/*
    * 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.pattern;
  
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.plugins.Plugin;
  
  import java.io.PrintWriter;
  import java.io.StringWriter;
  
  
  /**
   * Outputs the Throwable portion of the LoggingEvent as a full stacktrace
   * unless this converter's option is 'short', where it just outputs the first line of the trace, or if
   * the number of lines to print is explicitly specified.
   */
  @Plugin(name = "ThrowablePatternConverter", type = "Converter")
  @ConverterKeys({"ex", "throwable", "exception" })
  public class ThrowablePatternConverter extends LogEventPatternConverter {
  
      /**
       * Format the whole stack trace.
       */
      protected static final String FULL = "full";
      /**
       * Format only the first line of the throwable.
       */
      protected static final String SHORT = "short";
      /**
       * If "short", only first line of throwable report will be formatted.<br>
       * If "full", the whole stack trace will be formatted.<br>
       * If "numeric" the output will be limited to the specified number of lines.
       */
      protected final String option;
  
      /**
       * The number of lines to write.
       */
      protected final int lines;
  
      /**
       * Constructor.
       * @param name Name of converter.
       * @param style CSS style for output.
       * @param options options, may be null.
       */
      protected ThrowablePatternConverter(String name, String style, final String[] options) {
          super(name, style);
          int count = 0;
          if ((options != null) && (options.length > 0)) {
              option = options[0];
              if (option == null) {
              } else if (option.equalsIgnoreCase(SHORT)) {
                  count = 2;
              } else if (!option.equalsIgnoreCase(FULL)) {
                  count = Integer.parseInt(option);
              }
  
          } else {
              option = null;
          }
          lines = count;
      }
  
      /**
       * Gets an instance of the class.
       *
       * @param options pattern options, may be null.  If first element is "short",
       *                only the first line of the throwable will be formatted.
       * @return instance of class.
       */
      public static ThrowablePatternConverter newInstance(final String[] options) {
          return new ThrowablePatternConverter("Throwable", "throwable", options);
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public void format(final LogEvent event, final StringBuilder toAppendTo) {
          Throwable t = event.getThrown();
  
          if (t != null) {
              StringWriter w = new StringWriter();
              t.printStackTrace(new PrintWriter(w));
             int len = toAppendTo.length();
             if (len > 0 && !Character.isWhitespace(toAppendTo.charAt(len - 1))) {
                 toAppendTo.append(" ");
             }
             if (lines > 0) {
                 StringBuilder sb = new StringBuilder();
                 String[] array = w.toString().split("\n");
                 for (int i = 0; i < lines; ++i) {
                     sb.append(array[i]).append("\n");
                 }
                 toAppendTo.append(sb.toString());
 
             } else {
                 toAppendTo.append(w.toString());
             }
         }
     }
 
     /**
      * This converter obviously handles throwables.
      *
      * @return true.
      */
     @Override
     public boolean handlesThrowable() {
         return true;
     }
 }