/*
 * The contents of this file are subject to the Mozilla Public License Version 1.1
 * (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.mozilla.org/MPL/>.
 * 
 * Software distributed under the License is distributed on an "AS IS" basis, WITHOUT
 * WARRANTY OF ANY KIND, either express or implied. See the License for the specific
 * language governing rights and limitations under the License.
 * 
 * The Original Code is the Venice Web Community System.
 * 
 * The Initial Developer of the Original Code is Eric J. Bowersox <erbo@silcom.com>,
 * for Silverwrist Design Studios.  Portions created by Eric J. Bowersox are
 * Copyright (C) 2001 Eric J. Bowersox/Silverwrist Design Studios.  All Rights Reserved.
 * 
 * Contributor(s): 
 */
package com.silverwrist.util;

public class StringUtil
{
  public static String encodeStringSQL(String str)
  {
    if (str==null)
      return null;
    int ndx = str.indexOf('\'');
    if (ndx<0)
      return str;
    StringBuffer buf = new StringBuffer();
    while (ndx>=0)
    { // convert each single quote mark to a pair of them
      if (ndx>0)
	buf.append(str.substring(0,ndx));
      buf.append("''");
      str = str.substring(ndx+1);
      ndx = str.indexOf('\'');

    } // end while

    buf.append(str);
    return buf.toString();

  } // end encodeStringSQL

  public static String encodeHTML(String str)
  {
    if (str==null)
      return null;
    StringBuffer buf = new StringBuffer();
    for (int i=0; i<str.length(); i++)
    { // loop through the string encoding each character in turn
      switch (str.charAt(i))
      {
	case '"':
	  buf.append("&quot;");
	  break;

	case '&':
	  buf.append("&amp;");
	  break;

	case '<':
	  buf.append("&lt;");
	  break;

	case '>':
	  buf.append("&gt;");
	  break;

	default:
	  buf.append(str.charAt(i));
	  break;

      } // end switch

    } // end for

    return buf.toString();

  } // end encodeHTML

  public static boolean isStringEmpty(String s)
  {
    return ((s==null) || (s.length()==0));

  } // end isStringEmpty

  public static String replaceAllInstances(String base, String find, String replace)
  {
    String work = base;
    int ndx = work.indexOf(find);
    if (ndx<0)
      return work;  // trivial case
    StringBuffer b = new StringBuffer();
    while (ndx>=0)
    { // break off the first part of the string, then insert the replacement
      if (ndx>0)
	b.append(work.substring(0,ndx));
      b.append(replace);

      // break off the tail end
      ndx += find.length();
      if (ndx==work.length())
	work = null;
      else
	work = work.substring(ndx);

      // do the next find
      if (work!=null)
	ndx = work.indexOf(find);
      else
	ndx = -1;

    } // end while

    if (work!=null)
      b.append(work);
    return b.toString();

  } // end replaceAllInstances

} // end class StringUtil