Implement SubscribePendingTransactions

rpc/types_transaction.go

@@ -401,3 +401,39 @@ func (v *TransactionVersion) BigInt() (*big.Int, error) {
 		return big.NewInt(-1), errors.New(fmt.Sprint("TransactionVersion %i not supported", *v))
 	}
 }
+
+// SubPendingTxnsInput is the optional input of the starknet_subscribePendingTransactions subscription.
+type SubPendingTxnsInput struct {
+	// Get all transaction details, and not only the hash. If not provided, only hash is returned. Default is false
+	TransactionDetails bool `json:"transaction_details,omitempty"`
+	// Filter transactions to only receive notification from address list
+	SenderAddress *felt.Felt `json:"sender_address,omitempty"`
+}
+
+// SubPendingTxns is the response of the starknet_subscribePendingTransactions subscription.
+type SubPendingTxns struct {
+	// The hashes of the pending transactions. Only present if transactionDetails is false.
+	TransactionHashes []*felt.Felt
+	// The full transaction details. Only present if transactionDetails is true.
+	Transactions []*BlockTransaction
+}
+
+// UnmarshalJSON unmarshals the JSON data into a SubPendingTxns object.
+//
+// Parameters:
+// - data: The JSON data to be unmarshalled
+// Returns:
+// - error: An error if the unmarshalling process fails
+func (s *SubPendingTxns) UnmarshalJSON(data []byte) error {
+	var txnsHashes []*felt.Felt
+	if err := json.Unmarshal(data, &txnsHashes); err == nil {
+		s.TransactionHashes = txnsHashes
+		return nil
+	}
+	var txns []*BlockTransaction
+	if err := json.Unmarshal(data, &txns); err == nil {
+		s.Transactions = txns
+		return nil
+	}
+	return errors.New("failed to unmarshal SubPendingTxns")
+}

rpc/websocket.go

@@ -91,3 +91,26 @@ func (provider *WsProvider) SubscribeTransactionStatus(ctx context.Context, newS
 	// 	}
 	return sub, nil
 }
+
+// New Pending Transactions subscription
+// Creates a WebSocket stream which will fire events when a new pending transaction is added.
+// While there is no mempool, this notifies of transactions in the pending block.
+//
+// Parameters:
+// - ctx: The context.Context object for controlling the function call
+// - pendingTxns: The channel to send the new pending transactions to
+// - options: The optional input struct containing the optional filters. Set to nil if no filters are needed.
+// Returns:
+// - clientSubscription: The client subscription object, used to unsubscribe from the stream and to get errors
+// - error: An error, if any
+func (provider *WsProvider) SubscribePendingTransactions(ctx context.Context, pendingTxns chan<- *SubPendingTxns, options *SubPendingTxnsInput) (*client.ClientSubscription, error) {
+	if options == nil {
+		options = &SubPendingTxnsInput{}
+	}
+
+	sub, err := provider.c.Subscribe(ctx, "starknet", "_subscribePendingTransactions", pendingTxns, options)
+	if err != nil {
+		return nil, tryUnwrapToRPCErr(err, ErrTooManyAddressesInFilter)
+	}
+	return sub, nil
+}