Update screenshot

* Menu option starts a database update.

* Spinner to show that update is taking place.

CHANGELOG.md

@@ -0,0 +1,27 @@
+# Changelog
+
+## 0.10.2a - 2019-03-23
+
+### Added
+
+- Will fetch album art from the filesystem or MusicBrainz
+- Menu option to update the database
+- Album art preferences icon
+
+### Changed
+
+- Refactored command queue to be more reliable
+- Resizing the windows no longer makes the album view jump around
+- Fixed a crash when another client clears the queue
+
+## 0.8.0a - 2019-02-23
+
+### Added
+
+- Connects to MPD
+- Lists all albums
+- Will play an album
+- Queue is working
+- Transport controls are working
+- Seek bar is working
+- Media keys work

Cartfile

@@ -1 +1,3 @@
+github "SwiftyJSON/SwiftyJSON" ~> 4.0
+github "PromiseKit/Foundation" ~> 3.0
 github "nhurden/MediaKeyTap" "fix-tis-tsm-error"

Cartfile.resolved

@@ -1 +1,4 @@
+github "PromiseKit/Foundation" "3.3.1"
+github "SwiftyJSON/SwiftyJSON" "4.2.0"
+github "mxcl/PromiseKit" "6.8.3"
 github "nhurden/MediaKeyTap" "355d346c56243e6d56487fa46fcad945251e16ae"

