/*
 * 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.ha.tcp;

import java.io.IOException;
import java.util.StringTokenizer;
import java.util.regex.Pattern;
import java.util.ArrayList;
import java.util.List;
import java.util.Iterator;
import javax.servlet.ServletException;

import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.Context;
import org.apache.catalina.core.StandardContext;
import org.apache.catalina.ha.CatalinaCluster;
import org.apache.catalina.ha.ClusterManager;
import org.apache.catalina.ha.ClusterMessage;
import org.apache.catalina.ha.ClusterSession;
import org.apache.catalina.ha.ClusterValve;
import org.apache.catalina.ha.session.DeltaManager;
import org.apache.catalina.ha.session.DeltaSession;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.util.StringManager;
import org.apache.catalina.valves.ValveBase;

/**
 * <p>Implementation of a Valve that logs interesting contents from the
 * specified Request (before processing) and the corresponding Response
 * (after processing).  It is especially useful in debugging problems
 * related to headers and cookies.</p>
 *
 * <p>This Valve may be attached to any Container, depending on the granularity
 * of the logging you wish to perform.</p>
 *
 * <p>primaryIndicator=true, then the request attribute <i>org.apache.catalina.ha.tcp.isPrimarySession.</i>
 * is set true, when request processing is at sessions primary node.
 * </p>
 *
 * @author Craig R. McClanahan
 * @author Filip Hanik
 * @author Peter Rossbach
 * @version $Revision$ $Date$
 */

public class ReplicationValve
    extends ValveBase implements ClusterValve {
    
    private static org.apache.commons.logging.Log log =
        org.apache.commons.logging.LogFactory.getLog( ReplicationValve.class );

    // ----------------------------------------------------- Instance Variables

    /**
     * The descriptive information related to this implementation.
     */
    private static final String info =
        "org.apache.catalina.ha.tcp.ReplicationValve/2.0";


    /**
     * The StringManager for this package.
     */
    protected static StringManager sm =
        StringManager.getManager(Constants.Package);

    private CatalinaCluster cluster = null ;

    /**
     * holds file endings to not call for like images and others
     */
    protected java.util.regex.Pattern[] reqFilters = new java.util.regex.Pattern[0];
    
    /**
     * Orginal filter 
     */
    protected String filter ;
    
    /**
     * crossContext session container 
     */
    protected ThreadLocal crossContextSessions = new ThreadLocal() ;
    
    /**
     * doProcessingStats (default = off)
     */
    protected boolean doProcessingStats = false;
    
    protected long totalRequestTime = 0;
    protected long totalSendTime = 0;
    protected long nrOfRequests = 0;
    protected long lastSendTime = 0;
    protected long nrOfFilterRequests = 0;
    protected long nrOfSendRequests = 0;
    protected long nrOfCrossContextSendRequests = 0;
    
    /**
     * must primary change indicator set 
     */
    protected boolean primaryIndicator = false ;
    
    /**
     * Name of primary change indicator as request attribute
     */
    protected String primaryIndicatorName = "org.apache.catalina.ha.tcp.isPrimarySession";
   
    // ------------------------------------------------------------- Properties

    public ReplicationValve() {
    }
    
    /**
     * Return descriptive information about this Valve implementation.
     */
    public String getInfo() {

        return (info);

    }
    
    /**
     * @return Returns the cluster.
     */
    public CatalinaCluster getCluster() {
        return cluster;
    }
    
    /**
     * @param cluster The cluster to set.
     */
    public void setCluster(CatalinaCluster cluster) {
        this.cluster = cluster;
    }
 
    /**
     * @return Returns the filter
     */
    public String getFilter() {
       return filter ;
    }

    /**
     * compile filter string to regular expressions
     * @see Pattern#compile(java.lang.String)
     * @param filter
     *            The filter to set.
     */
    public void setFilter(String filter) {
        if (log.isDebugEnabled())
            log.debug(sm.getString("ReplicationValve.filter.loading", filter));
        this.filter = filter;
        StringTokenizer t = new StringTokenizer(filter, ";");
        this.reqFilters = new Pattern[t.countTokens()];
        int i = 0;
        while (t.hasMoreTokens()) {
            String s = t.nextToken();
            if (log.isTraceEnabled())
                log.trace(sm.getString("ReplicationValve.filter.token", s));
            try {
                reqFilters[i++] = Pattern.compile(s);
            } catch (Exception x) {
                log.error(sm.getString("ReplicationValve.filter.token.failure",
                        s), x);
            }
        }
    }

    /**
     * @return Returns the primaryIndicator.
     */
    public boolean isPrimaryIndicator() {
        return primaryIndicator;
    }

