package cn.mb.cloud.gateway.filter;

import com.alibaba.fastjson.JSON;
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.HttpStatus;
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.StandardCharsets;
import java.util.ArrayList;
import java.util.List;

/**
 * 日志拦截器
 */
@Slf4j
@Component
public class ResponseParamFilter implements GlobalFilter, Ordered {

    @Override
    public int getOrder() {
        return -1;
    }

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        try {
            ServerHttpRequest request = exchange.getRequest();
            String uri = request.getURI().getRawPath();
            ServerHttpResponse originalResponse = exchange.getResponse();
            DataBufferFactory bufferFactory = originalResponse.bufferFactory();
            HttpStatus statusCode = originalResponse.getStatusCode();
            if(statusCode == HttpStatus.OK){
                ServerHttpResponseDecorator decoratedResponse = new ServerHttpResponseDecorator(originalResponse) {
                    @Override
                    public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
                        if (body instanceof Flux) {
                            Flux<? extends DataBuffer> fluxBody = Flux.from(body);
                            return super.writeWith(fluxBody.map(dataBuffer -> {
                                byte[] content = new byte[dataBuffer.readableByteCount()];
                                dataBuffer.read(content);
                                DataBufferUtils.release(dataBuffer);//释放掉内存 Release memory
                                // 构建日志 build Journal
                                StringBuffer sb = new StringBuffer();
                                sb.append(" 响应操作 -> " + uri + " || 响应参数-> {} \n");

                                List<Object> rspArgs = new ArrayList<>();
                                rspArgs.add(originalResponse.getStatusCode());
                                String data = new String(content, StandardCharsets.UTF_8);//data
                                sb.append(data);
                                log.info(sb.toString(), rspArgs.toArray());
                                return bufferFactory.wrap(content);
                            }));
                        } else {
                            log.error("响应操作 -> " + uri + " || 响应参数-> {} \n", getStatusCode());
                        }
                        return super.writeWith(body);
                    }
                };
                return chain.filter(exchange.mutate().response(decoratedResponse).build());
            }
            return chain.filter(exchange);//降级处理返回数据 Downgrade processing returns data
        }catch (Exception e){
            log.error("gateway log exception.\n" + e);
            return chain.filter(exchange);
        }
    }
}