/*
    * 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.logging.log4j.core.jmx;
  
  import java.lang.management.ManagementFactory;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.Executor;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  
  import javax.management.InstanceAlreadyExistsException;
  import javax.management.MBeanRegistrationException;
  import javax.management.MBeanServer;
  import javax.management.NotCompliantMBeanException;
  import javax.management.ObjectName;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.core.Appender;
  import org.apache.logging.log4j.core.LoggerContext;
  import org.apache.logging.log4j.core.appender.AsyncAppender;
  import org.apache.logging.log4j.core.async.AsyncLogger;
  import org.apache.logging.log4j.core.async.AsyncLoggerConfig;
  import org.apache.logging.log4j.core.async.AsyncLoggerContext;
  import org.apache.logging.log4j.core.async.DaemonThreadFactory;
  import org.apache.logging.log4j.core.config.LoggerConfig;
  import org.apache.logging.log4j.core.impl.Log4jContextFactory;
  import org.apache.logging.log4j.core.selector.ContextSelector;
  import org.apache.logging.log4j.core.util.Loader;
  import org.apache.logging.log4j.spi.LoggerContextFactory;
  import org.apache.logging.log4j.status.StatusLogger;
  import org.apache.logging.log4j.util.PropertiesUtil;
  
  /**
   * Creates MBeans to instrument various classes in the log4j class hierarchy.
   * <p>
   * All instrumentation for Log4j 2 classes can be disabled by setting system property {@code -Dlog4j2.disable.jmx=true}.
   * </p>
   */
  public final class Server {
  
      /**
       * The domain part, or prefix ({@value} ) of the {@code ObjectName} of all MBeans that instrument Log4J2 components.
       */
      public static final String DOMAIN = "org.apache.logging.log4j2";
      private static final String PROPERTY_DISABLE_JMX = "log4j2.disable.jmx";
      private static final String PROPERTY_ASYNC_NOTIF = "log4j2.jmx.notify.async";
      private static final String THREAD_NAME_PREFIX = "log4j2.jmx.notif";
      private static final StatusLogger LOGGER = StatusLogger.getLogger();
      static final Executor executor = createExecutor();
  
      private Server() {
      }
  
      /**
       * Returns either a {@code null} Executor (causing JMX notifications to be sent from the caller thread) or a daemon
       * background thread Executor, depending on the value of system property "log4j2.jmx.notify.async". If this
       * property is not set, use a {@code null} Executor for web apps to avoid memory leaks and other issues when the
       * web app is restarted.
       * @see LOG4J2-938
       */
      private static ExecutorService createExecutor() {
          boolean defaultAsync = !isWebApp();
          boolean async = PropertiesUtil.getProperties().getBooleanProperty(PROPERTY_ASYNC_NOTIF, defaultAsync);
          return async ? Executors.newFixedThreadPool(1, new DaemonThreadFactory(THREAD_NAME_PREFIX)) : null;
      }
  
      /**
       * Returns {@code true} if we think we are running in a web container, based on the presence of the
       * {@code javax.servlet.Servlet} class in the classpath.
       */
      private static boolean isWebApp() {
          return Loader.isClassAvailable("javax.servlet.Servlet");
      }
  
      /**
       * Either returns the specified name as is, or returns a quoted value containing the specified name with the special
       * characters (comma, equals, colon, quote, asterisk, or question mark) preceded with a backslash.
       *
       * @param name the name to escape so it can be used as a value in an {@link ObjectName}.
       * @return the escaped name
       */
      public static String escape(final String name) {
          final StringBuilder sb = new StringBuilder(name.length() * 2);
         boolean needsQuotes = false;
         for (int i = 0; i < name.length(); i++) {
             final char c = name.charAt(i);
             switch (c) {
             case '\\':
             case '*':
             case '?':
             case '\"':
                 // quote, star, question & backslash must be escaped
                 sb.append('\\');
                 needsQuotes = true; // ... and can only appear in quoted value
                 break;
             case ',':
             case '=':
             case ':':
                 // no need to escape these, but value must be quoted
                 needsQuotes = true;
                 break;
             case '\r':
                 // drop \r characters: \\r gives "invalid escape sequence"
                 continue;
             case '\n':
                 // replace \n characters with \\n sequence
                 sb.append("\\n");
                 needsQuotes = true;
                 continue;
             }
             sb.append(c);
         }
         if (needsQuotes) {
             sb.insert(0, '\"');
             sb.append('\"');
         }
         return sb.toString();
     }
 
     public static void reregisterMBeansAfterReconfigure() {
         // avoid creating Platform MBean Server if JMX disabled
         if (PropertiesUtil.getProperties().getBooleanProperty(PROPERTY_DISABLE_JMX)) {
             LOGGER.debug("JMX disabled for log4j2. Not registering MBeans.");
             return;
         }
         final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
         reregisterMBeansAfterReconfigure(mbs);
     }
 
     public static void reregisterMBeansAfterReconfigure(final MBeanServer mbs) {
         if (PropertiesUtil.getProperties().getBooleanProperty(PROPERTY_DISABLE_JMX)) {
             LOGGER.debug("JMX disabled for log4j2. Not registering MBeans.");
             return;
         }
 
