// Generated, do not edit. sha256:9577dee0ed20ca611f2d96db3a931311a0d672a76d95d80dda4d00726259c4be
import { randomBytes, scrypt as scryptCb, createCipheriv, createDecipheriv, timingSafeEqual } from 'node:crypto';
import { promisify } from 'node:util';
import { readFile, writeFile, rm, mkdtemp, rename, access } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { secretsFile } from './keys.mjs';
import { run } from './db/conn.mjs';
import { initDatabase, dbFile } from './db.js';
import { keurBestand, wisselDatabaseBestand } from './db-restore.mjs';
import { fail } from '../shared/app-error.js';

const scrypt = promisify(scryptCb);

const MAGIC = Buffer.from('ASSETAPP-BACKUP', 'latin1');
const VERSIE = 1;
const SALT_LEN = 16;
const IV_LEN = 12;
const TAG_LEN = 16;
const KOP_LEN = MAGIC.length + 1 + SALT_LEN + IV_LEN + TAG_LEN;
const SCRYPT = Object.freeze({ N: 2 ** 15, r: 8, p: 1, maxmem: 96 * 1024 * 1024 });

const sleutelUit = (wachtwoord, salt) => scrypt(wachtwoord, salt, 32, SCRYPT);

function eisWachtwoord(wachtwoord) {
  const w = String(wachtwoord ?? '');
  if (w.length < 8) fail('dbfile.passTooShort', null, 'Choose a password of at least 8 characters for the backup.');
  return w;
}

const bestaat = async pad => { try { await access(pad); return true; } catch { return false; } };

async function databaseKopie() {
  const dir = await mkdtemp(join(tmpdir(), 'assetapp-backup-'));
  const uit = join(dir, 'db.sqlite');
  try {
    run(`VACUUM INTO '${uit.replace(/'/g, "''")}'`, []);
    return { bytes: await readFile(uit), opruimen: () => rm(dir, { recursive: true, force: true }) };
  } catch (e) {
    await rm(dir, { recursive: true, force: true });
    throw e;
  }
}

export async function createBackup(wachtwoord) {
  const w = eisWachtwoord(wachtwoord);
  const kopie = await databaseKopie();
  try {
    const geheimenPad = secretsFile();
    const geheimen = await bestaat(geheimenPad) ? await readFile(geheimenPad) : Buffer.from('{}', 'utf-8');
    const manifest = Buffer.from(JSON.stringify({
      v: 1, gemaakt: new Date().toISOString(), db: kopie.bytes.length, secrets: geheimen.length,
    }) + '\n', 'utf-8');
    const plat = Buffer.concat([manifest, kopie.bytes, geheimen]);

    const salt = randomBytes(SALT_LEN);
    const iv = randomBytes(IV_LEN);
    const c = createCipheriv('aes-256-gcm', await sleutelUit(w, salt), iv);
    const cijfer = Buffer.concat([c.update(plat), c.final()]);
    const bytes = Buffer.concat([MAGIC, Buffer.of(VERSIE), salt, iv, c.getAuthTag(), cijfer]);
    return { bytes, db: kopie.bytes.length, secrets: geheimen.length };
  } finally {
    await kopie.opruimen();
  }
}

async function openBackup(bytes, wachtwoord) {
  if (!bytes || bytes.length < KOP_LEN) fail('dbfile.notABackup', null, 'This file is not an AssetApp backup (too short).');
  if (!bytes.subarray(0, MAGIC.length).equals(MAGIC)) {
    fail('dbfile.notABackupUseRestore', null, 'This file is not an AssetApp backup; restore a loose .sqlite with "Terugzetten".');
  }
  const versie = bytes[MAGIC.length];
  if (versie !== VERSIE) fail('dbfile.unknownBackupVersion', { versie, kent: VERSIE }, `Unknown backup version (${versie}); this app knows version ${VERSIE}.`);

  let p = MAGIC.length + 1;
  const salt = bytes.subarray(p, p += SALT_LEN);
  const iv = bytes.subarray(p, p += IV_LEN);
  const tag = bytes.subarray(p, p += TAG_LEN);
  const cijfer = bytes.subarray(p);

  const d = createDecipheriv('aes-256-gcm', await sleutelUit(String(wachtwoord ?? ''), salt), iv);
  d.setAuthTag(tag);
  let plat;
  try {
    plat = Buffer.concat([d.update(cijfer), d.final()]);
  } catch {
    fail('dbfile.decryptFailed', null, 'Decryption failed: wrong password, or the file is damaged.');
  }

  const nl = plat.indexOf(0x0a);
  if (nl < 0) fail('dbfile.noManifest', null, 'Backup damaged: no manifest found.');
  let manifest;
  try { manifest = JSON.parse(plat.subarray(0, nl).toString('utf-8')); }
  catch { fail('dbfile.manifestUnreadable', null, 'Backup damaged: the manifest is unreadable.'); }
  const dbLen = Number(manifest.db), secretsLen = Number(manifest.secrets);
  if (!Number.isInteger(dbLen) || !Number.isInteger(secretsLen)
      || nl + 1 + dbLen + secretsLen !== plat.length) {
    fail('dbfile.manifestLengths', null, 'Backup damaged: the lengths in the manifest do not match the content.');
  }
  return {
    manifest,
    db: plat.subarray(nl + 1, nl + 1 + dbLen),
    secrets: plat.subarray(nl + 1 + dbLen),
  };
}

export async function restoreBackup(bytes, wachtwoord) {
  const { manifest, db, secrets } = await openBackup(bytes, wachtwoord);

  const doel = dbFile();
  const geheimenPad = secretsFile();
  const incoming = `${doel}.new`;
  await writeFile(incoming, db, { mode: 0o600 });
  let keuring;
  try {
    keuring = keurBestand(incoming);
  } catch (e) {
    await rm(incoming, { force: true });
    throw e;
  }
  let aantalGeheimen;
  try { aantalGeheimen = Object.keys(JSON.parse(secrets.toString('utf-8'))).length; }
  catch {
    await rm(incoming, { force: true });
    fail('dbfile.secretsUnreadable', null, 'Backup damaged: the secrets file is not readable JSON.');
  }

  const previousDb = `${doel}.previous`;
  const previousSecrets = `${geheimenPad}.previous`;
  await wisselDatabaseBestand(incoming, previousDb, async () => {
    if (await bestaat(geheimenPad)) {
      await rm(previousSecrets, { force: true });
      await rename(geheimenPad, previousSecrets);
    }
    await writeFile(geheimenPad, secrets, { mode: 0o600 });
  });

  const regel = initDatabase();
  return {
    gemaakt: manifest.gemaakt ?? null,
    versie: keuring.versie,
    wezen: keuring.wezen,
    geheimen: aantalGeheimen,
    previousDb,
    previousSecrets,
    regel,
  };
}

export function isBackupBestand(bytes) {
  return !!bytes && bytes.length >= MAGIC.length && bytes.subarray(0, MAGIC.length).equals(MAGIC);
}

export const FORMAAT = Object.freeze({ MAGIC, VERSIE, SALT_LEN, IV_LEN, TAG_LEN, KOP_LEN, SCRYPT });