package jnpf.workflow.admin.filter;

import java.io.IOException;

import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.servlet.HandlerMapping;

import jakarta.servlet.FilterChain;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;

/**
 * 引擎内部处理耗时日志（非反编译还原类，2026-07-17 自有增强）。
 * 日志标记 [engine-timing]；调用方 jnpf-flowable 侧有对应的 [flow-engine-timing]
 * 往返耗时，两者相减 = HTTP 编排开销（序列化 + 网络 + 容器转发），
 * 为"是否内嵌引擎进 jnpf-flowable"决策积累数据。只观测，不改变任何请求/响应。
 */
@Slf4j
@Component
public class RequestTimingFilter extends OncePerRequestFilter {

    @Override
    protected boolean shouldNotFilter(HttpServletRequest request) {
        return !request.getRequestURI().startsWith("/api/Flow");
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        long start = System.nanoTime();
        try {
            filterChain.doFilter(request, response);
        } finally {
            long costMs = (System.nanoTime() - start) / 1_000_000;
            log.info("[engine-timing] {} {} {}ms status={}", request.getMethod(), endpointPattern(request), costMs, response.getStatus());
        }
    }

    /**
     * 优先取 MVC 路由模板（如 /api/Flow/task/list/{instanceId}）使日志可按端点聚合、
     * 不泄露实例/任务业务标识；doFilter 之后该属性已由 HandlerMapping 填好，取不到时回退 URI。
     */
    private String endpointPattern(HttpServletRequest request) {
        Object pattern = request.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
        return pattern != null ? pattern.toString() : request.getRequestURI();
    }
}