/*
 * 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 Communities 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;

import java.util.*;

public class StringUtil
{
  /*--------------------------------------------------------------------------------
   * Static data members
   *--------------------------------------------------------------------------------
   */

  private static final String VAR_START = "${";
  private static final String VAR_END = "}";
  private static final char[] HTML_ENCODE_CHARS = { '"', '&', '<', '>' };

  /*--------------------------------------------------------------------------------
   * External static operations
   *--------------------------------------------------------------------------------
   */

  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;
    AnyCharMatcher nhc = new AnyCharMatcher(HTML_ENCODE_CHARS);
    int ndx = nhc.get(str);
    if (ndx<0)
      return str;   // trivial short-circuit case
    StringBuffer buf = new StringBuffer();
    while (ndx>=0)
    { // append the matched "head" and then the encoded character
      if (ndx>0)
	buf.append(str.substring(0,ndx));
      switch (str.charAt(ndx++))
      {
	case '"':
	  buf.append("&quot;");
	  break;

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

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

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

      } // end switch

      if (ndx==str.length())
	return buf.toString();  // munched the entire string - all done!
      str = str.substring(ndx);
      ndx = nhc.get(str);

    } // end while

    buf.append(str);  // append the unmatched tail
    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())
	return b.toString();   // entire string munched - we're done!
      work = work.substring(ndx);
      ndx = work.indexOf(find);

    } // end while

    // append the unmatched "tail" of the work string and then return result
    b.append(work);
    return b.toString();

  } // end replaceAllInstances

  public static String replaceAllVariables(String base, Map vars)
  {
    String work = base;
    boolean did_replace, retest;

    retest = true;
    do
    { // main loop for replacing all variables
      did_replace = false;
      Iterator it = vars.keySet().iterator();
      while (it.hasNext())
      { // variable start is there...
	if (retest)
	{ // only perform this test on the first iteration and after we know we've replaced a variable
	  if (work.indexOf(VAR_START)<0)
	    return work; // no more variables in text - all done!
	  retest = false;

	} // end if

	// get variable name and see if it's present
	String vname = it.next().toString();
	if (work.indexOf(VAR_START + vname + VAR_END)>=0)
	{ // OK, this variable is in place
	  work = replaceAllInstances(work,VAR_START + vname + VAR_END,vars.get(vname).toString());
	  did_replace = true;
	  retest = true;

	} // end if

      } // end while

    } while (did_replace);  // end do

    return work;  // all done!

  } // end replaceAllVariables

} // end class StringUtil