// Copyright 2017-2025 @polkadot/util authors & contributors
// SPDX-License-Identifier: Apache-2.0

import type { HexString } from '../types.js';

export const REGEX_HEX_PREFIXED = /^0x[\da-fA-F]+$/;

export const REGEX_HEX_NOPREFIX = /^[\da-fA-F]+$/;

/**
 * @name isHex
 * @summary Tests for a hex string.
 * @description
 * Checks to see if the input value is a `0x` prefixed hex string. Optionally (`bitLength` !== -1) checks to see if the bitLength is correct.
 * @example
 * <BR>
 *
 * ```javascript
 * import { isHex } from '@pezkuwi/util';
 *
 * isHex('0x1234'); // => true
 * isHex('0x1234', 8); // => false
 * ```
 */
export function isHex (value: unknown, bitLength = -1, ignoreLength?: boolean): value is HexString {
  return (
    typeof value === 'string' && (
      value === '0x' ||
      REGEX_HEX_PREFIXED.test(value)
    )
  ) && (
    bitLength === -1
      ? (ignoreLength || (value.length % 2 === 0))
      : (value.length === (2 + Math.ceil(bitLength / 4)))
  );
}
