/*
* Copyright 2003 Federal Chancellery Austria
*
* Licensed 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 at.gv.egovernment.moa.id.auth.builder;

import at.gv.egovernment.moa.id.BuildException;
import at.gv.egovernment.moa.util.StringUtils;

/**
 * Base class for HTML/XML builders providing commonly useful functions.
 * 
 * @author Paul Ivancsics
 * @version $Id$
 */
public class Builder {
  
  /**
   * Replaces a given number of occurences of a special tag in an XML or HTML template by a value.
   * @param template html template
   * @param tag special tag
   * @param value value replacing the tag
   * @param expected specifies if the tag is expected to present; if <code>true</code> and the tag
   *                 is not present, an exception is thrown; if <code>false</code> and the tag is
   *                 not present, the original string is returned
   * @param maxreplacements Set -1 to replace each occurence of tag, or limit replacements by a given positive number  
   * @return XML or HTML code, the tag replaced
   * @throws BuildException when template does not contain the tag
   */
  protected String replaceTag(
    String template, 
    String tag, 
    String value, 
    boolean expected, 
    int maxreplacements) 
  throws BuildException 
  {
    String result = template;
    int index = result.indexOf(tag);
    if (index < 0) {
      if (expected) {
    	// Substring not found but should
        throw new BuildException(
                "builder.01", 
                new Object[] {"&lt;" + tag.substring(1, tag.length() - 1) + "&gt;"});
      }
    } else {
       // replace each occurence
       if (maxreplacements == -1) {
         return StringUtils.replaceAll(template, tag, value);       
       } else {
         int found = 1;
         while (index > -1 && (found <= maxreplacements)) {
           result = result.substring(0, index) + value + result.substring(index + tag.length());
           index = result.indexOf(tag);
           if (index > -1) found += 1;
         }
       }
    }
    return result;
  }

}