xo-stack/packages/primitives/src/hd-private-node.ts

import { HDPublicNode } from './hd-public-node.js';
import { PrivateKey } from './private-key.js';

import {
  encodeHdPrivateKey,
  decodeHdPrivateKey,
  deriveHdPath,
  deriveHdPublicNode,
  deriveHdPrivateNodeFromSeed,
  generateRandomBytes,
} from '@bitauth/libauth';

import type {
  DecodedHdKey,
  HdKeyNetwork,
  HdPrivateNodeValid,
} from '@bitauth/libauth';

/**
 * Hierarchically Deterministic Private Node Entity.
 */
export class HDPrivateNode {
  // The HD Private Node.
  public readonly node: HdPrivateNodeValid;

  /**
   * Construct a new HD Private Node.
   *
   * @param node {HdPrivateNodeValid} The HD Private Node.
   */
  constructor(node: HdPrivateNodeValid) {
    this.node = node;
  }

  /**
   * Creates a HD Private Node from the given XPriv Key.
   *
   * @param xpriv {string} The XPriv Key.
   *
   * @throws {Error} If HD Private Node cannot be created.
   *
   * @returns {HDPrivateNode} The created HD Private Node.
   */
  public static fromXPriv(xpriv: string): HDPrivateNode {
    // Attempt to decode the XPriv Key.
    const decodeResult = decodeHdPrivateKey(xpriv);

    // If a string is returned, this indicates an error...
    if (typeof decodeResult === 'string') {
      throw new Error(decodeResult);
    }

    // Return a new HD Private Node from the given XPriv.
    return new HDPrivateNode(decodeResult.node);
  }

  /**
   * Creates a HD Private Node from a raw seed.
   *
   * @param seed {Uint8Array} The raw seed bytes.
   *
   * @throws {Error} If HD Private Node cannot be created.
   *
   * @returns {HDPrivateNode} The created HD Private Node.
   */
  public static fromSeed(seed: Uint8Array): HDPrivateNode {
    // If the seed is not 32 bytes, throw an error.
    /*if (seed.length !== 32) {
      throw new Error(
        `Failed to derive Private Node from seed: Seed must be 32 bytes (${seed.length} given)`
      );
    }*/

    // Attempt to derive HD Private Node from the given seed.
    const deriveResult = deriveHdPrivateNodeFromSeed(seed);

    // If a string is returned, this indicates an error...
    if (typeof deriveResult === 'string') {
      throw new Error(deriveResult);
    }

    // Return a new HD Private Node from the given seed.
    return new HDPrivateNode(deriveResult);
  }

  /**
   * Generates a random HD Private Node.
   *
   * @throws {Error} If HD Private Node cannot be created.
   *
   * @returns {HDPrivateNode} The created HD Private Node.
   */
  public static generateRandom(): HDPrivateNode {
    // Attempt to derive HD Private Node from randomly generated bytes.
    const deriveResult = deriveHdPrivateNodeFromSeed(generateRandomBytes(32));

    // If a string is returned, this indicates an error...
    if (typeof deriveResult === 'string') {
      throw new Error(deriveResult);
    }

    // Return the new HD Private Node from the random bytes.
    return new HDPrivateNode(deriveResult);
  }

  /**
   * Returns the XPriv string for this node.
   *
   * @returns {string} The XPriv string for this node.
   */
  public toString(): string {
    // Return the Mainnet XPriv.
    return this.toXPriv();
  }

  /**
   * Gets the Private Key entity for this node.
   *
   * @returns {PrivateKey} The Private Key Entity for this node.
   */
  public privateKey(): PrivateKey {
    // Return a Private Key Entity from the private key of our node.
    return new PrivateKey(this.node.privateKey);
  }

  /**
   * Derives a HD Private Node from the given BIP32 path.
   *
   * @param path {string} The BIP32 Path (e.g. m/44'/145'/0'/0/1).
   *
   * @throws {Error} If HD Private Node cannot be derived.
   *
   * @returns {HDPrivateNode} The derived HD Private Node
   */
  public derivePath(path: string): HDPrivateNode {
    // Attempt to derive the given path.
    const derivePathResult = deriveHdPath(this.node, path);

    // If a string is returned, this indicates an error...
    if (typeof derivePathResult === 'string') {
      throw new Error(derivePathResult);
    }

    // Return a new HD Private Node Entity derived from the given path.
    return new HDPrivateNode(derivePathResult);
  }

  /**
   * Derives a HD Public Node from this Private Node.
   *
   * @returns {HDPublicNode} The derived HD Public Node
   */
  public deriveHDPublicNode(): HDPublicNode {
    // Derive a HD Public Node from this HD Private Node.
    const publicNode = deriveHdPublicNode(this.node);

    // Return a new HD Public Node entity from our derived Public Node.
    return new HDPublicNode(publicNode);
  }

  /**
   * Converts this node to an XPriv Key for export.
   *
   * @param network {HdKeyNetwork} The network to encode for.
   *
   * @returns {string} The XPriv Key.
   */
  public toXPriv(network: HdKeyNetwork = 'mainnet'): string {
    // Create our node info structure.
    const nodeInfo: DecodedHdKey<HdPrivateNodeValid> = {
      network: network,
      node: this.node,
    };

    // Encode the XPriv from our node info.
    return encodeHdPrivateKey(nodeInfo).hdPrivateKey;
  }
}