Add saved/followed hashtags to new sidebar

Tusker/Screens/Main/NewMainTabBarViewController.swift

@@ -24,6 +24,7 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
     private var favoritesTab: UITab!
     private var myProfileTab: UITab!
     private var listsGroup: UITabGroup!
+    private var hashtagsGroup: UITabGroup!
     
     private var cancellables = Set<AnyCancellable>()
     
@@ -67,6 +68,17 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
         ]
         reloadLists(mastodonController.lists)
         
+        hashtagsGroup = UITabGroup(title: "Hashtags", image: nil, identifier: Tab.hashtags.rawValue, children: []) { _ in
+            return AdaptableNavigationController()
+        }
+        hashtagsGroup.preferredPlacement = .sidebarOnly
+        hashtagsGroup.sidebarActions = [
+            UIAction(title: "Add Hashtag…", image: UIImage(systemName: "plus"), handler: { [unowned self] _ in
+                self.showAddSavedHashtag()
+            })
+        ]
+        reloadHashtags()
+        
         if UIDevice.current.userInterfaceIdiom == .phone {
             self.tabs = [
                 homeTab,
@@ -83,13 +95,19 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
                 let vcToUpdate = self.selectedTab!.parent?.viewController ?? self.selectedTab!.viewController!
                 self.updateViewControllerSafeAreaInsets(vcToUpdate)
             }
-        }
-        
-        setupFastAccountSwitcher()
             
             mastodonController.$lists
                 .sink { [unowned self] in self.reloadLists($0) }
                 .store(in: &cancellables)
+            
+            mastodonController.$followedHashtags
+                .map { _ in () }
+                .merge(with: NotificationCenter.default.publisher(for: .savedHashtagsChanged).map { _ in () })
+                .sink { [unowned self] in self.reloadHashtags() }
+                .store(in: &cancellables)
+        }
+        
+        setupFastAccountSwitcher()
     }
     
     private func updatePadTabs() {
@@ -99,8 +117,9 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
             isCompact = true
             
             var exploreNavStack: [UIViewController]? = nil
-            if selectedTab?.parent == listsGroup {
+            if let parent = selectedTab?.parent,
-                let nav = listsGroup.viewController as! any NavigationControllerProtocol
+               parent === listsGroup || parent === hashtagsGroup {
+                let nav = parent.viewController as! any NavigationControllerProtocol
                 exploreNavStack = nav.viewControllers
                 nav.viewControllers = []
             }
@@ -121,24 +140,33 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
         } else {
             isCompact = false
             
-            var newTab: (UITab, [UIViewController])? = nil
+            var newTabAndNavigationStack: (UITab, [UIViewController])? = nil
             if wasCompact == true,
                selectedTab == exploreTab {
                 let nav = exploreTab.viewController as! any NavigationControllerProtocol
                 // skip over the ExploreViewController
                 if nav.viewControllers.count > 1 {
+                    var newTab: UITab?
                     switch nav.viewControllers[1] {
                     case let listVC as ListTimelineViewController:
                         if let tab = listsGroup.tab(forIdentifier: ListTab.identifier(for: listVC.list)) {
-                            newTab = (tab, Array(nav.viewControllers[1...]))
+                            newTab = tab
+                        }
+                    case let hashtagVC as HashtagTimelineViewController:
+                        if let tab = hashtagsGroup.tab(forIdentifier: HashtagTab.identifier(for: hashtagVC.hashtagName)) {
+                            newTab = tab
+                        }
+                    default:
+                        break
+                    }
+                    
+                    if let newTab {
+                        newTabAndNavigationStack = (newTab, Array(nav.viewControllers[1...]))
                         nav.viewControllers = [
                             nav.viewControllers[0], // leave the ExploreVC in place
                             InlineTrendsViewController(mastodonController: mastodonController), // re-insert an InlineTrendsVC
                         ]
                     }
-                    default:
-                        break
-                    }
                 }
             }
             
@@ -151,9 +179,10 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
                 myProfileTab,
                 composeTab,
                 listsGroup,
+                hashtagsGroup,
             ]
             
