Implement go to next unread

Multiplatform/Shared/SceneModel.swift

@@ -55,7 +55,10 @@ final class SceneModel: ObservableObject {
 	
 	/// Goes to the next unread item found in Sidebar and Timeline order, top to bottom
 	func goToNextUnread() {
-		
+		if !timelineModel.goToNextUnread() {
+			sidebarModel.goToNextUnread()
+			timelineModel.goToNextUnread()
+		}
 	}
 	
 	// MARK: Article Management API

Multiplatform/Shared/Sidebar/SidebarItem.swift

@@ -77,8 +77,22 @@ struct SidebarItem: Identifiable {
 		self.nameForDisplay = feed.nameForDisplay
 	}
 
+	/// Add a sidebar item to the child list
 	mutating func addChild(_ sidebarItem: SidebarItem) {
 		children.append(sidebarItem)
 	}
 	
+	/// Recursively visits each sidebar item.  Return true when done visiting.
+	@discardableResult
+	func visit(_ block: (SidebarItem) -> Bool) -> Bool {
+		let stop = block(self)
+		if !stop {
+			for child in children {
+				if child.visit(block) {
+					break
+				}
+			}
+		}
+		return stop
+	}
 }

Multiplatform/Shared/Sidebar/SidebarModel.swift

@@ -43,14 +43,11 @@ class SidebarModel: ObservableObject, UndoableCommandRunner {
 	// MARK: API
 
 	func goToNextUnread() {
-		guard let lastSelectedFeed = selectedFeeds.last,
-			  let currentSidebarItem = sidebarItems.first(where: { $0.feed?.feedID == lastSelectedFeed.feedID }) else {
-			return
-		}
+		guard let startFeed = selectedFeeds.first ?? sidebarItems.first?.children.first?.feed else { return }
 		
-		if !goToNextUnread(startingAt: currentSidebarItem) {
-			if let firstSidebarItem = sidebarItems.first {
-				goToNextUnread(startingAt: firstSidebarItem)
+		if !goToNextUnread(startingAt: startFeed) {
+			if let firstFeed = sidebarItems.first?.children.first?.feed {
+				goToNextUnread(startingAt: firstFeed)
 			}
 		}
 	}
@@ -193,15 +190,30 @@ private extension SidebarModel {
 	}
 	
 	@discardableResult
-	func goToNextUnread(startingAt: SidebarItem) -> Bool {
-		guard let startIndex = sidebarItems.firstIndex(where: { $0.id == startingAt.id }) else { return false }
-		
-		for i in startIndex..<sidebarItems.count {
-			if sidebarItems[i].unreadCount > 0, let feedID = sidebarItems[i].feed?.feedID {
-				select(feedID)
-				return true
+	func goToNextUnread(startingAt: Feed) -> Bool {
+
+		var foundStartFeed = false
+		var nextSidebarItem: SidebarItem? = nil
+		for section in sidebarItems {
+			if nextSidebarItem == nil  {
+				section.visit { sidebarItem in
+					if !foundStartFeed && sidebarItem.feed?.feedID == startingAt.feedID {
+						foundStartFeed = true
+						return false
+					}
+					if foundStartFeed && sidebarItem.unreadCount > 0 {
+						nextSidebarItem = sidebarItem
+						return true
+					}
+					return false
+				}
 			}
 		}
+
+		if let nextFeedID = nextSidebarItem?.feed?.feedID {
+			select(nextFeedID)
+			return true
+		}
 		
 		return false
 	}

Multiplatform/Shared/Timeline/TimelineModel.swift

@@ -315,12 +315,23 @@ class TimelineModel: ObservableObject, UndoableCommandRunner {
 		openIndicatedArticleInBrowser(article)
 	}
 
-	func canGoToNextUnread() -> Bool {
-		return false
-	}
-	
-	func goToNextUnread() {
+	@discardableResult
+	func goToNextUnread() -> Bool {
+		var startIndex: Int
+		if let firstArticle = selectedArticles.first, let index = timelineItems.firstIndex(where: { $0.article == firstArticle }) {
+			startIndex = index
+		} else {
+			startIndex = 0
+		}
 		
+		for i in startIndex..<timelineItems.count {
+			if !timelineItems[i].article.status.read {
+				select(timelineItems[i].article.articleID)
+				return true
+			}
+		}
+		
+		return false
 	}
 
 	func articleFor(_ articleID: String) -> Article? {
@@ -382,6 +393,11 @@ private extension TimelineModel {
 		runCommand(markReadCommand)
 	}
 	
+	func select(_ articleID: String) {
+		selectedArticleIDs = Set([articleID])
+		selectedArticleID = articleID
+	}
+	
 	// MARK: Timeline Management
 	
 	func resetReadFilter() {