Persephone.xcodeproj/project.pbxproj

@@ -16,29 +16,60 @@
 		E408D3B9220DE98F0006D9BE /* NSUserInterfaceItemIdentifier.swift in Sources */ = {isa = PBXBuildFile; fileRef = E408D3B8220DE98F0006D9BE /* NSUserInterfaceItemIdentifier.swift */; };
 		E408D3BE220E03EE0006D9BE /* RawRepresentable.swift in Sources */ = {isa = PBXBuildFile; fileRef = E408D3BD220E03EE0006D9BE /* RawRepresentable.swift */; };
 		E408D3C2220E134F0006D9BE /* AlbumViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E408D3C1220E134F0006D9BE /* AlbumViewController.swift */; };
-		E408D3CB220E341D0006D9BE /* AlbumItem.xib in Resources */ = {isa = PBXBuildFile; fileRef = E408D3C9220E341D0006D9BE /* AlbumItem.xib */; };
+		E408D3CB220E341D0006D9BE /* AlbumViewItem.xib in Resources */ = {isa = PBXBuildFile; fileRef = E408D3C9220E341D0006D9BE /* AlbumViewItem.xib */; };
 		E40F41F3221EDE27004B6CB8 /* Preferences.swift in Sources */ = {isa = PBXBuildFile; fileRef = E40F41F2221EDE27004B6CB8 /* Preferences.swift */; };
 		E40FE71B221B904300A4223F /* NSEvent.swift in Sources */ = {isa = PBXBuildFile; fileRef = E40FE71A221B904300A4223F /* NSEvent.swift */; };
 		E41B22C021FB6BBA00D544F6 /* libmpdclient.2.dylib in Frameworks */ = {isa = PBXBuildFile; fileRef = E41B22BF21FB6BBA00D544F6 /* libmpdclient.2.dylib */; settings = {ATTRIBUTES = (Required, ); }; };
 		E41B22C121FB6C3300D544F6 /* libmpdclient.2.dylib in Embed Libraries */ = {isa = PBXBuildFile; fileRef = E41B22BF21FB6BBA00D544F6 /* libmpdclient.2.dylib */; settings = {ATTRIBUTES = (CodeSignOnCopy, ); }; };
 		E41B22C621FB932700D544F6 /* MPDClient.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41B22C521FB932700D544F6 /* MPDClient.swift */; };
-		E41EA46C221636AF0068EF46 /* PreferencesViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41EA46B221636AF0068EF46 /* PreferencesViewController.swift */; };
+		E41E52FD223BF87300173814 /* MPDClient+Connection.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E52FC223BF87300173814 /* MPDClient+Connection.swift */; };
+		E41E52FF223BF95E00173814 /* MPDClient+Transport.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E52FE223BF95E00173814 /* MPDClient+Transport.swift */; };
+		E41E5301223BF99300173814 /* MPDClient+Queue.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E5300223BF99300173814 /* MPDClient+Queue.swift */; };
+		E41E5303223BF9C300173814 /* MPDClient+Idle.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E5302223BF9C300173814 /* MPDClient+Idle.swift */; };
+		E41E5305223BFB0700173814 /* MPDClient+Error.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E5304223BFB0700173814 /* MPDClient+Error.swift */; };
+		E41E5307223C019100173814 /* MPDClient+Status.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E5306223C019100173814 /* MPDClient+Status.swift */; };
+		E41E5309223C020400173814 /* MPDClient+Command.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E5308223C020400173814 /* MPDClient+Command.swift */; };
+		E41E530B223C033700173814 /* MPDClient+Album.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E530A223C033700173814 /* MPDClient+Album.swift */; };
+		E41E530E223EF4CF00173814 /* AlbumArtService+Caching.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E530D223EF4CF00173814 /* AlbumArtService+Caching.swift */; };
+		E41E5310223EF6CE00173814 /* AlbumArtService+Remote.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E530F223EF6CE00173814 /* AlbumArtService+Remote.swift */; };
+		E41E5312223EF74A00173814 /* AlbumArtService+Filesystem.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41E5311223EF74A00173814 /* AlbumArtService+Filesystem.swift */; };
+		E41EA46C221636AF0068EF46 /* GeneralPrefsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E41EA46B221636AF0068EF46 /* GeneralPrefsViewController.swift */; };
 		E421ACA3221F73C4008B2449 /* MediaKeyTap.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = E421ACA1221F73B8008B2449 /* MediaKeyTap.framework */; };
 		E421ACA4221F73C4008B2449 /* MediaKeyTap.framework in Embed Libraries */ = {isa = PBXBuildFile; fileRef = E421ACA1221F73B8008B2449 /* MediaKeyTap.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		E42410B62241B956005ED6DF /* MPDClient+Database.swift in Sources */ = {isa = PBXBuildFile; fileRef = E42410B52241B956005ED6DF /* MPDClient+Database.swift */; };
 		E42A8F3B22176D6400A13ED9 /* LICENSE.md in Resources */ = {isa = PBXBuildFile; fileRef = E42A8F3922176D6400A13ED9 /* LICENSE.md */; };
 		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 */; };
+		E450AD7E222620A10091BED3 /* AlbumItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = E450AD7D222620A10091BED3 /* AlbumItem.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, ); }; };
+		E450AD8F22262C620091BED3 /* PromiseKit.framework.dSYM in Resources */ = {isa = PBXBuildFile; fileRef = E450AD8E22262C620091BED3 /* PromiseKit.framework.dSYM */; };
+		E450AD9122262C780091BED3 /* SwiftyJSON.framework.dSYM in Resources */ = {isa = PBXBuildFile; fileRef = E450AD9022262C780091BED3 /* SwiftyJSON.framework.dSYM */; };
+		E450AD9222262C970091BED3 /* PromiseKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = E450AD8C22262C590091BED3 /* PromiseKit.framework */; };
+		E450AD9322262C970091BED3 /* PromiseKit.framework in Embed Libraries */ = {isa = PBXBuildFile; fileRef = E450AD8C22262C590091BED3 /* PromiseKit.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		E450AD9522262DF10091BED3 /* AlbumArtQueue.swift in Sources */ = {isa = PBXBuildFile; fileRef = E450AD9422262DF10091BED3 /* AlbumArtQueue.swift */; };
+		E450AD98222633920091BED3 /* Alamofire.framework.dSYM in Resources */ = {isa = PBXBuildFile; fileRef = E450AD96222633920091BED3 /* Alamofire.framework.dSYM */; };
+		E450AD9D2229B9050091BED3 /* String.swift in Sources */ = {isa = PBXBuildFile; fileRef = E450AD9C2229B9050091BED3 /* String.swift */; };
+		E450ADA12229E7C90091BED3 /* PMKFoundation.framework.dSYM in Resources */ = {isa = PBXBuildFile; fileRef = E450AD9F2229E7C90091BED3 /* PMKFoundation.framework.dSYM */; };
+		E450ADA32229E7E00091BED3 /* PMKFoundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = E450ADA02229E7C90091BED3 /* PMKFoundation.framework */; };
+		E450ADA42229E7E00091BED3 /* PMKFoundation.framework in Embed Libraries */ = {isa = PBXBuildFile; fileRef = E450ADA02229E7C90091BED3 /* PMKFoundation.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
+		E45962C62241A78500FC1A1E /* Command.swift in Sources */ = {isa = PBXBuildFile; fileRef = E45962C52241A78500FC1A1E /* Command.swift */; };
 		E465049A21E94DF500A70F4C /* WindowController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E465049921E94DF500A70F4C /* WindowController.swift */; };
 		E47E2FCC2220573500F747E6 /* MediaKeyTap.framework.dSYM in Resources */ = {isa = PBXBuildFile; fileRef = E47E2FCB2220573500F747E6 /* MediaKeyTap.framework.dSYM */; };
 		E47E2FD122205C4600F747E6 /* MainSplitViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FD022205C4600F747E6 /* MainSplitViewController.swift */; };
 		E47E2FD322205D2500F747E6 /* MainWindow.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FD222205D2500F747E6 /* MainWindow.swift */; };
-		E47E2FD5222071FD00F747E6 /* AlbumItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FD4222071FD00F747E6 /* AlbumItem.swift */; };
+		E47E2FD5222071FD00F747E6 /* AlbumViewItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FD4222071FD00F747E6 /* AlbumViewItem.swift */; };
 		E47E2FD72220720300F747E6 /* AlbumItemView.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FD62220720300F747E6 /* AlbumItemView.swift */; };
 		E47E2FDD2220A6D100F747E6 /* Time.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FDC2220A6D100F747E6 /* Time.swift */; };
 		E47E2FE52220AA0700F747E6 /* AlbumViewLayout.swift in Sources */ = {isa = PBXBuildFile; fileRef = E47E2FE42220AA0700F747E6 /* AlbumViewLayout.swift */; };
 		E4928E0B2218D62A001D4BEA /* CGColor.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4928E0A2218D62A001D4BEA /* CGColor.swift */; };
 		E4A642DA22090CBE00067D21 /* Status.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4A642D922090CBE00067D21 /* Status.swift */; };
+		E4A83BEF2221F8CF0098FED6 /* AlbumArtPrefsController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4A83BEE2221F8CF0098FED6 /* AlbumArtPrefsController.swift */; };
+		E4A83BF12221FAA00098FED6 /* PreferencesViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4A83BF02221FAA00098FED6 /* PreferencesViewController.swift */; };
+		E4A83BF4222207D50098FED6 /* AlbumArtService.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4A83BF3222207D50098FED6 /* AlbumArtService.swift */; };
+		E4C8B53C22342005009A20F3 /* PreferencesWindowController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4C8B53B22342005009A20F3 /* PreferencesWindowController.swift */; };
+		E4C8B53E22349002009A20F3 /* Idle.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4C8B53D22349002009A20F3 /* Idle.swift */; };
 		E4E8CC902204EC7F0024217A /* Delegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4E8CC8F2204EC7F0024217A /* Delegate.swift */; };
 		E4E8CC922204F4B80024217A /* QueueViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4E8CC912204F4B80024217A /* QueueViewController.swift */; };
 		E4E8CC942206097F0024217A /* NotificationsController.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4E8CC932206097F0024217A /* NotificationsController.swift */; };
@@ -75,7 +106,10 @@
 			dstSubfolderSpec = 10;
 			files = (
 				E41B22C121FB6C3300D544F6 /* libmpdclient.2.dylib in Embed Libraries */,
+				E450ADA42229E7E00091BED3 /* PMKFoundation.framework in Embed Libraries */,
 				E421ACA4221F73C4008B2449 /* MediaKeyTap.framework in Embed Libraries */,
+				E450AD8822262AEC0091BED3 /* SwiftyJSON.framework in Embed Libraries */,
+				E450AD9322262C970091BED3 /* PromiseKit.framework in Embed Libraries */,
 			);
 			name = "Embed Libraries";
 			runOnlyForDeploymentPostprocessing = 0;
@@ -108,7 +142,7 @@
 		E408D3B8220DE98F0006D9BE /* NSUserInterfaceItemIdentifier.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NSUserInterfaceItemIdentifier.swift; sourceTree = "<group>"; };
 		E408D3BD220E03EE0006D9BE /* RawRepresentable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RawRepresentable.swift; sourceTree = "<group>"; };
 		E408D3C1220E134F0006D9BE /* AlbumViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AlbumViewController.swift; sourceTree = "<group>"; };
-		E408D3C9220E341D0006D9BE /* AlbumItem.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = AlbumItem.xib; sourceTree = "<group>"; };
+		E408D3C9220E341D0006D9BE /* AlbumViewItem.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = AlbumViewItem.xib; sourceTree = "<group>"; };
 		E40F41F2221EDE27004B6CB8 /* Preferences.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Preferences.swift; sourceTree = "<group>"; };
 		E40FE71A221B904300A4223F /* NSEvent.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NSEvent.swift; sourceTree = "<group>"; };
 		E41B22BF21FB6BBA00D544F6 /* libmpdclient.2.dylib */ = {isa = PBXFileReference; lastKnownFileType = "compiled.mach-o.dylib"; name = libmpdclient.2.dylib; path = libmpdclient/output/libmpdclient.2.dylib; sourceTree = "<group>"; };
@@ -149,22 +183,52 @@
 		E41B22E921FB966C00D544F6 /* capabilities.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = capabilities.h; sourceTree = "<group>"; };
 		E41B22EA21FB966C00D544F6 /* queue.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = queue.h; sourceTree = "<group>"; };
 		E41B22EB21FB966C00D544F6 /* playlist.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = playlist.h; sourceTree = "<group>"; };
-		E41EA46B221636AF0068EF46 /* PreferencesViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PreferencesViewController.swift; sourceTree = "<group>"; };
+		E41E52FC223BF87300173814 /* MPDClient+Connection.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Connection.swift"; sourceTree = "<group>"; };
+		E41E52FE223BF95E00173814 /* MPDClient+Transport.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Transport.swift"; sourceTree = "<group>"; };
+		E41E5300223BF99300173814 /* MPDClient+Queue.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Queue.swift"; sourceTree = "<group>"; };
+		E41E5302223BF9C300173814 /* MPDClient+Idle.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Idle.swift"; sourceTree = "<group>"; };
+		E41E5304223BFB0700173814 /* MPDClient+Error.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Error.swift"; sourceTree = "<group>"; };
+		E41E5306223C019100173814 /* MPDClient+Status.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Status.swift"; sourceTree = "<group>"; };
+		E41E5308223C020400173814 /* MPDClient+Command.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Command.swift"; sourceTree = "<group>"; };
+		E41E530A223C033700173814 /* MPDClient+Album.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Album.swift"; sourceTree = "<group>"; };
+		E41E530D223EF4CF00173814 /* AlbumArtService+Caching.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "AlbumArtService+Caching.swift"; sourceTree = "<group>"; };
+		E41E530F223EF6CE00173814 /* AlbumArtService+Remote.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "AlbumArtService+Remote.swift"; sourceTree = "<group>"; };
+		E41E5311223EF74A00173814 /* AlbumArtService+Filesystem.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "AlbumArtService+Filesystem.swift"; sourceTree = "<group>"; };
+		E41EA46B221636AF0068EF46 /* GeneralPrefsViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GeneralPrefsViewController.swift; sourceTree = "<group>"; };
 		E421ACA1221F73B8008B2449 /* MediaKeyTap.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = MediaKeyTap.framework; path = Carthage/Build/Mac/MediaKeyTap.framework; sourceTree = "<group>"; };
+		E42410B52241B956005ED6DF /* MPDClient+Database.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "MPDClient+Database.swift"; sourceTree = "<group>"; };
 		E42A8F3922176D6400A13ED9 /* LICENSE.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = LICENSE.md; sourceTree = "<group>"; };
 		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>"; };
+		E450AD7D222620A10091BED3 /* AlbumItem.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AlbumItem.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>"; };
+		E450AD8E22262C620091BED3 /* PromiseKit.framework.dSYM */ = {isa = PBXFileReference; lastKnownFileType = wrapper.dsym; name = PromiseKit.framework.dSYM; path = Carthage/Build/Mac/PromiseKit.framework.dSYM; sourceTree = "<group>"; };
+		E450AD9022262C780091BED3 /* SwiftyJSON.framework.dSYM */ = {isa = PBXFileReference; lastKnownFileType = wrapper.dsym; name = SwiftyJSON.framework.dSYM; path = Carthage/Build/Mac/SwiftyJSON.framework.dSYM; sourceTree = "<group>"; };
+		E450AD9422262DF10091BED3 /* AlbumArtQueue.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AlbumArtQueue.swift; sourceTree = "<group>"; };
+		E450AD96222633920091BED3 /* Alamofire.framework.dSYM */ = {isa = PBXFileReference; lastKnownFileType = wrapper.dsym; name = Alamofire.framework.dSYM; path = Carthage/Build/Mac/Alamofire.framework.dSYM; sourceTree = "<group>"; };
+		E450AD97222633920091BED3 /* Alamofire.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Alamofire.framework; path = Carthage/Build/Mac/Alamofire.framework; sourceTree = "<group>"; };
+		E450AD9C2229B9050091BED3 /* String.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = String.swift; sourceTree = "<group>"; };
+		E450AD9E2229B9BC0091BED3 /* PersephoneBridgingHeader.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = PersephoneBridgingHeader.h; sourceTree = "<group>"; };
+		E450AD9F2229E7C90091BED3 /* PMKFoundation.framework.dSYM */ = {isa = PBXFileReference; lastKnownFileType = wrapper.dsym; name = PMKFoundation.framework.dSYM; path = Carthage/Build/Mac/PMKFoundation.framework.dSYM; sourceTree = "<group>"; };
+		E450ADA02229E7C90091BED3 /* PMKFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = PMKFoundation.framework; path = Carthage/Build/Mac/PMKFoundation.framework; sourceTree = "<group>"; };
+		E45962C52241A78500FC1A1E /* Command.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Command.swift; sourceTree = "<group>"; };
 		E465049921E94DF500A70F4C /* WindowController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = WindowController.swift; sourceTree = "<group>"; };
 		E47E2FCB2220573500F747E6 /* MediaKeyTap.framework.dSYM */ = {isa = PBXFileReference; lastKnownFileType = wrapper.dsym; name = MediaKeyTap.framework.dSYM; path = Carthage/Build/Mac/MediaKeyTap.framework.dSYM; sourceTree = "<group>"; };
 		E47E2FD022205C4600F747E6 /* MainSplitViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainSplitViewController.swift; sourceTree = "<group>"; };
 		E47E2FD222205D2500F747E6 /* MainWindow.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainWindow.swift; sourceTree = "<group>"; };
-		E47E2FD4222071FD00F747E6 /* AlbumItem.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AlbumItem.swift; sourceTree = "<group>"; };
+		E47E2FD4222071FD00F747E6 /* AlbumViewItem.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AlbumViewItem.swift; sourceTree = "<group>"; };
 		E47E2FD62220720300F747E6 /* AlbumItemView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AlbumItemView.swift; sourceTree = "<group>"; };
 		E47E2FDC2220A6D100F747E6 /* Time.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Time.swift; sourceTree = "<group>"; };
 		E47E2FE42220AA0700F747E6 /* AlbumViewLayout.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AlbumViewLayout.swift; sourceTree = "<group>"; };
 		E4928E0A2218D62A001D4BEA /* CGColor.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = CGColor.swift; sourceTree = "<group>"; };
 		E4A642D922090CBE00067D21 /* Status.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Status.swift; sourceTree = "<group>"; };
+		E4A83BEE2221F8CF0098FED6 /* AlbumArtPrefsController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AlbumArtPrefsController.swift; sourceTree = "<group>"; };
+		E4A83BF02221FAA00098FED6 /* PreferencesViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PreferencesViewController.swift; sourceTree = "<group>"; };
+		E4A83BF3222207D50098FED6 /* AlbumArtService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AlbumArtService.swift; sourceTree = "<group>"; };
+		E4C8B53B22342005009A20F3 /* PreferencesWindowController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PreferencesWindowController.swift; sourceTree = "<group>"; };
+		E4C8B53D22349002009A20F3 /* Idle.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Idle.swift; sourceTree = "<group>"; };
 		E4E8CC8F2204EC7F0024217A /* Delegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Delegate.swift; sourceTree = "<group>"; };
 		E4E8CC912204F4B80024217A /* QueueViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = QueueViewController.swift; sourceTree = "<group>"; };
 		E4E8CC932206097F0024217A /* NotificationsController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NotificationsController.swift; sourceTree = "<group>"; };
@@ -183,6 +247,9 @@
 			files = (
 				E41B22C021FB6BBA00D544F6 /* libmpdclient.2.dylib in Frameworks */,
 				E421ACA3221F73C4008B2449 /* MediaKeyTap.framework in Frameworks */,
+				E450AD8622262AE60091BED3 /* SwiftyJSON.framework in Frameworks */,
+				E450ADA32229E7E00091BED3 /* PMKFoundation.framework in Frameworks */,
+				E450AD9222262C970091BED3 /* PromiseKit.framework in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -229,6 +296,10 @@
 		E407861A2110CE6E006887B1 /* Persephone */ = {
 			isa = PBXGroup;
 			children = (
+				E450AD9E2229B9BC0091BED3 /* PersephoneBridgingHeader.h */,
+				E450AD8922262B420091BED3 /* Operations */,
+				E4A83BF2222207BE0098FED6 /* Services */,
+				E4A83BEC2221F5DD0098FED6 /* Preferences */,
 				E47E2FE32220AA0700F747E6 /* Layouts */,
 				E4F6B461221E124700ACF42A /* Models */,
 				E4F6B45E221E117600ACF42A /* DataSources */,
@@ -273,6 +344,7 @@
 				E40FE71A221B904300A4223F /* NSEvent.swift */,
 				E435E3E1221CD4E200184CFC /* NSFont.swift */,
 				E435E3E3221CD75D00184CFC /* NSImage.swift */,
+				E450AD9C2229B9050091BED3 /* String.swift */,
 			);
 			path = Extensions;
 			sourceTree = "<group>";
@@ -280,6 +352,15 @@
 		E408D3BC220E03D20006D9BE /* Extensions */ = {
 			isa = PBXGroup;
 			children = (
+				E41E52FC223BF87300173814 /* MPDClient+Connection.swift */,
+				E42410B52241B956005ED6DF /* MPDClient+Database.swift */,
+				E41E52FE223BF95E00173814 /* MPDClient+Transport.swift */,
+				E41E5300223BF99300173814 /* MPDClient+Queue.swift */,
+				E41E5302223BF9C300173814 /* MPDClient+Idle.swift */,
+				E41E5304223BFB0700173814 /* MPDClient+Error.swift */,
+				E41E5306223C019100173814 /* MPDClient+Status.swift */,
+				E41E5308223C020400173814 /* MPDClient+Command.swift */,
+				E41E530A223C033700173814 /* MPDClient+Album.swift */,
 				E408D3BD220E03EE0006D9BE /* RawRepresentable.swift */,
 			);
 			path = Extensions;
@@ -297,8 +378,16 @@
 		E41B22BE21FB6B3300D544F6 /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
-				E47E2FCB2220573500F747E6 /* MediaKeyTap.framework.dSYM */,
+				E450ADA02229E7C90091BED3 /* PMKFoundation.framework */,
+				E450AD9F2229E7C90091BED3 /* PMKFoundation.framework.dSYM */,
+				E450AD97222633920091BED3 /* Alamofire.framework */,
+				E450AD96222633920091BED3 /* Alamofire.framework.dSYM */,
+				E450AD8C22262C590091BED3 /* PromiseKit.framework */,
+				E450AD8E22262C620091BED3 /* PromiseKit.framework.dSYM */,
+				E450AD8522262AE60091BED3 /* SwiftyJSON.framework */,
+				E450AD9022262C780091BED3 /* SwiftyJSON.framework.dSYM */,
 				E421ACA1221F73B8008B2449 /* MediaKeyTap.framework */,
+				E47E2FCB2220573500F747E6 /* MediaKeyTap.framework.dSYM */,
 				E41B22BF21FB6BBA00D544F6 /* libmpdclient.2.dylib */,
 			);
 			name = Frameworks;
@@ -355,6 +444,24 @@
 			path = mpd;
 			sourceTree = "<group>";
 		};
+		E41E530C223EF4BA00173814 /* Extensions */ = {
+			isa = PBXGroup;
+			children = (
+				E41E530D223EF4CF00173814 /* AlbumArtService+Caching.swift */,
+				E41E530F223EF6CE00173814 /* AlbumArtService+Remote.swift */,
+				E41E5311223EF74A00173814 /* AlbumArtService+Filesystem.swift */,
+			);
+			path = Extensions;
+			sourceTree = "<group>";
+		};
+		E450AD8922262B420091BED3 /* Operations */ = {
+			isa = PBXGroup;
+			children = (
+				E450AD9422262DF10091BED3 /* AlbumArtQueue.swift */,
+			);
+			path = Operations;
+			sourceTree = "<group>";
+		};
 		E47E2FE32220AA0700F747E6 /* Layouts */ = {
 			isa = PBXGroup;
 			children = (
@@ -366,14 +473,42 @@
 		E4A642DB220912FA00067D21 /* MPDClient */ = {
 			isa = PBXGroup;
 			children = (
-				E408D3BC220E03D20006D9BE /* Extensions */,
 				E41B22C521FB932700D544F6 /* MPDClient.swift */,
+				E408D3BC220E03D20006D9BE /* Extensions */,
 				E4D1B595220BA27C0026F233 /* Protocols */,
 				E4D1B594220BA2490026F233 /* Models */,
 			);
 			path = MPDClient;
 			sourceTree = "<group>";
 		};
+		E4A83BEC2221F5DD0098FED6 /* Preferences */ = {
+			isa = PBXGroup;
+			children = (
+				E4A83BED2221F5E60098FED6 /* Controllers */,
+			);
+			path = Preferences;
+			sourceTree = "<group>";
+		};
+		E4A83BED2221F5E60098FED6 /* Controllers */ = {
+			isa = PBXGroup;
+			children = (
+				E41EA46B221636AF0068EF46 /* GeneralPrefsViewController.swift */,
+				E4A83BEE2221F8CF0098FED6 /* AlbumArtPrefsController.swift */,
+				E4A83BF02221FAA00098FED6 /* PreferencesViewController.swift */,
+				E4C8B53B22342005009A20F3 /* PreferencesWindowController.swift */,
+			);
+			path = Controllers;
+			sourceTree = "<group>";
+		};
+		E4A83BF2222207BE0098FED6 /* Services */ = {
+			isa = PBXGroup;
+			children = (
+				E41E530C223EF4BA00173814 /* Extensions */,
+				E4A83BF3222207D50098FED6 /* AlbumArtService.swift */,
+			);
+			path = Services;
+			sourceTree = "<group>";
+		};
 		E4D1B594220BA2490026F233 /* Models */ = {
 			isa = PBXGroup;
 			children = (
@@ -381,6 +516,8 @@
 				E4A642D922090CBE00067D21 /* Status.swift */,
 				E4EB2378220F10B8008C70C0 /* Pair.swift */,
 				E4EB237A220F7CF1008C70C0 /* Album.swift */,
+				E4C8B53D22349002009A20F3 /* Idle.swift */,
+				E45962C52241A78500FC1A1E /* Command.swift */,
 			);
 			path = Models;
 			sourceTree = "<group>";
@@ -396,9 +533,8 @@
 		E4D1B597220BA3A20026F233 /* Controllers */ = {
 			isa = PBXGroup;
 			children = (
-				E47E2FD4222071FD00F747E6 /* AlbumItem.swift */,
+				E47E2FD4222071FD00F747E6 /* AlbumViewItem.swift */,
 				E408D3C1220E134F0006D9BE /* AlbumViewController.swift */,
-				E41EA46B221636AF0068EF46 /* PreferencesViewController.swift */,
 				E4E8CC932206097F0024217A /* NotificationsController.swift */,
 				E4E8CC912204F4B80024217A /* QueueViewController.swift */,
 				E465049921E94DF500A70F4C /* WindowController.swift */,
@@ -411,7 +547,7 @@
 			isa = PBXGroup;
 			children = (
 				E40786212110CE70006887B1 /* Main.storyboard */,
-				E408D3C9220E341D0006D9BE /* AlbumItem.xib */,
+				E408D3C9220E341D0006D9BE /* AlbumViewItem.xib */,
 			);
 			path = Resources;
 			sourceTree = "<group>";
@@ -431,6 +567,7 @@
 				E47E2FDC2220A6D100F747E6 /* Time.swift */,
 				E40F41F2221EDE27004B6CB8 /* Preferences.swift */,
 				E4F6B462221E125900ACF42A /* SongItem.swift */,
+				E450AD7D222620A10091BED3 /* AlbumItem.swift */,
 			);
 			path = Models;
 			sourceTree = "<group>";
@@ -550,11 +687,15 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				E450AD9122262C780091BED3 /* SwiftyJSON.framework.dSYM in Resources */,
 				E42A8F3B22176D6400A13ED9 /* LICENSE.md in Resources */,
+				E450AD98222633920091BED3 /* Alamofire.framework.dSYM in Resources */,
 				E40786202110CE70006887B1 /* Assets.xcassets in Resources */,
 				E42A8F3C22176D6400A13ED9 /* README.md in Resources */,
-				E408D3CB220E341D0006D9BE /* AlbumItem.xib in Resources */,
+				E450AD8F22262C620091BED3 /* PromiseKit.framework.dSYM in Resources */,
+				E408D3CB220E341D0006D9BE /* AlbumViewItem.xib in Resources */,
 				E40786232110CE70006887B1 /* Main.storyboard in Resources */,
+				E450ADA12229E7C90091BED3 /* PMKFoundation.framework.dSYM in Resources */,
 				E47E2FCC2220573500F747E6 /* MediaKeyTap.framework.dSYM in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -600,34 +741,55 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				E4A83BEF2221F8CF0098FED6 /* AlbumArtPrefsController.swift in Sources */,
 				E4F6B467221E233200ACF42A /* AlbumDataSource.swift in Sources */,
 				E408D3C2220E134F0006D9BE /* AlbumViewController.swift in Sources */,
 				E40FE71B221B904300A4223F /* NSEvent.swift in Sources */,
 				E4928E0B2218D62A001D4BEA /* CGColor.swift in Sources */,
+				E4C8B53E22349002009A20F3 /* Idle.swift in Sources */,
 				E4F6B460221E119B00ACF42A /* QueueDataSource.swift in Sources */,
+				E4C8B53C22342005009A20F3 /* PreferencesWindowController.swift in Sources */,
+				E41E5307223C019100173814 /* MPDClient+Status.swift in Sources */,
+				E41E5310223EF6CE00173814 /* AlbumArtService+Remote.swift in Sources */,
+				E41E530B223C033700173814 /* MPDClient+Album.swift in Sources */,
+				E42410B62241B956005ED6DF /* MPDClient+Database.swift in Sources */,
 				E4A642DA22090CBE00067D21 /* Status.swift in Sources */,
 				E47E2FD72220720300F747E6 /* AlbumItemView.swift in Sources */,
+				E450AD9522262DF10091BED3 /* AlbumArtQueue.swift in Sources */,
+				E41E52FD223BF87300173814 /* MPDClient+Connection.swift in Sources */,
+				E450AD7E222620A10091BED3 /* AlbumItem.swift in Sources */,
 				E4E8CC942206097F0024217A /* NotificationsController.swift in Sources */,
 				E408D3B6220DD8970006D9BE /* Notification.swift in Sources */,
+				E45962C62241A78500FC1A1E /* Command.swift in Sources */,
 				E408D3B9220DE98F0006D9BE /* NSUserInterfaceItemIdentifier.swift in Sources */,
 				E4EB2379220F10B8008C70C0 /* Pair.swift in Sources */,
 				E4F6B463221E125900ACF42A /* SongItem.swift in Sources */,
+				E4A83BF12221FAA00098FED6 /* PreferencesViewController.swift in Sources */,
 				E465049A21E94DF500A70F4C /* WindowController.swift in Sources */,
 				E41B22C621FB932700D544F6 /* MPDClient.swift in Sources */,
 				E40F41F3221EDE27004B6CB8 /* Preferences.swift in Sources */,
 				E47E2FDD2220A6D100F747E6 /* Time.swift in Sources */,
 				E407861C2110CE6E006887B1 /* AppDelegate.swift in Sources */,
+				E41E5309223C020400173814 /* MPDClient+Command.swift in Sources */,
 				E47E2FE52220AA0700F747E6 /* AlbumViewLayout.swift in Sources */,
+				E41E52FF223BF95E00173814 /* MPDClient+Transport.swift in Sources */,
 				E47E2FD322205D2500F747E6 /* MainWindow.swift in Sources */,
 				E47E2FD122205C4600F747E6 /* MainSplitViewController.swift in Sources */,
 				E4E8CC9A22075D370024217A /* Song.swift in Sources */,
-				E41EA46C221636AF0068EF46 /* PreferencesViewController.swift in Sources */,
+				E41EA46C221636AF0068EF46 /* GeneralPrefsViewController.swift in Sources */,
 				E4E8CC902204EC7F0024217A /* Delegate.swift in Sources */,
-				E47E2FD5222071FD00F747E6 /* AlbumItem.swift in Sources */,
+				E4A83BF4222207D50098FED6 /* AlbumArtService.swift in Sources */,
+				E47E2FD5222071FD00F747E6 /* AlbumViewItem.swift in Sources */,
 				E408D3BE220E03EE0006D9BE /* RawRepresentable.swift in Sources */,
+				E41E530E223EF4CF00173814 /* AlbumArtService+Caching.swift in Sources */,
 				E4E8CC922204F4B80024217A /* QueueViewController.swift in Sources */,
+				E41E5312223EF74A00173814 /* AlbumArtService+Filesystem.swift in Sources */,
+				E41E5301223BF99300173814 /* MPDClient+Queue.swift in Sources */,
 				E4EB237B220F7CF1008C70C0 /* Album.swift in Sources */,
+				E450AD9D2229B9050091BED3 /* String.swift in Sources */,
+				E41E5303223BF9C300173814 /* MPDClient+Idle.swift in Sources */,
 				E435E3E4221CD75D00184CFC /* NSImage.swift in Sources */,
+				E41E5305223BFB0700173814 /* MPDClient+Error.swift in Sources */,
 				E435E3E2221CD4E200184CFC /* NSFont.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -731,6 +893,7 @@
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = macosx;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
+				SWIFT_OBJC_BRIDGING_HEADER = Persephone/PersephoneBridgingHeader.h;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
 			};
 			name = Debug;
@@ -784,6 +947,7 @@
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = macosx;
 				SWIFT_COMPILATION_MODE = wholemodule;
+				SWIFT_OBJC_BRIDGING_HEADER = Persephone/PersephoneBridgingHeader.h;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
 			};
 			name = Release;

