package cn.qinys.platform.gateway.filter;

import cn.qinys.platform.gateway.entity.GatewayLog;
import cn.qinys.platform.gateway.msgsender.IMessageService;
import com.alibaba.nacos.common.utils.StringUtils;
import org.reactivestreams.Publisher;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.cloud.gateway.filter.factory.rewrite.CachedBodyOutputMessage;
import org.springframework.cloud.gateway.route.Route;
import org.springframework.cloud.gateway.support.BodyInserterContext;
import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
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.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpRequestDecorator;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.http.server.reactive.ServerHttpResponseDecorator;
import org.springframework.stereotype.Component;
import org.springframework.util.MultiValueMap;
import org.springframework.web.reactive.function.BodyInserter;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.HandlerStrategies;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.nio.charset.StandardCharsets;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Objects;

/**
 * Create by Tanlie
 * Date 2022-03-14 14:45
 * Description
 */
@Component
public class AccessLogFilter implements GlobalFilter, Ordered {
    Logger logger = LoggerFactory.getLogger(this.getClass());
    private final List<HttpMessageReader<?>> messageReaders = HandlerStrategies.withDefaults().messageReaders();

    @Autowired
    IMessageService messageService;

    /**
     * 顺序必须是<-1，否则标准的NettyWriteResponseFilter将在您的过滤器得到一个被调用的机会之前发送响应
     * 也就是说如果不小于 -1 ，将不会执行获取后端响应的逻辑
     *
     * @return
     */
    @Override
    public int getOrder() {
        return -100;
    }

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        // 请求路径
        String requestPath = request.getPath().pathWithinApplication().value();
        Route route = this.getGatewayRoute(exchange);
        String ipAddress = this.getIpAddress(request);
        String token = request.getHeaders().getFirst("Authorization");
        GatewayLog gatewayLog = new GatewayLog();
        gatewayLog.setHttpSchema(request.getURI().getScheme());
        gatewayLog.setRequestMethod(request.getMethod().name());
        gatewayLog.setRequestPath(requestPath);
        gatewayLog.setTargetServer(route.getId());
        gatewayLog.setRequestTime(new Date());
        gatewayLog.setIp(ipAddress);
        gatewayLog.setToken(token);

        MediaType mediaType = request.getHeaders().getContentType();
        if (MediaType.APPLICATION_FORM_URLENCODED.isCompatibleWith(mediaType) || MediaType.APPLICATION_JSON.isCompatibleWith(mediaType)) {
            return this.writeBodyLog(exchange, chain, gatewayLog);
        } else {
            //文件上传
            return this.writeBasicLog(exchange, chain, gatewayLog);
        }
    }

    private Route getGatewayRoute(ServerWebExchange exchange) {
        return exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_ROUTE_ATTR);
    }

    private Mono<Void> writeBasicLog(ServerWebExchange exchange, GatewayFilterChain chain, GatewayLog accessLog) {
        StringBuilder builder = new StringBuilder();
        MultiValueMap<String, String> queryParams = exchange.getRequest().getQueryParams();
        for (Map.Entry<String, List<String>> entry : queryParams.entrySet()) {
            builder.append(entry.getKey()).append("=").append(StringUtils.join(entry.getValue(), ","));
        }
        accessLog.setRequestBody(builder.toString());
        //获取响应体
        ServerHttpResponseDecorator decoratedResponse = this.recordResponseLog(exchange, accessLog);
        return chain.filter(exchange.mutate().response(decoratedResponse).build())
                .then(Mono.fromRunnable(() -> {
                    // 打印日志
                    this.writeAccessLog(accessLog);
                }));
    }

    /**
     * 记录响应日志
     * 通过 DataBufferFactory 解决响应体分段传输问题。
     */
    private ServerHttpResponseDecorator recordResponseLog(ServerWebExchange exchange, GatewayLog gatewayLog) {
        ServerHttpResponse response = exchange.getResponse();
        DataBufferFactory bufferFactory = response.bufferFactory();

        return new ServerHttpResponseDecorator(response) {
            @Override
            public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
                if (body instanceof Flux) {
                    Date responseTime = new Date();
                    gatewayLog.setResponseTime(responseTime);
                    // 计算执行时间
                    long executeTime = (responseTime.getTime() - gatewayLog.getRequestTime().getTime());
                    gatewayLog.setExecuteTime(executeTime);
                    // 获取响应类型，如果是 json 就打印
                    String originalResponseContentType = exchange.getAttribute(ServerWebExchangeUtils.ORIGINAL_RESPONSE_CONTENT_TYPE_ATTR);

                    if (StringUtils.isNotBlank(originalResponseContentType)
                            && originalResponseContentType.contains("application/json")) {
                        Flux<? extends DataBuffer> fluxBody = Flux.from(body);
                        return super.writeWith(fluxBody.buffer().map(dataBuffers -> {
                            // 合并多个流集合，解决返回体分段传输
                            DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory();
                            DataBuffer join = dataBufferFactory.join(dataBuffers);
                            byte[] content = new byte[join.readableByteCount()];
                            join.read(content);
                            // 释放掉内存
                            DataBufferUtils.release(join);
                            String responseResult = new String(content, StandardCharsets.UTF_8);
                            gatewayLog.setResponseData(responseResult);
                            return bufferFactory.wrap(content);
                        }));
                    }
                }
                // if body is not a flux. never got there.
                return super.writeWith(body);
            }
        };
    }

