoader() on every request. Under high
    // load these calls took just long enough to appear as a hot spot (although
    // a very minor one) in a profiler.
    private static final ClassLoader MY_CLASSLOADER = PersistentValve.class.getClassLoader();

    private volatile boolean clBindRequired;

    protected Pattern filter = null;

    //------------------------------------------------------ Constructor

    public PersistentValve() {
        super(true);
    }


    // --------------------------------------------------------- Public Methods

    @Override
    public void setContainer(Container container) {
        super.setContainer(container);
        if (container instanceof Engine || container instanceof Host) {
            clBindRequired = true;
        } else {
            clBindRequired = false;
        }
    }


    /**
     * Select the appropriate child Context to process this request,
     * based on the specified request URI.  If no matching Context can
     * be found, return an appropriate HTTP error.
     *
     * @param request Request to be processed
     * @param response Response to be produced
     *
     * @exception IOException if an input/output error occurred
     * @exception ServletException if a servlet error occurred
     */
    @Override
    public void invoke(Request request, Response response)
        throws IOException, ServletException {

        // request without session
        if (isRequestWithoutSession(request.getDecodedRequestURI())) {
            getNext().invoke(request, response);
            return;
        }

        // Select the Context to be used for this Request
        Context context = request.getContext();
        if (context == null) {
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
                    sm.getString("standardHost.noContext"));
            return;
        }

        // Update the session last access time for our session (if any)
        String sessionId = request.getRequestedSessionId();
        Manager manager = context.getManager();
        if (sessionId != null && manager instanceof StoreManager) {
            Store store = ((StoreManager) manager).getStore();
            if (store != null) {
                Session session = null;
                try {
                    session = store.load(sessionId);
                } catch (Exception e) {
                    container.getLogger().error("deserializeError");
                }
                if (session != null) {
                    if (!session.isValid() ||
                        isSessionStale(session, System.currentTimeMillis())) {
                        if (container.getLogger().isDebugEnabled()) {
                            container.getLogger().debug("session swapped in is invalid or expired");
                        }
                        session.expire();
                        store.remove(sessionId);
                    } else {
                        session.setManager(manager);
                        // session.setId(sessionId); Only if new ???
                        manager.add(session);
                        // ((StandardSession)session).activate();
                        session.access();
                        session.endAccess();
                    }
                }
            }
        }
        if (container.getLogger().isDebugEnabled()) {
            container.getLogger().debug("sessionId: " + sessionId);
        }

        // Ask the next valve to process the request.
        getNext().invoke(request, response);

        // If still processing async, don't try to store the session
        if (!request.isAsync()) {
            // Read the sessionid after the response.
            // HttpSession hsess = hreq.getSession(false);
            Session hsess;
            try {
                hsess = request.getSessionInternal(false);
            } catch (Exception ex) {
                hsess = null;
            }
            String newsessionId = null;
            if (hsess!=null) {
                newsessionId = hsess.getIdInternal();
            }

            if (container.getLogger().isDebugEnabled()) {
                container.getLogger().debug("newsessionId: " + newsessionId);
            }
            if (newsessionId!=null) {
                try {
                    bind(context);

                    /* store the session and remove it from the manager */
                    if (manager instanceof StoreManager) {
                        Session session = manager.findSession(newsessionId);
                        Store store = ((StoreManager) manager).getStore();
                        boolean stored = false;
                        if (session != null) {
                            synchronized (session) {
                                if (store != null && session.isValid() &&
                                        !isSessionStale(session, System.currentTimeMillis())) {
                                    store.save(session);
                                    ((StoreManager) manager).removeSuper(session);
                                    session.recycle();
                                    stored = true;
                                }

                            }
                        }
                        if (!stored) {
                            if (container.getLogger().isDebugEnabled()) {
                                container.getLogger()
                                        .debug("newsessionId store: " + store + " session: " + session + " valid: "
                                                + (session == null ? "N/A" : Boolean.toString(session.isValid()))
                                                + " stale: " + isSessionStale(session, System.currentTimeMillis()));
                            }
                        }
                    } else {
                        if (container.getLogger().isDebugEnabled()) {
                            container.getLogger().debug("newsessionId Manager: " +
                                    manager);
                        }
                    }
                } finally {
                    unbind(context);
                }
            }
        }
    }


    /**
     * Indicate whether the session has been idle for longer
     * than its expiration date as of the supplied time.
     *
     * FIXME: Probably belongs in the Session class.
     * @param session The session to check
     * @param timeNow The current time to check for
     * @return <code>true</code> if the session is past its expiration
     */
    protected boolean isSessionStale(Session session, long timeNow) {

        if (session != null) {
            int maxInactiveInterval = session.getMaxInactiveInterval();
            if (maxInactiveInterval >= 0) {
                int timeIdle = (int) (session.getIdleTimeInternal() / 1000L);
                if (timeIdle >= maxInactiveInterval) {
                    return true;
                }
            }
        }

        return false;
    }


    private void bind(Context context) {
        if (clBindRequired) {
            context.bind(Globals.IS_SECURITY_ENABLED, MY_CLASSLOADER);
        }
    }


    private void unbind(Context context) {
        if (clBindRequired) {
            context.unbind(Globals.IS_SECURITY_ENABLED, MY_CLASSLOADER);
        }
    }

    protected boolean isRequestWithoutSession(String uri) {
        Pattern f = filter;
        return f != null && f.matcher(uri).matches();
    }

    public String getFilter() {
        if (filter == null) {
            return null;
        }
        return filter.toString();
    }

    public void setFilter(String filter) {
        if (filter == null || filter.length() == 0) {
            this.filter = null;
        } else {
            try {
                this.filter = Pattern.compile(filter);
            } catch (PatternSyntaxException pse) {
                container.getLogger().error(sm.getString("persistentValve.filter.failure", filter), pse);
            }
        }
    }
}
