package org.slf4j.impl;

import java.io.*;
import java.util.ArrayList;

/**
 * Utility class for working with xml data
 */
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
   * '<',  '>' , '&' or '"'
   * characters with respective predefined entity references.
   *
   * @param input The text to be converted.
   * @return The input string with the special characters replaced.
   * */
  static public String escapeTags(final 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
      || (input.indexOf('"') == -1 &&
      input.indexOf('&') == -1 &&
      input.indexOf('<') == -1 &&
      input.indexOf('>') == -1)) {
      return input;
    }

    StringBuffer buf = new StringBuffer(input.length() + 6);
    char ch;

    int len = input.length();
    for(int i=0; i < len; i++) {
      ch = input.charAt(i);
      if (ch > '>') {
        buf.append(ch);
      } else if(ch == '<') {
        buf.append("&lt;");
      } else if(ch == '>') {
        buf.append("&gt;");
      } else if(ch == '&') {
        buf.append("&amp;");
      } else if(ch == '"') {
        buf.append("&quot;");
      } else {
        buf.append(ch);
      }
    }
    return buf.toString();
  }

  /**
   * Ensures that embeded CDEnd strings (]]>) are handled properly
   * within message, NDC and throwable tag text.
   *
   * @param buf StringBuffer holding the XML data to this point.  The
   * initial CDStart (<![CDATA[) and final CDEnd (]]>) 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.
   * */
  static public void appendEscapingCDATA(final StringBuffer 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));
      }
    }
  }

  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 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;
  }


}