// VK Mini App SDK access via @vkontakte/vk-bridge. The bridge is imported lazily inside the
// functions that need it — not at module top level — because the SDK reads browser globals on
// import: the lazy import keeps the pure URL helpers below importable in the node test environment,
// and code-splits the bridge into a chunk loaded only on the /vk/ entry. This wraps the subset the
// app uses: launch detection, the signed launch parameters (for auth.vk) and the user's display name
// (VKWebAppGetUserInfo, since VK omits it from the signed launch params). Every helper is safe to
// call outside VK.

async function bridge() {
  return (await import('@vkontakte/vk-bridge')).default;
}

/**
 * onVKPath reports whether the app is served under the dedicated VK entry path (/vk/).
 */
export function onVKPath(): boolean {
  if (typeof location === 'undefined') return false;
  return location.pathname.startsWith('/vk/');
}

/**
 * vkLaunchParams returns the raw signed VK launch query string (the vk_* parameters plus sign) from
 * the page URL — the exact form the gateway verifies — or '' when the URL carries no signed launch
 * (an ordinary browser tab, or the /vk/ path opened directly).
 */
export function vkLaunchParams(): string {
  if (typeof location === 'undefined') return '';
  const query = location.search.replace(/^\?/, '');
  return new URLSearchParams(query).has('sign') ? query : '';
}

/**
 * insideVK reports whether the app launched as a VK Mini App — the URL carries signed launch
 * parameters (an ordinary browser tab has none).
 */
export function insideVK(): boolean {
  return vkLaunchParams() !== '';
}

/**
 * vkInit signals to the VK client that the Mini App has loaded (VKWebAppInit), dismissing VK's own
 * loading cover. Best-effort: it resolves even if the bridge is unavailable (outside VK), so the
 * caller can await it unconditionally.
 */
export async function vkInit(): Promise<void> {
  try {
    await (await bridge()).send('VKWebAppInit', {});
  } catch {
    // Outside VK there is no client to receive it; the launch continues regardless.
  }
}

/**
 * vkUserName fetches the launching user's display name via VKWebAppGetUserInfo, since VK omits it
 * from the signed launch params. Returns '' on any failure or outside VK, so the backend falls back
 * to a generated placeholder. The value is a cosmetic seed only — being unsigned, the gateway never
 * trusts it for identity.
 */
export async function vkUserName(): Promise<string> {
  try {
    const u = await (await bridge()).send('VKWebAppGetUserInfo', {});
    return [u.first_name, u.last_name].filter(Boolean).join(' ').trim();
  } catch {
    return '';
  }
}