Change Feeds to use diffable data sources

iOS/MasterFeed/MasterFeedDataSource.swift

@@ -0,0 +1,87 @@
+//
+//  MasterFeedDataSource.swift
+//  NetNewsWire-iOS
+//
+//  Created by Maurice Parker on 8/28/19.
+//  Copyright © 2019 Ranchero Software. All rights reserved.
+//
+
+import UIKit
+import RSCore
+import RSTree
+import Account
+
+class MasterFeedDataSource<SectionIdentifierType, ItemIdentifierType>: UITableViewDiffableDataSource<SectionIdentifierType, ItemIdentifierType> where SectionIdentifierType : Hashable, ItemIdentifierType : Hashable {
+
+	private var coordinator: AppCoordinator!
+	private var errorHandler: ((Error) -> ())!
+	
+	init(coordinator: AppCoordinator, errorHandler: @escaping (Error) -> (), tableView: UITableView, cellProvider: @escaping UITableViewDiffableDataSource<SectionIdentifierType, ItemIdentifierType>.CellProvider) {
+		super.init(tableView: tableView, cellProvider: cellProvider)
+		self.coordinator = coordinator
+		self.errorHandler = errorHandler
+	}
+	
+	override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
+		guard let node = coordinator.nodeFor(indexPath), !(node.representedObject is PseudoFeed) else {
+			return false
+		}
+		return true
+	}
+	
+	override func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool {
+		guard let node = coordinator.nodeFor(indexPath) else {
+			return false
+		}
+		return node.representedObject is Feed
+	}
+	
+	override func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
+
+		guard let sourceNode = coordinator.nodeFor(sourceIndexPath), let feed = sourceNode.representedObject as? Feed else {
+			return
+		}
+
+		// Based on the drop we have to determine a node to start looking for a parent container.
+		let destNode: Node = {
+			if destinationIndexPath.row == 0 {
+				return coordinator.rootNode.childAtIndex(destinationIndexPath.section)!
+			} else {
+				let movementAdjustment = sourceIndexPath > destinationIndexPath ? 1 : 0
+				let adjustedDestIndexPath = IndexPath(row: destinationIndexPath.row - movementAdjustment, section: destinationIndexPath.section)
+				return coordinator.nodeFor(adjustedDestIndexPath)!
+			}
+		}()
+
+		// Now we start looking for the parent container
+		let destParentNode: Node? = {
+			if destNode.representedObject is Container {
+				return destNode
+			} else {
+				if destNode.parent?.representedObject is Container {
+					return destNode.parent!
+				} else {
+					return nil
+				}
+			}
+		}()
+		
+		// Move the Feed
+		guard let source = sourceNode.parent?.representedObject as? Container, let destination = destParentNode?.representedObject as? Container else {
+			return
+		}
+		
+		BatchUpdate.shared.start()
+		source.account?.moveFeed(feed, from: source, to: destination) { result in
+			switch result {
+			case .success:
+				BatchUpdate.shared.end()
+			case .failure(let error):
+				self.errorHandler(error)
+			}
+		}
+
+	}
+	
+
+}