/*

  * Copyright (c) 2003-2011, Simon Brown

  * All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are met:

  *

  *   - Redistributions of source code must retain the above copyright

  *     notice, this list of conditions and the following disclaimer.

  *

  *   - Redistributions in binary form must reproduce the above copyright

  *     notice, this list of conditions and the following disclaimer in

  *     the documentation and/or other materials provided with the

  *     distribution.

  *

  *   - Neither the name of Pebble nor the names of its contributors may

  *     be used to endorse or promote products derived from this software

  *     without specific prior written permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

  * POSSIBILITY OF SUCH DAMAGE.

  */

 package net.sourceforge.pebble.util;

 import java.util.*;

 import java.util.regex.Matcher;

 import java.util.regex.Pattern;

 /**

  * A collection of utility methods for manipulating strings.

  *

  * @author    Simon Brown

  */

 public final class StringUtils {

   private static final Pattern OPENING_B_TAG_PATTERN = Pattern.compile("<b>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_B_TAG_PATTERN = Pattern.compile("</b>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_STRONG_TAG_PATTERN = Pattern.compile("<strong>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_STRONG_TAG_PATTERN = Pattern.compile("</strong>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_I_TAG_PATTERN = Pattern.compile("<i>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_I_TAG_PATTERN = Pattern.compile("</i>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_EM_TAG_PATTERN = Pattern.compile("<em>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_EM_TAG_PATTERN = Pattern.compile("</em>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_BLOCKQUOTE_TAG_PATTERN = Pattern.compile("<blockquote>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_BLOCKQUOTE_TAG_PATTERN = Pattern.compile("</blockquote>", Pattern.CASE_INSENSITIVE);

   private static final Pattern BR_TAG_PATTERN = Pattern.compile("<br */*>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_P_TAG_PATTERN = Pattern.compile("<p>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_P_TAG_PATTERN = Pattern.compile("</p>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_PRE_TAG_PATTERN = Pattern.compile("<pre>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_PRE_TAG_PATTERN = Pattern.compile("</pre>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_UL_TAG_PATTERN = Pattern.compile("<ul>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_UL_TAG_PATTERN = Pattern.compile("</ul>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_OL_TAG_PATTERN = Pattern.compile("<ol>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_OL_TAG_PATTERN = Pattern.compile("</ol>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_LI_TAG_PATTERN = Pattern.compile("<li>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_LI_TAG_PATTERN = Pattern.compile("</li>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_A_TAG_PATTERN = Pattern.compile("</a>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_A_TAG_PATTERN = Pattern.compile("<a href=.*?>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_SUP_TAG_PATTERN = Pattern.compile("<sup>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_SUP_TAG_PATTERN = Pattern.compile("</sup>", Pattern.CASE_INSENSITIVE);

   private static final Pattern OPENING_SUB_TAG_PATTERN = Pattern.compile("<sub>", Pattern.CASE_INSENSITIVE);

   private static final Pattern CLOSING_SUB_TAG_PATTERN = Pattern.compile("</sub>", Pattern.CASE_INSENSITIVE);

   public static final int MAX_CONTENT_LENGTH = 255;

   public static final int MAX_WORD_LENGTH = 20;

   public static final int MAX_NUM_OF_POSTS = 5;

   //HTML4 248 named entities

   private final static Map<String,String> htmlEntities = new HashMap<String,String>();

   private final static Collection<String> allowedSchemes = new ArrayList<String>();

   static {

         htmlEntities.put(" ", "\u00A0");

         htmlEntities.put("¡", "\u00A1");

         htmlEntities.put("¢", "\u00A2");

         htmlEntities.put("£", "\u00A3");

         htmlEntities.put("¤", "\u00A4");

         htmlEntities.put("¥", "\u00A5");

         htmlEntities.put("¦", "\u00A6");

         htmlEntities.put("§", "\u00A7");

         htmlEntities.put("¨", "\u00A8");

         htmlEntities.put("©", "\u00A9");

         htmlEntities.put("ª", "\u00AA");

         htmlEntities.put("«", "\u00AB");

