87 lines
1.8 KiB
Go
87 lines
1.8 KiB
Go
package radio
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import (
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"encoding/json"
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"sync"
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"time"
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)
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// Song stores artist and title of a song, a timestamp of when it started, and
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// a maximum number of listeners.
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type Song struct {
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Artist string
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Title string
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Duration time.Duration
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MaxListeners int
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StartAt time.Time
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}
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func (s *Song) ArtistTitle() string {
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return s.Artist + " - " + s.Title
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}
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func (s *Song) MarshalJSON() ([]byte, error) {
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return json.Marshal(&struct {
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Artist string `json:"artist"`
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Title string `json:"title"`
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Duration int64 `json:"duration_milliseconds"`
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MaxListeners int `json:"listeners"`
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StartAt string `json:"start_at"`
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}{
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Artist: s.Artist,
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Title: s.Title,
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Duration: s.Duration.Milliseconds(),
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MaxListeners: s.MaxListeners,
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StartAt: s.StartAt.UTC().Format(time.RFC3339)})
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}
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type SongList struct {
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mut sync.Mutex
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current Song
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lastSongs []Song
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listMaxLen int
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}
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func NewSongList(length int) *SongList {
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return &SongList{listMaxLen: length, lastSongs: make([]Song, 0, length)}
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}
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// Add a new song that is currently playing and update a list.
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func (sl *SongList) Add(newSong Song) {
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sl.mut.Lock()
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defer sl.mut.Unlock()
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if sl.current.StartAt.Year() == 1 {
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sl.current = newSong
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return
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}
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if len(sl.lastSongs) == sl.listMaxLen {
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sl.lastSongs = append(sl.lastSongs[1:], sl.current)
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} else {
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sl.lastSongs = append(sl.lastSongs, sl.current)
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}
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sl.current = newSong
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}
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// Current returns a current playing song.
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func (sl *SongList) Current() *Song {
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sl.mut.Lock()
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defer sl.mut.Unlock()
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if sl.current.StartAt.Year() == 1 {
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return nil
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}
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return &sl.current
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}
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// List returns a list of lastly played songs.
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func (sl *SongList) List() []Song {
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sl.mut.Lock()
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defer sl.mut.Unlock()
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return sl.lastSongs
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}
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func (sl *SongList) Len() int {
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return sl.listMaxLen
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}
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