@pharosnames/address-encoder/src/utils/hex.ts

Encodes and decodes address formats for various cryptocurrencies with Pharos network support

import { keccak_256 } from "@noble/hashes/sha3";
import { bytesToHex, hexToBytes, stringToBytes, type Hex } from "./bytes.js";

export const stripHexPrefix = (str: string): string =>
  str.startsWith("0x") ? str.slice(2) : str;

export const rawChecksumAddress = ({
  address,
  hash,
  length,
}: {
  address: string[];
  hash: Uint8Array;
  length: number;
}): Hex => {
  for (let i = 0; i < length; i += 2) {
    if (hash[i >> 1] >> 4 >= 8 && address[i]) {
      address[i] = address[i].toUpperCase();
    }
    if ((hash[i >> 1] & 0x0f) >= 8 && address[i + 1]) {
      address[i + 1] = address[i + 1].toUpperCase();
    }
  }

  return `0x${address.join("")}`;
};

export function checksumAddress(address_: string, chainId?: number): string {
  const hexAddress = chainId
    ? `${chainId}${address_.toLowerCase()}`
    : address_.substring(2).toLowerCase();
  const hash = keccak_256(stringToBytes(hexAddress));

  const address = (
    chainId ? hexAddress.substring(`${chainId}0x`.length) : hexAddress
  ).split("");
  return rawChecksumAddress({ address, hash, length: 40 });
}

export function isAddress(address: string): boolean {
  return /^0x[a-fA-F0-9]{40}$/.test(address);
}

export function isValidChecksumAddress(
  address: string,
  chainId?: number
): boolean {
  if (!isAddress(address)) return false;

  if (address === checksumAddress(address, chainId)) return true;

  const prefixlessAddress = stripHexPrefix(address);
  // all lowercase
  if (prefixlessAddress.toLowerCase() === prefixlessAddress) return true;
  // all uppercase
  if (prefixlessAddress.toUpperCase() === prefixlessAddress) return true;

  return false;
}

export const createHexChecksummedEncoder =
  (chainId?: number) => (source: Uint8Array) =>
    checksumAddress(bytesToHex(source), chainId);

export const createHexChecksummedDecoder =
  (chainId?: number) => (source: string) => {
    if (!isValidChecksumAddress(source, chainId)) {
      throw new Error("Unrecognised address format");
    }
    return hexToBytes(source as Hex);
  };