Fix crash on album end

This fixes the progress bar display

Persephone.xcodeproj/project.pbxproj

@@ -42,6 +42,7 @@
 		E42A8F3C22176D6400A13ED9 /* README.md in Resources */ = {isa = PBXBuildFile; fileRef = E42A8F3A22176D6400A13ED9 /* README.md */; };
 		E435E3E2221CD4E200184CFC /* NSFont.swift in Sources */ = {isa = PBXBuildFile; fileRef = E435E3E1221CD4E200184CFC /* NSFont.swift */; };
 		E435E3E4221CD75D00184CFC /* NSImage.swift in Sources */ = {isa = PBXBuildFile; fileRef = E435E3E3221CD75D00184CFC /* NSImage.swift */; };
+		E439109822640213002982E9 /* SongNotifierService.swift in Sources */ = {isa = PBXBuildFile; fileRef = E439109722640213002982E9 /* SongNotifierService.swift */; };
 		E450AD7E222620A10091BED3 /* Album.swift in Sources */ = {isa = PBXBuildFile; fileRef = E450AD7D222620A10091BED3 /* Album.swift */; };
 		E450AD8622262AE60091BED3 /* SwiftyJSON.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = E450AD8522262AE60091BED3 /* SwiftyJSON.framework */; };
 		E450AD8822262AEC0091BED3 /* SwiftyJSON.framework in Embed Libraries */ = {isa = PBXBuildFile; fileRef = E450AD8522262AE60091BED3 /* SwiftyJSON.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
@@ -210,6 +211,7 @@
 		E42A8F3A22176D6400A13ED9 /* README.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		E435E3E1221CD4E200184CFC /* NSFont.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NSFont.swift; sourceTree = "<group>"; };
 		E435E3E3221CD75D00184CFC /* NSImage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NSImage.swift; sourceTree = "<group>"; };
+		E439109722640213002982E9 /* SongNotifierService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SongNotifierService.swift; sourceTree = "<group>"; };
 		E450AD7D222620A10091BED3 /* Album.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Album.swift; sourceTree = "<group>"; };
 		E450AD8522262AE60091BED3 /* SwiftyJSON.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = SwiftyJSON.framework; path = Carthage/Build/Mac/SwiftyJSON.framework; sourceTree = "<group>"; };
 		E450AD8C22262C590091BED3 /* PromiseKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = PromiseKit.framework; path = Carthage/Build/Mac/PromiseKit.framework; sourceTree = "<group>"; };
@@ -523,6 +525,7 @@
 			isa = PBXGroup;
 			children = (
 				E4A83BF3222207D50098FED6 /* AlbumArtService.swift */,
+				E439109722640213002982E9 /* SongNotifierService.swift */,
 				E41E530C223EF4BA00173814 /* Extensions */,
 			);
 			path = Services;
@@ -797,6 +800,7 @@
 				E40F41F3221EDE27004B6CB8 /* Preferences.swift in Sources */,
 				E47E2FDD2220A6D100F747E6 /* Time.swift in Sources */,
 				E419E2872249B96600216A8C /* Song.swift in Sources */,
+				E439109822640213002982E9 /* SongNotifierService.swift in Sources */,
 				E407861C2110CE6E006887B1 /* AppDelegate.swift in Sources */,
 				E41E5309223C020400173814 /* MPDClient+Command.swift in Sources */,
 				E47E2FE52220AA0700F747E6 /* AlbumViewLayout.swift in Sources */,

Persephone/Controllers/QueueViewController.swift

@@ -49,6 +49,16 @@ class QueueViewController: NSViewController,
     dataSource.setQueueIcon(state)
   }
 
+  func notifyTrack() {
+    guard let currentSong = dataSource.currentSong,
+      let status = AppDelegate.mpdClient.status,
+      status.state == .playing
+    else { return }
+
+    SongNotifierService(song: currentSong, image: queueAlbumArtImage.image)
+      .deliver()
+  }
+
   @objc func queueChanged(_ notification: Notification) {
     guard let queue = notification.userInfo?[Notification.queueKey] as? [MPDClient.MPDSong]
       else { return }
@@ -77,6 +87,8 @@ class QueueViewController: NSViewController,
           } else {
             self.queueAlbumArtImage.image = NSImage.defaultCoverArt
           }
+
+          self.notifyTrack()
         }
         .cauterize()
     } else {

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
 
@@ -37,6 +38,9 @@ class QueueDataSource: NSObject, NSOutlineViewDataSource {
     }
     if newSongRowPos >= 0 {
       queue[newSongRowPos].isPlaying = true
+      currentSong = queue[newSongRowPos].song
+    } else {
+      currentSong = nil
     }
   }
 

Persephone/MPDClient/Extensions/MPDClient+Idle.swift

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

Persephone/Services/SongNotifierService.swift

@@ -0,0 +1,23 @@
+//
+//  SongNotifierService.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/4/14.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+
+struct SongNotifierService {
+  let song: Song
+  let image: NSImage?
+
+  func deliver() {
+    let notification = NSUserNotification()
+    notification.title = song.title
+    notification.subtitle = "\(song.artist) — \(song.album.title)"
+    notification.contentImage = image
+
+    NSUserNotificationCenter.default.deliver(notification)
+  }
+}