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import type { Keypair } from '../../types.ts';
import { bnToU8a, stringToU8a, u8aConcat } from 'https://deno.land/x/polkadot@0.2.40/util/mod.ts';
import { BN_BE_32_OPTS } from '../../bn.ts';import { hmacShaAsU8a } from '../../hmac/index.ts';import { secp256k1PairFromSeed, secp256k1PrivateKeyTweakAdd } from '../../secp256k1/index.ts';import { HARDENED, hdValidatePath } from '../validatePath.ts';
interface CodedKeypair extends Keypair {  chainCode: Uint8Array;}
const MASTER_SECRET = stringToU8a('Bitcoin seed');
function createCoded (secretKey: Uint8Array, chainCode: Uint8Array): CodedKeypair {  return {    chainCode,    publicKey: secp256k1PairFromSeed(secretKey).publicKey,    secretKey  };}
function deriveChild (hd: CodedKeypair, index: number): CodedKeypair {  const indexBuffer = bnToU8a(index, BN_BE_32_OPTS);  const data = index >= HARDENED    ? u8aConcat(new Uint8Array(1), hd.secretKey, indexBuffer)    : u8aConcat(hd.publicKey, indexBuffer);
  try {    const I = hmacShaAsU8a(hd.chainCode, data, 512);
    return createCoded(      secp256k1PrivateKeyTweakAdd(hd.secretKey, I.slice(0, 32)),      I.slice(32)    );  } catch {    // In case parse256(IL) >= n or ki == 0, proceed with the next value for i    return deriveChild(hd, index + 1);  }}
export function hdEthereum (seed: Uint8Array, path = ''): Keypair {  const I = hmacShaAsU8a(MASTER_SECRET, seed, 512);  let hd = createCoded(I.slice(0, 32), I.slice(32));
  if (!path || path === 'm' || path === 'M' || path === "m'" || path === "M'") {    return hd;  }
  if (!hdValidatePath(path)) {    throw new Error('Invalid derivation path');  }
  const parts = path.split('/').slice(1);
  for (const p of parts) {    hd = deriveChild(hd, parseInt(p, 10) + (      (p.length > 1) && p.endsWith("'")        ? HARDENED        : 0    ));  }
  return hd;}