/*
 * Copyright 2002-2019 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
 *
 *      https://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.springframework.context.annotation;

import java.lang.reflect.Constructor;

import org.springframework.beans.BeanInstantiationException;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.Aware;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.env.Environment;
import org.springframework.core.io.ResourceLoader;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

Common delegate code for the handling of parser strategies, e.g. TypeFilter, ImportSelector, ImportBeanDefinitionRegistrar 
Author:
Juergen Hoeller, Phillip Webb
Since:
4.3.3/**
 * Common delegate code for the handling of parser strategies, e.g.
 * {@code TypeFilter}, {@code ImportSelector}, {@code ImportBeanDefinitionRegistrar}
 *
 * @author Juergen Hoeller
 * @author Phillip Webb
 * @since 4.3.3
 */
abstract class ParserStrategyUtils {

	
Instantiate a class using an appropriate constructor and return the new instance as the specified assignable type. The returned instance will have BeanClassLoaderAware, BeanFactoryAware, EnvironmentAware, and ResourceLoaderAware contracts invoked if they are implemented by the given object. 
Since:
5.2/**
	 * Instantiate a class using an appropriate constructor and return the new
	 * instance as the specified assignable type. The returned instance will
	 * have {@link BeanClassLoaderAware}, {@link BeanFactoryAware},
	 * {@link EnvironmentAware}, and {@link ResourceLoaderAware} contracts
	 * invoked if they are implemented by the given object.
	 * @since 5.2
	 */
	@SuppressWarnings("unchecked")
	static <T> T instantiateClass(Class<?> clazz, Class<T> assignableTo, Environment environment,
			ResourceLoader resourceLoader, BeanDefinitionRegistry registry) {

		Assert.notNull(clazz, "Class must not be null");
		Assert.isAssignable(assignableTo, clazz);
		if (clazz.isInterface()) {
			throw new BeanInstantiationException(clazz, "Specified class is an interface");
		}
		ClassLoader classLoader = (registry instanceof ConfigurableBeanFactory ?
				((ConfigurableBeanFactory) registry).getBeanClassLoader() : resourceLoader.getClassLoader());
		T instance = (T) createInstance(clazz, environment, resourceLoader, registry, classLoader);
		ParserStrategyUtils.invokeAwareMethods(instance, environment, resourceLoader, registry, classLoader);
		return instance;
	}

	private static Object createInstance(Class<?> clazz, Environment environment,
			ResourceLoader resourceLoader, BeanDefinitionRegistry registry,
			@Nullable ClassLoader classLoader) {

		Constructor<?>[] constructors = clazz.getDeclaredConstructors();
		if (constructors.length == 1 && constructors[0].getParameterCount() > 0) {
			try {
				Constructor<?> constructor = constructors[0];
				Object[] args = resolveArgs(constructor.getParameterTypes(),
						environment, resourceLoader, registry, classLoader);
				return BeanUtils.instantiateClass(constructor, args);
			}
			catch (Exception ex) {
				throw new BeanInstantiationException(clazz, "No suitable constructor found", ex);
			}
		}
		return BeanUtils.instantiateClass(clazz);
	}

	private static Object[] resolveArgs(Class<?>[] parameterTypes,
			Environment environment, ResourceLoader resourceLoader,
			BeanDefinitionRegistry registry, @Nullable ClassLoader classLoader) {

			Object[] parameters = new Object[parameterTypes.length];
			for (int i = 0; i < parameterTypes.length; i++) {
				parameters[i] = resolveParameter(parameterTypes[i], environment,
						resourceLoader, registry, classLoader);
			}
			return parameters;
	}

	@Nullable
	private static Object resolveParameter(Class<?> parameterType,
			Environment environment, ResourceLoader resourceLoader,
			BeanDefinitionRegistry registry, @Nullable ClassLoader classLoader) {

		if (parameterType == Environment.class) {
			return environment;
		}
		if (parameterType == ResourceLoader.class) {
			return resourceLoader;
		}
		if (parameterType == BeanFactory.class) {
			return (registry instanceof BeanFactory ? registry : null);
		}
		if (parameterType == ClassLoader.class) {
			return classLoader;
		}
		throw new IllegalStateException("Illegal method parameter type: " + parameterType.getName());
	}

	private static void invokeAwareMethods(Object parserStrategyBean, Environment environment,
			ResourceLoader resourceLoader, BeanDefinitionRegistry registry, @Nullable ClassLoader classLoader) {

		if (parserStrategyBean instanceof Aware) {
			if (parserStrategyBean instanceof BeanClassLoaderAware && classLoader != null) {
				((BeanClassLoaderAware) parserStrategyBean).setBeanClassLoader(classLoader);
			}
			if (parserStrategyBean instanceof BeanFactoryAware && registry instanceof BeanFactory) {
				((BeanFactoryAware) parserStrategyBean).setBeanFactory((BeanFactory) registry);
			}
			if (parserStrategyBean instanceof EnvironmentAware) {
				((EnvironmentAware) parserStrategyBean).setEnvironment(environment);
			}
			if (parserStrategyBean instanceof ResourceLoaderAware) {
				((ResourceLoaderAware) parserStrategyBean).setResourceLoader(resourceLoader);
			}
		}
	}

}