import { readFileSync } from 'node:fs';
import { EjbcaProvider } from './ejbca';
import { LocalDevCaProvider } from './local-dev-provider';
import type { CaProvider } from './types';

export * from './types';

/**
 * Build the configured provider, or `null` when S/MIME enrolment is not set up.
 *
 * `null` rather than a throw, so an unconfigured deployment answers 503 on the
 * enrolment route and is otherwise unaffected. Enrolment is an opt-in feature of
 * a mail client; a missing CA secret must not stop anyone reading their mail.
 */
let cached: CaProvider | null | undefined;

export function getCaProvider(): CaProvider | null {
  if (cached !== undefined) return cached;
  cached = build();
  return cached;
}

function build(): CaProvider | null {
  const baseUrl = process.env.SMIME_CA_URL;
  if (!baseUrl) {
    // Explicit opt-in only, never a silent fallback: the real EJBCA needs a
    // client mTLS credential this environment doesn't have and lives on the
    // private dev-k8s network, unreachable from here tonight - see
    // local-dev-provider.ts's module header for exactly what this is (and
    // isn't) a substitute for.
    if (process.env.SMIME_CA_DEV_LOCAL === 'true') {
      return new LocalDevCaProvider();
    }
    return null;
  }

  // Read from the mounted secret by default (see deploy/k8s/ca/README.md § 5.3).
  // Paths are overridable for local development against a throwaway CA.
  const pfxPath = process.env.SMIME_CA_CLIENT_PFX_PATH ?? '/etc/smime-ca/client.p12';
  const caPath = process.env.SMIME_CA_CHAIN_PATH ?? '/etc/smime-ca/ca-chain.pem';
  const password = process.env.SMIME_CA_CLIENT_PFX_PASSWORD;

  if (!password) {
    console.error('[smime-ca] SMIME_CA_URL is set but SMIME_CA_CLIENT_PFX_PASSWORD is not');
    return null;
  }

  let clientPfx: Buffer;
  let serverCaPem: string;
  try {
    clientPfx = readFileSync(pfxPath);
    serverCaPem = readFileSync(caPath, 'utf8');
  } catch (cause) {
    // Loud, because the symptom otherwise is "enrolment returns 503" with no
    // indication that a file is simply not mounted.
    console.error(`[smime-ca] cannot read RA credential (${pfxPath} / ${caPath}):`, cause);
    return null;
  }

  return new EjbcaProvider({
    id: process.env.SMIME_CA_ID ?? 'ejbca',
    baseUrl: baseUrl.replace(/\/$/, ''),
    clientPfx,
    clientPfxPassword: password,
    serverCaPem,
    caName: process.env.SMIME_CA_NAME ?? 'VNC S/MIME Issuing CA Sandbox R1',
    certificateProfile: process.env.SMIME_CA_CERT_PROFILE ?? 'VNC S/MIME 1y',
    endEntityProfile: process.env.SMIME_CA_EE_PROFILE ?? 'VNC S/MIME User',
  });
}