From f29f690625cb1d31924af09f18434f5215469724 Mon Sep 17 00:00:00 2001
From: Brent Simmons <brent@ranchero.com>
Date: Wed, 19 Sep 2018 13:22:22 -0700
Subject: [PATCH] Start work on drop validation.

---
 .../Sidebar/SidebarOutlineDataSource.swift    | 32 ++++++++++++++-----
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/NetNewsWire/MainWindow/Sidebar/SidebarOutlineDataSource.swift b/NetNewsWire/MainWindow/Sidebar/SidebarOutlineDataSource.swift
index 84138d1bc..137021972 100644
--- a/NetNewsWire/MainWindow/Sidebar/SidebarOutlineDataSource.swift
+++ b/NetNewsWire/MainWindow/Sidebar/SidebarOutlineDataSource.swift
@@ -10,10 +10,12 @@ import AppKit
 import RSTree
 import Articles
 import RSCore
+import Account
 
 @objc final class SidebarOutlineDataSource: NSObject, NSOutlineViewDataSource {
 
 	let treeController: TreeController
+	static let dragOperationNone = NSDragOperation(rawValue: 0)
 
 	init(treeController: TreeController) {
 		self.treeController = treeController
@@ -38,22 +40,21 @@ import RSCore
 
 	func outlineView(_ outlineView: NSOutlineView, pasteboardWriterForItem item: Any) -> NSPasteboardWriting? {
 		let node = nodeForItem(item as AnyObject?)
-
-		guard !(node.representedObject is PseudoFeed) else {
-			// We don’t allow the built-in smart feeds to be dragged.
-			// This will have to be revisited later when there are user-created smart feeds that *can* be dragged.
+		guard nodeRepresentsDraggableItem(node) else {
 			return nil
 		}
-
 		return (node.representedObject as? PasteboardWriterOwner)?.pasteboardWriter
 	}
 
 	// MARK: - Drag and Drop
 
 	func outlineView(_ outlineView: NSOutlineView, validateDrop info: NSDraggingInfo, proposedItem item: Any?, proposedChildIndex index: Int) -> NSDragOperation {
-//		let draggingSourceOutlineView = info.draggingSource() as? NSOutlineView
-//		let isLocalDrop = draggingSourceOutlineView == outlineView
-		return NSDragOperation(rawValue: 0)
+		let draggingSourceOutlineView = info.draggingSource() as? NSOutlineView
+		let isLocalDrop = draggingSourceOutlineView == outlineView
+		if isLocalDrop {
+			return validateLocalDrop(info, proposedItem: item, proposedChildIndex: index)
+		}
+		return SidebarOutlineDataSource.dragOperationNone
 	}
 
 	func outlineView(_ outlineView: NSOutlineView, acceptDrop info: NSDraggingInfo, item: Any?, childIndex index: Int) -> Bool {
@@ -72,4 +73,19 @@ private extension SidebarOutlineDataSource {
 		}
 		return item as! Node
 	}
+
+	func nodeRepresentsDraggableItem(_ node: Node) -> Bool {
+		// Don’t allow PseudoFeed or Folder to be dragged.
+		// This will have to be revisited later. For instance,
+		// user-created smart feeds should be draggable, maybe.
+		// And we might allow dragging folders between accounts.
+		return node.representedObject is Feed
+	}
+
+	func validateLocalDrop(_ info: NSDraggingInfo, proposedItem item: Any?, proposedChildIndex index: Int) -> NSDragOperation {
+
+//		let node = nodeForItem(item)
+		return SidebarOutlineDataSource.dragOperationNone
+
+	}
 }