import debug from 'debug';
import packageJson from '@@/package.json';

export const RELEASE = 'v' + packageJson.version;

export const SERVER_DEBUG = debug('Server');

export const OLD_ENV = {
  /** @deprecated Only for migration purposes */
  PASSWORD: process.env.PASSWORD,
  /** @deprecated Only for migration purposes */
  PASSWORD_HASH: process.env.PASSWORD_HASH,
};

const detectAwg = async (): Promise<'awg' | 'wg'> => {
  /** TODO: delete on next major version */
  if (process.env.EXPERIMENTAL_AWG === 'true') {
    const OVERRIDE_AUTO_AWG = process.env.OVERRIDE_AUTO_AWG?.toLowerCase();

    if (
      OVERRIDE_AUTO_AWG === ('wg' as const) ||
      OVERRIDE_AUTO_AWG === ('awg' as const)
    ) {
      return OVERRIDE_AUTO_AWG;
    } else {
      return await exec('modinfo amneziawg')
        .then(() => 'awg' as const)
        .catch(() => 'wg' as const);
    }
  } else return 'wg';
};

export const WG_ENV = {
  /** UI is hosted on HTTP instead of HTTPS */
  INSECURE: process.env.INSECURE === 'true',
  /** Port the UI is listening on */
  PORT: assertEnv('PORT'),
  /** If IPv6 should be disabled */
  DISABLE_IPV6: process.env.DISABLE_IPV6 === 'true',
  WG_EXECUTABLE: await detectAwg(),
};

export const WG_INITIAL_ENV = {
  ENABLED: process.env.INIT_ENABLED === 'true',
  USERNAME: process.env.INIT_USERNAME,
  PASSWORD: process.env.INIT_PASSWORD,
  DNS: process.env.INIT_DNS?.split(',').map((x) => x.trim()),
  IPV4_CIDR: process.env.INIT_IPV4_CIDR,
  IPV6_CIDR: process.env.INIT_IPV6_CIDR,
  ALLOWED_IPS: process.env.INIT_ALLOWED_IPS?.split(',').map((x) => x.trim()),
  HOST: process.env.INIT_HOST,
  PORT: process.env.INIT_PORT
    ? Number.parseInt(process.env.INIT_PORT, 10)
    : undefined,
};

export const WG_OVERRIDE_ENV = {
  /** Override the WireGuard interface port */
  INTERFACE_PORT: process.env.OVERRIDE_INTERFACE_PORT
    ? Number.parseInt(process.env.OVERRIDE_INTERFACE_PORT, 10)
    : undefined,
  /** Override the network device/interface */
  INTERFACE_DEVICE: process.env.OVERRIDE_INTERFACE_DEVICE,
  /** Override the MTU setting */
  INTERFACE_MTU: process.env.OVERRIDE_INTERFACE_MTU
    ? Number.parseInt(process.env.OVERRIDE_INTERFACE_MTU, 10)
    : undefined,
};

function assertEnv<T extends string>(env: T) {
  const val = process.env[env];

  if (!val) {
    throw new Error(`Missing environment variable: ${env}`);
  }

  return val;
}

/**
 * Apply environment variable overrides to an interface object
 */
export function applyInterfaceOverrides<
  T extends { port: number; device: string; mtu: number },
>(wgInterface: T): T {
  return {
    ...wgInterface,
    port: WG_OVERRIDE_ENV.INTERFACE_PORT ?? wgInterface.port,
    device: WG_OVERRIDE_ENV.INTERFACE_DEVICE ?? wgInterface.device,
    mtu: WG_OVERRIDE_ENV.INTERFACE_MTU ?? wgInterface.mtu,
  };
}