/*
    * 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.web.appender;
  
  import java.io.Serializable;
  
  import javax.servlet.ServletContext;
  
  import org.apache.logging.log4j.core.Filter;
  import org.apache.logging.log4j.core.Layout;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.appender.AbstractAppender;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginBuilderAttribute;
  import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
  import org.apache.logging.log4j.core.layout.AbstractStringLayout;
  import org.apache.logging.log4j.core.layout.PatternLayout;
  import org.apache.logging.log4j.web.WebLoggerContextUtils;
  
  /**
   * Logs using the ServletContext's log method
   */
  @Plugin(name = "Servlet", category = "Core", elementType = "appender", printObject = true)
  public class ServletAppender extends AbstractAppender {
  
  	public static class Builder<B extends Builder<B>> extends AbstractAppender.Builder<B>
  			implements org.apache.logging.log4j.core.util.Builder<ServletAppender> {
  
          @PluginBuilderAttribute
          private boolean logThrowables;
  
  		@Override
  		public ServletAppender build() {
  			final String name = getName();
  			if (name == null) {
  				LOGGER.error("No name provided for ServletAppender");
  			}
  			final ServletContext servletContext = WebLoggerContextUtils.getServletContext();
  			if (servletContext == null) {
  				LOGGER.error("No servlet context is available");
  				return null;
  			}
  			Layout<? extends Serializable> layout = getLayout();
  			if (layout == null) {
  				layout = PatternLayout.createDefaultLayout();
  			} else if (!(layout instanceof AbstractStringLayout)) {
  				LOGGER.error("Layout must be a StringLayout to log to ServletContext");
  				return null;
  			}
  			return new ServletAppender(name, layout, getFilter(), servletContext, isIgnoreExceptions(), logThrowables);
  		}
  
          /**
           * Logs with {@link ServletContext#log(String, Throwable)} if true and with {@link ServletContext#log(String)} if false.
           * 
           * @return whether to log a Throwable with the servlet context.
           */
          public boolean isLogThrowables() {
              return logThrowables;
          }
  
          /**
           * Logs with {@link ServletContext#log(String, Throwable)} if true and with {@link ServletContext#log(String)} if false.
           */
          public void setLogThrowables(final boolean logThrowables) {
              this.logThrowables = logThrowables;
          }
  
  	}
      
      @PluginBuilderFactory
      public static <B extends Builder<B>> B newBuilder() {
          return new Builder<B>().asBuilder();
      }
  
      private final ServletContext servletContext;
      private final boolean logThrowables;
      
      private ServletAppender(final String name, final Layout<? extends Serializable> layout, final Filter filter,
              final ServletContext servletContext, final boolean ignoreExceptions, final boolean logThrowables) {
          super(name, filter, layout, ignoreExceptions);
          this.servletContext = servletContext;
          this.logThrowables = logThrowables;
      }
  
     @Override
     public void append(final LogEvent event) {
         final String serialized = ((AbstractStringLayout) getLayout()).toSerializable(event);
         if (logThrowables) {
             servletContext.log(serialized, event.getThrown());
         } else {
             servletContext.log(serialized);
         }
     }
 
     /**
      * Creates a Servlet Appender.
      * @param layout The layout to use (required). Must extend {@link AbstractStringLayout}.
      * @param filter The Filter or null.
      * @param name The name of the Appender (required).
      * @param ignoreExceptions If {@code true} (default) exceptions encountered when appending events are logged;
      *                         otherwise they are propagated to the caller.
      * @return The ServletAppender.
      * @deprecated Use {@link #newBuilder()}.
      */
     @Deprecated
     public static ServletAppender createAppender(final Layout<? extends Serializable> layout, final Filter filter,
             final String name, final boolean ignoreExceptions) {
         // @formatter:off
     	return newBuilder()
     			.withFilter(filter)
     			.withIgnoreExceptions(ignoreExceptions)
     			.withLayout(layout)
     			.withName(name)
     			.build();
     	// @formatter:on
     }
 
 }