/*
    * 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.appender.routing;
  
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  import org.apache.logging.log4j.core.Appender;
  import org.apache.logging.log4j.core.Filter;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.appender.AbstractAppender;
  import org.apache.logging.log4j.core.appender.rewrite.RewritePolicy;
  import org.apache.logging.log4j.core.config.AppenderControl;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.Node;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
  import org.apache.logging.log4j.core.config.plugins.PluginElement;
  import org.apache.logging.log4j.core.config.plugins.PluginFactory;
  import org.apache.logging.log4j.core.util.Booleans;
  
  /**
   * This Appender "routes" between various Appenders, some of which can be references to
   * Appenders defined earlier in the configuration while others can be dynamically created
   * within this Appender as required. Routing is achieved by specifying a pattern on
   * the Routing appender declaration. The pattern should contain one or more substitution patterns of
   * the form "$${[key:]token}". The pattern will be resolved each time the Appender is called using
   * the built in StrSubstitutor and the StrLookup plugin that matches the specified key.
   */
  @Plugin(name = "Routing", category = "Core", elementType = "appender", printObject = true)
  public final class RoutingAppender extends AbstractAppender {
      private static final long serialVersionUID = 1L;
      private static final String DEFAULT_KEY = "ROUTING_APPENDER_DEFAULT";
      private final Routes routes;
      private final Route defaultRoute;
      private final Configuration config;
      private final ConcurrentMap<String, AppenderControl> appenders =
              new ConcurrentHashMap<String, AppenderControl>();
      private final RewritePolicy rewritePolicy;
  
      private RoutingAppender(final String name, final Filter filter, final boolean ignoreExceptions, final Routes routes,
                              final RewritePolicy rewritePolicy, final Configuration config) {
          super(name, filter, null, ignoreExceptions);
          this.routes = routes;
          this.config = config;
          this.rewritePolicy = rewritePolicy;
          Route defRoute = null;
          for (final Route route : routes.getRoutes()) {
              if (route.getKey() == null) {
                  if (defRoute == null) {
                      defRoute = route;
                  } else {
                      error("Multiple default routes. Route " + route.toString() + " will be ignored");
                  }
              }
          }
          defaultRoute = defRoute;
      }
  
      @Override
      public void start() {
          // Register all the static routes.
          for (final Route route : routes.getRoutes()) {
              if (route.getAppenderRef() != null) {
                  final Appender appender = config.getAppender(route.getAppenderRef());
                  if (appender != null) {
                      final String key = route == defaultRoute ? DEFAULT_KEY : route.getKey();
                      appenders.put(key, new AppenderControl(appender, null, null));
                  } else {
                      LOGGER.error("Appender " + route.getAppenderRef() + " cannot be located. Route ignored");
                  }
              }
          }
          super.start();
      }
  
      @Override
      public void stop() {
          super.stop();
          final Map<String, Appender> map = config.getAppenders();
          for (final Map.Entry<String, AppenderControl> entry : appenders.entrySet()) {
              final String name = entry.getValue().getAppender().getName();
              if (!map.containsKey(name)) {
                 entry.getValue().getAppender().stop();
             }
         }
     }
 
     @Override
     public void append(LogEvent event) {
         if (rewritePolicy != null) {
             event = rewritePolicy.rewrite(event);
         }
         final String key = config.getStrSubstitutor().replace(event, routes.getPattern());
         final AppenderControl control = getControl(key, event);
         if (control != null) {
             control.callAppender(event);
         }
     }
 
     private synchronized AppenderControl getControl(final String key, final LogEvent event) {
         AppenderControl control = appenders.get(key);
         if (control != null) {
             return control;
         }
         Route route = null;
         for (final Route r : routes.getRoutes()) {
             if (r.getAppenderRef() == null && key.equals(r.getKey())) {
                 route = r;
                 break;
             }
         }
         if (route == null) {
             route = defaultRoute;
             control = appenders.get(DEFAULT_KEY);
             if (control != null) {
                 return control;
             }
         }
         if (route != null) {
             final Appender app = createAppender(route, event);
             if (app == null) {
                 return null;
             }
             control = new AppenderControl(app, null, null);
             appenders.put(key, control);
         }
 
         return control;
     }
 
     private Appender createAppender(final Route route, final LogEvent event) {
         final Node routeNode = route.getNode();
         for (final Node node : routeNode.getChildren()) {
             if (node.getType().getElementName().equals("appender")) {
                 final Node appNode = new Node(node);
                 config.createConfiguration(appNode, event);
                 if (appNode.getObject() instanceof Appender) {
                     final Appender app = (Appender) appNode.getObject();
                     app.start();
                     return app;
                 }
                 LOGGER.error("Unable to create Appender of type " + node.getName());
                 return null;
             }
         }
         LOGGER.error("No Appender was configured for route " + route.getKey());
         return null;
     }
 
     /**
      * Create a RoutingAppender.
      * @param name The name of the Appender.
      * @param ignore If {@code "true"} (default) exceptions encountered when appending events are logged; otherwise
      *               they are propagated to the caller.
      * @param routes The routing definitions.
      * @param config The Configuration (automatically added by the Configuration).
      * @param rewritePolicy A RewritePolicy, if any.
      * @param filter A Filter to restrict events processed by the Appender or null.
      * @return The RoutingAppender
      */
     @PluginFactory
     public static RoutingAppender createAppender(
             @PluginAttribute("name") final String name,
             @PluginAttribute("ignoreExceptions") final String ignore,
             @PluginElement("Routes") final Routes routes,
             @PluginConfiguration final Configuration config,
             @PluginElement("RewritePolicy") final RewritePolicy rewritePolicy,
             @PluginElement("Filter") final Filter filter) {
 
         final boolean ignoreExceptions = Booleans.parseBoolean(ignore, true);
         if (name == null) {
             LOGGER.error("No name provided for RoutingAppender");
             return null;
         }
         if (routes == null) {
             LOGGER.error("No routes defined for RoutingAppender");
             return null;
         }
         return new RoutingAppender(name, filter, ignoreExceptions, routes, rewritePolicy, config);
     }
 }