/*
    *  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.mina.util;
  
  import java.io.IOException;
  import java.io.LineNumberReader;
  import java.io.PrintWriter;
  import java.io.StringReader;
  import java.io.StringWriter;
  import java.util.ArrayList;
  
  /**
   * Utility class for working with xml data
   *
   * Implementation is heavily based on org.apache.log4j.helpers.Transform
   * 
   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
   */
  public class Transform {
  
      private static final String CDATA_START = "<![CDATA[";
  
      private static final String CDATA_END = "]]>";
  
      private static final String CDATA_PSEUDO_END = "]]&gt;";
  
      private static final String CDATA_EMBEDED_END = CDATA_END + CDATA_PSEUDO_END + CDATA_START;
  
      private static final int CDATA_END_LEN = CDATA_END.length();
  
      /**
       * This method takes a string which may contain HTML tags (ie,
       * &lt;b&gt;, &lt;table&gt;, etc) and replaces any
       * '&lt;',  '&gt;' , '&amp;' or '"'
       * characters with respective predefined entity references.
       *
       * @param input The text to be converted.
       * @return The input string with the special characters replaced.
       * */
      public static String escapeTags(String input) {
          // Check if the string is null, zero length or devoid of special characters
          // if so, return what was sent in.
  
          if (input == null || input.length() == 0) {
              return input;
          }
  
          StringBuilder buf = new StringBuilder(input.length() + 6);
          char ch;
  
          int len = input.length();
          
          for (int i = 0; i < len; i++) {
              ch = input.charAt(i);
              
              switch ( ch )
              {
                  case '<' :
                      buf.append("&lt;");
                      break;
                      
                  case '>' :
                      buf.append("&gt;");
                      break;
                      
                  case '&' :
                      buf.append("&amp;");
                      break;
                      
                  case '"' :
                      buf.append("&quot;");
                      break;
  
                  default :
                      buf.append(ch);
              }
          }
          
          return buf.toString();
      }
  
      /**
      * Ensures that embeded CDEnd strings (]]&gt;) are handled properly
      * within message, NDC and throwable tag text.
      *
      * @param buf StringBuffer holding the XML data to this point.  The
      * initial CDStart (&lt;![CDATA[) and final CDEnd (]]&gt;) of the CDATA
      * section are the responsibility of the calling method.
      * @param str The String that is inserted into an existing CDATA Section within buf.
      * */
     public static void appendEscapingCDATA(final StringBuilder buf, final String str) {
         if (str != null) {
             int end = str.indexOf(CDATA_END);
             
             if (end < 0) {
                 buf.append(str);
             } else {
                 int start = 0;
                 
                 while (end > -1) {
                     buf.append(str.substring(start, end));
                     buf.append(CDATA_EMBEDED_END);
                     start = end + CDATA_END_LEN;
                     
                     if (start < str.length()) {
                         end = str.indexOf(CDATA_END, start);
                     } else {
                         return;
                     }
                 }
                 
                 buf.append(str.substring(start));
             }
         }
     }
 
     /**
      * Converts a Throwable into an array of Strings
      * @param throwable The Throwable to convert 
      * @return string representation of the throwable
      */
     public static String[] getThrowableStrRep(Throwable throwable) {
         StringWriter sw = new StringWriter();
         PrintWriter pw = new PrintWriter(sw);
         throwable.printStackTrace(pw);
         pw.flush();
         LineNumberReader reader = new LineNumberReader(new StringReader(sw.toString()));
         ArrayList<String> lines = new ArrayList<>();
         
         try {
             String line = reader.readLine();
             
             while (line != null) {
                 lines.add(line);
                 line = reader.readLine();
             }
         } catch (IOException ex) {
             lines.add(ex.toString());
         }
         
         String[] rep = new String[lines.size()];
         lines.toArray(rep);
         
         return rep;
     }
 }