export default defineEventHandler(async (event) => {
  const { config, provider, providerConfig } = await buildOauthConfig(event);

  const session = await useWGSession(event);
  if (
    !session.data.oauth_nonce ||
    !session.data.oauth_verifier ||
    !session.data.oauth_state
  ) {
    throw createError({
      statusCode: 400,
      statusMessage: 'Missing OAuth State',
    });
  }

  const userInfo = await getUserInfo(
    event,
    config,
    {
      oauth_nonce: session.data.oauth_nonce,
      oauth_verifier: session.data.oauth_verifier,
      oauth_state: session.data.oauth_state,
    },
    providerConfig
  );

  const result = await Database.users.loginWithOAuth(
    provider,
    userInfo.sub,
    userInfo.preferred_username || userInfo.email,
    userInfo.email,
    userInfo.name || 'User'
  );

  if (!result.success) {
    switch (result.error) {
      case 'TOTP_REQUIRED':
        await session.update({
          pendingLogin: {
            type: 'oauth',
            userId: result.userId,
            remember: false,
          },
          oauth_nonce: undefined,
          oauth_state: undefined,
          oauth_verifier: undefined,
        });
        return sendRedirect(event, '/login/2fa');
      case 'USER_DISABLED':
        throw createError({
          statusCode: 401,
          statusMessage: 'User disabled',
        });
      case 'USER_ALREADY_LINKED':
        throw createError({
          statusCode: 401,
          statusMessage:
            'User already linked with different account or provider',
        });
      case 'AUTO_REGISTER_DISABLED':
        throw createError({
          statusCode: 401,
          statusMessage: 'Auto registration is disabled',
        });
      case 'UNEXPECTED_ERROR':
        throw createError({
          statusCode: 500,
          statusMessage: 'Unexpected error',
        });
    }
    assertUnreachable(result);
  }

  // Create session
  const data = await session.update({
    userId: result.user.id,
    oauth_nonce: undefined,
    oauth_state: undefined,
    oauth_verifier: undefined,
  });

  SERVER_DEBUG(
    `New OAuth Session: ${data.id} for ${result.user.id} (${result.user.username}) with ${provider}`
  );

  return sendRedirect(event, '/');
});