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dwelling-radio/internal/radio/icecast.go

233 lines
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package radio
import (
"bytes"
"dwelling-radio/pkg/watcher"
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"encoding/json"
"io"
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"net/http"
"os"
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"sync"
"syscall"
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"time"
"github.com/pkg/errors"
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)
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const (
IcecastPlaylistDateFormat = "02/Jan/2006:15:04:05 -0700"
SongTimeFormat = "2006 15:04-0700"
bufferSize = 16384
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)
var (
lastPlayedCache []Song
lastPlayedCacheMutex sync.Mutex
)
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type IcecastStatusDTO struct {
Icestats struct {
ServerStartISO8601 string `json:"server_start_iso8601"`
ServerStartDate string `json:"server_start"`
Source struct {
Artist string `json:"artist"`
Title string `json:"title"`
ListenerPeak int `json:"listener_peak"`
Listeners int `json:"listeners"`
} `json:"source"`
} `json:"icestats"`
}
func (is *IcecastStatusDTO) SongName() string {
return is.Icestats.Source.Artist + " - " + is.Icestats.Source.Title
}
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type IcecastStatus struct {
ServerStartISO8601 string `json:"server_start_iso8601"`
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ServerStartDate string `json:"server_start_date"`
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SongName string `json:"song"`
ListenerPeak int `json:"listener_peak"`
Listeners int `json:"listeners"`
}
type Song struct {
Time string `json:"time"`
Listeners string `json:"listeners"`
Song string `json:"song"`
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}
func IcecastGetStatus(icecastURL string) (*IcecastStatus, error) {
resp, err := http.Get(icecastURL)
if err != nil {
return nil, err
}
iceStatDTO := &IcecastStatusDTO{}
if err := json.NewDecoder(resp.Body).Decode(iceStatDTO); err != nil {
return nil, err
}
return &IcecastStatus{
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ServerStartISO8601: iceStatDTO.Icestats.ServerStartISO8601,
ServerStartDate: iceStatDTO.Icestats.ServerStartDate,
SongName: iceStatDTO.SongName(),
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ListenerPeak: iceStatDTO.Icestats.Source.ListenerPeak,
Listeners: iceStatDTO.Icestats.Source.Listeners,
}, nil
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}
func IcecastLastPlayedSongs(lastNSongs int, playlistPath string) ([]Song, error) {
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{
lastPlayedCacheMutex.Lock()
defer lastPlayedCacheMutex.Unlock()
if lpcLen := len(lastPlayedCache); lpcLen > 0 {
if lastNSongs > lpcLen {
lastNSongs = lpcLen
}
var ret []Song = make([]Song, lastNSongs)
copy(ret[:], lastPlayedCache[lpcLen-lastNSongs:])
return ret, nil
}
}
songs, err := icecastLastPlayedSongs(playlistPath, lastNSongs)
if err != nil {
return make([]Song, 0), err
}
return songs, nil
}
func IcecastLastSong(playlistPath string) (Song, error) {
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{
lastPlayedCacheMutex.Lock()
defer lastPlayedCacheMutex.Unlock()
if lpcLen := len(lastPlayedCache); lpcLen > 0 {
return lastPlayedCache[lpcLen-1], nil
}
}
song, err := icecastLastPlayedSongs(playlistPath, 1)
if err != nil {
return Song{}, err
}
return song[0], nil
}
func icecastLastPlayedSongs(playlistPath string, n int) ([]Song, error) {
songs := make([]Song, n)
var buf []byte
var offset int64 = 0
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playlist, err := os.Open(playlistPath)
if err != nil {
return nil, err
}
defer playlist.Close()
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playlist_stat, _ := playlist.Stat()
if playlist_stat.Size() == 0 {
return nil, nil
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}
if playlist_stat.Size() < bufferSize {
buf = make([]byte, playlist_stat.Size())
} else {
buf = make([]byte, bufferSize)
offset = playlist_stat.Size() - bufferSize
}
_, err = playlist.ReadAt(buf, offset)
if err != nil && err != io.EOF {
return nil, err
}
lines := bytes.Split(buf, []byte("\n"))
if len(lines) < 3 {
return nil, nil
}
lines = lines[:len(lines)-2]
if len(lines) > n {
lines = lines[len(lines)-n:]
}
for _, line := range lines {
fields := bytes.Split(line, []byte("|"))
tim, _ := time.Parse(IcecastPlaylistDateFormat, string(fields[0]))
songs = append(songs, Song{
Time: tim.Format(SongTimeFormat),
Listeners: string(fields[2]),
Song: string(fields[3])})
}
return songs, nil
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}
type PlaylistLogWatcher struct {
watcher *watcher.InotifyWatcher
changed chan uint32
}
func NewPlaylistLogWatcher() *PlaylistLogWatcher {
return &PlaylistLogWatcher{changed: make(chan uint32)}
}
func (pw *PlaylistLogWatcher) Watch(playlistPath string, n int) (err error) {
if pw.watcher != nil {
pw.watcher.Close()
}
pw.watcher, err = watcher.NewInotifyWatcher()
if err != nil {
return errors.Wrap(err, "cannot instantiate inotify watcher")
}
err = pw.watcher.AddWatch(playlistPath, watcher.ModIgnMask)
if err != nil {
return errors.Wrap(err, "cannot set a playlist to watch")
}
pw.watcher.WatchForMask(pw.changed, watcher.ModIgnMask)
go func() {
for {
select {
case mask := <-pw.changed:
if mask&syscall.IN_MODIFY > 0 {
lastPlayedCacheMutex.Lock()
if lastPlayedCache == nil {
lastPlayedCache = make([]Song, n)
}
if songs, err := icecastLastPlayedSongs(playlistPath, 1); err == nil && len(songs) > 0 {
if len(lastPlayedCache) == n {
lastPlayedCache = append(lastPlayedCache[1:], songs...)
} else {
lastPlayedCache = append(lastPlayedCache, songs...)
}
}
lastPlayedCacheMutex.Unlock()
} else if mask&syscall.IN_IGNORED > 0 {
pw.Close()
pw.Watch(playlistPath, n)
return
}
}
}
}()
return nil
}
func (pw *PlaylistLogWatcher) Close() {
pw.watcher.Close()
}