useMetakeep.ts

import {
  Connection,
  PublicKey,
  Transaction,
  VersionedTransaction,
} from '@solana/web3.js';
import {useCallback, useEffect, useMemo, useState} from 'react';
import {MetaKeep} from 'metakeep';

export function useMetakeepWallet({appId, email}: {appId: string; email: string;}) {
  const metakeep = useMemo(() => {
    if (!email || !appId) return null;
    return new MetaKeep({
      appId,
      user: {
        email,
      },
    });
  }, [appId, email]);

  const [publicKey, setPublicKey] = useState<PublicKey | null>(null);

  useEffect(() => {
    metakeep
      ?.getWallet()
      .then(res => setPublicKey(new PublicKey(res.wallet.solAddress)));
  }, [metakeep]);

  const signTransaction = useCallback(
    async <T extends Transaction | VersionedTransaction>(
      transaction: T
    ): Promise<T> => {
      if (!metakeep) throw new Error('metakeep is null');
      const metakeepRes: {signature: string} = await metakeep.signTransaction(
        transaction,
        'Withdraw USD'
      );
      const signature = Buffer.from(
        metakeepRes.signature.replace('0x', ''),
        'hex'
      );
      if (transaction instanceof Transaction) {
        transaction.signatures.push({
          publicKey: publicKey!,
          signature,
        });
        transaction.signatures = transaction.signatures.filter(
          sig => !!sig.signature
        );
      } else {
        transaction.signatures.push(signature);
      }

      return transaction;
    },
    [metakeep, publicKey]
  );

  const signMessage = useCallback(
    async (message: Uint8Array) => {
      if (!metakeep) throw new Error('metakeep is null');
      const {signature} = await metakeep.signMessage(
        Buffer.from(message).toString('utf8'),
        'Sign in'
      );
      return Uint8Array.from(Buffer.from(signature.slice(2), 'hex'));
    },
    [metakeep]
  );

  return {
    publicKey,
    signMessage,
    signTransaction,
  };
}