package evidence

// foregroundTracker remembers the last observed foreground window so the
// Windows polling Source emits only on change. hwnd is held as uintptr so this
// file stays platform-neutral (it must build and test on Linux).
type foregroundTracker struct {
	primed    bool
	available bool
	hwnd      uintptr
	title     string
}

// changed reports whether (available, hwnd, title) differs from the last
// observation and records the new values. The first call always returns true.
// Callers pass the zero values (hwnd 0, title "") when available is false, so a
// steady "no foreground window" run does not re-emit.
func (t *foregroundTracker) changed(available bool, hwnd uintptr, title string) bool {
	if t.primed && available == t.available && hwnd == t.hwnd && title == t.title {
		return false
	}
	t.primed, t.available, t.hwnd, t.title = true, available, hwnd, title
	return true
}