Persephone.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -1,9 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Workspace
    version = "1.0">
-   <FileRef
-      location = "group:../README.md">
-   </FileRef>
    <FileRef
       location = "self:">
    </FileRef>

Persephone/AppDelegate.swift

@@ -26,6 +26,13 @@ class AppDelegate: NSObject, NSApplicationDelegate, MediaKeyTapDelegate {
 
     mediaKeyTap = MediaKeyTap(delegate: self)
     mediaKeyTap?.start()
+
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(enableUpdateDatabaseMenuItem),
+      name: Notification.databaseUpdateFinished,
+      object: AppDelegate.mpdClient
+    )
   }
 
   func applicationWillTerminate(_ aNotification: Notification) {
@@ -68,4 +75,15 @@ class AppDelegate: NSObject, NSApplicationDelegate, MediaKeyTapDelegate {
   func disconnect() {
     AppDelegate.mpdClient.disconnect()
   }
+
+  @IBAction func updateDatabase(_ sender: NSMenuItem) {
+    sender.isEnabled = false
+    AppDelegate.mpdClient.updateDatabase()
+  }
+
+  @objc func enableUpdateDatabaseMenuItem() {
+    updateDatabaseMenuItem?.isEnabled = true
+  }
+
+  @IBOutlet weak var updateDatabaseMenuItem: NSMenuItem!
 }

Persephone/Assets.xcassets/coverArtPreferencesIcon.imageset/Contents.json

@@ -0,0 +1,22 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "filename" : "coverArtPreferencesIcon.png",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "coverArtPreferencesIcon@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

Persephone/Controllers/AlbumViewController.swift

@@ -11,6 +11,8 @@ import Cocoa
 class AlbumViewController: NSViewController,
                            NSCollectionViewDelegate,
                            NSCollectionViewDelegateFlowLayout {
+  var preferences = Preferences()
+
   let paddingWidth: CGFloat = 40
   let gutterWidth: CGFloat = 20
 
@@ -36,6 +38,8 @@ class AlbumViewController: NSViewController,
     )
 
     albumCollectionView.dataSource = dataSource
+
+    preferences.addObserver(self, forKeyPath: "mpdLibraryDir")
   }
 
   override func viewWillLayout() {
@@ -53,11 +57,25 @@ class AlbumViewController: NSViewController,
     layout.setScrollPosition()
   }
 
+  override func observeValue(
+    forKeyPath keyPath: String?,
+    of object: Any?,
+    change: [NSKeyValueChangeKey : Any]?,
+    context: UnsafeMutableRawPointer?
+    ) {
+    switch keyPath {
+    case "mpdLibraryDir":
+      albumCollectionView.reloadData()
+    default:
+      break
+    }
+  }
+
   @objc func updateAlbums(_ notification: Notification) {
     guard let albums = notification.userInfo?[Notification.albumsKey] as? [MPDClient.Album]
       else { return }
 
-    dataSource.albums = albums
+    dataSource.albums = albums.map { AlbumItem(album: $0, coverArt: nil) }
     albumCollectionView.reloadData()
   }
 

Persephone/Controllers/AlbumViewItem.swift

@@ -1,5 +1,5 @@
 //
-//  AlbumItem.swift
+//  AlbumViewItem.swift
 //  Persephone
 //
 //  Created by Daniel Barber on 2019/2/08.
@@ -8,9 +8,9 @@
 
 import Cocoa
 
-class AlbumItem: NSCollectionViewItem {
+class AlbumViewItem: NSCollectionViewItem {
   var observer: NSKeyValueObservation?
-  var album: MPDClient.Album?
+  var album: AlbumItem?
 
   override func viewDidLoad() {
     super.viewDidLoad()
@@ -27,10 +27,16 @@ class AlbumItem: NSCollectionViewItem {
     }
   }
 
-  func setAlbum(_ album: MPDClient.Album) {
+  func setAlbum(_ album: AlbumItem) {
     self.album = album
     albumTitle.stringValue = album.title
     albumArtist.stringValue = album.artist
+    
+    if let coverArt = album.coverArt {
+      albumCoverView.image = coverArt
+    } else {
+      albumCoverView.image = .defaultCoverArt
+    }
   }
 
   func setAppearance() {
@@ -47,7 +53,7 @@ class AlbumItem: NSCollectionViewItem {
   @IBAction func playAlbum(_ sender: Any) {
     guard let album = album else { return }
     
-    AppDelegate.mpdClient.playAlbum(album)
+    AppDelegate.mpdClient.playAlbum(album.album)
   }
 
   @IBOutlet var albumCoverView: NSImageView!

