/*
    * 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.log4j.pattern;
  
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.pattern.ConverterKeys;
  import org.apache.logging.log4j.core.pattern.LogEventPatternConverter;
  import org.apache.logging.log4j.core.pattern.PatternConverter;
  import org.apache.logging.log4j.util.TriConsumer;
  
  /**
   * Able to handle the contents of the LogEvent's MDC and either
   * output the entire contents of the properties, or to output the value of a specific key
   * within the property bundle when this pattern converter has the option set.
   */
  @Plugin(name = "Log4j1MdcPatternConverter", category = PatternConverter.CATEGORY)
  @ConverterKeys({ "properties" })
  public final class Log4j1MdcPatternConverter extends LogEventPatternConverter {
      /**
       * Name of property to output.
       */
      private final String key;
  
      /**
       * Private constructor.
       *
       * @param options options, may be null.
       */
      private Log4j1MdcPatternConverter(final String[] options) {
          super(options != null && options.length > 0 ? "Log4j1MDC{" + options[0] + '}' : "Log4j1MDC", "property");
          if (options != null && options.length > 0) {
              key = options[0];
          } else {
              key = null;
          }
      }
  
      /**
       * Obtains an instance of PropertiesPatternConverter.
       *
       * @param options options, may be null or first element contains name of property to format.
       * @return instance of PropertiesPatternConverter.
       */
      public static Log4j1MdcPatternConverter newInstance(final String[] options) {
          return new Log4j1MdcPatternConverter(options);
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public void format(final LogEvent event, final StringBuilder toAppendTo) {
          if (key == null) {
              // if there is no additional options, we output every single Key/Value pair for the MDC
              toAppendTo.append('{');
              event.getContextData().forEach(APPEND_EACH, toAppendTo);
              toAppendTo.append('}');
          } else {
              // otherwise they just want a single key output
              final Object val = event.getContextData().getValue(key);
              if (val != null) {
                  toAppendTo.append(val);
              }
          }
      }
  
      private static TriConsumer<String, Object, StringBuilder> APPEND_EACH = new TriConsumer<String, Object, StringBuilder>() {
          @Override
          public void accept(final String key, final Object value, final StringBuilder toAppendTo) {
              toAppendTo.append('{').append(key).append(',').append(value).append('}');
          }
      };
  }