         htmlEntities.put("¬", "\u00AC");

         htmlEntities.put("­", "\u00AD");

         htmlEntities.put("®", "\u00AE");

         htmlEntities.put("¯", "\u00AF");

         htmlEntities.put("°", "\u00B0");

         htmlEntities.put("±", "\u00B1");

         htmlEntities.put("²", "\u00B2");

         htmlEntities.put("³", "\u00B3");

         htmlEntities.put("´", "\u00B4");

         htmlEntities.put("µ", "\u00B5");

         htmlEntities.put("¶", "\u00B6");

         htmlEntities.put("·", "\u00B7");

         htmlEntities.put("¸", "\u00B8");

         htmlEntities.put("¹", "\u00B9");

         htmlEntities.put("º", "\u00BA");

         htmlEntities.put("»", "\u00BB");

         htmlEntities.put("¼", "\u00BC");

         htmlEntities.put("½", "\u00BD");

         htmlEntities.put("¾", "\u00BE");

         htmlEntities.put("¿", "\u00BF");

         htmlEntities.put("À", "\u00C0");

         htmlEntities.put("Á", "\u00C1");

         htmlEntities.put("Â", "\u00C2");

         htmlEntities.put("Ã", "\u00C3");

         htmlEntities.put("Ä", "\u00C4");

         htmlEntities.put("Å", "\u00C5");

         htmlEntities.put("Æ", "\u00C6");

         htmlEntities.put("Ç", "\u00C7");

         htmlEntities.put("È", "\u00C8");

         htmlEntities.put("É", "\u00C9");

         htmlEntities.put("Ê", "\u00CA");

         htmlEntities.put("Ë", "\u00CB");

         htmlEntities.put("Ì", "\u00CC");

         htmlEntities.put("Í", "\u00CD");

         htmlEntities.put("Î", "\u00CE");

         htmlEntities.put("Ï", "\u00CF");

         htmlEntities.put("Ð", "\u00D0");

         htmlEntities.put("Ñ", "\u00D1");

         htmlEntities.put("Ò", "\u00D2");

         htmlEntities.put("Ó", "\u00D3");

         htmlEntities.put("Ô", "\u00D4");

         htmlEntities.put("Õ", "\u00D5");

         htmlEntities.put("Ö", "\u00D6");

         htmlEntities.put("×", "\u00D7");

         htmlEntities.put("Ø", "\u00D8");

         htmlEntities.put("Ù", "\u00D9");

         htmlEntities.put("Ú", "\u00DA");

         htmlEntities.put("Û", "\u00DB");

         htmlEntities.put("Ü", "\u00DC");

         htmlEntities.put("Ý", "\u00DD");

         htmlEntities.put("Þ", "\u00DE");

         htmlEntities.put("ß", "\u00DF");

         htmlEntities.put("à", "\u00E0");

         htmlEntities.put("á", "\u00E1");

         htmlEntities.put("â", "\u00E2");

         htmlEntities.put("ã", "\u00E3");

         htmlEntities.put("ä", "\u00E4");

         htmlEntities.put("å", "\u00E5");

         htmlEntities.put("æ", "\u00E6");

         htmlEntities.put("ç", "\u00E7");

         htmlEntities.put("è", "\u00E8");

         htmlEntities.put("é", "\u00E9");

         htmlEntities.put("ê", "\u00EA");

         htmlEntities.put("ë", "\u00EB");

         htmlEntities.put("ì", "\u00EC");

         htmlEntities.put("í", "\u00ED");

         htmlEntities.put("î", "\u00EE");

         htmlEntities.put("ï", "\u00EF");

         htmlEntities.put("ð", "\u00F0");

         htmlEntities.put("ñ", "\u00F1");

         htmlEntities.put("ò", "\u00F2");

         htmlEntities.put("ó", "\u00F3");

         htmlEntities.put("ô", "\u00F4");

         htmlEntities.put("õ", "\u00F5");

         htmlEntities.put("ö", "\u00F6");

         htmlEntities.put("÷", "\u00F7");

         htmlEntities.put("ø", "\u00F8");

