package rate

import (
	"sync"
	"time"
)

type Limiter struct {
	rate       float64
	interval   time.Duration
	lastUpdate time.Time
	allowance  float64
	mutex      sync.Mutex
}

func NewLimiter(rate float64, interval time.Duration) *Limiter {
	return &Limiter{
		rate:       rate,
		interval:   interval,
		lastUpdate: time.Now(),
		allowance:  rate,
	}
}

func (l *Limiter) Allow() bool {
	l.mutex.Lock()
	defer l.mutex.Unlock()

	now := time.Now()
	elapsed := now.Sub(l.lastUpdate)
	l.lastUpdate = now

	l.allowance += elapsed.Seconds() * l.rate
	if l.allowance > l.rate {
		l.allowance = l.rate
	}

	if l.allowance < 1.0 {
		return false
	}

	l.allowance -= 1.0
	return true
}