Persephone/Controllers/NotificationsController.swift

@@ -36,6 +36,14 @@ class NotificationsController: MPDClientDelegate {
     )
   }
 
+  func willStartDatabaseUpdate(mpdClient: MPDClient) {
+    sendNotification(name: Notification.databaseUpdateStarted)
+  }
+
+  func didFinishDatabaseUpdate(mpdClient: MPDClient) {
+    sendNotification(name: Notification.databaseUpdateFinished)
+  }
+
   func didUpdateQueue(mpdClient: MPDClient, queue: [MPDClient.Song]) {
     sendNotification(
       name: Notification.queueChanged,

Persephone/Controllers/QueueViewController.swift

@@ -36,7 +36,7 @@ class QueueViewController: NSViewController,
     let newQueuePos = queueView.selectedRow - 1
 
     if newQueuePos >= 0 {
-      AppDelegate.mpdClient.playTrack(queuePos: newQueuePos)
+      AppDelegate.mpdClient.playTrack(at: newQueuePos)
     }
   }
 

Persephone/Controllers/WindowController.swift

@@ -36,6 +36,20 @@ class WindowController: NSWindowController {
       object: AppDelegate.mpdClient
     )
 
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(startDatabaseUpdatingIndicator),
+      name: Notification.databaseUpdateStarted,
+      object: AppDelegate.mpdClient
+    )
+
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(stopDatabaseUpdatingIndicator),
+      name: Notification.databaseUpdateFinished,
+      object: AppDelegate.mpdClient
+    )
+
     trackProgress.font = .timerFont
     trackRemaining.font = .timerFont
   }
@@ -132,6 +146,14 @@ class WindowController: NSWindowController {
     setTimeRemaining()
   }
 
+  @objc func startDatabaseUpdatingIndicator() {
+    databaseUpdatingIndicator.startAnimation(self)
+  }
+
+  @objc func stopDatabaseUpdatingIndicator() {
+    databaseUpdatingIndicator.stopAnimation(self)
+  }
+
   func setTimeElapsed() {
     guard let elapsedTimeMs = elapsedTimeMs else { return }
 
@@ -194,4 +216,5 @@ class WindowController: NSWindowController {
   @IBOutlet var trackProgress: NSTextField!
   @IBOutlet var trackProgressBar: NSSlider!
   @IBOutlet var trackRemaining: NSTextField!
+  @IBOutlet var databaseUpdatingIndicator: NSProgressIndicator!
 }

Persephone/DataSources/AlbumDataSource.swift

@@ -9,19 +9,29 @@
 import Cocoa
 
 class AlbumDataSource: NSObject, NSCollectionViewDataSource {
-  var albums: [MPDClient.Album] = []
+  var albums: [AlbumItem] = []
 
   func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
     return albums.count
   }
 
   func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
-    let item = collectionView.makeItem(withIdentifier: .albumItem, for: indexPath)
+    let item = collectionView.makeItem(withIdentifier: .albumViewItem, for: indexPath)
-    guard let albumItem = item as? AlbumItem else { return item }
+    guard let albumViewItem = item as? AlbumViewItem else { return item }
 
-    albumItem.view.wantsLayer = true
+    albumViewItem.view.wantsLayer = true
-    albumItem.setAlbum(albums[indexPath.item])
+    albumViewItem.setAlbum(albums[indexPath.item])
 
-    return albumItem
+    if albums[indexPath.item].coverArt == nil {
+      AlbumArtService(album: albums[indexPath.item]).fetchAlbumArt { image in
+        self.albums[indexPath.item].coverArt = image
+
+        DispatchQueue.main.async {
+          collectionView.reloadItems(at: [indexPath])
+        }
+      }
+    }
+
+    return albumViewItem
   }
 }

Persephone/DataSources/QueueDataSource.swift

@@ -14,9 +14,6 @@ class QueueDataSource: NSObject, NSOutlineViewDataSource {
 
   var queueIcon: NSImage? = nil
 
-  let playIcon = NSImage(named: "playButton")
-  let pauseIcon = NSImage(named: "pauseButton")
-
   func updateQueue(_ queue: [MPDClient.Song]) {
     queuePos = -1
     
@@ -41,9 +38,9 @@ class QueueDataSource: NSObject, NSOutlineViewDataSource {
   func setQueueIcon(_ state: MPDClient.Status.State) {
     switch state {
     case .playing:
-      queueIcon = playIcon
+      queueIcon = .playIcon
     case .paused:
-      queueIcon = pauseIcon
+      queueIcon = .pauseIcon
     default:
       queueIcon = nil
     }

Persephone/Extensions/NSImage.swift

@@ -11,4 +11,26 @@ import Cocoa
 extension NSImage {
   static let playIcon = NSImage(named: "playButton")
   static let pauseIcon = NSImage(named: "pauseButton")
+
+  static let defaultCoverArt = NSImage(named: "blankAlbum")
+
+  func toFitBox(size: NSSize) -> NSImage {
+    let newImage = NSImage(size: size)
+    newImage.lockFocus()
+    self.draw(in: newImage.alignmentRect)
+    newImage.unlockFocus()
+    return newImage
+  }
+
+  func jpegData(compressionQuality: CGFloat) -> Data? {
+    guard let image = cgImage(forProposedRect: nil, context: nil, hints: nil)
+      else { return nil }
+
+    let bitmapImageRep = NSBitmapImageRep(cgImage: image)
+
+    return bitmapImageRep.representation(
+      using: .jpeg,
+      properties: [.compressionFactor: compressionQuality]
+    )
+  }
 }

Persephone/Extensions/NSUserInterfaceItemIdentifier.swift

@@ -16,5 +16,5 @@ extension NSUserInterfaceItemIdentifier {
   static let queueSongArtist = NSUserInterfaceItemIdentifier("songArtistCell")
   static let queueSongTitle = NSUserInterfaceItemIdentifier("songTitleCell")
 
-  static let albumItem = NSUserInterfaceItemIdentifier("AlbumItem")
+  static let albumViewItem = NSUserInterfaceItemIdentifier("AlbumViewItem")
 }

Persephone/Extensions/Notification.swift

@@ -14,6 +14,8 @@ extension Notification {
 
   static let stateChanged = Name("MPDClientStateChanged")
   static let timeChanged = Name("MPDClientTimeChanged")
+  static let databaseUpdateStarted = Name("MPDClientDatabaseUpdateStarted")
+  static let databaseUpdateFinished = Name("MPDClientDatabaseUpdateFinished")
   static let queueChanged = Name("MPDClientQueueChanged")
   static let queuePosChanged = Name("MPDClientQueuePosChanged")
   static let loadedAlbums = Name("MPDClientLoadedAlbums")

Persephone/Extensions/String.swift

@@ -0,0 +1,24 @@
+//
+//  String.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/01.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+
+extension String {
+  func sha1() -> String {
+    let data = self.data(using: String.Encoding.utf8)!
+    var digest = [UInt8](repeating: 0, count:Int(CC_SHA1_DIGEST_LENGTH))
+
+    data.withUnsafeBytes {
+      _ = CC_SHA1($0, CC_LONG(data.count), &digest)
+    }
+
+    let hexBytes = digest.map { String(format: "%02hhx", $0) }
+
+    return hexBytes.joined()
+  }
+}

Persephone/Info.plist

@@ -17,7 +17,7 @@
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
 	<key>CFBundleShortVersionString</key>
-	<string>0.8.0</string>
+	<string>0.10.2a</string>
 	<key>CFBundleVersion</key>
 	<string>1</string>
 	<key>LSApplicationCategoryType</key>

Persephone/MPDClient/Extensions/MPDClient+Album.swift

@@ -0,0 +1,99 @@
+//
+//  MPDAlbum.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func fetchAllAlbums() {
+    enqueueCommand(command: .fetchAllAlbums)
+  }
+
+  func playAlbum(_ album: Album) {
+    enqueueCommand(command: .playAlbum, userData: ["album": album])
+  }
+
+  func getAlbumURI(for album: Album, callback: @escaping (String?) -> Void) {
+    enqueueCommand(
+      command: .getAlbumURI,
+      priority: .low,
+      userData: ["album": album, "callback": callback]
+    )
+  }
+
+  func sendPlayAlbum(_ album: Album) {
+    var songs: [Song] = []
+
+    mpd_run_clear(self.connection)
+    mpd_search_db_songs(self.connection, true)
+    mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_ALBUM, album.title)
+    mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_ALBUM_ARTIST, album.artist)
+    mpd_search_commit(self.connection)
+    while let mpdSong = mpd_recv_song(self.connection) {
+      songs.append(Song(mpdSong))
+    }
+    for song in songs {
+      mpd_run_add(self.connection, song.uri)
+    }
+    mpd_run_play_pos(self.connection, 0)
+  }
+
+  func allAlbums() {
+    var albums: [Album] = []
+    var artist: String = ""
+
+    mpd_search_db_tags(self.connection, MPD_TAG_ALBUM)
+    mpd_search_add_group_tag(self.connection, MPD_TAG_ALBUM_ARTIST)
+    mpd_search_commit(self.connection)
+
+    while let mpdPair = mpd_recv_pair(self.connection) {
+      let pair = Pair(mpdPair)
+
+      switch pair.name {
+      case "AlbumArtist":
+        artist = pair.value
+      case "Album":
+        albums.append(Album(title: pair.value, artist: artist))
+      default:
+        break
+      }
+
+      mpd_return_pair(self.connection, pair.mpdPair)
+    }
+
+    self.delegate?.didLoadAlbums(mpdClient: self, albums: albums)
+  }
+
+  func albumURI(for album: Album, callback: (String?) -> Void) {
+    var songURI: String?
+
+    guard isConnected else { return }
+
+    mpd_search_db_songs(self.connection, true)
+    mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_ALBUM, album.title)
+    mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_ALBUM_ARTIST, album.artist)
+    mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_TRACK, "1")
+
+    mpd_search_commit(self.connection)
+
+    while let mpdSong = mpd_recv_song(self.connection) {
+      let song = Song(mpdSong)
+
+      if songURI == nil {
+        songURI = song.uriString
+      }
+    }
+
+    callback(
+      songURI?
+        .split(separator: "/")
+        .dropLast()
+        .joined(separator: "/")
+    )
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Command.swift

@@ -0,0 +1,79 @@
+//
+//  CommandQueue.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+
+extension MPDClient {
+  func sendCommand(
+    command: Command,
+    userData: Dictionary<String, Any> = [:]
+  ) {
+    switch command {
+
+    // Transport commands
+    case .prevTrack:
+      sendPreviousTrack()
+    case .nextTrack:
+      sendNextTrack()
+    case .stop:
+      sendStop()
+    case .playPause:
+      sendPlay()
+    case .seekCurrentSong:
+      guard let timeInSeconds = userData["timeInSeconds"] as? Float
+        else { return }
+      sendSeekCurrentSong(timeInSeconds: timeInSeconds)
+
+    // Database commands
+    case .updateDatabase:
+      sendUpdateDatabase()
+
+    // Status commands
+    case .fetchStatus:
+      sendRunStatus()
+
+    // Queue commands
+    case .fetchQueue:
+      sendFetchQueue()
+    case .playTrack:
+      guard let queuePos = userData["queuePos"] as? Int
+        else { return }
+      sendPlayTrack(at: queuePos)
+
+    // Album commands
+    case .fetchAllAlbums:
+      allAlbums()
+    case .playAlbum:
+      guard let album = userData["album"] as? Album else { return }
+      sendPlayAlbum(album)
+    case .getAlbumURI:
+      guard let album = userData["album"] as? Album,
+        let callback = userData["callback"] as? (String?) -> Void
+        else { return }
+      albumURI(for: album, callback: callback)
+    }
+  }
+
+  func enqueueCommand(
+    command: Command,
+    priority: BlockOperation.QueuePriority = .normal,
+    userData: Dictionary<String, Any> = [:]
+  ) {
+    guard isConnected else { return }
+
+    noIdle()
+
+    let commandOperation = BlockOperation() { [unowned self] in
+      self.sendCommand(command: command, userData: userData)
+
+      self.idle()
+    }
+    commandOperation.queuePriority = priority
+    commandQueue.addOperation(commandOperation)
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Connection.swift

