/*
 * Copyright 2002-2018 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 org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.util.Assert;

/**
 * Standalone application context, accepting annotated classes as input - in particular
 * {@link Configuration @Configuration}-annotated classes, but also plain
 * {@link org.springframework.stereotype.Component @Component} types and JSR-330 compliant
 * classes using {@code javax.inject} annotations. Allows for registering classes one by
 * one using {@link #register(Class...)} as well as for classpath scanning using
 * {@link #scan(String...)}.
 *
 * <p>In case of multiple {@code @Configuration} classes, @{@link Bean} methods defined in
 * later classes will override those defined in earlier classes. This can be leveraged to
 * deliberately override certain bean definitions via an extra {@code @Configuration}
 * class.
 *
 * <p>See @{@link Configuration}'s javadoc for usage examples.
 *
 * @author Juergen Hoeller
 * @author Chris Beams
 * @since 3.0
 * @see #register
 * @see #scan
 * @see AnnotatedBeanDefinitionReader
 * @see ClassPathBeanDefinitionScanner
 * @see org.springframework.context.support.GenericXmlApplicationContext
 */
public class AnnotationConfigApplicationContext extends GenericApplicationContext implements AnnotationConfigRegistry {

        private final AnnotatedBeanDefinitionReader reader;

        private final ClassPathBeanDefinitionScanner scanner;


        /**
         * Create a new AnnotationConfigApplicationContext that needs to be populated
         * through {@link #register} calls and then manually {@linkplain #refresh refreshed}.
         */
        public AnnotationConfigApplicationContext() {
                this.reader = new AnnotatedBeanDefinitionReader(this);
                this.scanner = new ClassPathBeanDefinitionScanner(this);
        }

        /**
         * Create a new AnnotationConfigApplicationContext with the given DefaultListableBeanFactory.
         * @param beanFactory the DefaultListableBeanFactory instance to use for this context
         */
        public AnnotationConfigApplicationContext(DefaultListableBeanFactory beanFactory) {
                super(beanFactory);
                this.reader = new AnnotatedBeanDefinitionReader(this);
                this.scanner = new ClassPathBeanDefinitionScanner(this);
        }

        /**
         * Create a new AnnotationConfigApplicationContext, deriving bean definitions
         * from the given annotated classes and automatically refreshing the context.
         * @param annotatedClasses one or more annotated classes,
         * e.g. {@link Configuration @Configuration} classes
         */
        public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
                this();
                register(annotatedClasses);
                refresh();
        }

        /**
         * Create a new AnnotationConfigApplicationContext, scanning for bean definitions
         * in the given packages and automatically refreshing the context.
         * @param basePackages the packages to check for annotated classes
         */
        public AnnotationConfigApplicationContext(String... basePackages) {
                this();
                scan(basePackages);
                refresh();
        }


        /**
         * Propagates the given custom {@code Environment} to the underlying
         * {@link AnnotatedBeanDefinitionReader} and {@link ClassPathBeanDefinitionScanner}.
         */
        @Override
        public void setEnvironment(ConfigurableEnvironment environment) {
                super.setEnvironment(environment);
                this.reader.setEnvironment(environment);
                this.scanner.setEnvironment(environment);
        }

        /**
         * Provide a custom {@link BeanNameGenerator} for use with {@link AnnotatedBeanDefinitionReader}
         * and/or {@link ClassPathBeanDefinitionScanner}, if any.
         * <p>Default is {@link org.springframework.context.annotation.AnnotationBeanNameGenerator}.
         * <p>Any call to this method must occur prior to calls to {@link #register(Class...)}
         * and/or {@link #scan(String...)}.
         * @see AnnotatedBeanDefinitionReader#setBeanNameGenerator
         * @see ClassPathBeanDefinitionScanner#setBeanNameGenerator
         */
        public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) {
                this.reader.setBeanNameGenerator(beanNameGenerator);
                this.scanner.setBeanNameGenerator(beanNameGenerator);
                getBeanFactory().registerSingleton(
                                AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR, beanNameGenerator);
        }

        /**
         * Set the {@link ScopeMetadataResolver} to use for detected bean classes.
         * <p>The default is an {@link AnnotationScopeMetadataResolver}.
         * <p>Any call to this method must occur prior to calls to {@link #register(Class...)}
         * and/or {@link #scan(String...)}.
         */
        public void setScopeMetadataResolver(ScopeMetadataResolver scopeMetadataResolver) {
                this.reader.setScopeMetadataResolver(scopeMetadataResolver);
                this.scanner.setScopeMetadataResolver(scopeMetadataResolver);
        }

        @Override
        protected void prepareRefresh() {
                this.scanner.clearCache();
                super.prepareRefresh();
        }


        //---------------------------------------------------------------------
        // Implementation of AnnotationConfigRegistry
        //---------------------------------------------------------------------

        /**
         * Register one or more annotated classes to be processed.
         * <p>Note that {@link #refresh()} must be called in order for the context
         * to fully process the new classes.
         * @param annotatedClasses one or more annotated classes,
         * e.g. {@link Configuration @Configuration} classes
         * @see #scan(String...)
         * @see #refresh()
         */
        public void register(Class<?>... annotatedClasses) {
                Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified");
                this.reader.register(annotatedClasses);
        }

        /**
         * Perform a scan within the specified base packages.
         * <p>Note that {@link #refresh()} must be called in order for the context
         * to fully process the new classes.
         * @param basePackages the packages to check for annotated classes
         * @see #register(Class...)
         * @see #refresh()
         */
        public void scan(String... basePackages) {
                Assert.notEmpty(basePackages, "At least one base package must be specified");
                this.scanner.scan(basePackages);
        }

}