Remove legacy pasteboard writer for tracklist

Also refactoring:

- You're now able to drop between tracklist and playlist. They now use
  very similar logic for determining if it's reordering or inserting.
- Fix the drag image handler for table views without headers.
- Remove the tracklist indices pasteboard type.

Unfortunately there's some very similar code in both controllers,
because move does not return an IndexSet. This should be refactored.

Submariner/PasteboardType+Submariner.swift

@@ -20,8 +20,6 @@ extension NSPasteboard.PasteboardType {
     ///
     /// Usually multiple of these will exist on a pasteboard.
     static let libraryItem = NSPasteboard.PasteboardType(rawValue: "com.submarinerapp.item-url-string")
-    /// Tracks from the tracklist, represented as an index set.
-    static let tracklistIndices = NSPasteboard.PasteboardType(rawValue: "com.submarinerapp.tracklist-indices")
     /// The index of a row, as a raw integer in a Data wrapper.
     static let rowIndex = NSPasteboard.PasteboardType(rawValue: "com.submarinerapp.row-index")
 }

Submariner/SBPlaylist.swift

@@ -52,6 +52,11 @@ public class SBPlaylist: SBResource {
         trackIDs?.append(contentsOf: additionalIDs)
     }
 
+    func add(tracks: [SBTrack], at row: Int) {
+        let additionalIDs = tracks.map { $0.objectID.uriRepresentation() }
+        trackIDs?.insert(contentsOf: additionalIDs, at: row)
+    }
+
     func remove(indices: IndexSet) {
         trackIDs?.remove(atOffsets: indices)
     }

Submariner/SBPlaylistController.swift

@@ -142,27 +142,45 @@ import Cocoa
     }
 
     func tableView(_ tableView: NSTableView, validateDrop info: any NSDraggingInfo, proposedRow row: Int, proposedDropOperation dropOperation: NSTableView.DropOperation) -> NSDragOperation {
-        // internal drop track
-        if row != -1 && dropOperation == .above && info.draggingPasteboard.libraryItems() != nil {
-            return .move
+        guard row != -1 && dropOperation == .above else {
+            return []
         }
 
+        if let sourceTable = info.draggingSource as? SBTableView, sourceTable == tracksTableView {
+            return .move
+        } else if info.draggingPasteboard.libraryItems() != nil {
+            return .copy
+        }
         return []
     }
 
     func tableView(_ tableView: NSTableView, acceptDrop info: any NSDraggingInfo, row: Int, dropOperation: NSTableView.DropOperation) -> Bool {
-        if info.draggingSourceOperationMask.contains(.move) {
+        // XXX: For some reason, draggingSourceOperationMask has all bits set?
+        if let sourceTable = info.draggingSource as? SBTableView, sourceTable == tracksTableView {
             let indices = info.draggingPasteboard.rowIndices()
-
             playlist.moveTracks(fromOffsets: indices, toOffset: row)
 
-            tracksController.rearrangeObjects()
-            tracksTableView.reloadData()
-
-            // submit changes to server, this uses createPlaylist behind the scenes since we can reorder with it
-            if let server = playlist.server, let playlistID = playlist.itemId {
-                server.updatePlaylist(ID: playlistID, tracks: tracks)
+            // change selection to match new indices, since Array.move doesn't return them
+            var newRow = row
+            for index in indices {
+                if index < newRow {
+                    newRow -= 1
+                }
             }
+            let lastRow = newRow + indices.count - 1
+            let newRange = newRow...lastRow
+            let newIndexSet = IndexSet(integersIn: newRange)
+            tracksTableView.selectRowIndexes(newIndexSet, byExtendingSelection: false)
+        } else if let tracks = info.draggingPasteboard.libraryItems(managedObjectContext: self.managedObjectContext) {
+            playlist.add(tracks: tracks, at: row)
+        }
+
+        tracksController.rearrangeObjects()
+        tracksTableView.reloadData()
+
+        // submit changes to server, this uses createPlaylist behind the scenes since we can reorder with it
+        if let server = playlist.server, let playlistID = playlist.itemId {
+            server.updatePlaylist(ID: playlistID, tracks: tracks)
         }
         return true
     }