@@ -0,0 +1,50 @@
+//
+//  Connection.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func connect(host: String, port: Int) {
+    commandQueue.addOperation { [unowned self] in
+      guard let connection = mpd_connection_new(host, UInt32(port), 10000),
+        mpd_connection_get_error(connection) == MPD_ERROR_SUCCESS
+        else { return }
+
+      self.isConnected = true
+
+      guard let status = mpd_run_status(connection)
+        else { return }
+
+      self.connection = connection
+      self.status = Status(status)
+
+      self.fetchQueue()
+      self.fetchAllAlbums()
+      self.idle()
+
+      self.delegate?.didConnect(mpdClient: self)
+      self.delegate?.didUpdateState(mpdClient: self, state: self.status!.state)
+      self.delegate?.didUpdateTime(mpdClient: self, total: self.status!.totalTime, elapsedMs: self.status!.elapsedTimeMs)
+      self.delegate?.didUpdateQueue(mpdClient: self, queue: self.queue)
+      self.delegate?.didUpdateQueuePos(mpdClient: self, song: self.status!.song)
+    }
+  }
+
+  func disconnect() {
+    guard isConnected else { return }
+
+    noIdle()
+    commandQueue.addOperation { [unowned self] in
+      self.delegate?.willDisconnect(mpdClient: self)
+
+      mpd_connection_free(self.connection)
+      self.isConnected = false
+    }
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Database.swift

@@ -0,0 +1,20 @@
+//
+//  MPDClient+Database.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/19.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func updateDatabase() {
+    enqueueCommand(command: .updateDatabase)
+  }
+
+  func sendUpdateDatabase() {
+    mpd_run_update(connection, nil)
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Error.swift

@@ -0,0 +1,24 @@
+//
+//  Error.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func getLastErrorMessage() -> String? {
+    if mpd_connection_get_error(connection) == MPD_ERROR_SUCCESS {
+      return nil
+    }
+
+    if let errorMessage = mpd_connection_get_error_message(connection) {
+      return String(cString: errorMessage)
+    }
+
+    return nil
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Idle.swift

@@ -0,0 +1,64 @@
+//
+//  Idle.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func noIdle() {
+    if isIdle {
+      mpd_send_noidle(connection)
+      isIdle = false
+    }
+  }
+
+  func idle() {
+    if !self.isIdle && self.commandQueue.operationCount == 1 {
+      mpd_send_idle(self.connection)
+      self.isIdle = true
+
+      let result = mpd_recv_idle(self.connection, true)
+      self.handleIdleResult(result)
+    }
+  }
+
+  func handleIdleResult(_ result: mpd_idle) {
+    isIdle = false
+    
+    let mpdIdle = Idle(rawValue: result.rawValue)
+
+    if mpdIdle.contains(.database) {
+      self.fetchAllAlbums()
+    }
+    if mpdIdle.contains(.queue) {
+      self.fetchQueue()
+      self.delegate?.didUpdateQueue(mpdClient: self, queue: self.queue)
+    }
+    if mpdIdle.contains(.player) {
+      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)
+      }
+    }
+    if mpdIdle.contains(.update) {
+      self.fetchStatus()
+
+      if self.status?.updating ?? false {
+        self.delegate?.willStartDatabaseUpdate(mpdClient: self)
+      } else {
+        self.delegate?.didFinishDatabaseUpdate(mpdClient: self)
+      }
+    }
+    if !mpdIdle.isEmpty {
+      self.idle()
+    }
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Queue.swift

@@ -0,0 +1,34 @@
+//
+//  Queue.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func fetchQueue() {
+    sendCommand(command: .fetchQueue)
+  }
+
+  func playTrack(at queuePos: Int) {
+    enqueueCommand(command: .playTrack, userData: ["queuePos": queuePos])
+  }
+
+  func sendPlayTrack(at queuePos: Int) {
+    mpd_run_play_pos(self.connection, UInt32(queuePos))
+  }
+
+  func sendFetchQueue() {
+    self.queue = []
+    mpd_send_list_queue_meta(connection)
+
+    while let mpdSong = mpd_recv_song(connection) {
+      let song = Song(mpdSong)
+      self.queue.append(song)
+    }
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Status.swift

@@ -0,0 +1,21 @@
+//
+//  Status.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func fetchStatus() {
+    sendCommand(command: .fetchStatus)
+  }
+
+  func sendRunStatus() {
+    guard let status = mpd_run_status(connection) else { return }
+    self.status = Status(status)
+  }
+}

Persephone/MPDClient/Extensions/MPDClient+Transport.swift

@@ -0,0 +1,67 @@
+//
+//  Transport.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/15.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+import mpdclient
+
+extension MPDClient {
+  func playPause() {
+    enqueueCommand(command: .playPause)
+  }
+
+  func stop() {
+    enqueueCommand(command: .stop)
+  }
+
+  func prevTrack() {
+    enqueueCommand(command: .prevTrack)
+  }
+
+  func nextTrack() {
+    enqueueCommand(command: .nextTrack)
+  }
+
+  func seekCurrentSong(timeInSeconds: Float) {
+    enqueueCommand(
+      command: .seekCurrentSong,
+      userData: ["timeInSeconds": timeInSeconds]
+    )
+  }
+
+  func sendNextTrack() {
+    guard let state = status?.state,
+      state.isOneOf([.playing, .paused])
+      else { return }
+
+    mpd_run_next(connection)
+  }
+
+  func sendPreviousTrack() {
+    guard let state = status?.state,
+      state.isOneOf([.playing, .paused])
+      else { return }
+
+    mpd_run_previous(connection)
+  }
+
+  func sendStop() {
+    mpd_run_stop(connection)
+  }
+
+  func sendPlay() {
+    if status?.state == .stopped {
+      mpd_run_play(connection)
+    } else {
+      mpd_run_toggle_pause(connection)
+    }
+  }
+
+  func sendSeekCurrentSong(timeInSeconds: Float) {
+    mpd_run_seek_current(self.connection, timeInSeconds, false)
+  }
+}

Persephone/MPDClient/MPDClient.swift

@@ -12,285 +12,16 @@ import mpdclient
 class MPDClient {
   var delegate: MPDClientDelegate?
 
-  private var connection: OpaquePointer?
+  var connection: OpaquePointer?
-  private var isConnected: Bool = false
+  var isConnected: Bool = false
-  private var status: Status?
+  var isIdle: Bool = false
-  private var queue: [Song] = []
+  var status: Status?
+  var queue: [Song] = []
 
-  private let commandQueue = DispatchQueue(label: "commandQueue")
+  let commandQueue = OperationQueue()
-
-  enum Command {
-    case prevTrack, nextTrack, playPause, stop,
-      fetchStatus, fetchQueue, fetchAllAlbums
-  }
-
-  struct Idle: OptionSet {
-    let rawValue: UInt32
-
-    static let database = Idle(rawValue: 0x1)
-    static let storedPlaylist = Idle(rawValue: 0x2)
-    static let queue = Idle(rawValue: 0x4)
-    static let player = Idle(rawValue: 0x8)
-    static let mixer = Idle(rawValue: 0x10)
-    static let output = Idle(rawValue: 0x20)
-    static let options = Idle(rawValue: 0x40)
-    static let update = Idle(rawValue: 0x80)
-    static let sticker = Idle(rawValue: 0x100)
-    static let subscription = Idle(rawValue: 0x200)
-    static let message = Idle(rawValue: 0x400)
-  }
 
   init(withDelegate delegate: MPDClientDelegate?) {
+    commandQueue.maxConcurrentOperationCount = 1
     self.delegate = delegate
   }
-
-  func connect(host: String, port: Int) {
-    commandQueue.async { [unowned self] in
-      guard let connection = mpd_connection_new(host, UInt32(port), 10000),
-        mpd_connection_get_error(connection) == MPD_ERROR_SUCCESS
-        else { return }
-
-      self.isConnected = true
-
-      guard let status = mpd_run_status(connection)
-        else { return }
-
-      self.connection = connection
-      self.status = Status(status)
-
-      self.fetchQueue()
-      self.fetchAllAlbums()
-      self.idle()
-
-      self.delegate?.didConnect(mpdClient: self)
-      self.delegate?.didUpdateState(mpdClient: self, state: self.status!.state)
-      self.delegate?.didUpdateTime(mpdClient: self, total: self.status!.totalTime, elapsedMs: self.status!.elapsedTimeMs)
-      self.delegate?.didUpdateQueue(mpdClient: self, queue: self.queue)
-      self.delegate?.didUpdateQueuePos(mpdClient: self, song: self.status!.song)
-    }
-  }
-
-  func disconnect() {
-    guard isConnected else { return }
-
-    noIdle()
-    commandQueue.async { [unowned self] in
-      self.delegate?.willDisconnect(mpdClient: self)
-
-      mpd_connection_free(self.connection)
-      self.isConnected = false
-    }
-  }
-
-  func fetchStatus() {
-    sendCommand(command: .fetchStatus)
-  }
-
-  func fetchQueue() {
-    sendCommand(command: .fetchQueue)
-  }
-
-  func fetchAllAlbums() {
-    sendCommand(command: .fetchAllAlbums)
-  }
-
-  func playPause() {
-    queueCommand(command: .playPause)
-  }
-
-  func stop() {
-    queueCommand(command: .stop)
-  }
-
-  func prevTrack() {
-    queueCommand(command: .prevTrack)
-  }
-
-  func nextTrack() {
-    queueCommand(command: .nextTrack)
-  }
-
-  func playTrack(queuePos: Int) {
-    guard isConnected else { return }
-
-    noIdle()
-    commandQueue.async { [unowned self] in
-      mpd_run_play_pos(self.connection, UInt32(queuePos))
-    }
-    idle()
-  }
-
-  func seekCurrentSong(timeInSeconds: Float) {
-    noIdle()
-    commandQueue.async { [unowned self] in
-      mpd_run_seek_current(self.connection, timeInSeconds, false)
-    }
-    idle()
-  }
-
-  func playAlbum(_ album: Album) {
-    noIdle()
-    commandQueue.async { [unowned self] in
-      var songs: [Song] = []
-
-      mpd_run_clear(self.connection)
-      mpd_search_db_songs(self.connection, true)
-      mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_ALBUM, album.title)
-      mpd_search_add_tag_constraint(self.connection, MPD_OPERATOR_DEFAULT, MPD_TAG_ALBUM_ARTIST, album.artist)
-      mpd_search_commit(self.connection)
-      while let mpdSong = mpd_recv_song(self.connection) {
-        songs.append(Song(mpdSong))
-      }
-      for song in songs {
-        mpd_run_add(self.connection, song.uri)
-      }
-      mpd_run_play_pos(self.connection, 0)
-    }
-    idle()
-  }
-
-  func queueCommand(command: Command) {
-    guard isConnected else { return }
-
-    noIdle()
-    commandQueue.async { [unowned self] in
-      self.sendCommand(command: command)
-    }
-    idle()
-  }
-
-  func sendCommand(command: Command) {
-    switch command {
-
-    // Transport commands
-    case .prevTrack:
-      sendPreviousTrack()
-    case .nextTrack:
-      sendNextTrack()
-    case .stop:
-      sendStop()
-    case .playPause:
-      sendPlay()
-    case .fetchStatus:
-      sendRunStatus()
-    case .fetchQueue:
-      sendFetchQueue()
-    case .fetchAllAlbums:
-      allAlbums()
-    }
-  }
-
-  func sendNextTrack() {
-    guard let state = status?.state,
-      state.isOneOf([.playing, .paused])
-      else { return }
-
-    mpd_run_next(connection)
-  }
-
-  func sendPreviousTrack() {
-    guard let state = status?.state,
-      state.isOneOf([.playing, .paused])
-      else { return }
-
-    mpd_run_previous(connection)
-  }
-
-  func sendStop() {
-    mpd_run_stop(connection)
-  }
-
-  func sendPlay() {
-    if status?.state == .stopped {
-      mpd_run_play(connection)
-    } else {
-      mpd_run_toggle_pause(connection)
-    }
-  }
-
-  func sendRunStatus() {
-    guard let status = mpd_run_status(connection) else { return }
-    self.status = Status(status)
-  }
-
-  func sendFetchQueue() {
-    self.queue = []
-    mpd_send_list_queue_meta(connection)
-
-    while let mpdSong = mpd_recv_song(connection) {
-      let song = Song(mpdSong)
-      self.queue.append(song)
-    }
-  }
-
-  func allAlbums() {
-    var albums: [Album] = []
-    var artist: String = ""
-
-    mpd_search_db_tags(connection, MPD_TAG_ALBUM)
-    mpd_search_add_group_tag(connection, MPD_TAG_ALBUM_ARTIST)
-    mpd_search_commit(connection)
-    while let mpdPair = mpd_recv_pair(connection) {
-      let pair = Pair(mpdPair)
-
-      switch pair.name {
-      case "AlbumArtist":
-        artist = pair.value
-      case "Album":
-        albums.append(Album(title: pair.value, artist: artist))
-      default:
-        break
-      }
-
-      mpd_return_pair(connection, pair.mpdPair)
-    }
-
-    delegate?.didLoadAlbums(mpdClient: self, albums: albums)
-  }
-
-  func noIdle() {
-    mpd_send_noidle(connection)
-  }
-
-  func idle() {
-    commandQueue.async { [unowned self] in
-      mpd_send_idle(self.connection)
-
-      let result = mpd_recv_idle(self.connection, true)
-      self.handleIdleResult(result)
-    }
-  }
-
-  func handleIdleResult(_ result: mpd_idle) {
-    let mpdIdle = Idle(rawValue: result.rawValue)
-
-    if mpdIdle.contains(.queue) {
-      self.fetchQueue()
-      self.delegate?.didUpdateQueue(mpdClient: self, queue: self.queue)
-    }
-    if mpdIdle.contains(.player) {
-      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)
-      }
-    }
-    if !mpdIdle.isEmpty {
-      self.idle()
-    }
-  }
-
-  func getLastErrorMessage() -> String? {
-    if mpd_connection_get_error(connection) == MPD_ERROR_SUCCESS {
-      return nil
-    }
-
-    if let errorMessage = mpd_connection_get_error_message(connection) {
-      return String(cString: errorMessage)
-    }
-
-    return nil
-  }
 }

