package transport

import (
	"math/rand/v2"
	"net/http"
)

const charset = "abcdefghijklmnopqrstuvwxyz0123456789"

// genRequestID generates a random string of a given length.
func genRequestID() string {
	b := make([]byte, 32)
	for i := range b {
		b[i] = charset[rand.IntN(len(charset))]
	}
	return string(b)
}

// RequestID ...
func RequestID(next http.RoundTripper) http.RoundTripper {
	f := func(req *http.Request) (*http.Response, error) {
		requestID := genRequestID()
		ctx := req.Context()
		req.Header.Set("X-Request-Id", requestID)
		req = req.WithContext(ctx)
		return next.RoundTrip(req)
	}

	return RoundTripFunc(f)
}