Submariner/SBTableView+DragImage.swift

@@ -32,7 +32,9 @@ extension SBTableView {
     func setDragImage(of item: NSDraggingItem, for row: Int, at screenPoint: NSPoint) {
         // Find the left edge of the row by converting the header view origin to
         // the table view coordinate
-        var headerOrigin = convert(headerView?.frame.origin ?? NSZeroPoint, fromDescendant: headerView)
+        // If the header view doesn't exist (i.e. tracklist), let's use our superview,
+        // since we can't use ourself.
+        var headerOrigin = convert(headerView?.frame.origin ?? NSZeroPoint, fromDescendant: headerView ?? self.superview)
 
         // Generate the drag image from the current row with all the columns
         var p: NSPoint = .zero

Submariner/SBTracklistController.swift

@@ -27,7 +27,7 @@ import Cocoa
 
         title = "Tracklist"
 
-        playlistTableView.registerForDraggedTypes([.libraryItems, .libraryItem, .tracklistIndices])
+        playlistTableView.registerForDraggedTypes([.libraryItems, .libraryItem])
 
         notificationObserver = NotificationCenter.default.addObserver(forName: .SBPlayerPlaylistUpdated,
                                                                       object: nil,
@@ -126,42 +126,33 @@ import Cocoa
 
     // #MARK: - NSTableView Delegate
 
-    // FIXME: Replace with tableView:pasteboardWriterForRow:?
-    func tableView(_ tableView: NSTableView, writeRowsWith rowIndexes: IndexSet, to pboard: NSPasteboard) -> Bool {
-        do {
-            let data = try NSKeyedArchiver.archivedData(withRootObject: rowIndexes, requiringSecureCoding: true)
-
-            pboard.declareTypes([.tracklistIndices], owner: self)
-            pboard.setData(data, forType: .tracklistIndices)
-
-            return true
-        } catch {
-            return false
+    func tableView(_ tableView: NSTableView, pasteboardWriterForRow row: Int) -> (any NSPasteboardWriting)? {
+        if tableView == playlistTableView {
+            let track = SBPlayer.sharedInstance().playlist[row]
+            return SBLibraryItemPasteboardWriter(item: track, index: row)
         }
+        return nil
     }
 
     func tableView(_ tableView: NSTableView, validateDrop info: NSDraggingInfo, proposedRow row: Int, proposedDropOperation dropOperation: NSTableView.DropOperation) -> NSDragOperation {
         guard row != -1 && dropOperation == .above else {
             return []
         }
 
-        if let types = info.draggingPasteboard.types {
-            if types.contains(.tracklistIndices) {
-                return .move
-            } else if types.contains(.libraryItems) || types.contains(.libraryItem) { // for cursor
-                return .copy
-            }
+        if let sourceTable = info.draggingSource as? SBTableView, sourceTable == playlistTableView {
+            return .move
+        } else if info.draggingPasteboard.libraryItems() != nil {
+            return .copy
         }
-
         return []
     }
 
     static let allowedClasses = [NSIndexSet.self, NSArray.self, NSURL.self]
 
     func tableView(_ tableView: NSTableView, acceptDrop info: NSDraggingInfo, row: Int, dropOperation: NSTableView.DropOperation) -> Bool {
-        if let data = info.draggingPasteboard.data(forType: .tracklistIndices),
-           let rowIndexes = try? NSKeyedUnarchiver.unarchivedObject(ofClasses: SBTracklistController.allowedClasses,
-                                                                    from: data) as? IndexSet {
+        // XXX: For some reason, draggingSourceOperationMask has all bits set?
+        if let sourceTable = info.draggingSource as? SBTableView, sourceTable == playlistTableView {
+            let rowIndexes = info.draggingPasteboard.rowIndices()
             SBPlayer.sharedInstance().move(trackIndexSet: rowIndexes, index: row)
 
             // change selection to match new indices, since Array.move doesn't return them