package middleware

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

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

// RequestID 为每个请求生成唯一 ID，放入 context 和响应头
func RequestID() gin.HandlerFunc {
	return func(c *gin.Context) {
		// 优先使用客户端传来的 X-Request-ID
		id := c.GetHeader("X-Request-ID")
		if id == "" {
			b := make([]byte, 12)
			if _, err := rand.Read(b); err == nil {
				id = hex.EncodeToString(b)
			} else {
				id = "unknown"
			}
		}
		c.Set("request_id", id)
		c.Header("X-Request-ID", id)
		c.Next()
	}
}