dwelling-radio/internal/radio/song.go

package radio

import (
	"encoding/json"
	"sync"
	"time"
)

type Song struct {
	mutex        sync.Mutex
	Artist       string
	Title        string
	Duration     time.Duration
	Listeners    int64
	MaxListeners int64
	StartAt      time.Time
}

func (s *Song) SetFrom(os *Song) {
	s.mutex.Lock()
	s.Artist = os.Artist
	s.Title = os.Title
	s.Duration = os.Duration
	s.Listeners = os.Listeners
	s.MaxListeners = os.MaxListeners
	s.StartAt = os.StartAt
	s.mutex.Unlock()
}

func (s *Song) UpdateMaxListeners(listeners int64) {
	s.mutex.Lock()
	if listeners > s.MaxListeners {
		s.MaxListeners = listeners
	}
	s.mutex.Unlock()
}

// IncListeners increments by one an overall amount of listeners of this song.
func (s *Song) IncListeners() {
	s.mutex.Lock()
	s.Listeners++
	s.mutex.Unlock()
}

// DurationString returns song's duration as a string formatted as [H:]M:SS.
func (s *Song) DurationString() string {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	if s.Duration.Hours() >= 1 {
		return time.UnixMilli(s.Duration.Milliseconds()).Format("3:4:05")
	}
	return time.UnixMilli(s.Duration.Milliseconds()).Format("4:05")
}

func (s *Song) MarshalJSON() ([]byte, error) {
	s.mutex.Lock()
	defer s.mutex.Unlock()
	return json.Marshal(&struct {
		Artist       string `json:"artist"`
		Title        string `json:"title"`
		DurationMill int64  `json:"duration_msec,omitempty"`
		Listeners    int64  `json:"listeners"`
		MaxListeners int64  `json:"max_listeners"`
		StartAt      string `json:"start_at"`
	}{
		Artist:       s.Artist,
		Title:        s.Title,
		DurationMill: s.Duration.Milliseconds(),
		Listeners:    s.Listeners,
		MaxListeners: s.MaxListeners,
		StartAt:      s.StartAt.UTC().Format(time.RFC3339)})
}