/*
 * 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.wicket.protocol.http;

import org.apache.wicket.request.ILogData;
import org.apache.wicket.request.ILoggableRequestHandler;
import org.apache.wicket.request.IRequestHandler;
import org.apache.wicket.request.handler.logger.NoLogData;
import org.apache.wicket.session.ISessionStore;
import org.apache.wicket.util.io.IClusterable;
import org.apache.wicket.util.string.Strings;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Interface for the request logger and viewer.
 * 
 * @see org.apache.wicket.Application#newRequestLogger()
 * 
 * @author jcompagner
 */
public interface IRequestLogger
{
        /**
         * @return The total created sessions counter
         */
        int getTotalCreatedSessions();

        /**
         * @return The peak sessions counter
         */
        int getPeakSessions();

        /**
         * This method returns a List of the current requests that are in mem. This is a readonly list.
         * 
         * @return Collection of the current requests
         */
        List<RequestData> getRequests();

        /**
         * @return Collection of live Sessions Data
         */
        SessionData[] getLiveSessions();

        /**
         * @return The current active requests
         */
        int getCurrentActiveRequestCount();

        /**
         * @return The {@link org.apache.wicket.protocol.http.IRequestLogger.RequestData} for the current request.
         */
        RequestData getCurrentRequest();

        /**
         * @return The peak active requests
         */
        int getPeakActiveRequestCount();

        /**
         * @return The number of requests per minute.
         */
        long getRequestsPerMinute();

        /**
         * @return The average request time.
         */
        long getAverageRequestTime();

        /**
         * called when the session is created and has an id. (for http it means that the http session is
         * created)
         * 
         * @param id
         *            the session id
         */
        void sessionCreated(String id);

        /**
         * Method used to cleanup a livesession when the session was invalidated by the webcontainer
         * 
         * @param sessionId
         *            the session id
         */
        void sessionDestroyed(String sessionId);

        /**
         * This method is called when the request is over. This will set the total time a request takes
         * and cleans up the current request data.
         * 
         * @param timeTaken
         *            the time taken in milliseconds
         */
        void requestTime(long timeTaken);

        /**
         * Called to monitor removals of objects out of the {@link ISessionStore}
         * 
         * @param value
         *            the object being removed
         */
        void objectRemoved(Object value);

        /**
         * Called to monitor updates of objects in the {@link ISessionStore}
         * 
         * @param value
         *            the object being updated
         */
        void objectUpdated(Object value);

        /**
         * Called to monitor additions of objects in the {@link ISessionStore}
         * 
         * @param value
         *            the object being created/added
         */
        void objectCreated(Object value);

        /**
         * Sets the target that was the response target for the current request
         * 
         * @param target
         *            the response target
         */
        void logResponseTarget(IRequestHandler target);

        /**
         * Sets the target that was the event target for the current request
         * 
         * @param target
         *            the event target
         */
        void logEventTarget(IRequestHandler target);

        /**
         * Logs the URL that was requested by the browser.
         * 
         * @param url
         *            the requested URL
         */
        void logRequestedUrl(String url);

        /**
         * Perform the actual logging
         */
        void performLogging();

        /**
         * This class hold the information one request of a session has.
         * 
         * @author jcompagner
         */
        class SessionData implements IClusterable, Comparable<SessionData>
        {
                private static final long serialVersionUID = 1L;

                private final String sessionId;
                private final long startDate;
                private long lastActive;
                private long numberOfRequests;
                private long totalTimeTaken;
                private long sessionSize;
                private Object sessionInfo;

                /**
                 * Construct.
                 * 
                 * @param sessionId
                 */
                public SessionData(String sessionId)
                {
                        this.sessionId = sessionId;
                        startDate = System.currentTimeMillis();
                        numberOfRequests = 1;
                }

                /**
                 * @return The last active date.
                 */
                public Date getLastActive()
                {
                        return new Date(lastActive);
                }

                /**
                 * @return The start date of this session
                 */
                public Date getStartDate()
                {
                        return new Date(startDate);
                }

                /**
                 * @return The number of request for this session
                 */
                public long getNumberOfRequests()
                {
                        return numberOfRequests;
                }

                /**
                 * @return Returns the session size.
                 */
                public long getSessionSize()
                {
                        return sessionSize;
                }

                /**
                 * @return Returns the total time this session has spent in ms.
                 */
                public long getTotalTimeTaken()
                {
                        return totalTimeTaken;
                }

                /**
                 * @return The session info object given by the {@link ISessionLogInfo#getSessionInfo()}
                 *         session method.
                 */
                public Object getSessionInfo()
                {
                        return sessionInfo;
                }

                /**
                 * @return The session id
                 */
                public String getSessionId()
                {
                        return sessionId;
                }

                /**
                 * Adds {@code time} to the total server time.
                 * 
                 * @param time
                 */
                public void addTimeTaken(long time)
                {
                        lastActive = System.currentTimeMillis();
                        numberOfRequests++;
                        totalTimeTaken += time;
                }

                /**
                 * Sets additional session info (e.g. logged in user).
                 * 
                 * @param sessionInfo
                 */
                public void setSessionInfo(Object sessionInfo)
                {
                        this.sessionInfo = sessionInfo;
                }

                /**
                 * Sets the recorded session size.
                 * 
                 * @param size
                 */
                public void setSessionSize(long size)
                {
                        sessionSize = size;
                }

                @Override
                public int compareTo(SessionData sd)
                {
                        if (sd.startDate > startDate)
                        {
                                return 1;
                        }
                        else if (sd.startDate < startDate)
                        {
                                return -1;
                        }
                        return 0;
                }
        }


