import type { Serializer } from '@metaplex-foundation/umi-serializers-core';
import { InvalidBaseStringError } from './errors';

/**
 * A string serializer that uses base16 encoding.
 * @category Serializers
 */
export const base16: Serializer<string> = {
  description: 'base16',
  fixedSize: null,
  maxSize: null,
  serialize(value: string) {
    const lowercaseValue = value.toLowerCase();
    if (!lowercaseValue.match(/^[0123456789abcdef]*$/)) {
      throw new InvalidBaseStringError(value, 16);
    }
    const matches = lowercaseValue.match(/.{1,2}/g);
    return Uint8Array.from(
      matches ? matches.map((byte: string) => parseInt(byte, 16)) : []
    );
  },
  deserialize(buffer, offset = 0) {
    const value = buffer
      .slice(offset)
      .reduce((str, byte) => str + byte.toString(16).padStart(2, '0'), '');
    return [value, buffer.length];
  },
};