import {
  enterKeychainMode,
  hasKeychainShell,
  KeychainBoot,
  KeychainSessionTokens,
} from './sessions';
import { KEYCHAIN_TIMEOUT_MS, KeychainInvoke } from './keychainMirror';

/**
 * [Gitea #105] Desktop, step 2: at boot, before the app renders, read the login
 * tokens from the OS keychain into memory (see sessions.ts). Returns:
 * - `off`: not the desktop app, or no keychain here (Linux, older builds) —
 *   localStorage stays authoritative, exactly as before;
 * - a KeychainBoot from enterKeychainMode: `keychain` (go on), or `missing`
 *   (localStorage says the tokens are in the keychain but they can't be read;
 *   the caller shows Retry / Sign in again and must NOT start the mirror,
 *   which would clear the keychain entry it couldn't read).
 */
export type KeychainBootResult = { mode: 'off' } | KeychainBoot | { mode: 'error'; error: string };

const withTimeout = <T>(p: Promise<T>, ms: number): Promise<T> =>
  new Promise<T>((resolve, reject) => {
    const timer = setTimeout(() => reject(new Error('keychain timed out')), ms);
    p.then(
      (v) => {
        clearTimeout(timer);
        resolve(v);
      },
      (e) => {
        clearTimeout(timer);
        reject(e);
      },
    );
  });

const asTokens = (v: unknown): KeychainSessionTokens | null => {
  if (!v || typeof v !== 'object') return null;
  const t = v as Partial<KeychainSessionTokens>;
  if (typeof t.userId !== 'string' || typeof t.deviceId !== 'string') return null;
  if (typeof t.accessToken !== 'string') return null;
  return {
    userId: t.userId,
    deviceId: t.deviceId,
    accessToken: t.accessToken,
    ...(typeof t.refreshToken === 'string' ? { refreshToken: t.refreshToken } : {}),
  };
};

export async function bootKeychainSession(
  invoke: KeychainInvoke | undefined,
  timeoutMs = KEYCHAIN_TIMEOUT_MS,
): Promise<KeychainBootResult> {
  if (!invoke) return { mode: 'off' };
  let supported: unknown;
  try {
    supported = await withTimeout(invoke('secure_session_supported'), timeoutMs);
  } catch {
    supported = false;
  }
  if (supported !== true) {
    // A shell without a keychain to read from can only mean the store went
    // away (e.g. a downgrade of the desktop build): say so, don't log out.
    return hasKeychainShell()
      ? { mode: 'error', error: 'keychain not available' }
      : { mode: 'off' };
  }
  let stored: unknown;
  try {
    stored = await withTimeout(invoke('secure_session_get'), timeoutMs);
  } catch (e) {
    if (hasKeychainShell())
      return { mode: 'error', error: (e instanceof Error ? e.message : String(e)).slice(0, 200) };
    return { mode: 'off' };
  }
  return enterKeychainMode(asTokens(stored));
}