/*
 * Copyright (c) 2014, 2020 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.http.server.accesslog;

import static java.util.logging.Level.WARNING;

import java.util.Date;
import java.util.logging.Logger;

import org.glassfish.grizzly.Connection;
import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.http.server.HttpServer;
import org.glassfish.grizzly.http.server.HttpServerFilter;
import org.glassfish.grizzly.http.server.HttpServerProbe;
import org.glassfish.grizzly.http.server.Request;
import org.glassfish.grizzly.http.server.Response;

A Grizzly probe used to provide access logs generation. 
Author:
Pier Fumagalli, USRZ.com/**
 * A {@linkplain HttpServerProbe Grizzly probe} used to provide access logs generation.
 *
 * @author <a href="mailto:pier@usrz.com">Pier Fumagalli</a>
 * @author <a href="http://www.usrz.com/">USRZ.com</a>
 */
public class AccessLogProbe extends HttpServerProbe.Adapter {

    
The minimum response status that will trigger an entry in an access log configured by this instance
(default, log everything).
/**
     * The minimum <em>response status</em> that will trigger an entry in an access log configured by this instance
     * (default, log everything).
     */
    public static final int DEFAULT_STATUS_THRESHOLD = Integer.MIN_VALUE;

    /* Our timestamp request attribute */
    private static final String ATTRIBUTE_TIME_STAMP = AccessLogProbe.class.getName() + ".timeStamp";
    /* Our logger, for eventualities */
    private static final Logger LOGGER = Grizzly.logger(HttpServer.class);

    /* The appender to send formatted data to */
    private final AccessLogAppender appender;
    /* The format to format data to log */
    private final AccessLogFormat format;
    /* The minimum status threshold */
    private final int statusThreshold;

    
Create a new AccessLogProbe formatting data with the specified format and appending it to the specified appender. /**
     * Create a new {@link AccessLogProbe} formatting data with the specified {@linkplain AccessLogFormat format} and
     * appending it to the specified {@linkplain AccessLogAppender appender}.
     */
    public AccessLogProbe(AccessLogAppender appender, AccessLogFormat format) {
        this(appender, format, DEFAULT_STATUS_THRESHOLD);
    }

    
Create a new AccessLogProbe formatting data with the specified format and appending it to the specified appender. 

Only responses with status over the specified threshold will be logged, for example a threshold of
500 will only generate log entries for requests that terminated in error.

/**
     * Create a new {@link AccessLogProbe} formatting data with the specified {@linkplain AccessLogFormat format} and
     * appending it to the specified {@linkplain AccessLogAppender appender}.
     *
     * <p>
     * Only responses with <em>status</em> over the specified threshold will be logged, for example a threshold of
     * <code>500</code> will only generate log entries for requests that terminated in error.
     * </p>
     */
    public AccessLogProbe(AccessLogAppender appender, AccessLogFormat format, int statusThreshold) {
        if (appender == null) {
            throw new NullPointerException("Null access log appender");
        }
        if (format == null) {
            throw new NullPointerException("Null format");
        }
        this.appender = appender;
        this.format = format;
        this.statusThreshold = statusThreshold;
    }

    
Instrument the specified Request with an attribute marking its received time (in nanoseconds). /**
     * Instrument the specified {@link Request} with an attribute marking its <em>received</em> time (in
     * {@linkplain System#nanoTime() nanoseconds}).
     */
    @Override
    @SuppressWarnings("rawtypes")
    public void onRequestReceiveEvent(HttpServerFilter filter, Connection connection, Request request) {
        request.setAttribute(ATTRIBUTE_TIME_STAMP, System.nanoTime());
        /*
         * It seems that in some edge cases Grizzly is not caching the connection addresses in the request / response structure.
         * Internally the TCPNIOConnectionClass uses a Holder to store those (which provides lazy initialization). We force the
         * holders to get (and cache) the values by alling the "get(Local|Peer)Address()" methods.
         */
        connection.getLocalAddress();
        connection.getPeerAddress();
    }

    
Receive notification of the completion of a Response an possibly trigger an access log entry generation. /**
     * Receive notification of the completion of a {@link Response} an possibly trigger an access log entry generation.
     */
    @Override
    @SuppressWarnings("rawtypes")
    public void onRequestCompleteEvent(HttpServerFilter filter, Connection connection, Response response) {

        /* Only call the format/appender if we have to */
        if (response.getStatus() < statusThreshold) {
            return;
        }

        /* Calculate request timing */
        final Long requestNanos = (Long) response.getRequest().getAttribute(ATTRIBUTE_TIME_STAMP);

        final long timeStamp = System.currentTimeMillis();
        final long nanoStamp = System.nanoTime();

        final long responseNanos = requestNanos == null ? -1 : nanoStamp - requestNanos;
        final Date requestMillis = new Date(timeStamp - responseNanos / 1000000L);

        /* Create a formatted log entry string and append it */
        try {
            appender.append(format.format(response, requestMillis, responseNanos));
        } catch (Throwable throwable) {
            LOGGER.log(WARNING, "Exception caught appending to access log", throwable);
        }
    }

}