package spent

import (
	"sync"
	"time"
)

type Set struct {
	mu sync.Mutex
	m  map[string]time.Time
}

func New() *Set {
	return &Set{m: map[string]time.Time{}}
}

func (s *Set) Spend(key string, until, now time.Time) bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	for k, exp := range s.m {
		if now.After(exp) {
			delete(s.m, k)
		}
	}
	if _, used := s.m[key]; used {
		return false
	}
	s.m[key] = until
	return true
}

func (s *Set) Len() int {
	s.mu.Lock()
	defer s.mu.Unlock()
	return len(s.m)
}