/**

  * Copyright 2009 Timothy Johnston 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 com.timjohnstondev.unitconverter.logic;

 import java.util.Collections;

 import java.util.prefs.Preferences;

 import org.xml.sax.Attributes;

 import org.xml.sax.SAXException;

 import org.xml.sax.helpers.DefaultHandler;

 import com.timjohnstondev.unitconverter.Launcher;

 import com.timjohnstondev.unitconverter.model.ConversionFactor;

 import com.timjohnstondev.unitconverter.model.ConversionFormula;

 import com.timjohnstondev.unitconverter.model.Property;

 import com.timjohnstondev.unitconverter.model.PropertyList;

 /**

  * This {@code DefaultHandler} is made specifically for this application. It understands the XML file format being used

  * and the related application objects.

  */

 public class ConversionFactorParserHandler extends DefaultHandler

 {

   private Property property;

   private final PropertyList properties = new PropertyList();

   private final String propertyElementName = "Property";

   private final String nameAttributeName = "name";

   private final String formulaBasedAttributeName = "formulaBased";

   private final String factorElementName = "Factor";

   private final String unitNameAttributeName = "unitName";

   private final String unitSymbolAttributeName = "unitSymbol";

   private final String toUnitSymbolAttributeName = "toUnitSymbol";

   private final String formulaAttributeName = "formula";

   private final String factorAttributeName = "factor";

   private final String usesMolesAttributeName = "usesMoles";

   /**

    * Returns the {@link PropertyList} constructed by the parser.

    * 

    * @return the {@code PropertyList} constructed by the parser

    */

   public final PropertyList getPropertyList()

   {

     getPropertyOrderPreferences();

     return properties;

   }

   /**

    * Looks into the preference storage in JavaSoft Preference settings. If the property order settings are found, they

    * are used, else the defaults are used.

    */

   private void getPropertyOrderPreferences()

   {

     final Preferences userPref = Preferences.userNodeForPackage(Launcher.class);

     for (Property prop : properties)

     {

       final String key = "sortorder." + prop.getName().replaceAll(" ", "").toLowerCase();

       final int propertyOrder = userPref.getInt(key, Integer.MAX_VALUE);

       prop.setOrder(propertyOrder);

     }

     Collections.sort(properties);

   }

   @Override

   public final void startElement(final String uri, final String localName, final String qualifiedName,

       final Attributes attributes) throws SAXException

   {

     if (propertyElementName.equals(qualifiedName))

     {

       boolean hasFormula = false;

       final String isFormulaBased = attributes.getValue(formulaBasedAttributeName);

       if ("true".equals(isFormulaBased))

       {

         hasFormula = true;

       }

       boolean usesMoles = false;

       final String canUseMoles = attributes.getValue(usesMolesAttributeName);

       if ("true".equals(canUseMoles))

       {

         usesMoles = true;

       }

       property = new Property(attributes.getValue(nameAttributeName), hasFormula, usesMoles);

     }

     if (factorElementName.equals(qualifiedName))

     {

       addConversion(attributes);

     }

   }

   private void addConversion(final Attributes attributes)

   {

     if (property.hasFormula())

     {

       addConversionFormula(attributes);

     }

     else

     {

       addConversionFactor(attributes);

     }

   }

   private void addConversionFormula(final Attributes attributes)

   {

     final String unitName = attributes.getValue(unitNameAttributeName);

     final String unitSymbol = attributes.getValue(unitSymbolAttributeName);

     final String toUnitSymbol = attributes.getValue(toUnitSymbolAttributeName);

     final String formula = attributes.getValue(formulaAttributeName);

     property.addConversion(new ConversionFormula(unitName, unitSymbol, toUnitSymbol, formula));

   }

   private void addConversionFactor(final Attributes attributes)

   {

     final String unitName = attributes.getValue(unitNameAttributeName);

     final String unitSymbol = attributes.getValue(unitSymbolAttributeName);

     final String factor = attributes.getValue(factorAttributeName);

     property.addConversion(new ConversionFactor(unitName, unitSymbol, factor));

   }

   @Override

   public final void endElement(final String uri, final String localName, final String qualifiedName)

       throws SAXException

   {

     if (propertyElementName.equals(qualifiedName))

     {

       properties.add(property);

       property = null;

     }

   }

 }