Persephone/MPDClient/Models/Command.swift

@@ -0,0 +1,35 @@
+//
+//  Command.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/19.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+
+extension MPDClient {
+  enum Command {
+    // Transport commands
+    case prevTrack
+    case nextTrack
+    case playPause
+    case stop
+    case seekCurrentSong
+
+    // Database commands
+    case updateDatabase
+
+    // Status commands
+    case fetchStatus
+
+    // Queue commands
+    case fetchQueue
+    case playTrack
+
+    // Album commands
+    case fetchAllAlbums
+    case playAlbum
+    case getAlbumURI
+  }
+}

Persephone/MPDClient/Models/Idle.swift

@@ -0,0 +1,27 @@
+//
+//  Idle.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/09.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Foundation
+
+extension MPDClient {
+  struct Idle: OptionSet {
+    let rawValue: UInt32
+
+    static let database = Idle(rawValue: 0x1)
+    static let storedPlaylist = Idle(rawValue: 0x2)
+    static let queue = Idle(rawValue: 0x4)
+    static let player = Idle(rawValue: 0x8)
+    static let mixer = Idle(rawValue: 0x10)
+    static let output = Idle(rawValue: 0x20)
+    static let options = Idle(rawValue: 0x40)
+    static let update = Idle(rawValue: 0x80)
+    static let sticker = Idle(rawValue: 0x100)
+    static let subscription = Idle(rawValue: 0x200)
+    static let message = Idle(rawValue: 0x400)
+  }
+}

Persephone/MPDClient/Models/Song.swift

@@ -45,6 +45,10 @@ extension MPDClient {
       return mpd_song_get_uri(mpdSong)
     }
 
+    var uriString: String {
+      return String(cString: uri)
+    }
+
     func getTag(_ tagType: TagType) -> String {
       let mpdTagType = mpd_tag_type(rawValue: Int32(tagType.rawValue))
 

Persephone/MPDClient/Models/Status.swift

@@ -49,5 +49,11 @@ extension MPDClient {
     var song: Int {
       return Int(mpd_status_get_song_pos(mpdStatus))
     }
+
+    var updating: Bool {
+      let updating = mpd_status_get_update_id(mpdStatus)
+
+      return updating > 0
+    }
   }
 }

Persephone/MPDClient/Protocols/Delegate.swift

@@ -15,6 +15,9 @@ protocol MPDClientDelegate {
   func didUpdateState(mpdClient: MPDClient, state: MPDClient.Status.State)
   func didUpdateTime(mpdClient: MPDClient, total: UInt, elapsedMs: UInt)
 
+  func willStartDatabaseUpdate(mpdClient: MPDClient)
+  func didFinishDatabaseUpdate(mpdClient: MPDClient)
+
   func didUpdateQueue(mpdClient: MPDClient, queue: [MPDClient.Song])
   func didUpdateQueuePos(mpdClient: MPDClient, song: Int)
   

Persephone/Models/AlbumItem.swift

@@ -0,0 +1,26 @@
+//
+//  AlbumItem.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/2/26.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+
+struct AlbumItem {
+  var album: MPDClient.Album
+  var coverArt: NSImage?
+
+  var title: String {
+    return album.title
+  }
+
+  var artist: String {
+    return album.artist
+  }
+
+  var hash: String {
+    return "\(title) - \(artist)".sha1()
+  }
+}

Persephone/Models/Preferences.swift

@@ -9,6 +9,10 @@
 import Foundation
 
 struct Preferences {
+  let mpdHostDefault = "127.0.0.1"
+  let mpdPortDefault = 6600
+  let mpdLibraryDirDefault = "~/Music"
+
   let preferences = UserDefaults.standard
 
   var mpdHost: String? {
@@ -20,6 +24,10 @@ struct Preferences {
     }
   }
 
+  var mpdHostOrDefault: String {
+    return mpdHost ?? mpdHostDefault
+  }
+
   var mpdPort: Int? {
     get {
       return preferences.value(forKey: "mpdPort") as? Int
@@ -33,12 +41,34 @@ struct Preferences {
     }
   }
 
-  var mpdHostOrDefault: String {
+  var mpdPortOrDefault: Int {
-    return mpdHost ?? "127.0.0.1"
+    return mpdPort ?? mpdPortDefault
   }
 
-  var mpdPortOrDefault: Int {
+  var mpdLibraryDir: String? {
-    return mpdPort ?? 6600
+    get {
+      return preferences.string(forKey: "mpdLibraryDir")
+    }
+    set {
+      preferences.set(newValue, forKey: "mpdLibraryDir")
+    }
+  }
+
+  var mpdLibraryDirOrDefault: String {
+    return mpdLibraryDir ?? mpdLibraryDirDefault
+  }
+
+  var expandedMpdLibraryDir: String {
+    return NSString(string: mpdLibraryDirOrDefault).expandingTildeInPath
+  }
+
+  var fetchMissingArtworkFromInternet: Bool {
+    get {
+      return preferences.bool(forKey: "fetchMissingArtworkFromInternet")
+    }
+    set {
+      preferences.set(newValue, forKey: "fetchMissingArtworkFromInternet")
+    }
   }
 
   func addObserver(_ observer: NSObject, forKeyPath keyPath: String) {

Persephone/Operations/AlbumArtQueue.swift

@@ -0,0 +1,23 @@
+//
+//  AlbumArtOperationQueue.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/2/26.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+
+class AlbumArtQueue {
+  static let shared = AlbumArtQueue()
+
+  let queue = DispatchQueue(label: "AlbumArtQueue")
+  var lastDispatchedTime = DispatchTime(uptimeNanoseconds: 0) - 1
+
+  func addToQueue(workItem: DispatchWorkItem) {
+    let dispatchTime = max(lastDispatchedTime + 1, DispatchTime(uptimeNanoseconds: 0))
+    lastDispatchedTime = dispatchTime
+
+    queue.asyncAfter(deadline: dispatchTime, execute: workItem)
+  }
+}

Persephone/PersephoneBridgingHeader.h

@@ -0,0 +1,15 @@
+//
+//  PersephoneBridgingHeader.h
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/01.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+#ifndef PersephoneBridgingHeader_h
+#define PersephoneBridgingHeader_h
+
+
+#endif /* PersephoneBridgingHeader_h */
+
+#import <CommonCrypto/CommonCrypto.h>

Persephone/Preferences/Controllers/AlbumArtPrefsController.swift

@@ -0,0 +1,53 @@
+//
+//  AlbumArtPrefsController.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/2/23.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+
+class AlbumArtPrefsController: NSViewController {
+  var preferences = Preferences()
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    if let mpdLibraryDir = preferences.mpdLibraryDir {
+      mpdLibraryDirField.stringValue = mpdLibraryDir
+    }
+
+    if preferences.fetchMissingArtworkFromInternet {
+      fetchMissingArtworkFromInternet.state = .on
+    } else {
+      fetchMissingArtworkFromInternet.state = .off
+    }
+
+    preferredContentSize = NSMakeSize(view.frame.size.width, view.frame.size.height)
+  }
+
+  override func viewDidAppear() {
+    super.viewDidAppear()
+
+    guard let title = title
+      else { return }
+    self.parent?.view.window?.title = title
+  }
+
+  @IBAction func updateMpdLibraryDir(_ sender: NSTextField) {
+    preferences.mpdLibraryDir = sender.stringValue
+  }
+
+  @IBOutlet var mpdLibraryDirField: NSTextField!
+
+  @IBAction func updateFetchMissingArtworkFromInternet(_ sender: NSButton) {
+    if sender.state == .on {
+      preferences.fetchMissingArtworkFromInternet = true
+    } else {
+      preferences.fetchMissingArtworkFromInternet = false
+    }
+  }
+
+  @IBOutlet var fetchMissingArtworkFromInternet: NSButton!
+}

Persephone/Preferences/Controllers/GeneralPrefsViewController.swift

@@ -8,7 +8,7 @@
 
 import Cocoa
 
-class PreferencesViewController: NSViewController {
+class GeneralPrefsViewController: NSViewController {
   var preferences = Preferences()
 
   override func viewDidLoad() {
@@ -21,6 +21,16 @@ class PreferencesViewController: NSViewController {
     if let mpdPort = preferences.mpdPort {
       mpdPortField.stringValue = "\(mpdPort)"
     }
+
+    preferredContentSize = NSMakeSize(view.frame.size.width, view.frame.size.height)
+  }
+
+  override func viewDidAppear() {
+    super.viewDidAppear()
+
+    guard let title = title
+      else { return }
+    self.parent?.view.window?.title = title
   }
 
   @IBAction func updateMpdHost(_ sender: NSTextField) {

Persephone/Preferences/Controllers/PreferencesViewController.swift

@@ -0,0 +1,59 @@
+//
+//  PreferencesController.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/2/23.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+
+class PreferencesViewController: NSTabViewController {
+  private lazy var tabViewSizes: [String : NSSize] = [:]
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    if let viewController = self.tabViewItems.first?.viewController, let title = viewController.title {
+      tabViewSizes[title] = viewController.view.frame.size
+    }
+  }
+
+  override func transition(from fromViewController: NSViewController, to toViewController: NSViewController, options: NSViewController.TransitionOptions, completionHandler completion: (() -> Void)?) {
+    NSAnimationContext.runAnimationGroup({ context in
+      context.duration = 0.25
+
+      self.updateWindowFrameAnimated(viewController: toViewController)
+
+      super.transition(
+        from: fromViewController,
+        to: toViewController,
+        options: [.crossfade, .allowUserInteraction],
+        completionHandler: completion
+      )
+    }, completionHandler: nil)
+  }
+
+  func updateWindowFrameAnimated(viewController: NSViewController) {
+    guard let title = viewController.title,
+      let window = view.window
+      else { return }
+
+    let contentSize: NSSize
+
+    if tabViewSizes.keys.contains(title) {
+      contentSize = tabViewSizes[title]!
+    } else {
+      contentSize = viewController.view.frame.size
+      tabViewSizes[title] = contentSize
+    }
+
+    let newWindowSize = window.frameRect(forContentRect: NSRect(origin: NSPoint.zero, size: contentSize)).size
+
+    var frame = window.frame
+    frame.origin.y += frame.height
+    frame.origin.y -= newWindowSize.height
+    frame.size = newWindowSize
+    window.animator().setFrame(frame, display: false)
+  }
+}

Persephone/Preferences/Controllers/PreferencesWindowController.swift

@@ -0,0 +1,20 @@
+//
+//  PreferencesWindowController.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/09.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+
+class PreferencesWindowController: NSWindowController, NSWindowDelegate {
+  override func windowDidLoad() {
+    super.windowDidLoad()
+  }
+
+  func windowShouldClose(_ sender: NSWindow) -> Bool {
+    self.window?.orderOut(sender)
+    return false
+  }
+}

Persephone/Resources/AlbumViewItem.xib

@@ -6,7 +6,7 @@
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <objects>
-        <customObject id="-2" userLabel="File's Owner" customClass="AlbumItem" customModule="Persephone" customModuleProvider="target">
+        <customObject id="-2" userLabel="File's Owner" customClass="AlbumViewItem" customModule="Persephone" customModuleProvider="target">
             <connections>
                 <outlet property="albumArtist" destination="5Uu-j1-qyT" id="2Et-tX-InT"/>
                 <outlet property="albumCoverView" destination="Kfb-8f-ean" id="CXx-gB-gz8"/>
@@ -76,7 +76,7 @@
             </connections>
             <point key="canvasLocation" x="-22" y="125.5"/>
         </customView>
-        <collectionViewItem id="Qgu-aI-55A" customClass="AlbumItem" customModule="Persephone" customModuleProvider="target"/>
+        <collectionViewItem id="Qgu-aI-55A" customClass="AlbumViewItem" customModule="Persephone" customModuleProvider="target"/>
     </objects>
     <resources>
         <image name="blankAlbum" width="128" height="128"/>