         // now provide instrumentation for the newly configured
         // LoggerConfigs and Appenders
         try {
             final ContextSelector selector = getContextSelector();
             if (selector == null) {
                 LOGGER.debug("Could not register MBeans: no ContextSelector found.");
                 return;
             }
             final List<LoggerContext> contexts = selector.getLoggerContexts();
             for (final LoggerContext ctx : contexts) {
                 // first unregister the context and all nested loggers,
                 // appenders, statusLogger, contextSelector, ringbuffers...
                 unregisterLoggerContext(ctx.getName(), mbs);
 
                 final LoggerContextAdmin mbean = new LoggerContextAdmin(ctx, executor);
                 register(mbs, mbean, mbean.getObjectName());
 
                 if (ctx instanceof AsyncLoggerContext) {
                     final RingBufferAdmin rbmbean = AsyncLogger.createRingBufferAdmin(ctx.getName());
                     register(mbs, rbmbean, rbmbean.getObjectName());
                 }
 
                 // register the status logger and the context selector
                 // repeatedly
                 // for each known context: if one context is unregistered,
                 // these MBeans should still be available for the other
                 // contexts.
                 registerStatusLogger(ctx.getName(), mbs, executor);
                 registerContextSelector(ctx.getName(), selector, mbs, executor);
 
                 registerLoggerConfigs(ctx, mbs, executor);
                 registerAppenders(ctx, mbs, executor);
             }
         } catch (final Exception ex) {
             LOGGER.error("Could not register mbeans", ex);
         }
     }
 
     /**
      * Unregister all log4j MBeans from the platform MBean server.
      */
     public static void unregisterMBeans() {
         final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
         unregisterMBeans(mbs);
     }
 
     /**
      * Unregister all log4j MBeans from the specified MBean server.
      *
      * @param mbs the MBean server to unregister from.
      */
     public static void unregisterMBeans(final MBeanServer mbs) {
         unregisterStatusLogger("*", mbs);
         unregisterContextSelector("*", mbs);
         unregisterContexts(mbs);
         unregisterLoggerConfigs("*", mbs);
         unregisterAsyncLoggerRingBufferAdmins("*", mbs);
         unregisterAsyncLoggerConfigRingBufferAdmins("*", mbs);
         unregisterAppenders("*", mbs);
         unregisterAsyncAppenders("*", mbs);
     }
 
     /**
      * Returns the {@code ContextSelector} of the current {@code Log4jContextFactory}.
      *
      * @return the {@code ContextSelector} of the current {@code Log4jContextFactory}
      */
     private static ContextSelector getContextSelector() {
         final LoggerContextFactory factory = LogManager.getFactory();
         if (factory instanceof Log4jContextFactory) {
             final ContextSelector selector = ((Log4jContextFactory) factory).getSelector();
             return selector;
         }
         return null;
     }
 
     /**
      * Unregisters all MBeans associated with the specified logger context (including MBeans for {@code LoggerConfig}s
      * and {@code Appender}s from the platform MBean server.
      *
      * @param loggerContextName name of the logger context to unregister
      */
     public static void unregisterLoggerContext(final String loggerContextName) {
         final MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
         unregisterLoggerContext(loggerContextName, mbs);
     }
 
     /**
      * Unregisters all MBeans associated with the specified logger context (including MBeans for {@code LoggerConfig}s
      * and {@code Appender}s from the platform MBean server.
      *
      * @param contextName name of the logger context to unregister
      * @param mbs the MBean Server to unregister the instrumented objects from
      */
     public static void unregisterLoggerContext(final String contextName, final MBeanServer mbs) {
         final String pattern = LoggerContextAdminMBean.PATTERN;
         final String search = String.format(pattern, escape(contextName), "*");
         unregisterAllMatching(search, mbs); // unregister context mbean
 
         // now unregister all MBeans associated with this logger context
         unregisterStatusLogger(contextName, mbs);
         unregisterContextSelector(contextName, mbs);
         unregisterLoggerConfigs(contextName, mbs);
         unregisterAppenders(contextName, mbs);
         unregisterAsyncAppenders(contextName, mbs);
         unregisterAsyncLoggerRingBufferAdmins(contextName, mbs);
         unregisterAsyncLoggerConfigRingBufferAdmins(contextName, mbs);
     }
 
     private static void registerStatusLogger(final String contextName, final MBeanServer mbs, final Executor executor)
             throws InstanceAlreadyExistsException, MBeanRegistrationException, NotCompliantMBeanException {
 
         final StatusLoggerAdmin mbean = new StatusLoggerAdmin(contextName, executor);
         register(mbs, mbean, mbean.getObjectName());
     }
 
     private static void registerContextSelector(final String contextName, final ContextSelector selector,
             final MBeanServer mbs, final Executor executor) throws InstanceAlreadyExistsException,
             MBeanRegistrationException, NotCompliantMBeanException {
 