         htmlEntities.put("ù", "\u00F9");

         htmlEntities.put("ú", "\u00FA");

         htmlEntities.put("û", "\u00FB");

         htmlEntities.put("ü", "\u00FC");

         htmlEntities.put("ý", "\u00FD");

         htmlEntities.put("þ", "\u00FE");

         htmlEntities.put("ÿ", "\u00FF");

         htmlEntities.put("Œ", "\u0152");

         htmlEntities.put("œ", "\u0153");

         htmlEntities.put("Š", "\u0160");

         htmlEntities.put("š", "\u0161");

         htmlEntities.put("Ÿ", "\u0178");

         htmlEntities.put("ƒ", "\u0192");

         htmlEntities.put("ˆ", "\u02C6");

         htmlEntities.put("˜", "\u02DC");

         htmlEntities.put("Α", "\u0391");

         htmlEntities.put("Β", "\u0392");

         htmlEntities.put("Γ", "\u0393");

         htmlEntities.put("Δ", "\u0394");

         htmlEntities.put("Ε", "\u0395");

         htmlEntities.put("Ζ", "\u0396");

         htmlEntities.put("Η", "\u0397");

         htmlEntities.put("Θ", "\u0398");

         htmlEntities.put("Ι", "\u0399");

         htmlEntities.put("Κ", "\u039A");

         htmlEntities.put("Λ", "\u039B");

         htmlEntities.put("Μ", "\u039C");

         htmlEntities.put("Ν", "\u039D");

         htmlEntities.put("Ξ", "\u039E");

         htmlEntities.put("Ο", "\u039F");

         htmlEntities.put("Π", "\u03A0");

         htmlEntities.put("Ρ", "\u03A1");

         htmlEntities.put("Σ", "\u03A3");

         htmlEntities.put("Τ", "\u03A4");

         htmlEntities.put("Υ", "\u03A5");

         htmlEntities.put("Φ", "\u03A6");

         htmlEntities.put("Χ", "\u03A7");

         htmlEntities.put("Ψ", "\u03A8");

         htmlEntities.put("Ω", "\u03A9");

         htmlEntities.put("α", "\u03B1");

         htmlEntities.put("β", "\u03B2");

         htmlEntities.put("γ", "\u03B3");

         htmlEntities.put("δ", "\u03B4");

         htmlEntities.put("ε", "\u03B5");

         htmlEntities.put("ζ", "\u03B6");

         htmlEntities.put("η", "\u03B7");

         htmlEntities.put("θ", "\u03B8");

         htmlEntities.put("ι", "\u03B9");

         htmlEntities.put("κ", "\u03BA");

         htmlEntities.put("λ", "\u03BB");

         htmlEntities.put("μ", "\u03BC");

         htmlEntities.put("ν", "\u03BD");

         htmlEntities.put("ξ", "\u03BE");

         htmlEntities.put("ο", "\u03BF");

         htmlEntities.put("π", "\u03C0");

         htmlEntities.put("ρ", "\u03C1");

         htmlEntities.put("ς", "\u03C2");

         htmlEntities.put("σ", "\u03C3");

         htmlEntities.put("τ", "\u03C4");

         htmlEntities.put("υ", "\u03C5");

         htmlEntities.put("φ", "\u03C6");

         htmlEntities.put("χ", "\u03C7");

         htmlEntities.put("ψ", "\u03C8");

         htmlEntities.put("ω", "\u03C9");

         htmlEntities.put("ϑ", "\u03D1");

         htmlEntities.put("ϒ", "\u03D2");

         htmlEntities.put("ϖ", "\u03D6");

         htmlEntities.put(" ", "\u2002");

         htmlEntities.put(" ", "\u2003");

         htmlEntities.put(" ", "\u2009");

         htmlEntities.put("‌", "\u200C");

         htmlEntities.put("‍", "\u200D");

         htmlEntities.put("‎", "\u200E");

         htmlEntities.put("‏", "\u200F");

         htmlEntities.put("–", "\u2013");

         htmlEntities.put("—", "\u2014");

         htmlEntities.put("‘", "\u2018");

