package client

import (
	"math/rand/v2"
	"time"
)

const (
	BackoffMin = 1 * time.Second
	BackoffMax = 30 * time.Second
)

// Delay computes exponential backoff with ±20% jitter.
// attempt starts at 1 for the first failed try.
func Delay(attempt int) time.Duration {
	if attempt < 1 {
		attempt = 1
	}
	d := BackoffMin
	for i := 1; i < attempt; i++ {
		d *= 2
		if d >= BackoffMax {
			d = BackoffMax
			break
		}
	}
	jitter := 1.0 + (rand.Float64()*0.4 - 0.2)
	return time.Duration(float64(d) * jitter)
}