package main

import (
	"sync"
	"time"
)

type fingerprint string

type cachedAlert struct {
	expires time.Time
}

type cache struct {
	mu       sync.Mutex
	duration time.Duration
	alerts   map[fingerprint]*cachedAlert
}

func (a *cachedAlert) expired() bool {
	return a.expires.Before(time.Now())
}

func newCache(d time.Duration) *cache {
	c := new(cache)
	c.duration = d
	c.alerts = make(map[fingerprint]*cachedAlert)

	return c
}

func (c *cache) cleanup() {
	c.mu.Lock()
	defer c.mu.Unlock()
	for key, value := range c.alerts {
		if value.expired() {
			delete(c.alerts, key)
		}
	}
}

func (c *cache) set(f fingerprint) {
	c.mu.Lock()
	defer c.mu.Unlock()
	alert := new(cachedAlert)
	alert.expires = time.Now().Add(c.duration)

	c.alerts[f] = alert
}

func (c *cache) contains(f fingerprint) bool {
	c.mu.Lock()
	defer c.mu.Unlock()
	_, ok := c.alerts[f]
	return ok
}