package middleware

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

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

// RequestID attaches X-Request-ID to every request/response for tracing.
func RequestID() gin.HandlerFunc {
	return func(c *gin.Context) {
		id := c.GetHeader("X-Request-ID")
		if id == "" {
			id = newID()
		}
		c.Set("request_id", id)
		c.Header("X-Request-ID", id)
		c.Next()
	}
}

func newID() string {
	var b [16]byte
	if _, err := rand.Read(b[:]); err != nil {
		return "req-unknown"
	}
	return hex.EncodeToString(b[:])
}