// mdb-reader's browser environment, rewritten for this site: AES and the hashes
// come from @noble/ciphers and @noble/hashes (MIT, synchronous, no Node
// streams), in place of browserify-aes and create-hash, whose Buffer polyfill
// differs from mdb-reader's and returned short pages for encrypted .accdb files.
import { inflate as pakoInflate } from 'pako';
import { cbc, ecb, cfb } from '@noble/ciphers/aes.js';
import { sha1, md5 } from '@noble/hashes/legacy.js';
import { sha256, sha384, sha512 } from '@noble/hashes/sha2.js';

const HASHES = { sha1, sha256, sha384, sha512, md5 };

export function createHash(algorithm) {
  const fn = HASHES[String(algorithm).toLowerCase().replace(/-/g, '')];
  if (!fn) throw new Error(`Unsupported hash ${algorithm}`);
  const h = fn.create();
  return {
    update(data) { h.update(data); return this; },
    digest() { return Buffer.from(h.digest()); },
  };
}

export function createDecipheriv(algorithm, key, iv) {
  const mode = String(algorithm).toLowerCase().split('-').pop();
  const k = new Uint8Array(key);
  const make = mode === 'cbc' ? () => cbc(k, new Uint8Array(iv).subarray(0, 16), { disablePadding: true })
    : mode === 'ecb' ? () => ecb(k, { disablePadding: true })
    : mode === 'cfb' ? () => cfb(k, new Uint8Array(iv).subarray(0, 16))
    : null;
  if (!make) throw new Error(`Unsupported cipher ${algorithm}`);
  return {
    setAutoPadding() { return this; },
    update(data) { return Buffer.from(make().decrypt(new Uint8Array(data))); },
  };
}

export const environment = {
  inflate: (data) => Buffer.from(pakoInflate(data)),
};