import lombok.extern.slf4j.Slf4j;

import org.reactivestreams.Publisher;

import org.springframework.cloud.gateway.filter.GatewayFilterChain;

import org.springframework.cloud.gateway.filter.GlobalFilter;

import org.springframework.core.Ordered;

import org.springframework.core.io.buffer.DataBuffer;

import org.springframework.core.io.buffer.DataBufferFactory;

import org.springframework.core.io.buffer.DataBufferUtils;

import org.springframework.http.HttpMethod;

import org.springframework.http.MediaType;

import org.springframework.http.server.reactive.ServerHttpRequest;

import org.springframework.http.server.reactive.ServerHttpResponse;

import org.springframework.http.server.reactive.ServerHttpResponseDecorator;

import org.springframework.stereotype.Component;

import org.springframework.web.server.ServerWebExchange;

import reactor.core.publisher.Flux;

import reactor.core.publisher.Mono;

import java.nio.charset.Charset;

@Component

@Slf4j

public class HttpResponseGlobalFilter implements GlobalFilter, Ordered {

    @Override

    public int getOrder() {

        return -2;

    }

    @Override

    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {

        ServerHttpRequest serverHttpRequest = exchange.getRequest();

        ServerHttpResponse originalResponse = exchange.getResponse();

        String contentType = originalResponse.getHeaders().getFirst("Content-Type");

        if(contentType==null||!contentType.equals(MediaType.APPLICATION_JSON_VALUE)){

           return chain.filter(exchange);

        }

        //如果是post请求，将请求体取出来，再写入

        HttpMethod method = serverHttpRequest.getMethod();

        long contentLength = originalResponse.getHeaders().getContentLength();

        //当返回体里面没有任何数据的话不用后面的获取数据步骤

        if(contentLength<1){

            return chain.filter(exchange);

        }

        DataBufferFactory bufferFactory = originalResponse.bufferFactory();

        ServerHttpResponseDecorator decoratedResponse = new ServerHttpResponseDecorator(originalResponse) {

            @Override

            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {

                if (body instanceof Flux) {

                    Flux<? extends DataBuffer> fluxBody = (Flux<? extends DataBuffer>) body;

                    return super.writeWith(fluxBody.buffer().map(dataBuffers -> {//解决返回体分段传输

                        StringBuffer stringBuffer = new StringBuffer();

                        dataBuffers.forEach(dataBuffer -> {

                            byte[] content = new byte[dataBuffer.readableByteCount()];

                            dataBuffer.read(content);

                            DataBufferUtils.release(dataBuffer);

                            try {

                                stringBuffer.append(new String(content, "utf-8"));

                            } catch (Exception e) {

                                log.error("--list.add--error", e);

                            }

                        });

                        String result = stringBuffer.toString();

                        //TODO，result就是response的值，想修改、查看就随意而为了

                        String url = serverHttpRequest.getPath().toString();

                        String urlParams = serverHttpRequest.getQueryParams().toSingleValueMap().toString();

                        String accessId = "";

                        if( serverHttpRequest.getHeaders()!=null){

                            accessId= serverHttpRequest.getHeaders().getFirst("accessId");

                        }

                        //log.info("请求长度：" + StringUtils.length(requestBodyStr) + "，返回data长度:" + StringUtils.length(jsonObject.getString("data")));

                        //log.info("请求地址:【{}】请求参数:GET【{}】|POST:【\n{}\n】,响应数据:【\n{}\n】", url, urlParams, result);

                        log.info("\n" + "-------------------------------------------------------------------------------->>\n" +

                                        "locationtype: response\n" +

                                        "Url        : {}\n" +

                                        "HttpMethod : {}\n" +

                                        "accessId: {}\n" +

                                        "Param      : {}\n" +

                                        "\"<<--------------------------------------------------------------------------------"

                                ,url, method, accessId,result);

                        byte[] uppedContent = new String(result.getBytes(), Charset.forName("UTF-8")).getBytes();

                        originalResponse.getHeaders().setContentLength(uppedContent.length);

                        return bufferFactory.wrap(uppedContent);

                    }));

                }

                // if body is not a flux. never got there.

                return super.writeWith(body);

            }

        };

        // replace response with decorator

        return chain.filter(exchange.mutate().response(decoratedResponse).build());

    }

}