         final ContextSelectorAdmin mbean = new ContextSelectorAdmin(contextName, selector);
         register(mbs, mbean, mbean.getObjectName());
     }
 
     private static void unregisterStatusLogger(final String contextName, final MBeanServer mbs) {
         final String pattern = StatusLoggerAdminMBean.PATTERN;
         final String search = String.format(pattern, escape(contextName), "*");
         unregisterAllMatching(search, mbs);
     }
 
     private static void unregisterContextSelector(final String contextName, final MBeanServer mbs) {
         final String pattern = ContextSelectorAdminMBean.PATTERN;
         final String search = String.format(pattern, escape(contextName), "*");
         unregisterAllMatching(search, mbs);
     }
 
     private static void unregisterLoggerConfigs(final String contextName, final MBeanServer mbs) {
         final String pattern = LoggerConfigAdminMBean.PATTERN;
         final String search = String.format(pattern, escape(contextName), "*");
         unregisterAllMatching(search, mbs);
     }
 
     private static void unregisterContexts(final MBeanServer mbs) {
         final String pattern = LoggerContextAdminMBean.PATTERN;
         final String search = String.format(pattern, "*");
         unregisterAllMatching(search, mbs);
     }
 
     private static void unregisterAppenders(final String contextName, final MBeanServer mbs) {
         final String pattern = AppenderAdminMBean.PATTERN;
         final String search = String.format(pattern, escape(contextName), "*");
         unregisterAllMatching(search, mbs);
     }
 
     private static void unregisterAsyncAppenders(final String contextName, final MBeanServer mbs) {
         final String pattern = AsyncAppenderAdminMBean.PATTERN;
         final String search = String.format(pattern, escape(contextName), "*");
         unregisterAllMatching(search, mbs);
     }
 
     private static void unregisterAsyncLoggerRingBufferAdmins(final String contextName, final MBeanServer mbs) {
         final String pattern1 = RingBufferAdminMBean.PATTERN_ASYNC_LOGGER;
         final String search1 = String.format(pattern1, escape(contextName));
         unregisterAllMatching(search1, mbs);
     }
 
     private static void unregisterAsyncLoggerConfigRingBufferAdmins(final String contextName, final MBeanServer mbs) {
         final String pattern2 = RingBufferAdminMBean.PATTERN_ASYNC_LOGGER_CONFIG;
         final String search2 = String.format(pattern2, escape(contextName), "*");
         unregisterAllMatching(search2, mbs);
     }
 
     private static void unregisterAllMatching(final String search, final MBeanServer mbs) {
         try {
             final ObjectName pattern = new ObjectName(search);
             final Set<ObjectName> found = mbs.queryNames(pattern, null);
             for (final ObjectName objectName : found) {
                 LOGGER.debug("Unregistering MBean {}", objectName);
                 mbs.unregisterMBean(objectName);
             }
         } catch (final Exception ex) {
             LOGGER.error("Could not unregister MBeans for " + search, ex);
         }
     }
 
     private static void registerLoggerConfigs(final LoggerContext ctx, final MBeanServer mbs, final Executor executor)
             throws InstanceAlreadyExistsException, MBeanRegistrationException, NotCompliantMBeanException {
 
         final Map<String, LoggerConfig> map = ctx.getConfiguration().getLoggers();
         for (final String name : map.keySet()) {
             final LoggerConfig cfg = map.get(name);
             final LoggerConfigAdmin mbean = new LoggerConfigAdmin(ctx, cfg);
             register(mbs, mbean, mbean.getObjectName());
 
             if (cfg instanceof AsyncLoggerConfig) {
                 final AsyncLoggerConfig async = (AsyncLoggerConfig) cfg;
                 final RingBufferAdmin rbmbean = async.createRingBufferAdmin(ctx.getName());
                 register(mbs, rbmbean, rbmbean.getObjectName());
             }
         }
     }
 
     private static void registerAppenders(final LoggerContext ctx, final MBeanServer mbs, final Executor executor)
             throws InstanceAlreadyExistsException, MBeanRegistrationException, NotCompliantMBeanException {
 
         final Map<String, Appender> map = ctx.getConfiguration().getAppenders();
         for (final String name : map.keySet()) {
             final Appender appender = map.get(name);
 
             if (appender instanceof AsyncAppender) {
                 final AsyncAppender async = ((AsyncAppender) appender);
                 final AsyncAppenderAdmin mbean = new AsyncAppenderAdmin(ctx.getName(), async);
                 register(mbs, mbean, mbean.getObjectName());
             } else {
                 final AppenderAdmin mbean = new AppenderAdmin(ctx.getName(), appender);
                 register(mbs, mbean, mbean.getObjectName());
             }
         }
     }
 
     private static void register(final MBeanServer mbs, final Object mbean, final ObjectName objectName)
             throws InstanceAlreadyExistsException, MBeanRegistrationException, NotCompliantMBeanException {
         LOGGER.debug("Registering MBean {}", objectName);
         mbs.registerMBean(mbean, objectName);
     }
 }