package jnpf.config;

import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.jetbrains.annotations.NotNull;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import org.springframework.format.FormatterRegistry;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

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

/**
 * web相关的定制化配置
 * WebMvcConfigurerAdapter 这个类在SpringBoot2.0已过时，官方推荐直接实现WebMvcConfigurer 这个接口
 */
@Configuration
public class WebConfig implements WebMvcConfigurer {

    /**
     * 将 FastJsonHttpMessageConverter 加入spring管理,fegin 请求时，默认使用jackson
     * @return
     */
    @Bean
    @Order(1)
    public FastJsonHttpMessageConverter fastJsonHttpMessageConverter() {
        return getFastJsonHttpMessageConverter();
    }

    @NotNull
    private static FastJsonHttpMessageConverter getFastJsonHttpMessageConverter() {
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        //自定义fastjson配置
        FastJsonConfig config = new FastJsonConfig();
        config.setSerializerFeatures(
                // SerializerFeature.WriteMapNullValue, // 是否输出值为null的字段,默认为false,我们将它打开
                SerializerFeature.WriteNullListAsEmpty, // 将Collection类型字段的字段空值输出为[]
                SerializerFeature.WriteNullStringAsEmpty, // 将字符串类型字段的空值输出为空字符串
                // SerializerFeature.WriteNullNumberAsZero // 将数值类型字段的空值输出为0
                // SerializerFeature.WriteDateUseDateFormat
                SerializerFeature.DisableCircularReferenceDetect // 禁用循环引用
        );
        config.setSerializeFilters(new CustomValueFilter());
        fastJsonHttpMessageConverter.setFastJsonConfig(config);
        // 添加支持的MediaTypes;不添加时默认为*/*,也就是默认支持全部
        // 但是MappingJackson2HttpMessageConverter里面支持的MediaTypes为application/json
        // 参考它的做法, fastjson也只添加application/json的MediaType
        List<MediaType> fastMediaTypes = new ArrayList<>();
        fastMediaTypes.add(MediaType.APPLICATION_JSON);
        fastMediaTypes.add(MediaType.APPLICATION_XML);
        fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
        return fastJsonHttpMessageConverter;
    }

    /**
     * 使用fastjson代替jackson
     *
     * @param converters 转换器
     */
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        /*
         先把JackSon的消息转换器删除.
         备注: (1)源码分析可知，返回json的过程为:
                    Controller调用结束后返回一个数据对象，for循环遍历conventers，找到支持application/json的HttpMessageConverter，然后将返回的数据序列化成json。
                    具体参考org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor的writeWithMessageConverters方法
               (2)由于是list结构，我们添加的fastjson在最后。因此必须要将jackson的转换器删除，不然会先匹配上jackson，导致没使用fastjson
        */
//        for (int i = converters.size() - 1; i >= 0; i--) {
//            if (converters.get(i) instanceof MappingJackson2HttpMessageConverter) {
//                converters.remove(i);
//            }
//        }
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = getFastJsonHttpMessageConverter();
        converters.add(0, fastJsonHttpMessageConverter);
    }


    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new StringToDateConverter());
    }
}
