Arrow-key navigation in the add dialog

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/ui/form.go

@@ -0,0 +1,62 @@
+package ui
+
+import (
+	"github.com/gdamore/tcell/v2"
+	"github.com/rivo/tview"
+)
+
+// arrowNavigation lets a form be driven with the arrow keys:
+//   - Up/Down move between the fields and buttons,
+//   - Left/Right change the value of a closed dropdown without opening it
+//     (and move between the buttons),
+//
+// Enter or Space still opens a dropdown list. While a list is open it gets all keys.
+func arrowNavigation(f *tview.Form) {
+	f.SetInputCapture(func(ev *tcell.EventKey) *tcell.EventKey {
+		item, button := f.GetFocusedItemIndex()
+		if item < 0 && button < 0 {
+			return ev
+		}
+		dd, _ := focusedDropDown(f, item)
+		if dd != nil && dd.IsOpen() {
+			return ev
+		}
+		total := f.GetFormItemCount() + f.GetButtonCount()
+		pos := item
+		if button >= 0 {
+			pos = f.GetFormItemCount() + button
+		}
+		switch ev.Key() {
+		case tcell.KeyDown:
+			f.SetFocus(min(pos+1, total-1))
+		case tcell.KeyUp:
+			f.SetFocus(max(pos-1, 0))
+		case tcell.KeyLeft, tcell.KeyRight:
+			step := 1
+			if ev.Key() == tcell.KeyLeft {
+				step = -1
+			}
+			switch {
+			case dd != nil:
+				n := dd.GetOptionCount()
+				cur, _ := dd.GetCurrentOption()
+				dd.SetCurrentOption((cur + step + n) % n)
+			case button >= 0:
+				f.SetFocus(min(max(pos+step, f.GetFormItemCount()), total-1))
+			default:
+				return ev
+			}
+		default:
+			return ev
+		}
+		return nil
+	})
+}
+
+func focusedDropDown(f *tview.Form, item int) (*tview.DropDown, bool) {
+	if item < 0 {
+		return nil, false
+	}
+	dd, ok := f.GetFormItem(item).(*tview.DropDown)
+	return dd, ok
+}