export type Theme = 'dark' | 'light';

const THEME_KEY = 'tautkan_theme';
const OLD_THEME_KEY = 'retro_kanban_theme';

export function getTheme(): Theme {
  try {
    const saved = (localStorage.getItem(THEME_KEY) || localStorage.getItem(OLD_THEME_KEY)) as Theme;
    if (saved === 'dark' || saved === 'light') return saved;
  } catch {}
  return 'light'; // Default to modern Light mode
}

export function applyTheme(theme: Theme): void {
  const root = document.documentElement;
  if (theme === 'dark') {
    root.classList.add('dark');
    root.classList.remove('light');
  } else {
    root.classList.remove('dark');
    root.classList.add('light');
  }
  try {
    localStorage.setItem(THEME_KEY, theme);
  } catch {}
}

export function toggleTheme(): Theme {
  const current = getTheme();
  const next = current === 'dark' ? 'light' : 'dark';
  applyTheme(next);
  return next;
}