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/*
 * Schema.java July 2006
 *
 * Copyright (C) 2006, Niall Gallagher 
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General 
 * Public License along with this library; if not, write to the 
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330, 
 * Boston, MA  02111-1307  USA
 */

package org.simpleframework.xml.load;

import java.util.Map;

import org.simpleframework.xml.stream.Style;

/**
 * The Schema object is used to track which fields within
 * an object have been visited by a converter. This object is nessecary
 * for processing Composite objects. In particular it is
 * nessecary to keep track of which required nodes have been visited 
 * and which have not, if a required not has not been visited then the
 * XML source does not match the XML class schema and serialization
 * must fail before processing any further. 
 * 
 * @author Niall Gallagher
 */ 
class Schema {

   /**
    * Contains a map of all attributes present within the schema.
    */
   private LabelMap attributes;
   
   /**
    * Contains a map of all elements present within the schema.
    */
   private LabelMap elements;
   
   /**
    * This is the pointer to the schema class replace method.
    */
   private Conduit conduit;
   
   /**
    * This is the session that is to be used for serialization.
    */
   private Session session;
   
   /**
    * This is used to represent a text value within the schema.
    */
   private Label text;

   /**
    * This is the table used to maintain attributes by the source.
    */ 
   private Map table;
   
   /**
    * This is used to specify whether the type is a primitive class.
    */
   private boolean primitive;

   /**
    * Constructor for the Schema object. This is used 
    * to wrap the element and attribute XML annotations scanned from
    * a class schema. The schema tracks all fields visited so that
    * a converter can determine if all fields have been serialized.
    * 
    * @param schema this contains all labels scanned from the class
    * @param source this is the source object for serialization
    */
   public Schema(Scanner schema, Source source) throws Exception {   
      this.attributes = schema.getAttributes(source);
      this.elements = schema.getElements(source);
      this.primitive = schema.isPrimitive();
      this.conduit = schema.getConduit();
      this.session = source.getSession();
      this.text = schema.getText();
      this.table = session.getMap();
   }
   
   /**
    * This is used to determine whether the scanned class represents
    * a primitive type. A primitive type is a type that contains no
    * XML annotations and so cannot be serialized with an XML form.
    * Instead primitives a serialized using transformations.
    * 
    * @return this returns true if no XML annotations were found
    */
   public boolean isPrimitive() {
      return primitive;
   }
   
   /**
    * Returns a LabelMap that contains the details for
    * all fields marked as XML attributes. Labels contained within
    * this map are used to convert primitive types only.
    * 
    * @return map with the details extracted from the schema class
    */ 
   public LabelMap getAttributes() {
      return attributes;
   }   
   /**
    * Returns a LabelMap that contains the details for
    * all fields marked as XML elements. The annotations that are
    * considered elements are the ElementList and the
    * Element annotations. 
    * 
    * @return a map containing the details for XML elements
    */
   public LabelMap getElements() {
      return elements;
   }
   
   /**
    * This returns the Label that represents the text
    * annotation for the scanned class. Only a single text annotation
    * can be used per class, so this returns only a single label
    * rather than a LabelMap object. Also if this is
    * not null then the elements label map will be empty.
    * 
    * @return this returns the text label for the scanned class
    */
   public Label getText() {
      return text;
   }
   
   /**
    * This is used to replace the serialized object with another
    * instance, perhaps of a different type. This is useful when an
    * XML schema class wishes the insert another object into the
    * stream during the serialization process.
    * 
    * @param source the source object to invoke the method on
    * 
    * @return this returns the object that acts as the replacement
    * 
    * @throws Exception if the replacement method cannot complete
    */
   public Object replace(Object source) throws Exception {
      return conduit.replace(source, table);
   }
   
   /**
    * This is used to resolve the deserialized object with another
    * instance, perhaps of a different type. This is useful when an
    * XML schema class acts as a reference to another XML document
    * which needs to be loaded externally to create an object of
    * a different type, or just to substitute the instance.
    * 
    * @param source the source object to invoke the method on
    * 
    * @return this returns the object that acts as the substitute
    * 
    * @throws Exception if the replacement method cannot complete
    */
   public Object resolve(Object source) throws Exception {
      return conduit.resolve(source, table);
   }
   
   /**
    * This method is used to invoke the provided objects commit method
    * during the deserialization process. The commit method must be
    * marked with the Commit annotation so that when the
    * object is deserialized the persister has a chance to invoke the
    * method so that the object can build further data structures.
    * 
    * @param source this is the object that has just been deserialized
    * 
    * @throws Exception thrown if the commit process cannot complete
    */
   public void commit(Object source) throws Exception {
      conduit.commit(source, table);   
   }

   /**
    * This method is used to invoke the provided objects validation
    * method during the deserialization process. The validation method
    * must be marked with the Validate annotation so that
    * when the object is deserialized the persister has a chance to 
    * invoke that method so that object can validate its field values.
    * 
    * @param source this is the object that has just been deserialized
    * 
    * @throws Exception thrown if the validation process failed
    */
   public void validate(Object source) throws Exception {
      conduit.validate(source, table);        
   }
   
   /**
    * This method is used to invoke the provided objects persistence
    * method. This is invoked during the serialization process to
    * get the object a chance to perform an nessecary preparation
    * before the serialization of the object proceeds. The persist
    * method must be marked with the Persist annotation.
    * 
    * @param source the object that is about to be serialized
    * 
    * @throws Exception thrown if the object cannot be persisted
    */
   public void persist(Object source) throws Exception {
      conduit.persist(source, table);        
   }
   
   /**
    * This method is used to invoke the provided objects completion
    * method. This is invoked after the serialization process has
    * completed and gives the object a chance to restore its state
    * if the persist method required some alteration or locking.
    * This is marked with the Complete annotation.
    * 
    * @param source this is the object that has been serialized
    * 
    * @throws Exception thrown if the object cannot complete
    */
   public void complete(Object source) throws Exception {
      conduit.complete(source, table);
   }
}