/*
 * 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.web.context.support;

import java.io.IOException;

import groovy.lang.GroovyObject;
import groovy.lang.GroovySystem;
import groovy.lang.MetaClass;

import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.lang.Nullable;

/**
 * {@link org.springframework.web.context.WebApplicationContext} implementation which takes
 * its configuration from Groovy bean definition scripts and/or XML files, as understood by
 * a {@link org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader}.
 * This is essentially the equivalent of
 * {@link org.springframework.context.support.GenericGroovyApplicationContext}
 * for a web environment.
 *
 * <p>By default, the configuration will be taken from "/WEB-INF/applicationContext.groovy"
 * for the root context, and "/WEB-INF/test-servlet.groovy" for a context with the namespace
 * "test-servlet" (like for a DispatcherServlet instance with the servlet-name "test").
 *
 * <p>The config location defaults can be overridden via the "contextConfigLocation"
 * context-param of {@link org.springframework.web.context.ContextLoader} and servlet
 * init-param of {@link org.springframework.web.servlet.FrameworkServlet}. Config locations
 * can either denote concrete files like "/WEB-INF/context.groovy" or Ant-style patterns
 * like "/WEB-INF/*-context.groovy" (see {@link org.springframework.util.PathMatcher}
 * javadoc for pattern details). Note that ".xml" files will be parsed as XML content;
 * all other kinds of resources will be parsed as Groovy scripts.
 *
 * <p>Note: In case of multiple config locations, later bean definitions will
 * override ones defined in earlier loaded files. This can be leveraged to
 * deliberately override certain bean definitions via an extra Groovy script.
 *
 * <p><b>For a WebApplicationContext that reads in a different bean definition format,
 * create an analogous subclass of {@link AbstractRefreshableWebApplicationContext}.</b>
 * Such a context implementation can be specified as "contextClass" context-param
 * for ContextLoader or "contextClass" init-param for FrameworkServlet.
 *
 * @author Juergen Hoeller
 * @since 4.1
 * @see #setNamespace
 * @see #setConfigLocations
 * @see org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader
 * @see org.springframework.web.context.ContextLoader#initWebApplicationContext
 * @see org.springframework.web.servlet.FrameworkServlet#initWebApplicationContext
 */
public class GroovyWebApplicationContext extends AbstractRefreshableWebApplicationContext implements GroovyObject {

	/** Default config location for the root context. */
	public static final String DEFAULT_CONFIG_LOCATION = "/WEB-INF/applicationContext.groovy";

	/** Default prefix for building a config location for a namespace. */
	public static final String DEFAULT_CONFIG_LOCATION_PREFIX = "/WEB-INF/";

	/** Default suffix for building a config location for a namespace. */
	public static final String DEFAULT_CONFIG_LOCATION_SUFFIX = ".groovy";


	private final BeanWrapper contextWrapper = new BeanWrapperImpl(this);

	private MetaClass metaClass = GroovySystem.getMetaClassRegistry().getMetaClass(getClass());


	/**
	 * Loads the bean definitions via an GroovyBeanDefinitionReader.
	 * @see org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader
	 * @see #initBeanDefinitionReader
	 * @see #loadBeanDefinitions
	 */
	@Override
	protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
		// Create a new XmlBeanDefinitionReader for the given BeanFactory.
		GroovyBeanDefinitionReader beanDefinitionReader = new GroovyBeanDefinitionReader(beanFactory);

		// Configure the bean definition reader with this context's
		// resource loading environment.
		beanDefinitionReader.setEnvironment(getEnvironment());
		beanDefinitionReader.setResourceLoader(this);

		// Allow a subclass to provide custom initialization of the reader,
		// then proceed with actually loading the bean definitions.
		initBeanDefinitionReader(beanDefinitionReader);
		loadBeanDefinitions(beanDefinitionReader);
	}

	/**
	 * Initialize the bean definition reader used for loading the bean
	 * definitions of this context. Default implementation is empty.
	 * <p>Can be overridden in subclasses.
	 * @param beanDefinitionReader the bean definition reader used by this context
	 */
	protected void initBeanDefinitionReader(GroovyBeanDefinitionReader beanDefinitionReader) {
	}

	/**
	 * Load the bean definitions with the given GroovyBeanDefinitionReader.
	 * <p>The lifecycle of the bean factory is handled by the refreshBeanFactory method;
	 * therefore this method is just supposed to load and/or register bean definitions.
	 * <p>Delegates to a ResourcePatternResolver for resolving location patterns
	 * into Resource instances.
	 * @throws IOException if the required Groovy script or XML file isn't found
	 * @see #refreshBeanFactory
	 * @see #getConfigLocations
	 * @see #getResources
	 * @see #getResourcePatternResolver
	 */
	protected void loadBeanDefinitions(GroovyBeanDefinitionReader reader) throws IOException {
		String[] configLocations = getConfigLocations();
		if (configLocations != null) {
			for (String configLocation : configLocations) {
				reader.loadBeanDefinitions(configLocation);
			}
		}
	}

	/**
	 * The default location for the root context is "/WEB-INF/applicationContext.groovy",
	 * and "/WEB-INF/test-servlet.groovy" for a context with the namespace "test-servlet"
	 * (like for a DispatcherServlet instance with the servlet-name "test").
	 */
	@Override
	protected String[] getDefaultConfigLocations() {
		if (getNamespace() != null) {
			return new String[] {DEFAULT_CONFIG_LOCATION_PREFIX + getNamespace() + DEFAULT_CONFIG_LOCATION_SUFFIX};
		}
		else {
			return new String[] {DEFAULT_CONFIG_LOCATION};
		}
	}


	// Implementation of the GroovyObject interface

	@Override
	public void setMetaClass(MetaClass metaClass) {
		this.metaClass = metaClass;
	}

	@Override
	public MetaClass getMetaClass() {
		return this.metaClass;
	}

	@Override
	public Object invokeMethod(String name, Object args) {
		return this.metaClass.invokeMethod(this, name, args);
	}

	@Override
	public void setProperty(String property, Object newValue) {
		this.metaClass.setProperty(this, property, newValue);
	}

	@Override
	@Nullable
	public Object getProperty(String property) {
		if (containsBean(property)) {
			return getBean(property);
		}
		else if (this.contextWrapper.isReadableProperty(property)) {
			return this.contextWrapper.getPropertyValue(property);
		}
		throw new NoSuchBeanDefinitionException(property);
	}

}
