Add basic timeline fetching

Multiplatform/Shared/SceneModel.swift

@@ -20,10 +20,6 @@ final class SceneModel: ObservableObject {
 
 extension SceneModel: SidebarModelDelegate {
 	
-	func sidebarSelectionDidChange(_: SidebarModel, feeds: [Feed]?) {
-		print("**** sidebar selection changed ***")
-	}
-	
 	func unreadCount(for feed: Feed) -> Int {
 		// TODO: Get the count from the timeline if Feed is the current timeline
 		return feed.unreadCount

Multiplatform/Shared/Sidebar/SidebarModel.swift

@@ -11,7 +11,6 @@ import RSCore
 import Account
 
 protocol SidebarModelDelegate: class {
-	func sidebarSelectionDidChange(_: SidebarModel, feeds: [Feed]?)
 	func unreadCount(for: Feed) -> Int
 }
 

Multiplatform/Shared/Timeline/TimelineContainerView.swift

@@ -30,10 +30,3 @@ struct TimelineContainerView: View {
 	}
 	
 }
-
-struct TimelineContainerView_Previews: PreviewProvider {
-	static var previews: some View {
-		TimelineContainerView()
-			.environmentObject(SceneModel())
-	}
-}

Multiplatform/Shared/Timeline/TimelineItemView.swift

@@ -13,7 +13,11 @@ struct TimelineItemView: View {
 	var timelineItem: TimelineItem
 	
     var body: some View {
-		Text(verbatim: timelineItem.article.title ?? "N/A")
+		VStack {
+			Text(verbatim: timelineItem.article.title ?? "N/A")
+				.frame(maxWidth: .infinity, alignment: .leading)
+			Divider()
+		}
     }
 }
 

Multiplatform/Shared/Timeline/TimelineModel.swift

@@ -9,6 +9,7 @@
 import Foundation
 import RSCore
 import Account
+import Articles
 
 protocol TimelineModelDelegate: class {
 	func timelineRequestedWebFeedSelection(_: TimelineModel, webFeed: WebFeed)
@@ -21,6 +22,28 @@ class TimelineModel: ObservableObject {
 	@Published var timelineItems = [TimelineItem]()
 	
 	private var feeds = [Feed]()
+	private var fetchSerialNumber = 0
+	private let fetchRequestQueue = FetchRequestQueue()
+	private var exceptionArticleFetcher: ArticleFetcher?
+	private var isReadFiltered = false
+	
+	private var articles = [Article]()
+	
+	private var sortDirection = AppDefaults.timelineSortDirection {
+		didSet {
+			if sortDirection != oldValue {
+				sortParametersDidChange()
+			}
+		}
+	}
+	
+	private var groupByFeed = AppDefaults.timelineGroupByFeed {
+		didSet {
+			if groupByFeed != oldValue {
+				sortParametersDidChange()
+			}
+		}
+	}
 	
 	init() {
 	}
@@ -29,12 +52,72 @@ class TimelineModel: ObservableObject {
 	
 	func rebuildTimelineItems(_ feed: Feed) {
 		feeds = [feed]
+		fetchAndReplaceArticlesAsync()
 	}
 	
 }
 
 // MARK: Private
+
 private extension TimelineModel {
 	
+	func sortParametersDidChange() {
+		performBlockAndRestoreSelection {
+			let unsortedArticles = Set(articles)
+			replaceArticles(with: unsortedArticles)
+		}
+	}
 	
+	func performBlockAndRestoreSelection(_ block: (() -> Void)) {
+//		let savedSelection = selectedArticleIDs()
+		block()
+//		restoreSelection(savedSelection)
+	}
+
+	// MARK: Article Fetching
+	
+	func fetchAndReplaceArticlesAsync() {
+		cancelPendingAsyncFetches()
+		
+		var fetchers = feeds as [ArticleFetcher]
+		if let fetcher = exceptionArticleFetcher {
+			fetchers.append(fetcher)
+			exceptionArticleFetcher = nil
+		}
+		
+		fetchUnsortedArticlesAsync(for: fetchers) { [weak self] (articles) in
+			self?.replaceArticles(with: articles)
+		}
+	}
+
+	func cancelPendingAsyncFetches() {
+		fetchSerialNumber += 1
+		fetchRequestQueue.cancelAllRequests()
+	}
+
+	func fetchUnsortedArticlesAsync(for representedObjects: [Any], completion: @escaping ArticleSetBlock) {
+		// The callback will *not* be called if the fetch is no longer relevant — that is,
+		// if it’s been superseded by a newer fetch, or the timeline was emptied, etc., it won’t get called.
+		precondition(Thread.isMainThread)
+		cancelPendingAsyncFetches()
+		let fetchOperation = FetchRequestOperation(id: fetchSerialNumber, readFilter: isReadFiltered ?? true, representedObjects: representedObjects) { [weak self] (articles, operation) in
+			precondition(Thread.isMainThread)
+			guard !operation.isCanceled, let strongSelf = self, operation.id == strongSelf.fetchSerialNumber else {
+				return
+			}
+			completion(articles)
+		}
+		fetchRequestQueue.add(fetchOperation)
+	}
+	
+	func replaceArticles(with unsortedArticles: Set<Article>) {
+		articles = Array(unsortedArticles).sortedByDate(sortDirection, groupByFeed: groupByFeed)
+		timelineItems = articles.map { TimelineItem(article: $0) }
+		
+		// TODO: Update unread counts and other item done in didSet on AppKit
+	}
+
+
+	// MARK: - Notifications
+
 }

Multiplatform/Shared/Timeline/TimelineView.swift

@@ -13,12 +13,19 @@ struct TimelineView: View {
 	@EnvironmentObject private var timelineModel: TimelineModel
 
 	var body: some View {
-        Text(/*@START_MENU_TOKEN@*/"Hello, World!"/*@END_MENU_TOKEN@*/)
-    }
-}
-
-struct TimelineView_Previews: PreviewProvider {
-    static var previews: some View {
-        TimelineView()
+		ScrollView {
+			LazyVStack() {
+				ForEach(timelineModel.timelineItems) { timelineItem in
+					TimelineItemView(timelineItem: timelineItem)
+				}
+			}
+		}
     }
+	
+//	var body: some View {
+//		List(timelineModel.timelineItems) { timelineItem in
+//			TimelineItemView(timelineItem: timelineItem)
+//		}
+//	}
+	
 }