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
}