/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * Licensed 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 io.undertow.server.handlers.accesslog;


import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import io.undertow.attribute.ExchangeAttribute;
import io.undertow.attribute.ExchangeAttributes;
import io.undertow.attribute.SubstituteEmptyWrapper;
import io.undertow.predicate.Predicate;
import io.undertow.predicate.Predicates;
import io.undertow.server.ExchangeCompletionListener;
import io.undertow.server.HandlerWrapper;
import io.undertow.server.HttpHandler;
import io.undertow.server.HttpServerExchange;
import io.undertow.server.handlers.builder.HandlerBuilder;

Access log handler. This handler will generate access log messages based on the provided format string, and pass these messages into the provided AccessLogReceiver. 
 This handler can log any attribute that is provides via the ExchangeAttribute mechanism. A general guide to the most common attribute is provided before, however this mechanism is extensible. 


This factory produces token handlers for the following patterns

%a - Remote IP address
%A - Local IP address
%b - Bytes sent, excluding HTTP headers, or '-' if no bytes
were sent
%B - Bytes sent, excluding HTTP headers
%h - Remote host name
%H - Request protocol
%l - Remote logical username from identd (always returns '-')
%m - Request method
%o - Obfuscated remote IP address (IPv4: last byte removed,
IPv6: cut off after second colon, ie. '1.2.3.' or 'fe08:44:')
%p - Local port
%q - Query string (excluding the '?' character)
%r - First line of the request
%s - HTTP status code of the response
%t - Date and time, in Common Log Format format
%u - Remote user that was authenticated
%U - Requested URL path
%v - Local server name
%D - Time taken to process the request, in millis
%T - Time taken to process the request, in seconds
%I - current Request thread name (can compare later with stacktraces)

In addition, the caller can specify one of the following aliases for
commonly utilized patterns:

common - %h %l %u %t "%r" %s %b
combined -
%h %l %u %t "%r" %s %b "%{i,Referer}" "%{i,User-Agent}"
commonobf - %o %l %u %t "%r" %s %b
combinedobf -
%o %l %u %t "%r" %s %b "%{i,Referer}" "%{i,User-Agent}"



There is also support to write information from the cookie, incoming
header, or the session

It is modeled after the apache syntax:

%{i,xxx} for incoming headers
%{o,xxx} for outgoing response headers
%{c,xxx} for a specific cookie
%{r,xxx} xxx is an attribute in the ServletRequest
%{s,xxx} xxx is an attribute in the HttpSession

Author:
Stuart Douglas/**
 * Access log handler. This handler will generate access log messages based on the provided format string,
 * and pass these messages into the provided {@link AccessLogReceiver}.
 * <p>
 * This handler can log any attribute that is provides via the {@link io.undertow.attribute.ExchangeAttribute}
 * mechanism. A general guide to the most common attribute is provided before, however this mechanism is extensible.
 * <p>
 * <p>
 * <p>This factory produces token handlers for the following patterns</p>
 * <ul>
 * <li><b>%a</b> - Remote IP address
 * <li><b>%A</b> - Local IP address
 * <li><b>%b</b> - Bytes sent, excluding HTTP headers, or '-' if no bytes
 * were sent
 * <li><b>%B</b> - Bytes sent, excluding HTTP headers
 * <li><b>%h</b> - Remote host name
 * <li><b>%H</b> - Request protocol
 * <li><b>%l</b> - Remote logical username from identd (always returns '-')
 * <li><b>%m</b> - Request method
 * <li><b>%o</b> - Obfuscated remote IP address (IPv4: last byte removed,
 * IPv6: cut off after second colon, ie. '1.2.3.' or 'fe08:44:')
 * <li><b>%p</b> - Local port
 * <li><b>%q</b> - Query string (excluding the '?' character)
 * <li><b>%r</b> - First line of the request
 * <li><b>%s</b> - HTTP status code of the response
 * <li><b>%t</b> - Date and time, in Common Log Format format
 * <li><b>%u</b> - Remote user that was authenticated
 * <li><b>%U</b> - Requested URL path
 * <li><b>%v</b> - Local server name
 * <li><b>%D</b> - Time taken to process the request, in millis
 * <li><b>%T</b> - Time taken to process the request, in seconds
 * <li><b>%I</b> - current Request thread name (can compare later with stacktraces)
 * </ul>
 * <p>In addition, the caller can specify one of the following aliases for
 * commonly utilized patterns:</p>
 * <ul>
 * <li><b>common</b> - <code>%h %l %u %t "%r" %s %b</code>
 * <li><b>combined</b> -
 * <code>%h %l %u %t "%r" %s %b "%{i,Referer}" "%{i,User-Agent}"</code>
 * <li><b>commonobf</b> - <code>%o %l %u %t "%r" %s %b</code>
 * <li><b>combinedobf</b> -
 * <code>%o %l %u %t "%r" %s %b "%{i,Referer}" "%{i,User-Agent}"</code>
 * </ul>
 * <p>
 * <p>
 * There is also support to write information from the cookie, incoming
 * header, or the session<br>
 * It is modeled after the apache syntax:
 * <ul>
 * <li><code>%{i,xxx}</code> for incoming headers
 * <li><code>%{o,xxx}</code> for outgoing response headers
 * <li><code>%{c,xxx}</code> for a specific cookie
 * <li><code>%{r,xxx}</code> xxx is an attribute in the ServletRequest
 * <li><code>%{s,xxx}</code> xxx is an attribute in the HttpSession
 * </ul>
 *
 * @author Stuart Douglas
 */
public class AccessLogHandler implements HttpHandler {