Persephone/Resources/Base.lproj/Main.storyboard

@@ -62,6 +62,20 @@
                                     </items>
                                 </menu>
                             </menuItem>
+                            <menuItem title="Database" id="usv-UH-vkC">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                                <menu key="submenu" title="Database" autoenablesItems="NO" id="rFP-zL-1X4">
+                                    <items>
+                                        <menuItem title="Update" keyEquivalent="u" id="EJg-93-1F6">
+                                            <attributedString key="attributedTitle"/>
+                                            <modifierMask key="keyEquivalentModifierMask" option="YES" command="YES"/>
+                                            <connections>
+                                                <action selector="updateDatabase:" target="Voe-Tx-rLC" id="FO1-Ge-TUL"/>
+                                            </connections>
+                                        </menuItem>
+                                    </items>
+                                </menu>
+                            </menuItem>
                             <menuItem title="Window" id="aUF-d1-5bR">
                                 <modifierMask key="keyEquivalentModifierMask"/>
                                 <menu key="submenu" title="Window" systemMenu="window" id="Td7-aD-5lo">
@@ -105,7 +119,11 @@
                         <outlet property="delegate" destination="Voe-Tx-rLC" id="PrD-fu-P6m"/>
                     </connections>
                 </application>
-                <customObject id="Voe-Tx-rLC" customClass="AppDelegate" customModule="Persephone" customModuleProvider="target"/>
+                <customObject id="Voe-Tx-rLC" customClass="AppDelegate" customModule="Persephone" customModuleProvider="target">
+                    <connections>
+                        <outlet property="updateDatabaseMenuItem" destination="EJg-93-1F6" id="gMf-SQ-lyI"/>
+                    </connections>
+                </customObject>
                 <customObject id="YLy-65-1bz" customClass="NSFontManager"/>
                 <customObject id="Ady-hI-5gd" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
             </objects>
@@ -185,9 +203,17 @@
                                         </textFieldCell>
                                     </textField>
                                 </toolbarItem>
+                                <toolbarItem implicitItemIdentifier="6B3CE282-B6C1-48BF-8962-1A02892D8DF8" label="" paletteLabel="" tag="-1" sizingBehavior="auto" id="fw4-Lp-bWJ">
+                                    <nil key="toolTip"/>
+                                    <progressIndicator key="view" identifier="databaseUpdatingIndicator" wantsLayer="YES" horizontalHuggingPriority="750" verticalHuggingPriority="750" maxValue="100" displayedWhenStopped="NO" bezeled="NO" indeterminate="YES" controlSize="small" style="spinning" id="LpV-iM-o6t">
+                                        <rect key="frame" x="0.0" y="14" width="16" height="16"/>
+                                        <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
+                                    </progressIndicator>
+                                </toolbarItem>
                             </allowedToolbarItems>
                             <defaultToolbarItems>
                                 <toolbarItem reference="p3r-ty-Pxf"/>
+                                <toolbarItem reference="fw4-Lp-bWJ"/>
                                 <toolbarItem reference="9ol-aR-mzv"/>
                                 <toolbarItem reference="n52-8S-6kR"/>
                                 <toolbarItem reference="s1h-EC-nvL"/>
@@ -200,6 +226,7 @@
                         </connections>
                     </window>
                     <connections>
+                        <outlet property="databaseUpdatingIndicator" destination="LpV-iM-o6t" id="y0T-eR-ygY"/>
                         <outlet property="trackProgress" destination="kx6-xm-TAN" id="XDv-Th-Agj"/>
                         <outlet property="trackProgressBar" destination="KMy-xf-rmN" id="a67-JU-cyQ"/>
                         <outlet property="trackRemaining" destination="9WZ-ij-lrb" id="0pH-d7-wvD"/>
@@ -239,7 +266,7 @@
         <!--Window Controller-->
         <scene sceneID="Rpk-bo-5kf">
             <objects>
-                <windowController id="xYu-7w-E5x" sceneMemberID="viewController">
+                <windowController id="xYu-7w-E5x" customClass="PreferencesWindowController" customModule="Persephone" customModuleProvider="target" sceneMemberID="viewController">
                     <window key="window" title="Preferences" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" releasedWhenClosed="NO" visibleAtLaunch="NO" frameAutosaveName="" animationBehavior="default" id="3FN-my-6kU">
                         <windowStyleMask key="styleMask" titled="YES" closable="YES"/>
                         <rect key="contentRect" x="245" y="301" width="416" height="100"/>
@@ -249,24 +276,107 @@
                         </connections>
                     </window>
                     <connections>
-                        <segue destination="nYi-sw-ZNp" kind="relationship" relationship="window.shadowedContentViewController" id="607-3F-gJf"/>
+                        <segue destination="zhe-qh-Mal" kind="relationship" relationship="window.shadowedContentViewController" id="iWi-v3-HxM"/>
                     </connections>
                 </windowController>
                 <customObject id="0sd-8B-etN" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="915" y="-89"/>
+            <point key="canvasLocation" x="915" y="-155"/>
         </scene>
-        <!--Preferences View Controller-->
+        <!--General-->
+        <scene sceneID="5er-B6-hoB">
+            <objects>
+                <tabViewController title="General" selectedTabViewItemIndex="0" tabStyle="toolbar" id="zhe-qh-Mal" customClass="PreferencesViewController" customModule="Persephone" customModuleProvider="target" sceneMemberID="viewController">
+                    <tabViewItems>
+                        <tabViewItem label="General" identifier="generalPreferencesTab" image="NSPreferencesGeneral" id="kn0-fa-vM3"/>
+                        <tabViewItem label="Album Art" identifier="albumArtPreferencesTab" image="coverArtPreferencesIcon" id="4Lj-dz-bOK"/>
+                    </tabViewItems>
+                    <viewControllerTransitionOptions key="transitionOptions" allowUserInteraction="YES"/>
+                    <tabView key="tabView" type="noTabsNoBorder" id="6dC-M0-oC5">
+                        <rect key="frame" x="0.0" y="0.0" width="418" height="300"/>
+                        <autoresizingMask key="autoresizingMask"/>
+                        <font key="font" metaFont="message"/>
+                        <connections>
+                            <outlet property="delegate" destination="zhe-qh-Mal" id="LUL-qN-JlP"/>
+                        </connections>
+                    </tabView>
+                    <connections>
+                        <outlet property="tabView" destination="6dC-M0-oC5" id="jFQ-3f-s5E"/>
+                        <segue destination="nYi-sw-ZNp" kind="relationship" relationship="tabItems" id="Jr4-ql-vhk"/>
+                        <segue destination="3C9-vU-zjZ" kind="relationship" relationship="tabItems" id="zOQ-NT-Tof"/>
+                    </connections>
+                </tabViewController>
+                <customObject id="XtF-QO-9W0" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="916" y="236"/>
+        </scene>
+        <!--Album Art-->
+        <scene sceneID="pQx-0G-WVt">
+            <objects>
+                <viewController title="Album Art" id="3C9-vU-zjZ" customClass="AlbumArtPrefsController" customModule="Persephone" customModuleProvider="target" sceneMemberID="viewController">
+                    <view key="view" id="PyK-v2-kus">
+                        <rect key="frame" x="0.0" y="0.0" width="524" height="100"/>
+                        <autoresizingMask key="autoresizingMask"/>
+                        <subviews>
+                            <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="zZn-Rm-e1f">
+                                <rect key="frame" x="53" y="62" width="104" height="17"/>
+                                <textFieldCell key="cell" lineBreakMode="clipping" title="Music Directory:" id="sPn-V6-CfK">
+                                    <font key="font" usesAppearanceFont="YES"/>
+                                    <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
+                                    <color key="backgroundColor" name="textBackgroundColor" catalog="System" colorSpace="catalog"/>
+                                </textFieldCell>
+                            </textField>
+                            <textField verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="gDk-ca-eOa">
+                                <rect key="frame" x="162" y="58" width="288" height="22"/>
+                                <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" selectable="YES" editable="YES" sendsActionOnEndEditing="YES" borderStyle="bezel" placeholderString="~/Music" drawsBackground="YES" id="7WZ-b7-GUs">
+                                    <font key="font" metaFont="system"/>
+                                    <color key="textColor" name="controlTextColor" catalog="System" colorSpace="catalog"/>
+                                    <color key="backgroundColor" name="textBackgroundColor" catalog="System" colorSpace="catalog"/>
+                                </textFieldCell>
+                                <connections>
+                                    <action selector="updateMpdLibraryDir:" target="3C9-vU-zjZ" id="3Ta-fH-5Zh"/>
+                                </connections>
+                            </textField>
+                            <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="pRL-MG-1Be">
+                                <rect key="frame" x="160" y="27" width="265" height="18"/>
+                                <buttonCell key="cell" type="check" title="Fetch missing artwork from MusicBrainz" bezelStyle="regularSquare" imagePosition="left" inset="2" id="LpD-Ew-HMd">
+                                    <behavior key="behavior" changeContents="YES" doesNotDimImage="YES" lightByContents="YES"/>
+                                    <font key="font" metaFont="system"/>
+                                </buttonCell>
+                                <connections>
+                                    <action selector="updateFetchMissingArtworkFromInternet:" target="3C9-vU-zjZ" id="I7x-9V-xJr"/>
+                                </connections>
+                            </button>
+                        </subviews>
+                        <constraints>
+                            <constraint firstItem="zZn-Rm-e1f" firstAttribute="leading" secondItem="PyK-v2-kus" secondAttribute="leading" constant="55" id="F9T-mO-lMa"/>
+                            <constraint firstItem="gDk-ca-eOa" firstAttribute="top" secondItem="PyK-v2-kus" secondAttribute="top" constant="20" symbolic="YES" id="NSz-Xf-KZS"/>
+                            <constraint firstAttribute="trailing" secondItem="gDk-ca-eOa" secondAttribute="trailing" constant="74" id="QMb-TP-IdQ"/>
+                            <constraint firstItem="pRL-MG-1Be" firstAttribute="top" secondItem="gDk-ca-eOa" secondAttribute="bottom" constant="15" id="bD6-hA-Wz5"/>
+                            <constraint firstItem="gDk-ca-eOa" firstAttribute="leading" secondItem="zZn-Rm-e1f" secondAttribute="trailing" constant="7" id="oZ5-45-Pe5"/>
+                            <constraint firstItem="gDk-ca-eOa" firstAttribute="leading" secondItem="pRL-MG-1Be" secondAttribute="leading" id="sBG-Yb-ii6"/>
+                            <constraint firstItem="zZn-Rm-e1f" firstAttribute="top" secondItem="PyK-v2-kus" secondAttribute="top" constant="21" id="wHW-jd-TaG"/>
+                        </constraints>
+                    </view>
+                    <connections>
+                        <outlet property="fetchMissingArtworkFromInternet" destination="pRL-MG-1Be" id="Xcp-sb-iZm"/>
+                        <outlet property="mpdLibraryDirField" destination="gDk-ca-eOa" id="myi-BQ-0NS"/>
+                    </connections>
+                </viewController>
+                <customObject id="KzD-E3-lpA" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="1626" y="339"/>
+        </scene>
+        <!--General-->
         <scene sceneID="xTC-Y5-Agk">
             <objects>
-                <viewController id="nYi-sw-ZNp" customClass="PreferencesViewController" customModule="Persephone" customModuleProvider="target" sceneMemberID="viewController">
+                <viewController title="General" id="nYi-sw-ZNp" customClass="GeneralPrefsViewController" customModule="Persephone" customModuleProvider="target" sceneMemberID="viewController">
                     <view key="view" id="Uwt-Lw-ILP">
                         <rect key="frame" x="0.0" y="0.0" width="420" height="100"/>
                         <autoresizingMask key="autoresizingMask"/>
                         <subviews>
-                            <textField verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="wPm-sJ-e9E">
+                            <textField verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="wPm-sJ-e9E">
                                 <rect key="frame" x="162" y="58" width="184" height="22"/>
-                                <autoresizingMask key="autoresizingMask"/>
                                 <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" selectable="YES" editable="YES" sendsActionOnEndEditing="YES" borderStyle="bezel" alignment="left" placeholderString="127.0.0.1" drawsBackground="YES" id="MSX-mn-2ma">
                                     <font key="font" usesAppearanceFont="YES"/>
                                     <color key="textColor" name="controlTextColor" catalog="System" colorSpace="catalog"/>
@@ -276,9 +386,11 @@
                                     <action selector="updateMpdHost:" target="nYi-sw-ZNp" id="Y7x-N9-6ag"/>
                                 </connections>
                             </textField>
-                            <textField verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="IbX-oV-soD">
+                            <textField verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="IbX-oV-soD">
                                 <rect key="frame" x="162" y="26" width="80" height="22"/>
-                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
+                                <constraints>
+                                    <constraint firstAttribute="width" constant="80" id="WAb-PB-Z1Y"/>
+                                </constraints>
                                 <textFieldCell key="cell" scrollable="YES" lineBreakMode="clipping" selectable="YES" editable="YES" sendsActionOnEndEditing="YES" state="on" borderStyle="bezel" placeholderString="6600" drawsBackground="YES" id="i9j-nB-bqq">
                                     <numberFormatter key="formatter" formatterBehavior="custom10_4" numberStyle="decimal" usesGroupingSeparator="NO" minimumIntegerDigits="1" maximumIntegerDigits="2000000000" maximumFractionDigits="3" id="UiQ-gi-Hbp">
                                         <real key="minimum" value="0.0"/>
@@ -292,18 +404,19 @@
                                     <action selector="updateMpdPort:" target="nYi-sw-ZNp" id="406-EC-aO2"/>
                                 </connections>
                             </textField>
-                            <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="kvB-99-zwY">
+                            <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="kvB-99-zwY">
                                 <rect key="frame" x="76" y="62" width="80" height="17"/>
-                                <autoresizingMask key="autoresizingMask"/>
+                                <constraints>
+                                    <constraint firstAttribute="width" constant="76" id="4VR-n5-bGr"/>
+                                </constraints>
                                 <textFieldCell key="cell" lineBreakMode="clipping" alignment="right" title="Server Host:" id="AVi-g9-Irz">
                                     <font key="font" metaFont="system"/>
                                     <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
                                     <color key="backgroundColor" name="textBackgroundColor" catalog="System" colorSpace="catalog"/>
                                 </textFieldCell>
                             </textField>
-                            <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="AU9-wN-kbU">
+                            <textField horizontalHuggingPriority="251" verticalHuggingPriority="750" misplaced="YES" translatesAutoresizingMaskIntoConstraints="NO" id="AU9-wN-kbU">
                                 <rect key="frame" x="77" y="30" width="77" height="17"/>
-                                <autoresizingMask key="autoresizingMask"/>
                                 <textFieldCell key="cell" lineBreakMode="clipping" alignment="right" title="Server Port:" id="DgA-xT-2ir">
                                     <font key="font" metaFont="system"/>
                                     <color key="textColor" name="labelColor" catalog="System" colorSpace="catalog"/>
@@ -311,6 +424,18 @@
                                 </textFieldCell>
                             </textField>
                         </subviews>
+                        <constraints>
+                            <constraint firstItem="wPm-sJ-e9E" firstAttribute="top" secondItem="Uwt-Lw-ILP" secondAttribute="top" constant="20" symbolic="YES" id="1u9-dh-XrA"/>
+                            <constraint firstItem="wPm-sJ-e9E" firstAttribute="leading" secondItem="kvB-99-zwY" secondAttribute="trailing" constant="8" symbolic="YES" id="655-3c-mJH"/>
+                            <constraint firstItem="AU9-wN-kbU" firstAttribute="top" secondItem="kvB-99-zwY" secondAttribute="bottom" constant="15" id="FPR-mZ-SUo"/>
+                            <constraint firstItem="IbX-oV-soD" firstAttribute="top" secondItem="wPm-sJ-e9E" secondAttribute="bottom" constant="10" symbolic="YES" id="G7a-VX-OLJ"/>
+                            <constraint firstItem="kvB-99-zwY" firstAttribute="top" secondItem="Uwt-Lw-ILP" secondAttribute="top" constant="21" id="ITg-Ag-wpl"/>
+                            <constraint firstItem="kvB-99-zwY" firstAttribute="leading" secondItem="Uwt-Lw-ILP" secondAttribute="leading" constant="78" id="Kw0-2i-oST"/>
+                            <constraint firstItem="IbX-oV-soD" firstAttribute="leading" secondItem="AU9-wN-kbU" secondAttribute="trailing" constant="10" id="Y6y-25-qRM"/>
+                            <constraint firstAttribute="trailing" secondItem="wPm-sJ-e9E" secondAttribute="trailing" constant="74" id="cX3-Sz-RXR"/>
+                            <constraint firstItem="kvB-99-zwY" firstAttribute="centerX" secondItem="AU9-wN-kbU" secondAttribute="centerX" id="fdg-fL-UzL"/>
+                            <constraint firstItem="wPm-sJ-e9E" firstAttribute="leading" secondItem="IbX-oV-soD" secondAttribute="leading" id="qBw-Ri-Z4l"/>
+                        </constraints>
                     </view>
                     <connections>
                         <outlet property="mpdHostField" destination="wPm-sJ-e9E" id="PR7-oL-tVQ"/>
@@ -319,7 +444,7 @@
                 </viewController>
                 <customObject id="lzf-yO-5pP" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="917" y="217"/>
+            <point key="canvasLocation" x="1574" y="69"/>
         </scene>
         <!--Queue View Controller-->
         <scene sceneID="QcX-dC-cTZ">
@@ -478,7 +603,7 @@
                 </viewController>
                 <customObject id="du4-e9-TfX" userLabel="First Responder" customClass="NSResponder" sceneMemberID="firstResponder"/>
             </objects>
-            <point key="canvasLocation" x="848" y="635"/>
+            <point key="canvasLocation" x="834" y="679"/>
         </scene>
         <!--Album View Controller-->
         <scene sceneID="7Ua-Hj-zWt">
@@ -494,7 +619,7 @@
                                     <rect key="frame" x="0.0" y="0.0" width="450" height="300"/>
                                     <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                     <subviews>
-                                        <collectionView id="lfq-AB-epE">
+                                        <collectionView identifier="albumCollectionView" id="lfq-AB-epE">
                                             <rect key="frame" x="0.0" y="0.0" width="450" height="158"/>
                                             <autoresizingMask key="autoresizingMask" widthSizable="YES"/>
                                             <collectionViewLayout key="collectionViewLayout" id="YE8-sD-l5P" customClass="AlbumViewLayout" customModule="Persephone" customModuleProvider="target"/>
@@ -533,6 +658,8 @@
         </scene>
     </scenes>
     <resources>
+        <image name="NSPreferencesGeneral" width="32" height="32"/>
+        <image name="coverArtPreferencesIcon" width="32" height="32"/>
         <image name="nextTrackButton" width="17" height="17"/>
         <image name="playButton" width="17" height="17"/>
         <image name="prevTrackButton" width="17" height="17"/>

