Make clean up availability take read count into consideration. Issue #2352

Mac/MainWindow/MainWindowController.swift

@@ -918,9 +918,7 @@ private extension MainWindowController {
 	}
 	
 	func validateCleanUp(_ item: NSValidatedUserInterfaceItem) -> Bool {
-		let isSidebarFiltered = sidebarViewController?.isReadFiltered ?? false
+		return timelineContainerViewController?.isCleanUpAvailable ?? false
-		let isTimelineFiltered = timelineContainerViewController?.isReadFiltered ?? false
-		return isSidebarFiltered || isTimelineFiltered
 	}
 
 	func validateToggleReadFeeds(_ item: NSValidatedUserInterfaceItem) -> Bool {

Mac/MainWindow/Timeline/TimelineContainerViewController.swift

@@ -45,6 +45,11 @@ final class TimelineContainerViewController: NSViewController {
 		return regularTimelineViewController.isReadFiltered
 	}
 
+	var isCleanUpAvailable: Bool {
+		guard let currentTimelineViewController = currentTimelineViewController, mode(for: currentTimelineViewController) == .regular else { return false }
+		return regularTimelineViewController.isCleanUpAvailable
+	}
+	
 	lazy var regularTimelineViewController = {
 		return TimelineViewController(delegate: self)
 	}()

Mac/MainWindow/Timeline/TimelineViewController.swift

@@ -43,6 +43,15 @@ final class TimelineViewController: NSViewController, UndoableCommandRunner, Unr
 		}
 	}
 	
+	var isCleanUpAvailable: Bool {
+		guard isReadFiltered ?? false else { return false }
+		
+		let readSelectedCount = selectedArticles.filter({ $0.status.read }).count
+		let readArticleCount = articles.count - unreadCount
+		let availableToCleanCount = readArticleCount - readSelectedCount
+		return availableToCleanCount > 0
+	}
+	
 	var representedObjects: [AnyObject]? {
 		didSet {
 			if !representedObjectArraysAreEqual(oldValue, representedObjects) {