    /**
     * 解决 request body 只能读取一次问题，
     * 参考: org.springframework.cloud.gateway.filter.factory.rewrite.ModifyRequestBodyGatewayFilterFactory
     *
     * @param exchange
     * @param chain
     * @param gatewayLog
     * @return
     */
    @SuppressWarnings("unchecked")
    private Mono<Void> writeBodyLog(ServerWebExchange exchange, GatewayFilterChain chain, GatewayLog gatewayLog) {
        ServerRequest serverRequest = ServerRequest.create(exchange, messageReaders);

        Mono<String> modifiedBody = serverRequest.bodyToMono(String.class)
                .flatMap(body -> {
                    gatewayLog.setRequestBody(body);
                    return Mono.just(body);
                });

        // 通过 BodyInserter 插入 body(支持修改body), 避免 request body 只能获取一次
        BodyInserter bodyInserter = BodyInserters.fromPublisher(modifiedBody, String.class);
        HttpHeaders headers = new HttpHeaders();
        headers.putAll(exchange.getRequest().getHeaders());
        // the new content type will be computed by bodyInserter
        // and then set in the request decorator
        headers.remove(HttpHeaders.CONTENT_LENGTH);

        CachedBodyOutputMessage outputMessage = new CachedBodyOutputMessage(exchange, headers);
        return bodyInserter.insert(outputMessage, new BodyInserterContext())
                .then(Mono.defer(() -> {
                    // 重新封装请求
                    ServerHttpRequest decoratedRequest = this.requestDecorate(exchange, headers, outputMessage);
                    // 记录响应日志
                    ServerHttpResponseDecorator decoratedResponse = this.recordResponseLog(exchange, gatewayLog);
                    // 记录普通的
                    return chain.filter(exchange.mutate().request(decoratedRequest).response(decoratedResponse).build())
                            .then(Mono.fromRunnable(() -> {
                                // 打印日志
                                this.writeAccessLog(gatewayLog);
                            }));
                }));
    }


    /**
     * 请求装饰器，重新计算 headers
     *
     * @param exchange
     * @param headers
     * @param outputMessage
     * @return
     */
    private ServerHttpRequestDecorator requestDecorate(ServerWebExchange exchange, HttpHeaders headers,
                                                       CachedBodyOutputMessage outputMessage) {
        return new ServerHttpRequestDecorator(exchange.getRequest()) {
            @Override
            public HttpHeaders getHeaders() {
                long contentLength = headers.getContentLength();
                HttpHeaders httpHeaders = new HttpHeaders();
                httpHeaders.putAll(super.getHeaders());
                if (contentLength > 0) {
                    httpHeaders.setContentLength(contentLength);
                } else {
                    // TODO: this causes a 'HTTP/1.1 411 Length Required' // on
                    // httpbin.org
                    httpHeaders.set(HttpHeaders.TRANSFER_ENCODING, "chunked");
                }
                return httpHeaders;
            }

            @Override
            public Flux<DataBuffer> getBody() {
                return outputMessage.getBody();
            }
        };
    }

    /**
     * 打印日志
     *
     * @param gatewayLog 网关日志
     *                   推入消息队列
     * @author javadaily
     * @date 2021/3/24 14:53
     */
    private void writeAccessLog(GatewayLog gatewayLog) {
        messageService.send(gatewayLog);
    }


    private String getIpAddress(ServerHttpRequest request) {
        HttpHeaders headers = request.getHeaders();
        String ip = headers.getFirst("x-forwarded-for");
        if (ip != null && ip.length() != 0 && !"unknown".equalsIgnoreCase(ip)) {
            // 多次反向代理后会有多个ip值，第一个ip才是真实ip
            if (ip.contains(",")) {
                ip = ip.split(",")[0];
            }
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = headers.getFirst("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = headers.getFirst("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = headers.getFirst("HTTP_CLIENT_IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = headers.getFirst("HTTP_X_FORWARDED_FOR");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = headers.getFirst("X-Real-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = Objects.requireNonNull(request.getRemoteAddress()).getAddress().getHostAddress();
        }
        return ip;
    }


}