        /**
         * This class hold the information one request of a session has.
         * 
         * @author jcompagner
         */
        class RequestData implements IClusterable
        {
                private static final long serialVersionUID = 1L;

                private long startDate;
                private long timeTaken;
                private final List<String> entries = new ArrayList<>(5);
                private Map<String, Object> userData;
                private String requestedUrl;
                private IRequestHandler eventTarget;
                private IRequestHandler responseTarget;
                private String sessionId;
                private long totalSessionSize;
                private Object sessionInfo;
                private int activeRequest;

                /**
                 * @return The time taken for this request
                 */
                public Long getTimeTaken()
                {
                        return timeTaken;
                }

                /**
                 * @param activeRequest
                 *            The number of active request when this request happened
                 */
                public void setActiveRequest(int activeRequest)
                {
                        this.activeRequest = activeRequest;
                }

                /**
                 * @return The number of active request when this request happened
                 */
                public int getActiveRequest()
                {
                        return activeRequest;
                }

                /**
                 * @return The session object info, created by {@link ISessionLogInfo#getSessionInfo()}
                 */
                public Object getSessionInfo()
                {
                        return sessionInfo;
                }

                /**
                 * Set the session info object of the session for this request.
                 * 
                 * @param sessionInfo
                 */
                public void setSessionInfo(Object sessionInfo)
                {
                        this.sessionInfo = sessionInfo;
                }

                /**
                 * @param sizeInBytes
                 */
                public void setSessionSize(long sizeInBytes)
                {
                        totalSessionSize = sizeInBytes;
                }

                /**
                 * @param id
                 */
                public void setSessionId(String id)
                {
                        sessionId = id;
                }

                /**
                 * @return The time taken for this request
                 */
                public Date getStartDate()
                {
                        return new Date(startDate);
                }

                /**
                 * @return The event target
                 */
                public IRequestHandler getEventTarget()
                {
                        return eventTarget;
                }

                /**
                 * @return The class of the event target
                 */
                public Class<? extends IRequestHandler> getEventTargetClass()
                {
                        return eventTarget == null ? null : eventTarget.getClass();
                }

                /**
                 * @return The log data for the eventTarget, or {@link NoLogData} if the request handler is
                 *         not loggable
                 */
                public ILogData getEventTargetLog()
                {
                        if (eventTarget instanceof ILoggableRequestHandler)
                                return ((ILoggableRequestHandler)eventTarget).getLogData();
                        return new NoLogData();
                }

                /**
                 * @return The response target
                 */
                public IRequestHandler getResponseTarget()
                {
                        return responseTarget;
                }

                /**
                 * @return The class of the response target
                 */
                public Class<? extends IRequestHandler> getResponseTargetClass()
                {
                        return responseTarget == null ? null : responseTarget.getClass();
                }

                /**
                 * @return The log data for the responseTarget, or {@link NoLogData} if the request handler
                 *         is not loggable
                 */
                public ILogData getResponseTargetLog()
                {
                        if (responseTarget instanceof ILoggableRequestHandler)
                                return ((ILoggableRequestHandler)responseTarget).getLogData();
                        return new NoLogData();
                }

                /**
                 * @return the requested URL by the browser
                 */
                public String getRequestedUrl()
                {
                        return requestedUrl;
                }

                /**
                 * @param requestedUrl
                 */
                public void setRequestedUrl(String requestedUrl)
                {
                        this.requestedUrl = requestedUrl;
                }

                /**
                 * @param target
                 */
                public void setResponseTarget(IRequestHandler target)
                {
                        responseTarget = target;
                }

                /**
                 * @param target
                 */
                public void setEventTarget(IRequestHandler target)
                {
                        eventTarget = target;
                }

                /**
                 * @param timeTaken
                 */
                public void setTimeTaken(long timeTaken)
                {
                        this.timeTaken = timeTaken;
                        startDate = System.currentTimeMillis() - timeTaken;
                }

                /**
                 * @param string
                 */
                public void addEntry(String string)
                {
                        entries.add(string);
                }

                /**
                 * @param key
                 * @param value
                 */
                public void addUserData(String key, Object value)
                {
                        getUserData().put(key, value);
                }

                /**
                 * @param key
                 * @return
                 */
                public Object getUserData(String key)
                {
                        return getUserData().get(key);
                }

                /**
                 * @return the userData Map
                 */
                public Map<String, Object> getUserData()
                {
                        if (userData == null) {
                                userData = new HashMap<>();
                        }

                        return userData;
                }

                /**
                 * @return All entries of the objects that are created/updated or removed in this request
                 */
                public String getAlteredObjects()
                {
                        return Strings.join(", ", entries);
                }

                /**
                 * @return The session id for this request
                 */
                public String getSessionId()
                {
                        return sessionId;
                }

                /**
                 * @return The total session size.
                 */
                public Long getSessionSize()
                {
                        return totalSessionSize;
                }

                @Override
                public String toString()
                {
                        return "Request[timetaken=" + getTimeTaken() + ",sessioninfo=" + sessionInfo +
                                ",sessionid=" + sessionId + ",sessionsize=" + totalSessionSize + ",request=" +
                                eventTarget + ",response=" + responseTarget + ",alteredobjects=" +
                                getAlteredObjects() + ",activerequest=" + activeRequest + "]";
                }
        }

        /**
         * This interface can be implemented in a custom session object. to give an object that has more
         * information for the current session (state of session).
         * 
         * @author jcompagner
         */
        interface ISessionLogInfo
        {
                /**
                 * If you use the request logger log functionality then this object should have a nice
                 * String representation. So make sure that the toString() is implemented for the returned
                 * object.
                 * 
                 * @return The custom object stored in the request loggers current request.
                 */
                Object getSessionInfo();
        }
}