support.ts

import {pack} from '@ethersproject/solidity';
import ethers from 'ethers';
import {keccak256} from '@ethersproject/keccak256';
import {verifyMessage} from '@ethersproject/wallet';
import { BigNumber } from 'ethers';

class SignedRecordUtils {
  messageToSign(
    tokenId: string,
    ownerAddress: string,
    key: string,
  ): string {
    return keccak256(this.abiCoding(tokenId, ownerAddress, key))
  }

  recoverAddress(
    tokenId: string,
    ownerAddress: string,
    key: string,
    signature: string,
  ): string {
    return verifyMessage(
      this.messageToSign(tokenId, ownerAddress, key),
      signature,
    );
  }

  abiCoding(tokenId: string, ownerAddress: string, key: string): string {
    return pack(
      ['uint256', 'address', 'bytes32'],
      [tokenId, ownerAddress, keccak256(key)],
    );
  }
}