feat: add keyboard commands for discovery news table

Mastodon/Scene/Discovery/Hashtags/DiscoveryHashtagsViewController.swift

@@ -150,7 +150,7 @@ extension DiscoveryHashtagsViewController: TableViewControllerNavigateable {
             navigateToTag(direction: direction, indexPath: indexPathForSelectedRow)
         } else {
             // set first visible item selected
-            navigateToFirstVisibleStatus()
+            navigateToFirstVisibleTag()
         }
     }
     
@@ -185,7 +185,7 @@ extension DiscoveryHashtagsViewController: TableViewControllerNavigateable {
         tableView.selectRow(at: indexPath, animated: true, scrollPosition: scrollPosition)
     }
     
-    private func navigateToFirstVisibleStatus() {
+    private func navigateToFirstVisibleTag() {
         guard let indexPathsForVisibleRows = tableView.indexPathsForVisibleRows else { return }
         guard let diffableDataSource = viewModel.diffableDataSource else { return }
         

Mastodon/Scene/Discovery/News/DiscoveryNewsViewController.swift

@@ -131,3 +131,99 @@ extension DiscoveryNewsViewController: ScrollViewContainer {
         tableView
     }
 }
+
+extension DiscoveryNewsViewController {
+    override var keyCommands: [UIKeyCommand]? {
+        return navigationKeyCommands
+    }
+}
+
+extension DiscoveryNewsViewController: TableViewControllerNavigateable {
+    
+    func navigate(direction: TableViewNavigationDirection) {
+        if let indexPathForSelectedRow = tableView.indexPathForSelectedRow {
+            // navigate up/down on the current selected item
+            navigateToLink(direction: direction, indexPath: indexPathForSelectedRow)
+        } else {
+            // set first visible item selected
+            navigateToFirstVisibleLink()
+        }
+    }
+    
+    private func navigateToLink(direction: TableViewNavigationDirection, indexPath: IndexPath) {
+        guard let diffableDataSource = viewModel.diffableDataSource else { return }
+        let items = diffableDataSource.snapshot().itemIdentifiers
+        guard let selectedItem = diffableDataSource.itemIdentifier(for: indexPath),
+              let selectedItemIndex = items.firstIndex(of: selectedItem) else {
+            return
+        }
+
+        let _navigateToItem: DiscoveryItem? = {
+            var index = selectedItemIndex
+            while 0..<items.count ~= index {
+                index = {
+                    switch direction {
+                    case .up:   return index - 1
+                    case .down: return index + 1
+                    }
+                }()
+                guard 0..<items.count ~= index else { return nil }
+                let item = items[index]
+                
+                guard Self.validNavigateableItem(item) else { continue }
+                return item
+            }
+            return nil
+        }()
+        
+        guard let item = _navigateToItem, let indexPath = diffableDataSource.indexPath(for: item) else { return }
+        let scrollPosition: UITableView.ScrollPosition = overrideNavigationScrollPosition ?? Self.navigateScrollPosition(tableView: tableView, indexPath: indexPath)
+        tableView.selectRow(at: indexPath, animated: true, scrollPosition: scrollPosition)
+    }
+    
+    private func navigateToFirstVisibleLink() {
+        guard let indexPathsForVisibleRows = tableView.indexPathsForVisibleRows else { return }
+        guard let diffableDataSource = viewModel.diffableDataSource else { return }
+        
+        var visibleItems: [DiscoveryItem] = indexPathsForVisibleRows.sorted().compactMap { indexPath in
+            guard let item = diffableDataSource.itemIdentifier(for: indexPath) else { return nil }
+            guard Self.validNavigateableItem(item) else { return nil }
+            return item
+        }
+        if indexPathsForVisibleRows.first?.row != 0, visibleItems.count > 1 {
+            // drop first when visible not the first cell of table
+            visibleItems.removeFirst()
+        }
+        guard let item = visibleItems.first, let indexPath = diffableDataSource.indexPath(for: item) else { return }
+        let scrollPosition: UITableView.ScrollPosition = overrideNavigationScrollPosition ?? Self.navigateScrollPosition(tableView: tableView, indexPath: indexPath)
+        tableView.selectRow(at: indexPath, animated: true, scrollPosition: scrollPosition)
+    }
+    
+    static func validNavigateableItem(_ item: DiscoveryItem) -> Bool {
+        switch item {
+        case .link:
+            return true
+        default:
+            return false
+        }
+    }
+    
+    func open() {
+        guard let indexPathForSelectedRow = tableView.indexPathForSelectedRow else { return }
+        guard let diffableDataSource = viewModel.diffableDataSource else { return }
+        guard let item = diffableDataSource.itemIdentifier(for: indexPathForSelectedRow) else { return }
+        
+        guard case let .link(link) = item else { return }
+        guard let url = URL(string: link.url) else { return }
+        coordinator.present(
+            scene: .safari(url: url),
+            from: self,
+            transition: .safariPresent(animated: true, completion: nil)
+        )
+    }
+    
+    func navigateKeyCommandHandlerRelay(_ sender: UIKeyCommand) {
+        navigateKeyCommandHandler(sender)
+    }
+
+}