    /**
     * @param primaryIndicator The primaryIndicator to set.
     */
    public void setPrimaryIndicator(boolean primaryIndicator) {
        this.primaryIndicator = primaryIndicator;
    }
    
    /**
     * @return Returns the primaryIndicatorName.
     */
    public String getPrimaryIndicatorName() {
        return primaryIndicatorName;
    }
    
    /**
     * @param primaryIndicatorName The primaryIndicatorName to set.
     */
    public void setPrimaryIndicatorName(String primaryIndicatorName) {
        this.primaryIndicatorName = primaryIndicatorName;
    }
    
    /**
     * Calc processing stats
     */
    public boolean isDoProcessingStats() {
        return doProcessingStats;
    }

    /**
     * Set Calc processing stats
     * @see #resetStatistics()
     */
    public void setDoProcessingStats(boolean doProcessingStats) {
        this.doProcessingStats = doProcessingStats;
    }

    /**
     * @return Returns the lastSendTime.
     */
    public long getLastSendTime() {
        return lastSendTime;
    }
    
    /**
     * @return Returns the nrOfRequests.
     */
    public long getNrOfRequests() {
        return nrOfRequests;
    }
    
    /**
     * @return Returns the nrOfFilterRequests.
     */
    public long getNrOfFilterRequests() {
        return nrOfFilterRequests;
    }

    /**
     * @return Returns the nrOfCrossContextSendRequests.
     */
    public long getNrOfCrossContextSendRequests() {
        return nrOfCrossContextSendRequests;
    }

    /**
     * @return Returns the nrOfSendRequests.
     */
    public long getNrOfSendRequests() {
        return nrOfSendRequests;
    }

    /**
     * @return Returns the totalRequestTime.
     */
    public long getTotalRequestTime() {
        return totalRequestTime;
    }
    
    /**
     * @return Returns the totalSendTime.
     */
    public long getTotalSendTime() {
        return totalSendTime;
    }

    /**
     * @return Returns the reqFilters.
     */
    protected java.util.regex.Pattern[] getReqFilters() {
        return reqFilters;
    }
    
    /**
     * @param reqFilters The reqFilters to set.
     */
    protected void setReqFilters(java.util.regex.Pattern[] reqFilters) {
        this.reqFilters = reqFilters;
    }
    
    
    // --------------------------------------------------------- Public Methods
    
    /**
     * Register all cross context sessions inside endAccess.
     * Use a list with contains check, that the Portlet API can include a lot of fragments from same or
     * different applications with session changes.
     *
     * @param session cross context session
     */
    public void registerReplicationSession(DeltaSession session) {
        List sessions = (List)crossContextSessions.get();
        if(sessions != null) {
            if(!sessions.contains(session)) {
                if(log.isDebugEnabled())
                    log.debug(sm.getString("ReplicationValve.crossContext.registerSession",
                        session.getIdInternal(),
                        session.getManager().getContainer().getName()));
                sessions.add(session);
            }
        }
    }

    /**
     * Log the interesting request parameters, invoke the next Valve in the
     * sequence, and log the interesting response parameters.
     *
     * @param request The servlet request to be processed
     * @param response The servlet response to be created
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public void invoke(Request request, Response response)
        throws IOException, ServletException
    {
        long totalstart = 0;

        //this happens before the request
        if(isDoProcessingStats()) {
            totalstart = System.currentTimeMillis();
        }
        if (primaryIndicator) {
            createPrimaryIndicator(request) ;
        }
        Context context = request.getContext();
        boolean isCrossContext = context != null
                && context instanceof StandardContext
                && ((StandardContext) context).getCrossContext();
        try {
            if(isCrossContext) {
                if(log.isDebugEnabled())
                    log.debug(sm.getString("ReplicationValve.crossContext.add"));
                //FIXME add Pool of Arraylists
                crossContextSessions.set(new ArrayList());
            }
            getNext().invoke(request, response);
            Manager manager = request.getContext().getManager();
            if (manager != null && manager instanceof ClusterManager) {
                ClusterManager clusterManager = (ClusterManager) manager;
                CatalinaCluster containerCluster = (CatalinaCluster) getContainer().getCluster();
                if (containerCluster == null) {
                    if (log.isWarnEnabled())
                        log.warn(sm.getString("ReplicationValve.nocluster"));
                    return;
                }
                // valve cluster can access manager - other cluster handle replication 
                // at host level - hopefully!
                if(containerCluster.getManager(clusterManager.getName()) == null)
                    return ;
                if(containerCluster.hasMembers()) {
                    sendReplicationMessage(request, totalstart, isCrossContext, clusterManager, containerCluster);
                } else {
                    resetReplicationRequest(request,isCrossContext);
                }        
            }
        } finally {
            // Array must be remove: Current master request send endAccess at recycle. 
            // Don't register this request session again!
            if(isCrossContext) {
                if(log.isDebugEnabled())
                    log.debug(sm.getString("ReplicationValve.crossContext.remove"));
                // crossContextSessions.remove() only exist at Java 5
                // register ArrayList at a pool
                crossContextSessions.set(null);
            }
        }
    }

