/***
    * 
    */
   package ar.com.epere4.java2excel.parser;
   
   import java.io.IOException;
   import java.io.InputStream;
   
   import net.socialchange.doctype.Doctype;
  import net.socialchange.doctype.DoctypeChangerStream;
  import net.socialchange.doctype.DoctypeGenerator;
  import net.socialchange.doctype.DoctypeImpl;
  
  import org.apache.commons.digester.Digester;
  import org.xml.sax.SAXException;
  
  import ar.com.epere4.java2excel.parser.impl.BodyDtdImpl;
  import ar.com.epere4.java2excel.parser.impl.HeaderDtdImpl;
  import ar.com.epere4.java2excel.parser.impl.Java2ExcelDtdImpl;
  import ar.com.epere4.java2excel.parser.impl.PropertyDtdImpl;
  
  /***
   * @author epere4
   */
  public class Parser {
      /***
       * This is the public id of java2excel DTD.
       * 
       * @see Doctype#getPublicId()
       */
      public static final String JAVA2EXCEL_PUBLIC_ID = 
          "-//epere4/DTD Java2Excel mapping file//EN";
  
      /***
       * This is the system id of java2excel DTD.
       * 
       * @see Doctype#getSystemId()
       */
      public static final String JAVA2EXCEL_SYSTEM_ID = 
          "http://java2excel.sourceforge.net/dtd/java2excel-mapping.dtd";
  
      /***
       * The root element in the dtd, that needs to be the root element in the
       * xml.
       * 
       * @see Doctype#getRootElement()
       */
      public static final String JAVA2EXCEL_ROOT_ELEMENT = "java2excel";
  
      /***
       * The url that identifies the local dtd location.
       */
      public static final String JAVA2EXCEL_LOCAL_DTD_URL = Parser.class
              .getResource("/ar/com/epere4/java2excel/dtd/java2excel-mapping.dtd")
              .toString();
  
      /***
       * Default Constructor.
       */
      protected Parser() {
      }
  
      /***
       * This parses the xml input and returns an instance of
       * {@link Java2ExcelDtd} ready to be processed.
       * 
       * @param input
       *            the xml. Must validate against
       *            {@link #JAVA2EXCEL_LOCAL_DTD_URL}.
       * @return an instance of {@link Java2ExcelDtd} ready to be processed
       * @throws IOException
       *             if in input/output error comes up.
       * @throws SAXException
       *             if the is a problem with the xml format.
       * @since 17/02/2006
       */
      public final Java2ExcelDtd parse(final InputStream input)
              throws IOException, SAXException {
          final Digester digester = new Digester();
          digester.register(JAVA2EXCEL_PUBLIC_ID, JAVA2EXCEL_LOCAL_DTD_URL);
          digester.setValidating(true);
          digester.push(new Java2ExcelDtdImpl());
          addRules(digester);
  
          return (Java2ExcelDtd) digester.parse(replaceDoctype(input));
      }
  
      /***
       * Replaces the old doctype for a new one, so we enforce the xml validation
       * with the official dtd.
       * 
       * @param inputXml
       *            the input stream that has the xml.
       * @return the changed input stream that must be passed to the
       *         {@link Digester}.
       * @since 17/02/2006
       */
      private InputStream replaceDoctype(final InputStream inputXml) {
          DoctypeChangerStream changer = new DoctypeChangerStream(inputXml);
         changer.setGenerator(new DoctypeGenerator() {
             public Doctype generate(final Doctype old) {
                 return new DoctypeImpl(JAVA2EXCEL_ROOT_ELEMENT,
                         JAVA2EXCEL_PUBLIC_ID, JAVA2EXCEL_SYSTEM_ID, null);
             }
         });
         return changer;
     }
 
     /***
      * This method adds the necessary rules to the digester so it can read and
      * interprete the xml config file.
      * 
      * @param d
      *            the digester
      * @since 17/02/2006
      */
     private static void addRules(final Digester d) {
         // --------------------------------------------------
         // when we encounter a "header" tag, do the following:
 
         // create a new instance of class HeaderDtdImpl, and push that
         // object onto the digester stack of objects
         d.addObjectCreate("java2excel/header", HeaderDtdImpl.class);
 
         // map *any* attributes on the tag to appropriate
         // setter-methods on the top object on the stack (the HeaderDtdImpl
         // instance created by the preceeding rule).
         //
         // For example:
         // if attribute "id" exists on the xml tag, and method setId
         // with one parameter exists on the object that is on top of
         // the digester object stack, then a call will be made to that
         // method. The value will be type-converted from string to
         // whatever type the target method declares (where possible),
         // using the commons ConvertUtils functionality.
         //
         // Attributes on the xml tag for which no setter methods exist
         // on the top object on the stack are just ignored.
         d.addSetProperties("java2excel/header");
 
         // call the setHeader method on the second-to-top object on
         // the stack (the Java2ExcelDtdImpl object), passing the top object
         // on the stack (the recently created HeaderDtdImpl object).
         d.addSetNext("java2excel/header", "setHeader");
 
         d.addObjectCreate("java2excel/body", BodyDtdImpl.class);
         d.addSetProperties("java2excel/body");
         d.addSetProperties("java2excel/body/properties");
         d.addSetNext("java2excel/body", "setBody");
 
         d.addObjectCreate("java2excel/body/properties/property",
                 PropertyDtdImpl.class);
         d.addSetProperties("java2excel/body/properties/property");
         d.addSetNext("java2excel/body/properties/property", "addProperty");
         d.addSetNestedProperties("java2excel/body/properties/property");
 
     }
 }