package org.kuali.rice.core.api.mo;

 import org.apache.commons.collections.CollectionUtils;

 import java.util.ArrayList;

 import java.util.Collections;

 import java.util.List;

 /**

  * A set of simple utilities to assist with common idioms in immutable model objects and their builders.

  *

  * @author Kuali Rice Team (rice.collab@kuali.org)

  */

 public class ModelObjectUtils {

     /**

      * Takes the given list of {@code ModelBuilder} objects and invokes the

      * {@link org.kuali.rice.core.api.mo.ModelBuilder#build()} method on each of them, adding them to a new list and

      * return an unmodifiable copy.  If the given list is empty or null, will return an empty and unmodifiable list.

      *

      * @param builderList the list of builders to build and add to resulting list, may be empty or null

      * @param <T> the type of the object that is built by the builders in the list, it is up to the caller of this

      *        method to ensure they define the proper parameterized list for the return type.

      * @return an unmodifiable list containing objects built from the given list of model builders

      */

     public static <T> List<T> buildImmutableCopy(List<? extends ModelBuilder> builderList) {

         if (CollectionUtils.isEmpty(builderList)) {

             return Collections.emptyList();

         }

         List<T> copy = new ArrayList<T>();

         for (ModelBuilder builder : builderList) {

             // since ModelBuilder is not parameterized, this code must assume that the appropriate type of object is built

             @SuppressWarnings("unchecked")

             T built = (T)builder.build();

             copy.add(built);

         }

         return Collections.unmodifiableList(copy);

     }

     /**

      * Takes the given list and returns an unmodifiable copy of that list containing the same elements as the original

      * list.  This method handles a null list being passed to it by returning an unmodifiable empty list.

      *

      * @param listToCopy the list to copy

      * @param <T> the type of the elements in the given list

      *

      * @return an unmodifiable copy containing the same elements as the given list

      */

     public static <T> List<T> createImmutableCopy(List<T> listToCopy) {

         if (CollectionUtils.isEmpty(listToCopy)) {

             return Collections.emptyList();

         }

         return Collections.unmodifiableList(new ArrayList<T>(listToCopy));

     }

     private ModelObjectUtils() {

         throw new UnsupportedOperationException("Do not call.");

     }

 }