    private final HttpHandler next;
    private final AccessLogReceiver accessLogReceiver;
    private final String formatString;
    private final ExchangeAttribute tokens;
    private final ExchangeCompletionListener exchangeCompletionListener = new AccessLogCompletionListener();
    private final Predicate predicate;

    public AccessLogHandler(final HttpHandler next, final AccessLogReceiver accessLogReceiver, final String formatString, ClassLoader classLoader) {
        this(next, accessLogReceiver, formatString, classLoader, Predicates.truePredicate());
    }

    public AccessLogHandler(final HttpHandler next, final AccessLogReceiver accessLogReceiver, final String formatString, ClassLoader classLoader, Predicate predicate) {
        this.next = next;
        this.accessLogReceiver = accessLogReceiver;
        this.predicate = predicate;
        this.formatString = handleCommonNames(formatString);
        this.tokens = ExchangeAttributes.parser(classLoader, new SubstituteEmptyWrapper("-")).parse(this.formatString);
    }

    public AccessLogHandler(final HttpHandler next, final AccessLogReceiver accessLogReceiver, String formatString, final ExchangeAttribute attribute) {
        this(next, accessLogReceiver, formatString, attribute, Predicates.truePredicate());
    }

    public AccessLogHandler(final HttpHandler next, final AccessLogReceiver accessLogReceiver, String formatString, final ExchangeAttribute attribute, Predicate predicate) {
        this.next = next;
        this.accessLogReceiver = accessLogReceiver;
        this.predicate = predicate;
        this.formatString = handleCommonNames(formatString);
        this.tokens = attribute;
    }



    private static String handleCommonNames(String formatString) {
        if(formatString.equals("common")) {
            return "%h %l %u %t \"%r\" %s %b";
        } else if (formatString.equals("combined")) {
            return "%h %l %u %t \"%r\" %s %b \"%{i,Referer}\" \"%{i,User-Agent}\"";
        } else if(formatString.equals("commonobf")) {
            return "%o %l %u %t \"%r\" %s %b";
        } else if (formatString.equals("combinedobf")) {
            return "%o %l %u %t \"%r\" %s %b \"%{i,Referer}\" \"%{i,User-Agent}\"";
        }
        return formatString;
    }


    @Override
    public void handleRequest(final HttpServerExchange exchange) throws Exception {
        exchange.addExchangeCompleteListener(exchangeCompletionListener);
        next.handleRequest(exchange);
    }

    private class AccessLogCompletionListener implements ExchangeCompletionListener {
        @Override
        public void exchangeEvent(final HttpServerExchange exchange, final NextListener nextListener) {
            try {
                if(predicate == null || predicate.resolve(exchange)) {
                    accessLogReceiver.logMessage(tokens.readAttribute(exchange));
                }
            } finally {
                nextListener.proceed();
            }
        }
    }

    @Override
    public String toString() {
        return "AccessLogHandler{" +
                "formatString='" + formatString + '\'' +
                '}';
    }

    public static class Builder implements HandlerBuilder {

        @Override
        public String name() {
            return "access-log";
        }

        @Override
        public Map<String, Class<?>> parameters() {
            Map<String, Class<?>> params = new HashMap<>();
            params.put("format", String.class);
            params.put("category", String.class);
            return params;
        }

        @Override
        public Set<String> requiredParameters() {
            return Collections.singleton("format");
        }

        @Override
        public String defaultParameter() {
            return "format";
        }

        @Override
        public HandlerWrapper build(Map<String, Object> config) {
            return new Wrapper((String) config.get("format"), (String) config.get("category"));
        }

    }

    private static class Wrapper implements HandlerWrapper {

        private final String format;
        private final String category;

        private Wrapper(String format, String category) {
            this.format = format;
            this.category = category;
        }

        @Override
        public HttpHandler wrap(HttpHandler handler) {
            if (category == null || category.trim().isEmpty()) {
                return new AccessLogHandler(handler, new JBossLoggingAccessLogReceiver(), format, Wrapper.class.getClassLoader());
            } else {
                return new AccessLogHandler(handler, new JBossLoggingAccessLogReceiver(category), format, Wrapper.class.getClassLoader());
            }
        }
    }
}