/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Lotus
 * Development Corporation., http://www.lotus.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.xalan.xslt;

import java.util.*;
import org.w3c.dom.*;
import org.apache.xalan.xpath.*;
import org.apache.xalan.xslt.res.XSLTErrorResources;
import org.apache.xalan.xpath.xml.PrefixResolver;
import org.apache.xalan.xpath.xml.XSLMessages;

/**
 * <meta name="usage" content="advanced"/>
 * Class to hold an Attribute Value Template.
 */
public class AVT implements java.io.Serializable
{
  /**
   * If the AVT is not complex, just hold the simple string.
   */
  String m_simpleString = null;
  
  /**
   * If the AVT is complex, hold a Vector of AVTParts.
   */
  Vector m_parts = null;
  
  /**
   * The name of the attribute.
   */
  String m_name;
  
  /**
   * The attribute type;
   */
  String m_type;
    
  /**
   * Construct an AVT by parsing the string, and either 
   * constructing a vector of AVTParts, or simply hold 
   * on to the string if the AVT is simple.
   */
  public AVT(String name, 
             String type,
             String stringedValue,
             PrefixResolver namespaceContext,
             Stylesheet stylesheet,
             XSLTEngineImpl execContext)
    throws org.xml.sax.SAXException
  {
    m_name = name;
    m_type = type;
    StringTokenizer tokenizer = new StringTokenizer(stringedValue, "{}\"\'", true);
    int nTokens = tokenizer.countTokens();
    if(nTokens < 2)
    {
      m_simpleString = stringedValue; // then do the simple thing
    }
    else
    {
      m_parts = new Vector(nTokens+1);
      StringBuffer buffer = new StringBuffer(32);
      StringBuffer exprBuffer = new StringBuffer(32);
      String t = null; // base token
      String lookahead= null; // next token
      String error = null; // if non-null, break from loop
      while(tokenizer.hasMoreTokens())
      {
        if( lookahead != null )
        {
          t = lookahead;
          lookahead = null;
        }
        else t = tokenizer.nextToken();
        
        if(t.length() == 1)
        {
          switch(t.charAt(0))
          {
          case('\"'):
          case('\''):
            {
              // just keep on going, since we're not in an attribute template
              buffer.append(t);
              break;
            }
          case('{'):
            {
              // Attribute Value Template start
              lookahead = tokenizer.nextToken();
              if(lookahead.equals("{"))
              {
                // Double curlys mean escape to show curly
                buffer.append(lookahead);
                lookahead = null;
                break; // from switch
              }
              /*
              else if(lookahead.equals("\"") || lookahead.equals("\'"))
              {
              // Error. Expressions can not begin with quotes.
              error = "Expressions can not begin with quotes.";
              break; // from switch
              }
              */
              else
              {
                if(buffer.length() > 0)
                {
                  m_parts.addElement(new AVTPartSimple(buffer.toString()));
                  buffer.setLength(0);
                }

                exprBuffer.setLength(0);
                while(null != lookahead)
                {
                  if(lookahead.length() == 1)
                  {
                    switch(lookahead.charAt(0))
                    {
                    case '\'':
                    case '\"':
                      {
                        // String start
                        exprBuffer.append(lookahead);
                        String quote = lookahead;
                        // Consume stuff 'till next quote
                        lookahead = tokenizer.nextToken();
                        while(!lookahead.equals(quote))
                        {
                          exprBuffer.append(lookahead);
                          lookahead = tokenizer.nextToken();
                        }
                        exprBuffer.append(lookahead);
                        lookahead = tokenizer.nextToken();
                        break;
                      }
                    case '{':
                      {
                        // What's another curly doing here?
                        error = XSLMessages.createMessage(XSLTErrorResources.ER_NO_CURLYBRACE, null); //"Error: Can not have \"{\" within expression.";
                        break;
                      }
                    case '}':
                      {
                        // Proper close of attribute template.
                        // Evaluate the expression.
                        // XObject xobj = evalXPathStr(expression, contextNode, namespaceContext);
                        // buffer.append(xobj.str());
                        buffer.setLength(0);
                        
                        XPath xpath = stylesheet.createXPath(exprBuffer.toString(), namespaceContext);
                        m_parts.addElement(new AVTPartXPath(xpath));
                        
                        lookahead = null; // breaks out of inner while loop
                        break;
                      }
                    default:
                      {
                        // part of the template stuff, just add it.
                        exprBuffer.append(lookahead);
                        lookahead = tokenizer.nextToken();
                      }
                    } // end inner switch
                  } // end if lookahead length == 1
                  else
                  {
                    // part of the template stuff, just add it.
                    exprBuffer.append(lookahead);
                    lookahead = tokenizer.nextToken();
                  }
                } // end while(!lookahead.equals("}"))
                if(error != null)
                {
                  break; // from inner while loop
                }
              }
              break;
            }
          case('}'):
            {
              lookahead = tokenizer.nextToken();
              if(lookahead.equals("}"))
              {
                // Double curlys mean escape to show curly
                buffer.append(lookahead);
                lookahead = null; // swallow
              }
              else
              {
                // Illegal, I think...
                execContext.warn(XSLTErrorResources.WG_FOUND_CURLYBRACE); //"Found \"}\" but no attribute template open!");
                buffer.append("}");
                // leave the lookahead to be processed by the next round.
              }
              break;
            }
          default:
            {
              // Anything else just add to string.
              buffer.append(t);
            }
          } // end switch t
        } // end if length == 1
        else
        {
          // Anything else just add to string.
          buffer.append(t);
        }
        if(null != error)
        {
          execContext.warn(XSLTErrorResources.WG_ATTR_TEMPLATE, new Object[] {error}); //"Attr Template, "+error);
          break;
        }
      } // end while(tokenizer.hasMoreTokens())
      
      if(buffer.length() > 0)
      {
        m_parts.addElement(new AVTPartSimple(buffer.toString()));
        buffer.setLength(0);
      }
            
    } // end else nTokens > 1
    
    if(null == m_parts && (null == m_simpleString))
    {
      // Error?
      m_simpleString = "";
    }
  }
  
  /**
   * Evaluate the AVT and return a String.
   * @param context The current source tree context.
   * @param nsNode The current namespace context (stylesheet tree context).
   * @param NodeList The current Context Node List.
   */
  public String evaluate(XPathSupport execContext, Node context, 
                  org.apache.xalan.xpath.xml.PrefixResolver nsNode, 
                  StringBuffer buf)
    throws org.xml.sax.SAXException
  {
    if(null != m_simpleString)
    {
      return m_simpleString;
    }
    else if(null != m_parts)
    {
      buf.setLength(0);
      int n = m_parts.size();
      for(int i = 0; i < n; i++)
      {
        AVTPart part = (AVTPart)m_parts.elementAt(i);
        part.evaluate(execContext, buf, context, nsNode);
      }
      return buf.toString();
    }
    else
    {
      return "";
    }
  }
}