/*
    * Copyright 2002,2004 The Apache Software Foundation.
    *
    * 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 org.apache.commons.jelly.tags.util;
  
  import org.apache.commons.jelly.JellyTagException;
  import org.apache.commons.jelly.MissingAttributeException;
  import org.apache.commons.jelly.TagSupport;
  import org.apache.commons.jelly.XMLOutput;
  import org.apache.commons.jelly.expression.Expression;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.apache.commons.lang.StringUtils;
  
  import org.xml.sax.SAXException;
  
  /***
   * A tag that replaces occurrences of a character or string in its body or
   * (or value) and places the result into the context
   *
   * @author dion
   */
  public class ReplaceTag extends TagSupport {
      /*** The Log to which logging calls will be made. */
      private static final Log log = LogFactory.getLog(ReplaceTag.class);
  
      /*** The variable name to export. */
      private String var;
  
      /*** The expression to evaluate. */
      private Expression value;
  
      /*** the old character to be replaced */
      private String oldChar;
  
      /*** the new character that will replace the old */
      private String newChar;
  
      /*** the old string to be replace */
      private String oldString;
  
      /*** the new string that will replace the old */
      private String newString;
  
      // Tag interface
      //-------------------------------------------------------------------------
      public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
          // check required properties
          if (oldChar != null) {
              oldString = oldChar.substring(0,1);
          }
  
          if (newChar != null) {
              newString = newChar.substring(0,1);
          }
  
          if (oldString == null) {
              throw new MissingAttributeException("oldChar or oldString must be provided");
          }
  
          if (newString == null) {
              throw new MissingAttributeException("newChar or newString must be provided");
          }
  
          // get either the value or the body of the tag
          Object answer = null;
          if ( value != null ) {
              answer = value.evaluateAsString(context);
          } else {
              answer = getBodyText(false);
          }
  
          // set the result in the context, or output it
          if (answer != null) {
              String stringAnswer = StringUtils.replace(answer.toString(), oldString, newString);
              if ( var != null ) {
                  context.setVariable(var, stringAnswer);
              } else {
                  try {
                      output.write(stringAnswer);
                  } catch (SAXException e) {
                      throw new JellyTagException(e);
                  }
              }
          }
     }
 
     /***
      * Returns the newChar used in replacing. Should only be a single
      * character.
      * @return String
      */
     public String getNewChar()
     {
         return newChar;
     }
 
     /***
      * Returns the oldChar that will be replaced. Should only be a single
      * character.
      * @return String
      */
     public String getOldChar()
     {
         return oldChar;
     }
 
     /***
      * Returns the newString that will be replaced.
      * @return String
      */
     public String getNew()
     {
         return newString;
     }
 
     /***
      * Returns the oldString that will be replaced.
      * @return String
      */
     public String getOld()
     {
         return oldString;
     }
 
     /***
      * Returns the value.
      * @return Expression
      */
     public Expression getValue()
     {
         return value;
     }
 
     /***
      * Returns the var.
      * @return String
      */
     public String getVar()
     {
         return var;
     }
 
     /***
      * Sets the newChar.
      * @param newChar The newChar to set
      */
     public void setNewChar(String newChar)
     {
         this.newChar = newChar;
     }
 
     /***
      * Sets the oldChar.
      * @param oldChar The oldChar to set
      */
     public void setOldChar(String oldChar)
     {
         this.oldChar = oldChar;
     }
 
     /***
      * Sets the newString.
      * @param newString The newString to set
      */
     public void setNew(String newString)
     {
         this.newString = newString;
     }
 
     /***
      * Sets the oldString.
      * @param oldString The oldString to set
      */
     public void setOld(String oldString)
     {
         this.oldString = oldString;
     }
 
     /***
      * Sets the value.
      * @param value The value to set
      */
     public void setValue(Expression value)
     {
         this.value = value;
     }
 
     /***
      * Sets the var.
      * @param var The var to set
      */
     public void setVar(String var)
     {
         this.var = var;
     }
 
 }