Send desktop notifications on track or state change

Persephone/Controllers/QueueViewController.swift

@@ -47,6 +47,20 @@ class QueueViewController: NSViewController,
       else { return }
 
     dataSource.setQueueIcon(state)
+    notifyTrack()
+  }
+
+  func notifyTrack() {
+    guard let currentSong = dataSource.currentSong,
+      let status = AppDelegate.mpdClient.status,
+      status.state == .playing
+    else { return }
+
+    let notification = NSUserNotification()
+    notification.title = currentSong.title
+    notification.subtitle = "\(currentSong.artist) — \(currentSong.album.title)"
+
+    NSUserNotificationCenter.default.deliver(notification)
   }
 
   @objc func queueChanged(_ notification: Notification) {

Persephone/DataSources/QueueDataSource.swift

@@ -11,6 +11,7 @@ import Cocoa
 class QueueDataSource: NSObject, NSOutlineViewDataSource {
   var queue: [QueueItem] = []
   var queuePos: Int = -1
+  var currentSong: Song?
 
   var queueIcon: NSImage? = nil
 
@@ -38,6 +39,8 @@ class QueueDataSource: NSObject, NSOutlineViewDataSource {
     if newSongRowPos >= 0 {
       queue[newSongRowPos].isPlaying = true
     }
+
+    currentSong = queue[newSongRowPos].song
   }
 
   func setQueueIcon(_ state: MPDClient.MPDStatus.State) {

Persephone/MPDClient/Extensions/MPDClient+Idle.swift

@@ -43,9 +43,9 @@ extension MPDClient {
       self.fetchStatus()
 
       if let status = self.status {
-        self.delegate?.didUpdateState(mpdClient: self, state: status.state)
-        self.delegate?.didUpdateTime(mpdClient: self, total: status.totalTime, elapsedMs: status.elapsedTimeMs)
         self.delegate?.didUpdateQueuePos(mpdClient: self, song: status.song)
+        self.delegate?.didUpdateTime(mpdClient: self, total: status.totalTime, elapsedMs: status.elapsedTimeMs)
+        self.delegate?.didUpdateState(mpdClient: self, state: status.state)
       }
     }
     if mpdIdle.contains(.update) {