/*
    * This file is a part of CAST project.
    * (c) Copyright 2007, AGH University of Science & Technology
    * https://caribou.iisg.agh.edu.pl/trac/cast
    *
    * Licensed under the Eclipse Public License, Version 1.0 (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.eclipse.org/legal/epl-v10.html
   */
  /*
   * File: ModelParser.java
   * Created: 2008-07-15
   * Author: apohllo
   * $Id: ModelParser.java 2335 2009-01-13 16:40:16Z entrop $
   */
  
  package pl.edu.agh.cast.model.mapper.internal;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.Method;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.xml.sax.Attributes;
  import org.xml.sax.SAXException;
  import org.xml.sax.helpers.DefaultHandler;
  
  import pl.edu.agh.cast.model.base.IDataSet;
  import pl.edu.agh.cast.model.base.IEntity;
  import pl.edu.agh.cast.model.base.IModel;
  import pl.edu.agh.cast.model.base.IRelation;
  import pl.edu.agh.cast.model.mapper.Mappable;
  
  /**
   * The parser of the XML representation of the model.
   *
   * @author AGH CAST Team
   */
  class ModelParser extends DefaultHandler {
  	private static final String NULL = "null"; //$NON-NLS-1$
  
  	private static final String INT_TYPE = "int"; //$NON-NLS-1$
  
  	private static final String DOUBLE_TYPE = "double"; //$NON-NLS-1$
  
  	private static final String BOOLEAN_TYPE = "boolean"; //$NON-NLS-1$
  
  	private static final String LONG_TYPE = "long"; //$NON-NLS-1$
  
  	private static final String SETTER_PREFIX = "set"; //$NON-NLS-1$
  
  	/**
  	 *
  	 */
  	private Map<Long, Mappable> cache = new HashMap<Long, Mappable>();
  
  	private IDataSet dataSet;
  
  	private Mappable mappable;
  
  	private String mappableQName;
  
  	private Method setterMethod;
  
  	private Class returnType;
  
  	private IModel model;
  
  	private Map<String, Class> typeMap;
  
  	private StringBuilder contentBuffer = new StringBuilder();
  
  	public ModelParser(IModel newModel, Map<String, Class> newTypeMap) {
  		model = newModel;
  		typeMap = newTypeMap;
  	}
  
  	/**
  	 * Parse next element
  	 *
  	 * There are elements of three type:
  	 * <ul>
  	 * <li>root, which is simply discarded
  	 * <li>mapped element, which has some attributes
  	 * <li>attribute, which is attached to the mapped element
  	 * </ul>
  	 *
  	 * @throws SAXException
  	 */
  	@Override
  	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
  		// skip the root node
  		if (qName.equals(XMLSaver.ROOT)) {
  			if (model.getId() == null) {
  				model.setId(attributes.getValue(XMLSaver.ID));
  			}
  			return;
 		}
 		try {
 			if (mappableQName == null) {
 				// we are outside of XML node denoting model element - this is beginning of it
 				Class<Mappable> klass = Helper.mappedClass(qName, typeMap);
 				Constructor<Mappable> constructor = Helper.getConstructor(klass);
 				mappable = constructor.newInstance((Object[])null);
 				if (mappable instanceof IRelation) {
 					IRelation relation = (IRelation)mappable;
 					IEntity source = (IEntity)cache.get(Long.parseLong(attributes.getValue(XMLSaver.SOURCE)));
 					if (source == null) {
 						throw new SAXException("Relation references entity which was not yet " + //$NON-NLS-1$
 						        "parsed. Data set: " + dataSet); //$NON-NLS-1$
 					}
 					relation.setSource(source);
 					source.addRelation(relation);
 					IEntity target = (IEntity)cache.get(Long.parseLong(attributes.getValue(XMLSaver.TARGET)));
 					if (target == null) {
 						throw new SAXException("Relation references entity which was not yet " + //$NON-NLS-1$
 						        "parsed. Data set: " + dataSet); //$NON-NLS-1$
 					}
 					relation.setTarget(target);
 					target.addRelation(relation);
 				} else if (mappable instanceof IDataSet) {
 					dataSet = (IDataSet)mappable;
 					model.addDataSet(dataSet);
 					dataSet.setModel(model);
 				}
 				mappableQName = qName;
 				mappable.setMid(Long.parseLong(attributes.getValue(XMLSaver.ID)));
 				cache.put(mappable.getMid(), mappable);
 			} else {
 				// we are inside of XML node denoting model element - this is an attribute
 				String setterName = SETTER_PREFIX + qName.substring(3);
 				String typeName = attributes.getValue(XMLSaver.TYPE);
 				if (typeName.equals(LONG_TYPE)) {
 					returnType = long.class;
 				} else if (typeName.equals(BOOLEAN_TYPE)) {
 					returnType = boolean.class;
 				} else if (typeName.equals(DOUBLE_TYPE)) {
 					returnType = double.class;
 				} else if (typeName.equals(INT_TYPE)) {
 					returnType = int.class;
 				} else {
 					returnType = Class.forName(typeName);
 				}
 
 				setterMethod = mappable.getClass().getMethod(setterName, returnType);
 
 			}
 		} catch (Exception e) {
 			e.printStackTrace();
 			throw new SAXException(e);
 		}
 	}
 
 	/**
 	 * Appends characters stored in the buffer to the character table
 	 *
 	 * @param ch
 	 *            The character table.
 	 * @param start
 	 *            The lower index of the character table where the characters shoudl be stored.
 	 * @param length
 	 *            The number of characters to be stored.
 	 */
 	@Override
 	public void characters(char[] ch, int start, int length) {
 		if (setterMethod != null) {
 			// attribute data
 			contentBuffer.append(ch, start, length);
 		}
 	}
 
 	/**
 	 * {@inheritDoc}
 	 *
 	 * @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
 	 */
 	@Override
 	public void endElement(String uri, String localName, String qName) throws SAXException {
 		if (setterMethod != null) {
 			// attribute end tag
 			Object value = null;
 			String valueString = contentBuffer.toString();
 			contentBuffer.setLength(0);
 			try {
 				if (valueString.equals(NULL)) {
 					value = null;
 				} else if (String.class.equals(returnType)) {
 					value = valueString;
 				} else if (Long.class.equals(returnType) || long.class.equals(returnType)) {
 					value = Long.parseLong(valueString);
 				} else if (Integer.class.equals(returnType) || int.class.equals(returnType)) {
 					value = Integer.parseInt(valueString);
 				} else if (Double.class.equals(returnType) || double.class.equals(returnType)) {
 					value = Double.parseDouble(valueString);
 				} else if (Date.class.equals(returnType)) {
 					value = XMLSaver.DATE_FORMAT.parse(valueString);
 				} else if (Boolean.class.equals(returnType) || boolean.class.equals(returnType)) {
 					if (valueString.equals("true")) { //$NON-NLS-1$
 						value = new Boolean(true);
 					} else {
 						value = new Boolean(false);
 					}
 				}
 				setterMethod.invoke(mappable, new Object[] { value });
 				setterMethod = null;
 			} catch (Exception e) {
 				throw new SAXException(e);
 			}
 		} else if (mappableQName != null) {
 			// element end tag
 			if (mappableQName.equals(qName)) {
 				if (mappable instanceof IRelation) {
 					// the relation must be added after all its attributes (especially date)
 					// are set
 					dataSet.addRelation((IRelation)mappable);
 				}
 				mappableQName = null;
 				mappable = null;
 			}
 		}
 	}
 }