protected override void OnKeyDown()

in HashCalculator/Controls/NavMenuListView.cs [111:187]
67 lines of code
14 McCabe index (conditional complexity)

        protected override void OnKeyDown(KeyRoutedEventArgs e)
        {
            var focusedItem = FocusManager.GetFocusedElement();

            switch (e.Key)
            {
                case VirtualKey.Up:
                    this.TryMoveFocus(FocusNavigationDirection.Up);
                    e.Handled = true;
                    break;

                case VirtualKey.Down:
                    this.TryMoveFocus(FocusNavigationDirection.Down);
                    e.Handled = true;
                    break;

                case VirtualKey.Tab:
                    var shiftKeyState = CoreWindow.GetForCurrentThread().GetKeyState(VirtualKey.Shift);
                    var shiftKeyDown = (shiftKeyState & CoreVirtualKeyStates.Down) == CoreVirtualKeyStates.Down;

                    // If we're on the header item then this will be null and we'll still get the default behavior.
                    if (focusedItem is ListViewItem)
                    {
                        var currentItem = (ListViewItem)focusedItem;
                        bool onlastitem = currentItem != null && this.IndexFromContainer(currentItem) == this.Items.Count - 1;
                        bool onfirstitem = currentItem != null && this.IndexFromContainer(currentItem) == 0;

                        if (!shiftKeyDown)
                        {
                            if (onlastitem)
                            {
                                this.TryMoveFocus(FocusNavigationDirection.Next);
                            }
                            else
                            {
                                this.TryMoveFocus(FocusNavigationDirection.Down);
                            }
                        }
                        else // Shift + Tab
                        {
                            if (onfirstitem)
                            {
                                this.TryMoveFocus(FocusNavigationDirection.Previous);
                            }
                            else
                            {
                                this.TryMoveFocus(FocusNavigationDirection.Up);
                            }
                        }
                    }
                    else if (focusedItem is Control)
                    {
                        if (!shiftKeyDown)
                        {
                            this.TryMoveFocus(FocusNavigationDirection.Down);
                        }
                        else // Shift + Tab
                        {
                            this.TryMoveFocus(FocusNavigationDirection.Up);
                        }
                    }

                    e.Handled = true;
                    break;

                case VirtualKey.Space:
                case VirtualKey.Enter:
                    // Fire our event using the item with current keyboard focus
                    this.InvokeItem(focusedItem);
                    e.Handled = true;
                    break;

                default:
                    base.OnKeyDown(e);
                    break;
            }
        }