         htmlEntities.put("’", "\u2019");

         htmlEntities.put("‚", "\u201A");

         htmlEntities.put("“", "\u201C");

         htmlEntities.put("”", "\u201D");

         htmlEntities.put("„", "\u201E");

         htmlEntities.put("†", "\u2020");

         htmlEntities.put("‡", "\u2021");

         htmlEntities.put("•", "\u2022");

         htmlEntities.put("…", "\u2026");

         htmlEntities.put("‰", "\u2030");

         htmlEntities.put("′", "\u2032");

         htmlEntities.put("″", "\u2033");

         htmlEntities.put("‹", "\u2039");

         htmlEntities.put("›", "\u203A");

         htmlEntities.put("‾", "\u203E");

         htmlEntities.put("⁄", "\u2044");

         htmlEntities.put("€", "\u20AC");

         htmlEntities.put("ℑ", "\u2111");

         htmlEntities.put("℘", "\u2118");

         htmlEntities.put("ℜ", "\u211C");

         htmlEntities.put("™", "\u2122");

         htmlEntities.put("ℵ", "\u2135");

         htmlEntities.put("←", "\u2190");

         htmlEntities.put("↑", "\u2191");

         htmlEntities.put("→", "\u2192");

         htmlEntities.put("↓", "\u2193");

         htmlEntities.put("↔", "\u2194");

         htmlEntities.put("↵", "\u21B5");

         htmlEntities.put("⇐", "\u21D0");

         htmlEntities.put("⇑", "\u21D1");

         htmlEntities.put("⇒", "\u21D2");

         htmlEntities.put("⇓", "\u21D3");

         htmlEntities.put("⇔", "\u21D4");

         htmlEntities.put("∀", "\u2200");

         htmlEntities.put("∂", "\u2202");

         htmlEntities.put("∃", "\u2203");

         htmlEntities.put("∅", "\u2205");

         htmlEntities.put("∇", "\u2207");

         htmlEntities.put("∈", "\u2208");

         htmlEntities.put("∉", "\u2209");

         htmlEntities.put("∋", "\u220B");

         htmlEntities.put("∏", "\u220F");

         htmlEntities.put("∑", "\u2211");

         htmlEntities.put("−", "\u2212");

         htmlEntities.put("∗", "\u2217");

         htmlEntities.put("√", "\u221A");

         htmlEntities.put("∝", "\u221D");

         htmlEntities.put("∞", "\u221E");

         htmlEntities.put("∠", "\u2220");

         htmlEntities.put("∧", "\u2227");

         htmlEntities.put("∨", "\u2228");

         htmlEntities.put("∩", "\u2229");

         htmlEntities.put("∪", "\u222A");

         htmlEntities.put("∫", "\u222B");

         htmlEntities.put("∴", "\u2234");

         htmlEntities.put("∼", "\u223C");

         htmlEntities.put("≅", "\u2245");

         htmlEntities.put("≈", "\u2248");

         htmlEntities.put("≠", "\u2260");

         htmlEntities.put("≡", "\u2261");

         htmlEntities.put("≤", "\u2264");

         htmlEntities.put("≥", "\u2265");

         htmlEntities.put("⊂", "\u2282");

         htmlEntities.put("⊃", "\u2283");

         htmlEntities.put("⊄", "\u2284");

         htmlEntities.put("⊆", "\u2286");

         htmlEntities.put("⊇", "\u2287");

         htmlEntities.put("⊕", "\u2295");

         htmlEntities.put("⊗", "\u2297");

         htmlEntities.put("⊥", "\u22A5");

         htmlEntities.put("⋅", "\u22C5");

         htmlEntities.put("⌈", "\u2308");

         htmlEntities.put("⌉", "\u2309");

         htmlEntities.put("⌊", "\u230A");

         htmlEntities.put("⌋", "\u230B");

         htmlEntities.put("⟨", "\u2329");

         htmlEntities.put("⟩", "\u232A");

         htmlEntities.put("◊", "\u25CA");

         htmlEntities.put("♠", "\u2660");

         htmlEntities.put("♣", "\u2663");

         htmlEntities.put("♥", "\u2665");

         htmlEntities.put("♦", "\u2666");

   allowedSchemes.add("https://");

   allowedSchemes.add("http://");

   allowedSchemes.add("ftp://");

   allowedSchemes.add("mailto:");

   }

   /**

    * Filters out characters that have meaning within JSP and HTML, and

    * replaces them with "escaped" versions.

