morningalarm/internal/cron.go

package morningalarm

import (
	"time"

	"github.com/robfig/cron/v3"
)

// nextAlarm returns the time of the next alarm to fire from the perspective of cron
func (ma *MorningAlarm) nextAlarm() *time.Time {
	if len(ma.cr.Entries()) == 0 {
		return nil
	}

	min := ma.cr.Entries()[0].Next

	for _, entry := range ma.cr.Entries() {
		if entry.Next.Before(min) {
			min = entry.Next
		}
	}

	return &min
}

// armAlarm arms an alarm to fire at the specified time
func (ma *MorningAlarm) armAlarm(alarm *alarm) (cron.EntryID, error) {
	return ma.cr.AddFunc(alarm.Time, ma.fireAlarm)
}

// disarmAlarm disarms an alarm and prevents it from firing at the specified time
func (ma *MorningAlarm) disarmAlarm(alarm *alarm) {
	ma.cr.Remove(alarm.cronID)
}

// fireAlarm function that is called when an alarm is fired
func (ma *MorningAlarm) fireAlarm() {
	ma.playWakeUpMusic()
}