package middleware

import (
	"crypto/rand"
	"encoding/hex"

	"github.com/gin-gonic/gin"
)

// Trace 注入 trace_id 中间件
func Trace() gin.HandlerFunc {
	return func(c *gin.Context) {
		traceID := c.GetHeader("X-Trace-Id")
		if traceID == "" {
			b := make([]byte, 8)
			_, _ = rand.Read(b)
			traceID = hex.EncodeToString(b)
		}
		c.Set("trace_id", traceID)
		c.Header("X-Trace-Id", traceID)
		c.Next()
	}
}