package com.xiaopeng.automaticPilot.filter;

import com.alibaba.fastjson2.JSON;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.MDC;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.util.ContentCachingRequestWrapper;
import org.springframework.web.util.ContentCachingResponseWrapper;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

/**
 * 请求/响应日志过滤器
 * 打印：traceId、method、uri、queryString、请求体、响应状态、耗时、响应体
 */
@Slf4j
@Component
@Order(Ordered.HIGHEST_PRECEDENCE + 10)
public class RequestResponseLoggingFilter extends OncePerRequestFilter {

    /** 不打印 body 的路径前缀（健康检查、actuator 等） */
    private static final Set<String> EXCLUDE_PATHS = new HashSet<>(Arrays.asList(
            "/actuator", "/healthcheck", "/health", "/prometheus"
    ));

    /** 只对这些 Content-Type 打印 body（避免打印二进制流） */
    private static final Set<String> LOGGABLE_CONTENT_TYPES = new HashSet<>(Arrays.asList(
            MediaType.APPLICATION_JSON_VALUE,
            MediaType.APPLICATION_JSON_UTF8_VALUE,
            MediaType.TEXT_PLAIN_VALUE,
            MediaType.TEXT_XML_VALUE,
            MediaType.APPLICATION_XML_VALUE,
            "application/x-www-form-urlencoded"
    ));

    private static final int MAX_BODY_LENGTH = 2000;

    @Override
    protected boolean shouldNotFilter(HttpServletRequest request) {
        String uri = request.getRequestURI();
        return EXCLUDE_PATHS.stream().anyMatch(uri::startsWith);
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
                                    FilterChain chain) throws ServletException, IOException {
        // 初始化 MDC（Filter 先于 Interceptor 执行，在此统一设置）
        String traceId = request.getHeader("X-Trace-Id");
        if (traceId == null || traceId.isEmpty()) {
            traceId = java.util.UUID.randomUUID().toString().replace("-", "");
        }
        MDC.put("traceId",    traceId);
        MDC.put("clientIp",   getClientIp(request));
        MDC.put("requestUri", request.getRequestURI());
        response.setHeader("X-Trace-Id", traceId);

        ContentCachingRequestWrapper reqWrapper  = new ContentCachingRequestWrapper(request);
        ContentCachingResponseWrapper respWrapper = new ContentCachingResponseWrapper(response);

        long start = System.currentTimeMillis();
        try {
            chain.doFilter(reqWrapper, respWrapper);
        } finally {
            long cost = System.currentTimeMillis() - start;
            logRequest(reqWrapper);
            logResponse(respWrapper, cost);
            // 必须把响应体写回，否则客户端收不到数据
            respWrapper.copyBodyToResponse();
            MDC.clear();
        }
    }

    private String getClientIp(HttpServletRequest request) {
        String ip = request.getHeader("X-Forwarded-For");
        if (ip != null && !ip.isEmpty() && !"unknown".equalsIgnoreCase(ip)) {
            return ip.split(",")[0].trim();
        }
        ip = request.getHeader("X-Real-IP");
        if (ip != null && !ip.isEmpty() && !"unknown".equalsIgnoreCase(ip)) {
            return ip;
        }
        return request.getRemoteAddr();
    }

    private void logRequest(ContentCachingRequestWrapper request) {
        String traceId = MDC.get("traceId");
        String uri     = request.getRequestURI();
        String query   = request.getQueryString();
        String method  = request.getMethod();
        String body    = extractBody(request.getContentAsByteArray(), request.getContentType());

        log.info(">>> [{}] {} {}{} | body={}",
                traceId,
                method,
                uri,
                query != null ? "?" + query : "",
                body);
    }

    private void logResponse(ContentCachingResponseWrapper response, long cost) {
        String traceId = MDC.get("traceId");
        int    status  = response.getStatus();
        String body    = extractBody(response.getContentAsByteArray(), response.getContentType());

        log.info("<<< [{}] status={} cost={}ms | body={}",
                traceId, status, cost, body);
    }

    private String extractBody(byte[] bodyBytes, String contentType) {
        if (bodyBytes == null || bodyBytes.length == 0) {
            return "";
        }
        if (!isLoggableContentType(contentType)) {
            return "[binary, " + bodyBytes.length + " bytes]";
        }
        String body = new String(bodyBytes, StandardCharsets.UTF_8);
        if (body.length() > MAX_BODY_LENGTH) {
            body = body.substring(0, MAX_BODY_LENGTH) + "...(truncated)";
        }
        return body;
    }

    private boolean isLoggableContentType(String contentType) {
        if (contentType == null) return true;
        String ct = contentType.toLowerCase();
        return LOGGABLE_CONTENT_TYPES.stream().anyMatch(ct::contains);
    }
}