Persephone/Services/AlbumArtService.swift

@@ -0,0 +1,54 @@
+//
+//  AlbumArtService.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/2/23.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+import PromiseKit
+
+class AlbumArtService {
+  var preferences = Preferences()
+  let album: AlbumItem
+  
+  let cachedArtworkSize = 180
+  let cachedArtworkQuality: CGFloat = 0.5
+
+  var session = URLSession(configuration: .default)
+  let cacheQueue = DispatchQueue(label: "albumArtCacheQueue")
+
+  init(album: AlbumItem) {
+    self.album = album
+  }
+
+  func fetchAlbumArt(callback: @escaping (_ image: NSImage?) -> Void) {
+    cacheQueue.async {
+      firstly {
+        self.getCachedArtwork()
+      }.then { artwork -> Promise<NSImage?> in
+        artwork.map(Promise.value) ?? self.cacheIfNecessary(self.getArtworkFromFilesystem())
+      }.then { artwork -> Promise<NSImage?> in
+        artwork.map(Promise.value) ?? self.cacheIfNecessary(self.getArtworkFromMusicBrainz().map(Optional.some))
+      }.tap { result in
+        switch result {
+        case .fulfilled(nil), .rejected(MusicBrainzError.noArtworkAvailable):
+          self.cacheArtwork(data: Data())
+        default:
+          break
+        }
+      }.recover { error in
+        .value(nil)
+      }.done(callback)
+    }
+  }
+
+  func cacheIfNecessary(_ promise: Promise<NSImage?>) -> Promise<NSImage?> {
+    return promise.get { image in
+      if let data = image?.jpegData(compressionQuality: self.cachedArtworkQuality) {
+        self.cacheArtwork(data: data)
+      }
+    }
+  }
+}

Persephone/Services/Extensions/AlbumArtService+Caching.swift

@@ -0,0 +1,35 @@
+//
+//  AlbumArtService+Caching.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/17.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+import PromiseKit
+
+extension AlbumArtService {
+  static let cacheDir = try! FileManager.default.url(for: .cachesDirectory, in: .userDomainMask, appropriateFor: nil, create: true).appendingPathComponent(Bundle.main.bundleIdentifier!)
+
+  func getCachedArtwork() -> Promise<NSImage?> {
+    return Promise { seal in
+      let cacheFilePath = AlbumArtService.cacheDir.appendingPathComponent(album.hash).path
+      let data = FileManager.default.contents(atPath: cacheFilePath)
+      let image = data.flatMap(NSImage.init(data:))
+
+      seal.fulfill(image)
+    }
+  }
+
+  func cacheArtwork(data: Data?) {
+    guard let bundleIdentifier = Bundle.main.bundleIdentifier,
+      let cacheDir = try? FileManager.default.url(for: .cachesDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
+        .appendingPathComponent(bundleIdentifier)
+      else { return }
+
+    let cacheFilePath = cacheDir.appendingPathComponent(album.hash).path
+
+    FileManager.default.createFile(atPath: cacheFilePath, contents: data, attributes: nil)
+  }
+}

Persephone/Services/Extensions/AlbumArtService+Filesystem.swift

@@ -0,0 +1,49 @@
+//
+//  AlbumArtService+Filesystem.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/17.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+import PromiseKit
+
+extension AlbumArtService {
+  func getArtworkFromFilesystem() -> Promise<NSImage?> {
+    let coverArtFilenames = [
+      "folder.jpg",
+      "cover.jpg",
+      "\(album.artist) - \(album.title).jpg"
+    ]
+
+    return getAlbumURI().map { albumURI in
+        let musicDir = self.preferences.expandedMpdLibraryDir
+
+        return coverArtFilenames
+          .lazy
+          .map { "\(musicDir)/\($0)" }
+          .compactMap(self.tryImage)
+          .first
+      }
+  }
+
+  func getAlbumURI() -> Promise<String> {
+    return Promise { seal in
+      AppDelegate.mpdClient.getAlbumURI(for: album.album, callback: seal.fulfill)
+    }
+      .compactMap { $0 }
+  }
+
+  func tryImage(_ filePath: String) -> NSImage? {
+    guard let data = FileManager.default.contents(atPath: filePath),
+      let image = NSImage(data: data)
+      else { return nil }
+
+    let imageThumb = image.toFitBox(
+      size: NSSize(width: self.cachedArtworkSize, height: self.cachedArtworkSize)
+    )
+
+    return imageThumb
+  }
+}

Persephone/Services/Extensions/AlbumArtService+Remote.swift

@@ -0,0 +1,54 @@
+//
+//  AlbumArtService+Remote.swift
+//  Persephone
+//
+//  Created by Daniel Barber on 2019/3/17.
+//  Copyright © 2019 Dan Barber. All rights reserved.
+//
+
+import Cocoa
+import SwiftyJSON
+import PromiseKit
+import PMKFoundation
+
+extension AlbumArtService {
+  enum MusicBrainzError: Error {
+    case noArtworkAvailable
+  }
+
+  func getRemoteArtwork() -> Promise<NSImage> {
+    return Promise { seal in
+      let albumArtWorkItem = DispatchWorkItem {
+        self.getArtworkFromMusicBrainz().pipe(to: seal.resolve)
+      }
+
+      AlbumArtQueue.shared.addToQueue(workItem: albumArtWorkItem)
+    }
+  }
+
+  func getArtworkFromMusicBrainz() -> Promise<NSImage> {
+    var search = URLComponents(string: "https://musicbrainz.org/ws/2/release/")!
+    search.query = "query=artist:\(album.artist) AND release:\(album.title) AND country:US&limit=1&fmt=json"
+
+    return URLSession.shared.dataTask(.promise, with: search.url!).validate()
+      .compactMap {
+        JSON($0.data)
+      }.compactMap {
+        $0["releases"][0]["id"].string
+      }.compactMap {
+        URLComponents(string: "https://coverartarchive.org/release/\($0)/front-500")?.url
+      }.then { (url: URL?) -> Promise<(data: Data, response: URLResponse)> in
+        return URLSession.shared.dataTask(.promise, with: url!).validate()
+      }.compactMap {
+        NSImage(data: $0.data)?.toFitBox(
+          size: NSSize(width: self.cachedArtworkSize, height: self.cachedArtworkSize)
+        )
+      }.recover { error -> Promise<NSImage> in
+        if case PMKHTTPError.badStatusCode(404, _, _) = error {
+          throw MusicBrainzError.noArtworkAvailable
+        } else {
+          throw error
+        }
+      }
+  }
+}

bin/release

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+set -o pipefail && \
+
+xcodebuild \
+  -project Persephone.xcodeproj \
+  -scheme Persephone \
+  -destination platform\=macOS build \
+  -configuration Release \
+| xcpretty