-            if let (tab, navStack) = newTab {
+            if let (tab, navStack) = newTabAndNavigationStack {
                 let nav = tab.parent!.viewController as! any NavigationControllerProtocol
                 nav.viewControllers = navStack
                 // Setting the tab now seems to be clobbered by the UITabBarController itself updating in response
@@ -193,7 +222,7 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
             root = FavoritesViewController(mastodonController: mastodonController)
         case .myProfile:
             root = MyProfileViewController(mastodonController: mastodonController)
-        case .lists:
+        case .lists, .hashtags:
             fatalError("unreachable")
         }
         return embedInNavigationController(root)
@@ -217,11 +246,37 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
     }
     
     private func reloadLists(_ lists: [List]) {
+        let viewControllerProvider = { [unowned self] (tab: UITab) in
+            let tab = tab as! ListTab
+            return ListTimelineViewController(for: tab.list, mastodonController: self.mastodonController)
+        }
         listsGroup.children = lists.map { list in
-            ListTab(list: list) { [unowned self] _ in
+            ListTab(list: list, viewControllerProvider: viewControllerProvider)
-                return ListTimelineViewController(for: list, mastodonController: self.mastodonController)
         }
     }
+    
+    private func reloadHashtags() {
+        let viewControllerProvider = { [unowned self] (tab: UITab) in
+            let tab = tab as! HashtagTab
+            return HashtagTimelineViewController(forNamed: tab.hashtagName, mastodonController: self.mastodonController)
+        }
+        var seenTags: Set<String> = []
+        var tabs: [UITab] = []
+        let savedReq = SavedHashtag.fetchRequest(account: mastodonController.accountInfo!)
+        let saved = (try? mastodonController.persistentContainer.viewContext.fetch(savedReq)) ?? []
+        for hashtag in saved {
+            seenTags.insert(hashtag.name)
+            tabs.append(HashtagTab(hashtagName: hashtag.name, viewControllerProvider: viewControllerProvider))
+        }
+        
+        let followedReq = FollowedHashtag.fetchRequest()
+        let followed = (try? mastodonController.persistentContainer.viewContext.fetch(followedReq)) ?? []
+        for hashtag in followed where !seenTags.contains(hashtag.name) {
+            tabs.append(HashtagTab(hashtagName: hashtag.name, viewControllerProvider: viewControllerProvider))
+        }
+        
+        tabs.sort(using: SemiCaseSensitiveComparator.keyPath(\.title))
+        hashtagsGroup.children = tabs
     }
     
     @objc func handleComposeKeyCommand() {
@@ -244,6 +299,12 @@ final class NewMainTabBarViewController: BaseMainTabBarViewController {
         service.run()
     }
     
+    private func showAddSavedHashtag() {
+        let addController = AddSavedHashtagViewController(mastodonController: mastodonController)
+        let nav = EnhancedNavigationViewController(rootViewController: addController)
+        present(nav, animated: true)
+    }
+    
     fileprivate func updateViewControllerSafeAreaInsets(_ vc: UIViewController) {
         guard vc is MultiColumnNavigationController || (vc as? AdaptableNavigationController)?.current is MultiColumnNavigationController else {
             return
@@ -317,6 +378,7 @@ extension NewMainTabBarViewController {
         case myProfile
         
         case lists
+        case hashtags
     }
 }
 
@@ -356,7 +418,7 @@ extension NewMainTabBarViewController: UITabBarControllerDelegate {
         // get the new transition animation.
         // This would be much less complicated if the controller just used the individual VCs of items in a group.
         if let group = newTab.parent,
-           group.identifier == Tab.lists.rawValue,
+           group === listsGroup || group === hashtagsGroup,
            let nav = group.viewController as? any NavigationControllerProtocol {
             updateViewControllerSafeAreaInsets(nav)
             
@@ -430,6 +492,13 @@ extension NewMainTabBarViewController: UITabBarController.Sidebar.Delegate {
             } else {
                 return nil
             }
+        } else if let hashtagTab = tab as? HashtagTab {
+            let timelineActivity = UserActivityManager.showTimelineActivity(timeline: .tag(hashtag: hashtagTab.hashtagName), accountID: id)
+            if let timelineActivity {
+                activity = timelineActivity
+            } else {
+                return nil
+            }
         } else if let tabID = Tab(rawValue: tab.identifier) {
             switch tabID {
             case .home:
@@ -448,7 +517,7 @@ extension NewMainTabBarViewController: UITabBarController.Sidebar.Delegate {
                 return nil
             case .compose:
                 activity = UserActivityManager.newPostActivity(accountID: id)
-            case .lists:
+            case .lists, .hashtags:
                 return nil
             }
         } else {
@@ -671,3 +740,17 @@ private class ListTab: UITab {
         "list:\(list.id)"
     }
 }
+
+@available(iOS 18.0, *)
+private class HashtagTab: UITab {
+    let hashtagName: String
+    
+    init(hashtagName: String, viewControllerProvider: @escaping (UITab) -> UIViewController) {
+        self.hashtagName = hashtagName
+        super.init(title: hashtagName, image: UIImage(systemName: "number"), identifier: Self.identifier(for: hashtagName), viewControllerProvider: viewControllerProvider)
+    }
+    
+    static func identifier(for name: String) -> String {
+        "hashtag:\(name)"
+    }
+}