    *

    * @param s   the String to filter

    * @return  the filtered String

    */

   public static String transformHTML(String s) {

     if (s == null) {

       return null;

     }

     StringBuffer buf = new StringBuffer(s.length());

     // loop through every character and replace if necessary

     int length = s.length();

     for (int i = 0; i < length; i++) {

       switch (s.charAt(i)) {

         case '<':

           buf.append("<");

           break;

         case '>':

           buf.append(">");

           break;

         case '&':

           buf.append("&");

           break;

         case '\"':

             buf.append(""");

             break;

         default :

           buf.append(s.charAt(i));

       }

     }

     return buf.toString();

   }

   /**

    * Transforms the given String into a subset of HTML displayable on a web

    * page. The subset includes <b>, <i>, <p>, <br>,

    * <pre> and <a href> (and their corresponding end tags).

    *

    * @param s   the String to transform

    * @return    the transformed String

    */

   public static String transformToHTMLSubset(String s) {

     if (s == null) {

       return null;

     }

     s = replace(s, OPENING_B_TAG_PATTERN, "<b>");

     s = replace(s, CLOSING_B_TAG_PATTERN, "</b>");

     s = replace(s, OPENING_STRONG_TAG_PATTERN, "<strong>");

     s = replace(s, CLOSING_STRONG_TAG_PATTERN, "</strong>");

     s = replace(s, OPENING_I_TAG_PATTERN, "<i>");

     s = replace(s, CLOSING_I_TAG_PATTERN, "</i>");

     s = replace(s, OPENING_EM_TAG_PATTERN, "<em>");

     s = replace(s, CLOSING_EM_TAG_PATTERN, "</em>");

     s = replace(s, OPENING_BLOCKQUOTE_TAG_PATTERN, "<blockquote>");

     s = replace(s, CLOSING_BLOCKQUOTE_TAG_PATTERN, "</blockquote>");

     s = replace(s, BR_TAG_PATTERN, "<br />");

     s = replace(s, OPENING_P_TAG_PATTERN, "<p>");

     s = replace(s, CLOSING_P_TAG_PATTERN, "</p>");

     s = replace(s, OPENING_PRE_TAG_PATTERN, "<pre>");

     s = replace(s, CLOSING_PRE_TAG_PATTERN, "</pre>");

     s = replace(s, OPENING_UL_TAG_PATTERN, "<ul>");

     s = replace(s, CLOSING_UL_TAG_PATTERN, "</ul>");

     s = replace(s, OPENING_OL_TAG_PATTERN, "<ol>");

     s = replace(s, CLOSING_OL_TAG_PATTERN, "</ol>");

     s = replace(s, OPENING_LI_TAG_PATTERN, "<li>");

     s = replace(s, CLOSING_LI_TAG_PATTERN, "</li>");

     s = replace(s, OPENING_SUP_TAG_PATTERN, "<sup>");

     s = replace(s, CLOSING_SUP_TAG_PATTERN, "</sup>");

     s = replace(s, OPENING_SUB_TAG_PATTERN, "<sub>");

     s = replace(s, CLOSING_SUB_TAG_PATTERN, "</sub>");

     // HTTP links - remove all attributes other than href

     s = replace(s, CLOSING_A_TAG_PATTERN, "</a>");

     Matcher m = OPENING_A_TAG_PATTERN.matcher(s);

     // Use a single buffer for efficiency

     StringBuffer buffer = new StringBuffer();

     // The position in the original string that we are up to

     int position = 0;

     while (m.find()) {

       int start = m.start();

       int end = m.end();

       buffer.append(s.subSequence(position, start)).append("<a href=");

