dwelling-radio/internal/radio/icecast.go

package radio

import (
	"dwelling-radio/pkg/watcher"
	"encoding/json"
	"fmt"
	"net/http"
	"os/exec"
	"strings"
	"sync"
	"time"

	"github.com/pkg/errors"
)

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) Song() string {
	return is.Icestats.Source.Artist + " - " + is.Icestats.Source.Title
}

type IcecastStatus struct {
	ServerStartISO8601 string `json:"server_start_iso8601"`
	ServerStartDate    string `json:"server_start_date"`
	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"`
}

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{
		ServerStartISO8601: iceStatDTO.Icestats.ServerStartISO8601,
		ServerStartDate:    iceStatDTO.Icestats.ServerStartDate,
		SongName:           iceStatDTO.Song(),
		ListenerPeak:       iceStatDTO.Icestats.Source.ListenerPeak,
		Listeners:          iceStatDTO.Icestats.Source.Listeners,
	}, nil
}

func IcecastLastPlayedSongs(lastNSongs int, playlistPath string) ([]Song, error) {
	{
		lastPlayedCacheMutex.Lock()
		defer lastPlayedCacheMutex.Unlock()
		if lpcLen := len(lastPlayedCache); lpcLen > 0 {
			if lastNSongs > lpcLen {
				lastNSongs = lpcLen
			}
			return lastPlayedCache[lpcLen-lastNSongs:], nil
		}
	}

	return lastPlayedSongs(lastNSongs, playlistPath)
}

func IcecastLastSong(playlistPath string) (Song, error) {
	{
		lastPlayedCacheMutex.Lock()
		defer lastPlayedCacheMutex.Unlock()
		if lpcLen := len(lastPlayedCache); lpcLen > 0 {
			return lastPlayedCache[lpcLen-1], nil
		}
	}

	songs, err := lastPlayedSongs(1, playlistPath)
	if len(songs) == 0 {
		return Song{}, nil
	}

	return songs[0], err
}

func lastPlayedSongs(lastNSongs int, playlistPath string) ([]Song, error) {
	songs := make([]Song, 0)

	cmd := fmt.Sprintf("tail -n%d %s | head -n-1 | cut -d'|' -f1,3,4", lastNSongs+1, playlistPath)
	out, err := exec.Command("bash", "-c", cmd).CombinedOutput()
	if err != nil {
		return songs, err
	}

	if len(out) == 0 {
		return songs, nil
	}

	for _, song := range strings.Split(string(out), "\n") {
		ts := strings.Split(song, "|")
		if len(ts) <= 1 {
			continue
		}
		tim, _ := time.Parse("02/Jan/2006:15:04:05 -0700", ts[0])
		songs = append(songs, Song{
			Time:      tim.Format("15:04-0700"),
			Listeners: ts[1],
			Song:      ts[2]})
	}

	return songs, nil
}

var playlistWatcher watcher.InotifyWatcher
var playlistFired chan uint32 = make(chan uint32)
var lastPlayedCache []Song
var lastPlayedCacheMutex sync.Mutex

func IcecastWatchPlaylist(playlistPath string, lastNSongs int) error {
	playlistWatcher, err := watcher.NewInotifyWatcher()
	if err != nil {
		return errors.Wrap(err, "cannot instantiate inotify watcher")
	}

	err = playlistWatcher.AddWatch(playlistPath, watcher.ModMask)
	if err != nil {
		return errors.Wrap(err, "cannot set a playlist to watch")
	}

	playlistWatcher.WatchForMask(playlistFired, watcher.ModMask)

	go func() {
		for {
			select {
			case <-playlistFired:
				lastPlayedCacheMutex.Lock()
				songs, err := lastPlayedSongs(lastNSongs, playlistPath)
				if err == nil && len(songs) > 0 {
					lastPlayedCache = songs
				}
				lastPlayedCacheMutex.Unlock()
			}
		}
	}()

	songs, err := lastPlayedSongs(lastNSongs, playlistPath)
	if err == nil && len(songs) > 0 {
		lastPlayedCache = songs
	}

	return nil
}

func IcecastWatchClose() {
	playlistWatcher.Close()
}