morningalarm/internal/store.go

package morningalarm

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

// addAlarm adds an alarm to the list of alarms and starts a cron job to fire it at the specified time
func (ma *MorningAlarm) addAlarm(time, name string) (*alarm, error) {
	// Check if alarm already exists
	if ma.getAlarm(name) != nil {
		return nil, errors.New("Alarm with name " + name + " already exists")
	}

	alarm := alarm{
		Name:     name,
		Time:     time,
		Disabled: false,
	}

	alarm.cronID, _ = ma.armAlarm(&alarm)

	ma.alarms = append(ma.alarms, alarm)

	return &alarm, nil
}

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

	return nil
}

// loadAlarmsFromFile loads the list of alarms from alarms.json into memory
func (ma *MorningAlarm) loadAlarmsFromFile() 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
	}

	err = json.Unmarshal(content, &ma.alarms)

	if err != nil {
		return err
	}

	return nil
}

// saveAlarmsToFile saves the list of alarms to alarms.json
func (ma *MorningAlarm) saveAlarmsToFile() 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
}

// removeAlarm removes an alarm from the list of alarms and stops cron from firing it. Returns true if the alarm was removed, false if it was not found
func (ma *MorningAlarm) removeAlarm(name string) bool {
	for _, alarm := range ma.alarms {
		if alarm.Name == name {

			// Stop cron from firing the alarm
			ma.disarmAlarm(&alarm)

			// Remove alarm from list of alarms
			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
}

// armAllAlarms arms all alarms in the list of alarms that are not disabled and returns an error if any of them fail to arm
func (ma *MorningAlarm) armAllAlarms() error {
	for _, alarm := range ma.alarms {
		if !alarm.Disabled {
			id, err := ma.armAlarm(&alarm)

			if err != nil {
				return err
			}

			alarm.cronID = id
		}
	}

	return nil
}

// setDisabled sets the disabled status of an alarm
func (ma *MorningAlarm) setDisabled(name string, disabled bool) {
	for i, alarm := range ma.alarms {
		if alarm.Name == name {
			if alarm.Disabled == disabled {
				return
			}

			ma.alarms[i].Disabled = disabled

			if disabled {
				ma.disarmAlarm(&alarm)
			} else {
				id, _ := ma.armAlarm(&alarm)
				ma.alarms[i].cronID = id
			}

			return
		}
	}
}