       String link = s.substring(start, end);

       int startOfHrefIndex = link.indexOf("href="");

       if (startOfHrefIndex > -1) {

         int startOfHrefValue = startOfHrefIndex + "href="".length();

         int endOfHrefIndex = link.indexOf(""", startOfHrefValue);

         buffer.append("\"").append(validateUrl(link.substring(startOfHrefValue, endOfHrefIndex))).append("\"");

       } else {

         startOfHrefIndex = link.indexOf("href='");

         if (startOfHrefIndex > -1) {

           int startOfHrefValue = startOfHrefIndex + "href='".length();

           int endOfHrefIndex = link.indexOf("'", startOfHrefIndex+"href='".length());

           buffer.append("'").append(validateUrl(link.substring(startOfHrefValue, endOfHrefIndex))).append("'");

         }

       }

       buffer.append(">");

       position = end;

     }

     // If position is still 0 there were no matches, so don't do anything

     if (position > 0) {

       buffer.append(s.subSequence(position, s.length()));

       s = buffer.toString();

     }

     // escaped angle brackets and other allowed entities

     s = s.replaceAll("<", "<");

     s = s.replaceAll(">", ">");

     s = s.replaceAll("&([#a-zA-Z0-9]{1,}?);", "&$1;");

     return s;

   }

   private static String replace(String string, Pattern pattern, String replacement) {

     Matcher m = pattern.matcher(string);

     return m.replaceAll(replacement);

   }

   /**

    * Filters out newline characters.

    *

    * @param s   the String to filter

    * @return  the filtered String

    */

   public static String filterNewlines(String s) {

     if (s == null) {

       return null;

     }

     StringBuffer buf = new StringBuffer(s.length());

     // loop through every character and replace if necessary

     int length = s.length();

     for (int i = 0; i < length; i++) {

       switch (s.charAt(i)) {

         case '\r':

           break;

         default :

           buf.append(s.charAt(i));

       }

     }

     return buf.toString();

   }

   /**

    * Filters out all HTML tags.

    *

    * @param s   the String to filter

    * @return    the filtered String

    */

   public static String filterHTML(String s) {

     if (s == null) {

       return null;

     }

     s = s.replaceAll("<", "");

     s = s.replaceAll(">", "");

     s = s.replaceAll(" ", "");

     s = s.replaceAll("(?s)<!--.*?-->", "");

     return s.replaceAll("(?s)<.*?>", "");

   }

   public static String truncate(String s) {

     return truncate(s, MAX_CONTENT_LENGTH);

   }

   public static String truncate(String s, int maxLength) {

     String content = StringUtils.filterHTML(s);

     // then truncate, if necessary

     if (content == null) {

       return "";

     } else {

       StringBuffer buf = new StringBuffer();

       String words[] = content.split("\\s");

       for (int i = 0; i < words.length; i++) {

         if (buf.length() + words[i].length() > maxLength) {

           // truncate here

           buf.append("...");

           return buf.toString();

         } else if (words[i].length() > MAX_WORD_LENGTH) {

           // truncate here

           buf.append(words[i].substring(0, MAX_WORD_LENGTH));

           buf.append("...");

           return buf.toString();

         } else {

           buf.append(words[i]);

           if ((i+1) < words.length) {

             buf.append(" ");

           }

         }

       }

       return buf.toString();

     }

   }

   public static String stripScriptTags(String html) {

     if (html == null) {

       return html;

     }

     html = html.replaceAll("<script.*?>.*?</script.*?>", "");

     html = html.replaceAll("<script.*?/>", "");

     return html;

   }

   public static String unescapeHTMLEntities(String source) {

      Iterator<String> it = htmlEntities.keySet().iterator(); 

          while(it.hasNext()) { 

                  String key = it.next(); 

                  String val = htmlEntities.get(key); 

                  source = source.replaceAll(key, val);

          } 

      return source;

   }

   public static String validateUrl(String url) {

     if (url == null || url.length() == 0) {

       return null;

     }

     // whitelist, don't blacklist.

     for (String scheme : allowedSchemes) {

       if (url.startsWith(scheme)) {

         return url;

       }

     }

     return "http://" + url;

   }

 }