morningalarm/internal/cron.go

package morningalarm

import (
	"encoding/json"
	"errors"
	"os"
	"time"

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

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
}

func (ma *MorningAlarm) addAlarm(spec string, name string) (cron.EntryID, error) {
	// Check if alarm already exists
	if ma.getAlarm(name) != nil {
		return 0, errors.New("Alarm already exists")
	}

	id, err := ma.cr.AddFunc(spec, ma.fireAlarm)

	if err != nil {
		return 0, err
	}

	ma.alarms = append(ma.alarms, alarm{
		id:   id,
		Time: spec,
		Name: name,
	})

	return id, nil
}

func (ma *MorningAlarm) saveAlarms() error {
	content, err := json.Marshal(ma.alarms)

	if err != nil {
		return err
	}

	err = os.WriteFile("alarms.json", content, 0644)

	if err != nil {
		return err
	}

	return nil
}

func (ma *MorningAlarm) loadAlarms() error {
	if _, err := os.Stat("alarms.json"); os.IsNotExist(err) {
		ma.alarms = []alarm{}
		return nil
	}

	content, err := os.ReadFile("alarms.json")

	if err != nil {
		return err
	}

	var ent []alarm
	err = json.Unmarshal(content, &ent)

	if err != nil {
		return err
	}

	for _, entry := range ent {
		_, err := ma.addAlarm(entry.Time, entry.Name)

		if err != nil {
			return err
		}
	}

	return nil
}

func (ma *MorningAlarm) fireAlarm() {
	ma.playWakeUpMusic()
}

func (ma *MorningAlarm) getAlarm(name string) *alarm {
	for _, alarm := range ma.alarms {
		if alarm.Name == name {
			return &alarm
		}
	}

	return nil
}

func (ma *MorningAlarm) deleteAlarm(name string) bool {
	for _, alarm := range ma.alarms {
		if alarm.Name == name {
			ma.cr.Remove(alarm.id)

			for i, a := range ma.alarms {
				if a.Name == name {
					ma.alarms = append(ma.alarms[:i], ma.alarms[i+1:]...)
					break
				}
			}

			return true
		}
	}

	return false
}