    
    /**
     * reset the active statitics 
     */
    public void resetStatistics() {
        totalRequestTime = 0 ;
        totalSendTime = 0 ;
        lastSendTime = 0 ;
        nrOfFilterRequests = 0 ;
        nrOfRequests = 0 ;
        nrOfSendRequests = 0;
        nrOfCrossContextSendRequests = 0;
    }
    
    /**
     * Return a String rendering of this object.
     */
    public String toString() {

        StringBuffer sb = new StringBuffer("ReplicationValve[");
        if (container != null)
            sb.append(container.getName());
        sb.append("]");
        return (sb.toString());

    }

    // --------------------------------------------------------- Protected Methods

    /**
     * @param request
     * @param totalstart
     * @param isCrossContext
     * @param clusterManager
     * @param containerCluster
     */
    protected void sendReplicationMessage(Request request, long totalstart, boolean isCrossContext, ClusterManager clusterManager, CatalinaCluster containerCluster) {
        //this happens after the request
        long start = 0;
        if(isDoProcessingStats()) {
            start = System.currentTimeMillis();
        }
        try {
            // send invalid sessions
            // DeltaManager returns String[0]
            if (!(clusterManager instanceof DeltaManager))
                sendInvalidSessions(clusterManager, containerCluster);
            // send replication
            sendSessionReplicationMessage(request, clusterManager, containerCluster);
            if(isCrossContext)
                sendCrossContextSession(containerCluster);
        } catch (Exception x) {
            // FIXME we have a lot of sends, but the trouble with one node stops the correct replication to other nodes!
            log.error(sm.getString("ReplicationValve.send.failure"), x);
        } finally {
            // FIXME this stats update are not cheap!!
            if(isDoProcessingStats()) {
                updateStats(totalstart,start);
            }
        }
    }

    /**
     * Send all changed cross context sessions to backups
     * @param containerCluster
     */
    protected void sendCrossContextSession(CatalinaCluster containerCluster) {
        Object sessions = crossContextSessions.get();
        if(sessions != null && sessions instanceof List
                && ((List)sessions).size() >0) {
            for(Iterator iter = ((List)sessions).iterator(); iter.hasNext() ;) {          
                Session session = (Session)iter.next();
                if(log.isDebugEnabled())
                    log.debug(sm.getString("ReplicationValve.crossContext.sendDelta",  
                            session.getManager().getContainer().getName() ));
                sendMessage(session,(ClusterManager)session.getManager(),containerCluster);
                if(isDoProcessingStats()) {
                    nrOfCrossContextSendRequests++;
                }
            }
        }
    }
  
    /**
     * Fix memory leak for long sessions with many changes, when no backup member exists!
     * @param request current request after responce is generated
     * @param isCrossContext check crosscontext threadlocal
     */
    protected void resetReplicationRequest(Request request, boolean isCrossContext) {
        Session contextSession = request.getSessionInternal(false);
        if(contextSession != null & contextSession instanceof DeltaSession){
            resetDeltaRequest(contextSession);
            ((DeltaSession)contextSession).setPrimarySession(true);
        }
        if(isCrossContext) {
            Object sessions = crossContextSessions.get();
            if(sessions != null && sessions instanceof List
               && ((List)sessions).size() >0) {
                Iterator iter = ((List)sessions).iterator();
                for(; iter.hasNext() ;) {          
                    Session session = (Session)iter.next();
                    resetDeltaRequest(session);
                    if(session instanceof DeltaSession)
                        ((DeltaSession)contextSession).setPrimarySession(true);

                }
            }
        }                     
    }

    /**
     * Reset DeltaRequest from session
     * @param session HttpSession from current request or cross context session
     */
    protected void resetDeltaRequest(Session session) {
        if(log.isDebugEnabled()) {
            log.debug(sm.getString("ReplicationValve.resetDeltaRequest" , 
                session.getManager().getContainer().getName() ));
        }
        ((DeltaSession)session).resetDeltaRequest();
    }

