NowPlaying is not a repo, now it is part of the main engine

engine/nowplaying.go

@@ -0,0 +1,102 @@
+package engine
+
+import (
+	"container/list"
+	"sync"
+	"time"
+)
+
+const NowPlayingExpire = 60 * time.Minute
+
+type NowPlayingInfo struct {
+	TrackID    string
+	Start      time.Time
+	Username   string
+	PlayerId   int
+	PlayerName string
+}
+
+// This repo must have the semantics of a FIFO queue, for each playerId
+type NowPlayingRepository interface {
+	// Insert at the head of the queue
+	Enqueue(*NowPlayingInfo) error
+
+	// Removes and returns the element at the end of the queue
+	Dequeue(playerId int) (*NowPlayingInfo, error)
+
+	// Returns the element at the head of the queue (last inserted one)
+	Head(playerId int) (*NowPlayingInfo, error)
+
+	// Returns the element at the end of the queue (first inserted one)
+	Tail(playerId int) (*NowPlayingInfo, error)
+
+	// Size of the queue for the playerId
+	Count(playerId int) (int64, error)
+
+	// Returns all heads from all playerIds
+	GetAll() ([]*NowPlayingInfo, error)
+}
+
+var playerMap = sync.Map{}
+
+type nowPlayingRepository struct{}
+
+func NewNowPlayingRepository() NowPlayingRepository {
+	r := &nowPlayingRepository{}
+	return r
+}
+
+func (r *nowPlayingRepository) getList(id int) *list.List {
+	l, _ := playerMap.LoadOrStore(id, list.New())
+	return l.(*list.List)
+}
+
+func (r *nowPlayingRepository) Enqueue(info *NowPlayingInfo) error {
+	l := r.getList(info.PlayerId)
+	l.PushFront(info)
+	return nil
+}
+
+func (r *nowPlayingRepository) Dequeue(playerId int) (*NowPlayingInfo, error) {
+	l := r.getList(playerId)
+	e := l.Back()
+	if e == nil {
+		return nil, nil
+	}
+	l.Remove(e)
+	return e.Value.(*NowPlayingInfo), nil
+}
+
+func (r *nowPlayingRepository) Head(playerId int) (*NowPlayingInfo, error) {
+	l := r.getList(playerId)
+	e := l.Front()
+	if e == nil {
+		return nil, nil
+	}
+	return e.Value.(*NowPlayingInfo), nil
+}
+
+func (r *nowPlayingRepository) Tail(playerId int) (*NowPlayingInfo, error) {
+	l := r.getList(playerId)
+	e := l.Back()
+	if e == nil {
+		return nil, nil
+	}
+	return e.Value.(*NowPlayingInfo), nil
+}
+
+func (r *nowPlayingRepository) Count(playerId int) (int64, error) {
+	l := r.getList(playerId)
+	return int64(l.Len()), nil
+}
+
+func (r *nowPlayingRepository) GetAll() ([]*NowPlayingInfo, error) {
+	var all []*NowPlayingInfo
+	playerMap.Range(func(playerId, l interface{}) bool {
+		ll := l.(*list.List)
+		e := ll.Front()
+		all = append(all, e.Value.(*NowPlayingInfo))
+		return true
+	})
+	return all, nil
+}