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Java Simplified. Extensions and Useful Constructs for the Java Platform. Codeprimate Elements (a.k.a. cp-elements) is a Java library and micro-framework used to simplify the development of software applications written in Java. Elements packages several APIs into one library in order to address various application concerns and aspects of software design and development collectively and conveniently. Elements is a highly simple, yet robust and proven library built on solid OO principles, software design patterns and best practices to effectively solve common and reoccurring problems in software development.

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/*
 * Copyright 2016 Author or Authors.
 *
 * 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 org.cp.elements.data.conversion.converters;

import static org.cp.elements.lang.ElementsExceptionsFactory.newConversionException;

import java.util.ServiceLoader;

import org.cp.elements.data.conversion.AbstractConverter;
import org.cp.elements.data.conversion.ConversionException;
import org.cp.elements.data.conversion.Converter;
import org.cp.elements.lang.Assert;
import org.cp.elements.lang.Identifiable;
import org.cp.elements.lang.factory.ObjectFactory;
import org.cp.elements.lang.factory.ObjectFactoryAware;
import org.cp.elements.lang.factory.ObjectFactoryReferenceHolder;

/**
 * {@link IdentifiableConverter} converts a {@link Long} into an instance of an {@link Identifiable} object.
 *
 * @author John J. Blum
 * @see java.lang.Long
 * @see org.cp.elements.data.conversion.AbstractConverter
 * @see org.cp.elements.lang.Identifiable
 * @see org.cp.elements.lang.factory.ObjectFactory
 * @see org.cp.elements.lang.factory.ObjectFactoryAware
 * @see org.cp.elements.lang.factory.ObjectFactoryReferenceHolder
 * @since 1.0.0
 */
@SuppressWarnings("unused")
public class IdentifiableConverter extends AbstractConverter> implements ObjectFactoryAware {

  private ObjectFactory objectFactory;

  public IdentifiableConverter() {
    this(ObjectFactoryReferenceHolder.hasReference() ? ObjectFactoryReferenceHolder.get()
      : ServiceLoader.load(ObjectFactory.class).iterator().next());
  }

  public IdentifiableConverter(ObjectFactory objectFactory) {
    setObjectFactory(objectFactory);
  }

  @Override
  public final void setObjectFactory(ObjectFactory objectFactory) {
    this.objectFactory = objectFactory;
  }

  protected ObjectFactory getObjectFactory() {

    Assert.state(this.objectFactory != null, "No ObjectFactory was configured");

    return this.objectFactory;
  }

  /**
   * Determines whether this {@link Converter} can convert {@link Object Objects}
   * {@link Class from type} {@link Class to type}.
   *
   * @param fromType {@link Class type} to convert from.
   * @param toType {@link Class type} to convert to.
   * @return a boolean indicating whether this {@link Converter} can convert {@link Object Objects}
   * {@link Class from type} {@link Class to type}.
   * @see org.cp.elements.data.conversion.ConversionService#canConvert(Class, Class)
   * @see #canConvert(Object, Class)
   */
  @Override
  public boolean canConvert(Class fromType, Class toType) {
    return Long.class.equals(fromType) && toType != null && Identifiable.class.isAssignableFrom(toType);
  }

  /**
   * Converts an {@link Object} of {@link Class type S} into an {@link Object} of {@link Class qualifying type QT}.
   *
   * @param  {@link Class qualifying type} extending {@link Class type T}.
   * @param value {@link Object} of {@link Class type S} to convert.
   * @param identifiableType the {@link Class qualifying type} of the {@link Object} resolved in the conversion.
   * @return the converted {@link Object} of {@link Class qualifying type QT}.
   * @throws ConversionException if the {@link Object} cannot be converted.
   * @throws IllegalArgumentException if {@link Class qualifying type} is {@literal null}.
   * @see org.cp.elements.data.conversion.ConversionService#convert(Object, Class)
   * @see #convert(Object)
   */
  @Override
  public > QT convert(Long value, Class identifiableType) {

    try {

      Identifiable identifiableObject =
        getObjectFactory().create(identifiableType, new Class[] { Long.class }, value);

      if (identifiableObject.isNew()) {
        identifiableObject.setId(value);
      }

      return identifiableType.cast(identifiableObject);
    }
    catch (Throwable cause) {
      throw newConversionException(cause, "Cannot convert Long [%1$d] into an Object of type [%2$s]",
        value, identifiableType);
    }
  }
}