    /**
     * Send Cluster Replication Request
     * @param request current request
     * @param manager session manager
     * @param cluster replication cluster
     */
    protected void sendSessionReplicationMessage(Request request,
            ClusterManager manager, CatalinaCluster cluster) {
        Session session = request.getSessionInternal(false);
        if (session != null) {
            String uri = request.getDecodedRequestURI();
            // request without session change
            if (!isRequestWithoutSessionChange(uri)) {
                if (log.isDebugEnabled())
                    log.debug(sm.getString("ReplicationValve.invoke.uri", uri));
                sendMessage(session,manager,cluster);
            } else
                if(isDoProcessingStats())
                    nrOfFilterRequests++;
        }

    }

   /**
    * Send message delta message from request session 
    * @param request current request
    * @param manager session manager
    * @param cluster replication cluster
    */
    protected void sendMessage(Session session,
             ClusterManager manager, CatalinaCluster cluster) {
        String id = session.getIdInternal();
        if (id != null) {
            send(manager, cluster, id);
        }
    }

    /**
     * send manager requestCompleted message to cluster
     * @param manager SessionManager
     * @param cluster replication cluster
     * @param sessionId sessionid from the manager
     * @see DeltaManager#requestCompleted(String)
     * @see SimpleTcpCluster#send(ClusterMessage)
     */
    protected void send(ClusterManager manager, CatalinaCluster cluster, String sessionId) {
        ClusterMessage msg = manager.requestCompleted(sessionId);
        if (msg != null) {
            if(manager.isSendClusterDomainOnly()) {
                cluster.sendClusterDomain(msg);
            } else {
                cluster.send(msg);
            }
            if(isDoProcessingStats())
                nrOfSendRequests++;
        }
    }
    
    /**
     * check for session invalidations
     * @param manager
     * @param cluster
     */
    protected void sendInvalidSessions(ClusterManager manager, CatalinaCluster cluster) {
        String[] invalidIds=manager.getInvalidatedSessions();
        if ( invalidIds.length > 0 ) {
            for ( int i=0;i<invalidIds.length; i++ ) {
                try {
                    send(manager,cluster,invalidIds[i]);
                } catch ( Exception x ) {
                    log.error(sm.getString("ReplicationValve.send.invalid.failure",invalidIds[i]),x);
                }
            }
        }
    }
    
    /**
     * is request without possible session change
     * @param uri The request uri
     * @return True if no session change
     */
    protected boolean isRequestWithoutSessionChange(String uri) {

        boolean filterfound = false;

        for (int i = 0; (i < reqFilters.length) && (!filterfound); i++) {
            java.util.regex.Matcher matcher = reqFilters[i].matcher(uri);
            filterfound = matcher.matches();
        }
        return filterfound;
    }

    /**
     * protocol cluster replications stats
     * @param requestTime
     * @param clusterTime
     */
    protected  void updateStats(long requestTime, long clusterTime) {
        synchronized(this) {
            lastSendTime=System.currentTimeMillis();
            totalSendTime+=lastSendTime - clusterTime;
            totalRequestTime+=lastSendTime - requestTime;
            nrOfRequests++;
        }
        if(log.isInfoEnabled()) {
            if ( (nrOfRequests % 100) == 0 ) {
                 log.info(sm.getString("ReplicationValve.stats",
                     new Object[]{
                         new Long(totalRequestTime/nrOfRequests),
                         new Long(totalSendTime/nrOfRequests),
                         new Long(nrOfRequests),
                         new Long(nrOfSendRequests),
                         new Long(nrOfCrossContextSendRequests),
                         new Long(nrOfFilterRequests),
                         new Long(totalRequestTime),
                         new Long(totalSendTime)}));
             }
        }
    }


    /**
     * Mark Request that processed at primary node with attribute
     * primaryIndicatorName
     * 
     * @param request
     * @throws IOException
     */
    protected void createPrimaryIndicator(Request request) throws IOException {
        String id = request.getRequestedSessionId();
        if ((id != null) && (id.length() > 0)) {
            Manager manager = request.getContext().getManager();
            Session session = manager.findSession(id);
            if (session instanceof ClusterSession) {
                ClusterSession cses = (ClusterSession) session;
                if (cses != null) {
                    Boolean isPrimary = new Boolean(cses.isPrimarySession());
                    if (log.isDebugEnabled())
                        log.debug(sm.getString(
                                "ReplicationValve.session.indicator", request.getContext().getName(),id,
                                primaryIndicatorName, isPrimary));
                    request.setAttribute(primaryIndicatorName, isPrimary);
                }
            } else {
                if (log.isDebugEnabled()) {
                    if (session != null) {
                        log.debug(sm.getString(
                                "ReplicationValve.session.found", request.getContext().getName(),id));
                    } else {
                        log.debug(sm.getString(
                                "ReplicationValve.session.invalid", request.getContext().getName(),id));
                    }
                }
            }
        }
    }

}