/*
 * Copyright 2005-2010 the original 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.wamblee.test.inject;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.wamblee.inject.Injector;
import org.wamblee.inject.InjectorBuilder;
import org.wamblee.inject.InjectorFactory;
import org.wamblee.test.persistence.JpaBuilder;

/**
 * <p>
 * The test injector factory provides dependency injection of a contextual entity manager
 * using the support/inject mini framework. It supports dependency injection of fields
 * annoted with <code>&#064;PersistenceContext</code>. It only supports one persistence context
 * at the moment. This injector can be easily used together with {@link JpaBuilder#getContextualEntityManager()}
 * for obtaining an entity manager in unit test. 
 * </p>
 * 
 * <p>
 * The reason it is needed is because standard injection mechanisms (such as weld CDI) do not support
 * entity manager injection in a Java SE environment out of the box.  
 * </p>
 *
 * <p>
 * To use it, construct the factory using one of the available constructors and set 
 * <code>InjectorBuilder.setInjectorFactory(InjectorFactory)</code>.
 * </p>
 * 
 * @author Erik Brakkee
 *
 */
public class JavaEETestInjectorFactory implements InjectorFactory {

    private List<Binding> bindings;
    private InjectorFactory delegate;
    
    /**
     * Constructs the factory. 
     * @param aInjectorFactory Injector factory to delegate to. 
     */
    public JavaEETestInjectorFactory(InjectorFactory aInjectorFactory) {
        bindings = new ArrayList<Binding>();        
        delegate = aInjectorFactory;
    }

    /**
     * Adds default entity manager binding. Any field annotated with @PersistenceContext and of type 
     * entity manager will get injected.
     * @param aEntityManager Entitymanager object to inject.
     * @return Factory to allow chaining.
     */
    public JavaEETestInjectorFactory addEntityManagerBinding(EntityManager aEntityManager) {
        Binding em = new Binding(EntityManager.class, PersistenceContext.class, aEntityManager);
        addBinding(em);
        return this;
    }
    
    /**
     * Adds another custom injection binding. 
     * @param aBinding Injection binding to use. 
     * @return the factoryto allow chaining.
     */
    public JavaEETestInjectorFactory addBinding(Binding aBinding) { 
        bindings.add(aBinding);
        return this; 
    }

    /**
     * Constructs the factory with the default injector factory obtained from 
     * {@link InjectorBuilder#getInjector()}. 
     */
    public JavaEETestInjectorFactory() {
        this(getDefaultInjectorFactory());
    }

    private static InjectorFactory getDefaultInjectorFactory() {
        InjectorBuilder.setInjectorFactory(null);
        return InjectorBuilder.getInjectorFactory();
    }

    @Override
    public Injector create(Class aClass) {
        return new JavaEETestInjector(aClass, bindings, delegate
            .create(aClass));
    }
}