/**
 * signerCapabilities — safely probe what a Nostr signer can do.
 * ─────────────────────────────────────────────────────────────────────────────
 * The NUser extension signer exposes `.nip44` / `.nip04` as GETTERS that call
 * `.nostr` (window.nostr) and THROW "Browser extension not available" when the
 * extension isn't present. Accessing `user.signer?.nip44` during render will
 * therefore crash the whole React tree for extension logins whose extension
 * isn't injected yet (page-load race) or is missing entirely.
 *
 * These helpers determine capability WITHOUT touching the throwing getter:
 * we look at the login type + probe `window.nostr` directly (a plain property
 * read that never throws). Use `hasNip44(user, logins)` anywhere you'd
 * otherwise write `!!user?.signer?.nip44` in a render path.
 */

interface MaybeUser {
  pubkey?: string;
}

interface MaybeLogin {
  type: string;
  pubkey?: string;
}

function windowNostr(): { nip44?: unknown; nip04?: unknown } | undefined {
  return (globalThis as { nostr?: { nip44?: unknown; nip04?: unknown } }).nostr;
}

/**
 * Resolve the login that backs the current user.
 *
 * IMPORTANT: we cannot rely solely on `l.pubkey === user.pubkey`. Depending on
 * the login method and how Nostrify rehydrates from localStorage, the top-level
 * `pubkey` on a stored login object is not always populated (nsec logins in
 * particular expose the pubkey nested under the decrypted key material). When a
 * pubkey match fails we fall back to the ACTIVE login (`logins[0]`), which is
 * exactly the login `useCurrentUser` turns into `users[0]` / `user`. Without
 * this fallback, a perfectly capable nsec/amber user gets wrongly told
 * "Encryption Required" on the Stash page.
 */
function resolveLogin(
  user: MaybeUser | null | undefined,
  logins: readonly MaybeLogin[],
): MaybeLogin | undefined {
  if (!user?.pubkey || logins.length === 0) return undefined;
  return logins.find((l) => l.pubkey === user.pubkey) ?? logins[0];
}

/** True if the user's signer can do NIP-44 encryption. Never throws. */
export function hasNip44(
  user: MaybeUser | null | undefined,
  logins: readonly MaybeLogin[],
): boolean {
  const login = resolveLogin(user, logins);
  if (!login) return false;
  // nsec + bunker: NIP-44 always available (pure JS / remote signer implements it)
  if (login.type === 'nsec' || login.type === 'bunker') return true;
  // amber (NIP-55): the Amber signer implements nip44_encrypt / nip44_decrypt
  // over native intents (CapacitorAmberSigner) and URL redirects (AmberSigner).
  if (login.type === 'x-amber') return true;
  // extension: probe window.nostr directly (no throwing getter)
  if (login.type === 'extension') return !!windowNostr()?.nip44;
  // unknown: no NIP-44
  return false;
}

/**
 * True when the active signer prompts the user for EVERY cryptographic op —
 * i.e. Amber (NIP-55), where each sign/encrypt/decrypt launches Amber's
 * Approve/Reject screen as a foreground intent.
 *
 * This matters for passive decryption: with an extension/nsec/bunker signer,
 * decrypting many events in a background query is silent and instant, so it's
 * fine to do it automatically (on mount/focus). With Amber, the SAME code
 * launches Amber once per event — so Amber visibly flashes on navigation and
 * can storm the user with popups. Callers use this to gate/defer passive
 * decryption (only decrypt on explicit user intent, don't auto-refetch) when
 * the signer is interactive.
 */
export function isInteractiveSigner(
  user: MaybeUser | null | undefined,
  logins: readonly MaybeLogin[],
): boolean {
  const login = resolveLogin(user, logins);
  if (!login) return false;
  // Amber (NIP-55) is the only signer that requires a user interaction per op.
  return login.type === 'x-amber';
}

/** True if the user's signer can do NIP-04 encryption. Never throws. */
export function hasNip04(
  user: MaybeUser | null | undefined,
  logins: readonly MaybeLogin[],
): boolean {
  const login = resolveLogin(user, logins);
  if (!login) return false;
  if (login.type === 'nsec' || login.type === 'bunker') return true;
  if (login.type === 'x-amber') return true;
  if (login.type === 'extension') return !!windowNostr()?.nip04;
  return false;
}