/*
    * 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.layout;
  
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  import org.apache.logging.log4j.core.config.plugins.PluginAttr;
  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.helpers.OptionConverter;
  import org.apache.logging.log4j.core.pattern.LogEventPatternConverter;
  import org.apache.logging.log4j.core.pattern.PatternFormatter;
  import org.apache.logging.log4j.core.pattern.PatternParser;
  import org.apache.logging.log4j.core.pattern.RegexReplacement;
  
  import java.nio.charset.Charset;
  import java.util.List;
  
  /**
   * <p>A flexible layout configurable with pattern string. The goal of this class
   * is to {@link org.apache.logging.log4j.core.Layout#toByteArray format} a {@link LogEvent} and return the results.
   * The format of the result depends on the <em>conversion pattern</em>.
   * <p>
   * <p/>
   * <p>The conversion pattern is closely related to the conversion
   * pattern of the printf function in C. A conversion pattern is
   * composed of literal text and format control expressions called
   * <em>conversion specifiers</em>.
   *
   * See the Log4j Manual for details on the supported pattern converters.
   */
  @Plugin(name = "PatternLayout", type = "Core", elementType = "layout", printObject = true)
  public final class PatternLayout extends AbstractStringLayout {
      /**
       * Default pattern string for log output. Currently set to the
       * string <b>"%m%n"</b> which just prints the application supplied
       * message.
       */
      public static final String DEFAULT_CONVERSION_PATTERN = "%m%n";
  
      /**
       * A conversion pattern equivalent to the TTCCCLayout.
       * Current value is <b>%r [%t] %p %c %x - %m%n</b>.
       */
      public static final String TTCC_CONVERSION_PATTERN =
          "%r [%t] %p %c %x - %m%n";
  
      /**
       * A simple pattern.
       * Current value is <b>%d [%t] %p %c - %m%n</b>.
       */
      public static final String SIMPLE_CONVERSION_PATTERN =
          "%d [%t] %p %c - %m%n";
  
      private static final String KEY = "Converter";
  
      /**
       * Initial converter for pattern.
       */
      private List<PatternFormatter> formatters;
  
      /**
       * Conversion pattern.
       */
      private final String conversionPattern;
  
      /**
       * True if any element in pattern formats information from exceptions.
       */
      private boolean handlesExceptions;
  
      /**
       * The current Configuration.
       */
      private final Configuration config;
  
      private final RegexReplacement replace;
  
      /**
       * Constructs a EnhancedPatternLayout using the supplied conversion pattern.
       *
       * @param config The Configuration.
       * @param replace The regular expression to match.
      * @param pattern conversion pattern.
      * @param charset The character set.
      */
     private PatternLayout(Configuration config, final RegexReplacement replace, final String pattern,
                          final Charset charset) {
         super(charset);
         this.replace = replace;
         this.conversionPattern = pattern;
         this.config = config;
         PatternParser parser = createPatternParser(config);
         formatters = parser.parse((pattern == null) ? DEFAULT_CONVERSION_PATTERN : pattern);
         handlesExceptions = parser.handlesExceptions();
     }
 
     /**
      * Set the <b>ConversionPattern</b> option. This is the string which
      * controls formatting and consists of a mix of literal content and
      * conversion specifiers.
      *
      * @param conversionPattern conversion pattern.
      */
     public void setConversionPattern(final String conversionPattern) {
         String pattern = OptionConverter.convertSpecialChars(conversionPattern);
         if (pattern == null) {
             return;
         }
         PatternParser parser = createPatternParser(this.config);
         formatters = parser.parse(pattern);
         handlesExceptions = parser.handlesExceptions();
     }
 
     /**
      * Formats a logging event to a writer.
      *
      *
      * @param event logging event to be formatted.
      * @return The event formatted as a String.
      */
     public String toSerializable(final LogEvent event) {
         StringBuilder buf = new StringBuilder();
         for (PatternFormatter formatter : formatters) {
             formatter.format(event, buf);
         }
         String str = buf.toString();
         if (replace != null) {
             str = replace.format(str);
         }
         return str;
     }
 
     /**
      * Create a PatternParser.
      * @param config The Configuration.
      * @return The PatternParser.
      */
     public static PatternParser createPatternParser(Configuration config) {
         if (config == null) {
             return new PatternParser(config, KEY, LogEventPatternConverter.class);
         }
         PatternParser parser = (PatternParser) config.getComponent(KEY);
         if (parser == null) {
             parser = new PatternParser(config, KEY, LogEventPatternConverter.class);
             config.addComponent(KEY, parser);
             parser = (PatternParser) config.getComponent(KEY);
         }
         return parser;
     }
 
     @Override
     public String toString() {
         return conversionPattern;
     }
 
     /**
      * Create a pattern layout.
      * @param pattern The pattern. If not specified, defaults to DEFAULT_CONVERSION_PATTERN.
      * @param config The Configuration. Some Converters require access to the Interpolator.
      * @param replace A Regex replacement String.
      * @param charset The character set.
      * @return The PatternLayout.
      */
     @PluginFactory
     public static PatternLayout createLayout(@PluginAttr("pattern") String pattern,
                                              @PluginConfiguration Configuration config,
                                              @PluginElement("replace") RegexReplacement replace,
                                              @PluginAttr("charset") String charset) {
         Charset c = Charset.isSupported("UTF-8") ? Charset.forName("UTF-8") : Charset.defaultCharset();
         if (charset != null) {
             if (Charset.isSupported(charset)) {
                 c = Charset.forName(charset);
             } else {
                 LOGGER.error("Charset " + charset + " is not supported for layout, using " + c.displayName());
             }
         }
         return new PatternLayout(config, replace, pattern == null ? DEFAULT_CONVERSION_PATTERN : pattern, c);
     }
 }