Added last played list cache with updating using Inotify watcher.

internal/radio/icecast.go

@@ -1,12 +1,15 @@
 package radio
 
 import (
+	"dwelling-radio/pkg/watcher"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"os/exec"
 	"strings"
 	"time"
+
+	"github.com/pkg/errors"
 )
 
 type IcecastStatusDTO struct {
@@ -64,6 +67,30 @@ func IcecastGetStatus(icecastURL string) (*IcecastStatus, error) {
 }
 
 func IcecastLastPlayedSongs(lastNSongs int, playlistPath string) ([]Song, error) {
+	if len(lastPlayedCache) > 0 {
+		if lastNSongs > len(lastPlayedCache) {
+			lastNSongs = len(lastPlayedCache)
+		}
+		return lastPlayedCache[len(lastPlayedCache)-lastNSongs:], nil
+	}
+
+	return lastPlayedSongs(lastNSongs, playlistPath)
+}
+
+func IcecastLastSong(playlistPath string) (Song, error) {
+	if len(lastPlayedCache) > 0 {
+		return lastPlayedCache[len(lastPlayedCache)-1], nil
+	}
+
+	songs, err := IcecastLastPlayedSongs(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'|' -f1,4", lastNSongs+1, playlistPath)
@@ -93,3 +120,48 @@ func IcecastLastPlayedSongs(lastNSongs int, playlistPath string) ([]Song, error)
 
 	return songs, nil
 }
+
+var playlistWatcher watcher.InotifyWatcher
+var playlistFired chan uint32
+var lastPlayedCache []Song
+
+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)
+	fmt.Println(playlistPath)
+	if err != nil {
+		return errors.Wrap(err, "cannot set a playlist to watch")
+	}
+
+	playlistFired = make(chan uint32)
+
+	playlistWatcher.WatchForMask(playlistFired, watcher.ModMask)
+
+	go func() {
+		for {
+			select {
+			case <-playlistFired:
+				songs, err := lastPlayedSongs(lastNSongs, playlistPath)
+				fmt.Println("do we get here?", err)
+				if err == nil && len(songs) > 0 {
+					lastPlayedCache = songs
+				}
+			}
+		}
+	}()
+
+	songs, err := lastPlayedSongs(lastNSongs, playlistPath)
+	if err == nil && len(songs) > 0 {
+		lastPlayedCache = songs
+	}
+
+	return nil
+}
+
+func IcecastWatchClose() {
+	playlistWatcher.Close()
+}