/*

  * Copyright 2006-2008 The Kuali Foundation

  * 

  * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php

  * 

  * 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 org.kuali.rice.kns.util.comparator;

 import java.beans.PropertyDescriptor;

 import java.io.Serializable;

 import java.lang.reflect.InvocationTargetException;

 import java.util.Collections;

 import java.util.Comparator;

 import java.util.Iterator;

 import java.util.List;

 import org.apache.commons.beanutils.PropertyUtils;

 import org.apache.commons.collections.comparators.ComparableComparator;

 import org.kuali.rice.kns.exception.BeanComparisonException;

 import org.kuali.rice.kns.util.TypeUtils;

 /**

  * This class compares the two beans using multiple property names.

  * 

  * 

  */

 public class BeanPropertyComparator implements Comparator, Serializable {

     private static final long serialVersionUID = -2675700473766186018L;

     boolean ignoreCase;

     private List propertyNames;

     private Comparator stringComparator;

     private Comparator booleanComparator;

     private Comparator genericComparator;

     /**

      * Constructs a PropertyComparator for comparing beans using the properties named in the given List; if the List is null, the

      * beans will be compared directly (by Properties will be compared in the order in which they are listed. Case will be ignored

      * in String comparisons.

      * 

      * @param propertyNames List of property names (as Strings) used to compare beans

      */

     public BeanPropertyComparator(List propertyNames) {

         this(propertyNames, true);

     }

     /**

      * Constructs a PropertyComparator for comparing beans using the properties named in the given List. Properties will be compared

      * in the order in which they are listed. Case will be ignored if ignoreCase is true.

      * 

      * @param propertyNames List of property names (as Strings) used to compare beans

      * @param ignoreCase if true, case will be ignored during String comparisons

      */

     public BeanPropertyComparator(List propertyNames, boolean ignoreCase) {

         if (propertyNames == null) {

             throw new IllegalArgumentException("invalid (null) propertyNames list");

         }

         if (propertyNames.size() == 0) {

             throw new IllegalArgumentException("invalid (empty) propertyNames list");

         }

         this.propertyNames = Collections.unmodifiableList(propertyNames);

         this.ignoreCase = ignoreCase;

         if (ignoreCase) {

             this.stringComparator = String.CASE_INSENSITIVE_ORDER;

         }

         else {

             this.stringComparator = ComparableComparator.getInstance();

         }

         this.booleanComparator = new Comparator() {

             public int compare(Object o1, Object o2) {

                 int compared = 0;

                 Boolean b1 = (Boolean) o1;

                 Boolean b2 = (Boolean) o2;

                 if (!b1.equals(b2)) {

                     if (b1.equals(Boolean.FALSE)) {

                         compared = -1;

                     }

                     else {

                         compared = 1;

                     }

                 }

                 return compared;

             }

         };

         this.genericComparator = ComparableComparator.getInstance();

     }

     /**

      * Compare two JavaBeans by the properties given to the constructor. If no propertues

      * 

      * @param o1 Object The first bean to get data from to compare against

      * @param o2 Object The second bean to get data from to compare

      * @return int negative or positive based on order

      */

     public int compare(Object o1, Object o2) {

         int compared = 0;

         try {

             for (Iterator i = propertyNames.iterator(); (compared == 0) && i.hasNext();) {

                 String currentProperty = i.next().toString();

                 // choose appropriate comparator

                 Comparator currentComparator = null;

                 try {

                     PropertyDescriptor propertyDescriptor = PropertyUtils.getPropertyDescriptor(o1, currentProperty);

                     Class propertyClass = propertyDescriptor.getPropertyType();

                     if (propertyClass.equals(String.class)) {

                         currentComparator = this.stringComparator;

                     }

                     else if (TypeUtils.isBooleanClass(propertyClass)) {

                         currentComparator = this.booleanComparator;

                     }

                     else {

                         currentComparator = this.genericComparator;

                     }

                 }

                 catch (NullPointerException e) {

                     throw new BeanComparisonException("unable to find property '" + o1.getClass().getName() + "." + currentProperty + "'", e);

                 }

                 // compare the values

                 Object value1 = PropertyUtils.getProperty(o1, currentProperty);

                 Object value2 = PropertyUtils.getProperty(o2, currentProperty);

                 compared = currentComparator.compare(value1, value2);

             }

         }

         catch (IllegalAccessException e) {

             throw new BeanComparisonException("unable to compare property values", e);

         }

         catch (NoSuchMethodException e) {

             throw new BeanComparisonException("unable to compare property values", e);

         }

         catch (InvocationTargetException e) {

             throw new BeanComparisonException("unable to compare property values", e);

         }

         return compared;

     }

 }