package com.theory.springdemo;

import java.util.List;

import org.springframework.beans.factory.config.BeanDefinition;

import org.springframework.beans.factory.support.AbstractBeanDefinition;

import org.springframework.beans.factory.support.BeanDefinitionBuilder;

import org.springframework.beans.factory.support.ManagedList;

import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;

import org.springframework.beans.factory.xml.ParserContext;

import org.springframework.util.xml.DomUtils;

import org.w3c.dom.Element;

public class ComponentBeanDefinitionParser extends AbstractBeanDefinitionParser {

    protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {

        return parseComponentElement2(element);

    }

    // 这个是自己编写的，没有采用官方文档中定义的示例ComponentFactoryBean

    private static AbstractBeanDefinition parseComponentElement2(Element ele) {

        BeanDefinitionBuilder bean = BeanDefinitionBuilder.rootBeanDefinition(Component.class);

        bean.addPropertyValue("name", ele.getAttribute("name"));

        List<Element> childElements = DomUtils.getChildElementsByTagName(ele, "component");

        //List<BeanDefinition> children = new ArrayList<>(); // 不能用这个，转换之类的会报错，ManageList是继承的ArrayList

        ManagedList<BeanDefinition> children = new ManagedList<BeanDefinition>(childElements.size());

        for (Element child : childElements) {

            AbstractBeanDefinition cc = parseComponentElement2(child);

            children.add(cc);

        }

        bean.addPropertyValue("components", children);

        return bean.getBeanDefinition();

    }

    // 以下的代码都是官方文档中的

    private static AbstractBeanDefinition parseComponentElement(Element element) {

        BeanDefinitionBuilder factory = BeanDefinitionBuilder.rootBeanDefinition(ComponentFactoryBean.class);

        factory.addPropertyValue("parent", parseComponent(element));

        List<Element> childElements = DomUtils.getChildElementsByTagName(element, "component");

        if (childElements != null && childElements.size() > 0) {

            parseChildComponents(childElements, factory);

        }

        return factory.getBeanDefinition();

    }

    private static BeanDefinition parseComponent(Element element) {

        BeanDefinitionBuilder component = BeanDefinitionBuilder.rootBeanDefinition(Component.class);

        component.addPropertyValue("name", element.getAttribute("name"));

        return component.getBeanDefinition();

    }

    private static void parseChildComponents(List<Element> childElements, BeanDefinitionBuilder factory) {

        ManagedList<BeanDefinition> children = new ManagedList<BeanDefinition>(childElements.size());

        for (Element element : childElements) {

            children.add(parseComponentElement(element));

        }

        factory.addPropertyValue("children", children);

    }

}