validateSolanaPayTransaction method

Future<TransactionDetails> validateSolanaPayTransaction({ required TransactionId signature, required Ed25519HDPublicKey recipient, required Decimal amount, Ed25519HDPublicKey? splToken, Iterable<Ed25519HDPublicKey>? reference, Commitment commitment = Commitment.finalized, })

Validates that a given transaction signature corresponds with a transaction containing a valid Solana Pay transfer.

Implementation

Future<TransactionDetails> validateSolanaPayTransaction({
  required TransactionId signature,
  required Ed25519HDPublicKey recipient,
  required Decimal amount,
  Ed25519HDPublicKey? splToken,
  Iterable<Ed25519HDPublicKey>? reference,
  Commitment commitment = Commitment.finalized,
}) async {
  final response = await rpcClient.getTransaction(
    signature,
    commitment: commitment,
  );

  if (response == null) {
    throw const ValidateTransactionException('Transaction not found.');
  }

  final meta = response.meta;
  if (meta == null) {
    throw const ValidateTransactionException('Missing meta.');
  }

  if (meta.err != null) {
    throw const ValidateTransactionException('Transaction error.');
  }

  final Decimal preAmount, postAmount;
  if (splToken == null) {
    final accountIndex = (response.transaction as ParsedTransaction)
        .message
        .accountKeys
        .indexWhere((a) => a.pubkey == recipient.toBase58());
    if (accountIndex == -1) {
      throw const ValidateTransactionException('Recipient not found.');
    }

    preAmount = Decimal.fromInt(meta.preBalances[accountIndex])
        .shift(-solDecimalPlaces);
    postAmount = Decimal.fromInt(meta.postBalances[accountIndex])
        .shift(-solDecimalPlaces);
  } else {
    final recipientATA =
        await findAssociatedTokenAddress(owner: recipient, mint: splToken);
    final accountIndex = (response.transaction as ParsedTransaction)
        .message
        .accountKeys
        .indexWhere((a) => a.pubkey == recipientATA.toBase58());
    if (accountIndex == -1) {
      throw const ValidateTransactionException('Recipient not found.');
    }

    final preBalance = meta.preTokenBalances
        .firstWhereOrNull((a) => a.accountIndex == accountIndex);
    final postBalance = meta.postTokenBalances
        .firstWhereOrNull((a) => a.accountIndex == accountIndex);

    preAmount =
        Decimal.parse(preBalance?.uiTokenAmount.uiAmountString ?? '0');
    postAmount =
        Decimal.parse(postBalance?.uiTokenAmount.uiAmountString ?? '0');
  }

  if (postAmount - preAmount < amount) {
    throw const ValidateTransactionException('Amount not transferred.');
  }

  if (reference != null) {
    final keys = (response.transaction as ParsedTransaction)
        .message
        .accountKeys
        .map((e) => e.pubkey);
    if (reference.any((e) => !keys.contains(e.toBase58()))) {
      throw const ValidateTransactionException('Reference not found.');
    }
  }

  return response;
}