/*
    * 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 java.io.PrintWriter;
  import java.io.StringWriter;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  
  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.impl.ThrowableFormatOptions;
  import org.apache.logging.log4j.core.layout.PatternLayout;
  import org.apache.logging.log4j.util.Strings;
  
  
  /**
   * Outputs the Throwable portion of the LoggingEvent as a full stack trace
   * 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", category = PatternConverter.CATEGORY)
  @ConverterKeys({ "ex", "throwable", "exception" })
  public class ThrowablePatternConverter extends LogEventPatternConverter {
  
      protected final List<PatternFormatter> formatters;
      private String rawOption;
  
      /**
       * The number of lines to write.
       */
      protected final ThrowableFormatOptions options;
  
      /**
       * Constructor.
       * @param name Name of converter.
       * @param style CSS style for output.
       * @param options options, may be null.
       * @param config
       */
      protected ThrowablePatternConverter(final String name, final String style, final String[] options, final Configuration config) {
          super(name, style);
          this.options = ThrowableFormatOptions.newInstance(options);
          if (options != null && options.length > 0) {
              rawOption = options[0];
          }
          if (this.options.getSuffix() != null) {
              final PatternParser parser = PatternLayout.createPatternParser(config);
              final List<PatternFormatter> parsedFormatters = parser.parse(this.options.getSuffix());
              // filter out nested formatters that will handle throwable
              boolean hasThrowableFormatter = false;
              for (final PatternFormatter formatter : parsedFormatters) {
                  if (formatter.handlesThrowable()) {
                      hasThrowableFormatter = true;
                  }
              }
              if (!hasThrowableFormatter) {
                  this.formatters = parsedFormatters;
              } else {
                  final List<PatternFormatter> formatters = new ArrayList<>();
                  for (final PatternFormatter formatter : parsedFormatters) {
                      if (!formatter.handlesThrowable()) {
                          formatters.add(formatter);
                      }
                  }
                  this.formatters = formatters;
              }
          } else {
              this.formatters = Collections.emptyList();
          }
  
      }
  
      /**
       * Gets an instance of the class.
       *
       *
       * @param config
       * @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 Configuration config, final String[] options) {
         return new ThrowablePatternConverter("Throwable", "throwable", options, config);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public void format(final LogEvent event, final StringBuilder buffer) {
         final Throwable t = event.getThrown();
 
         if (isSubShortOption()) {
             formatSubShortOption(t, getSuffix(event), buffer);
         }
         else if (t != null && options.anyLines()) {
             formatOption(t, getSuffix(event), buffer);
         }
     }
 
     private boolean isSubShortOption() {
         return ThrowableFormatOptions.MESSAGE.equalsIgnoreCase(rawOption) ||
                 ThrowableFormatOptions.LOCALIZED_MESSAGE.equalsIgnoreCase(rawOption) ||
                 ThrowableFormatOptions.FILE_NAME.equalsIgnoreCase(rawOption) ||
                 ThrowableFormatOptions.LINE_NUMBER.equalsIgnoreCase(rawOption) ||
                 ThrowableFormatOptions.METHOD_NAME.equalsIgnoreCase(rawOption) ||
                 ThrowableFormatOptions.CLASS_NAME.equalsIgnoreCase(rawOption);
     }
 
     private void formatSubShortOption(final Throwable t, final String suffix, final StringBuilder buffer) {
         StackTraceElement[] trace;
         StackTraceElement throwingMethod = null;
         int len;
 
         if (t != null) {
             trace = t.getStackTrace();
             if (trace !=null && trace.length > 0) {
                 throwingMethod = trace[0];
             }
         }
 
         if (t != null && throwingMethod != null) {
             String toAppend = Strings.EMPTY;
 
             if (ThrowableFormatOptions.CLASS_NAME.equalsIgnoreCase(rawOption)) {
                 toAppend = throwingMethod.getClassName();
             }
             else if (ThrowableFormatOptions.METHOD_NAME.equalsIgnoreCase(rawOption)) {
                 toAppend = throwingMethod.getMethodName();
             }
             else if (ThrowableFormatOptions.LINE_NUMBER.equalsIgnoreCase(rawOption)) {
                 toAppend = String.valueOf(throwingMethod.getLineNumber());
             }
             else if (ThrowableFormatOptions.MESSAGE.equalsIgnoreCase(rawOption)) {
                 toAppend = t.getMessage();
             }
             else if (ThrowableFormatOptions.LOCALIZED_MESSAGE.equalsIgnoreCase(rawOption)) {
                 toAppend = t.getLocalizedMessage();
             }
             else if (ThrowableFormatOptions.FILE_NAME.equalsIgnoreCase(rawOption)) {
                 toAppend = throwingMethod.getFileName();
             }
 
             len = buffer.length();
             if (len > 0 && !Character.isWhitespace(buffer.charAt(len - 1))) {
                 buffer.append(' ');
             }
             buffer.append(toAppend);
 
             if (Strings.isNotBlank(suffix)) {
                 buffer.append(' ');
                 buffer.append(suffix);
             }
         }
     }
 
     private void formatOption(final Throwable throwable, final String suffix, final StringBuilder buffer) {
         final StringWriter w = new StringWriter();
 
         throwable.printStackTrace(new PrintWriter(w));
         final int len = buffer.length();
         if (len > 0 && !Character.isWhitespace(buffer.charAt(len - 1))) {
             buffer.append(' ');
         }
         if (!options.allLines() || !Strings.LINE_SEPARATOR.equals(options.getSeparator()) || Strings.isNotBlank(suffix)) {
             final StringBuilder sb = new StringBuilder();
             final String[] array = w.toString().split(Strings.LINE_SEPARATOR);
             final int limit = options.minLines(array.length) - 1;
             final boolean suffixNotBlank = Strings.isNotBlank(suffix);
             for (int i = 0; i <= limit; ++i) {
                 sb.append(array[i]);
                 if (suffixNotBlank) {
                     sb.append(' ');
                     sb.append(suffix);
                 }
                 if (i < limit) {
                     sb.append(options.getSeparator());
                 }
             }
             buffer.append(sb.toString());
 
         } else {
             buffer.append(w.toString());
         }
     }
 
     /**
      * This converter obviously handles throwables.
      *
      * @return true.
      */
     @Override
     public boolean handlesThrowable() {
         return true;
     }
 
     protected String getSuffix(final LogEvent event) {
         //noinspection ForLoopReplaceableByForEach
         final StringBuilder toAppendTo = new StringBuilder();
         for (int i = 0, size = formatters.size(); i <  size; i++) {
             formatters.get(i).format(event, toAppendTo);
         }
         return toAppendTo.toString();
     }
 }