package tcp

import "time"

type limiter struct {
	burst  float64
	tokens float64
	last   time.Time
}

func newLimiter(perSec int) *limiter {
	if perSec < 1 {
		perSec = 20
	}
	now := time.Now()
	return &limiter{burst: float64(perSec), tokens: float64(perSec), last: now}
}

func (l *limiter) Allow() bool {
	if l == nil {
		return true
	}
	now := time.Now()
	elapsed := now.Sub(l.last).Seconds()
	l.tokens += elapsed * l.burst
	if l.tokens > l.burst {
		l.tokens = l.burst
	}
	l.last = now
	if l.tokens < 1 {
		return false
	}
	l.tokens--
	return true
}