package middleware

import (
	"net/http"
	"time"

	"hfb_sys/backend/pkg/response"

	"github.com/gin-gonic/gin"
	"go.uber.org/zap"
)

// 正常请求不记录访问日志；只有慢请求、服务端错误、限流和有诊断价值的认证失败会输出。
const slowRequestThresholdMs = 500

func RequestLogger(logger *zap.Logger) gin.HandlerFunc {
	return func(c *gin.Context) {
		start := time.Now()
		c.Next()

		latencyMs := float64(time.Since(start).Microseconds()) / 1000
		status := c.Writer.Status()
		path := c.Request.URL.Path
		route := c.FullPath()
		authFailure := meaningfulAuthFailure(c)

		if shouldSkipHTTPLog(path, route, status, latencyMs) && !authFailure {
			return
		}

		fields := []zap.Field{
			zap.String("request_id", GetRequestID(c)),
			zap.String("method", c.Request.Method),
			zap.String("path", path),
			zap.String("route", route),
			zap.Int("status", status),
			zap.String("code", response.CodeFromContext(c)),
			zap.Float64("duration_ms", latencyMs),
			zap.String("client_ip", c.ClientIP()),
		}
		if userID, ok := c.Get(ContextUserID); ok {
			fields = append(fields, zap.Any("user_id", userID))
		}
		if adminID, ok := c.Get(ContextAdminID); ok {
			fields = append(fields, zap.Any("admin_id", adminID))
		}
		if reason, ok := c.Get(ContextAuthFailureReason); ok {
			fields = append(fields, zap.Any("auth_failure_reason", reason))
		}
		if source, ok := c.Get(ContextAuthTokenSource); ok {
			fields = append(fields, zap.Any("auth_token_source", source))
		}
		if detail, ok := c.Get(ContextAuthFailureDetail); ok {
			fields = append(fields, zap.Any("auth_failure_detail", detail))
		}
		if tokenVersion, ok := c.Get(ContextAuthTokenVersion); ok {
			fields = append(fields, zap.Any("auth_token_version", tokenVersion))
		}
		if currentVersion, ok := c.Get(ContextAuthCurrentVersion); ok {
			fields = append(fields, zap.Any("auth_current_token_version", currentVersion))
		}
		if len(c.Errors) > 0 {
			fields = append(fields,
				zap.String("error", c.Errors.Last().Err.Error()),
				zap.Int("error_count", len(c.Errors)),
			)
		}
		if stack, ok := c.Get(contextPanicStack); ok {
			fields = append(fields, zap.Any("stack", stack))
		}

		switch {
		case status >= 500:
			logger.Error("HTTP 请求失败", fields...)
		case status == http.StatusTooManyRequests:
			logger.Warn("HTTP 请求被限流", fields...)
		case authFailure:
			logger.Warn("后台认证失败", fields...)
		case latencyMs >= slowRequestThresholdMs:
			logger.Warn("HTTP 慢请求", fields...)
		}
	}
}

// shouldSkipHTTPLog 判断是否为无需记录的普通请求。
func shouldSkipHTTPLog(_, _ string, status int, latencyMs float64) bool {
	if status >= 500 || status == http.StatusTooManyRequests {
		return false
	}
	if latencyMs >= slowRequestThresholdMs {
		return false
	}
	return true
}

func meaningfulAuthFailure(c *gin.Context) bool {
	value, ok := c.Get(ContextAuthFailureReason)
	if !ok {
		return false
	}
	reason, _ := value.(string)
	return reason != "" && reason != "missing"
}