Send & Receive on Lightning

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Estimating Lightning Fees

Before sending or receiving payments, you can estimate the associated fees:

// Estimate fees for sending a payment
const sendFees = await sparkWallet.getLightningPaymentFees(
  "SEND",
  invoice // BOLT11 encoded invoice
);
console.log("Estimated send fees:", sendFees.toString(), "sats");

// Estimate fees for receiving a payment
const receiveFees = await sparkWallet.getLightningPaymentFees(
  "RECEIVE",
  invoice // BOLT11 encoded invoice
);
console.log("Estimated receive fees:", receiveFees.toString(), "sats");

// For zero-amount invoices, specify the amount.
// Zero-amount invoices are not currently supported on Spark.
const zeroInvoiceFees = await sparkWallet.get_lightning_payment_fees(
  "SEND",
  invoice,
  BigInt(1000) // Amount in satoshis
);

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Sending a Lightning Payment

Follow these steps to send a Lightning invoice:

1. Pay a Lightning Invoice

   const invoice = "lnbc1..."; // Encoded Lightning invoice
   
   // For zero-amount invoices, specify the amount
   const paymentRequest = await sparkWallet.payLightningInvoice(invoice, BigInt(1000));
   // Or for regular invoices
   const paymentRequest = await sparkWallet.payLightningInvoice(invoice);
   

2. Confirm the Payment

   Once the payment is outbound, you can confirm the payment by checking it’s status:

   const status = await sparkWallet.getLightningPaymentRequest(paymentRequest.request_id);
   console.log("Payment Status:", status.status);
   console.log("Fees paid:", status.fees_sats.toString(), "sats");
   

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Receiving a Lightning Payment

To receive payments, generate and share your Lightning invoice with the sender.

1. Generate an Invoice

   const amount = BigInt(50000); // Amount in satoshis
   const expirySeconds = 3600; // Optional: Set invoice expiry (defaults to 24 hours)
   
   const { encoded_invoice, fees_on_receive_sats } = await sparkWallet.createLightningInvoice(
     amount,
     expirySeconds
   );
   
   console.log("Your Invoice:", encoded_invoice);
   console.log("Fees on receive:", fees_on_receive_sats.toString(), "sats");
   

2. Wait for Payment

   Monitor your wallet to confirm receipt of the payment.

   await sparkWallet.syncWallet();
   const btcBalance = await sparkWallet.getBtcBalance();
   console.log("BTC Balance:", btcBalance);
   

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Best Practices

• Invoice Expiry: Set appropriate expiry times for invoices using the expirySeconds parameter (defaults to 24 hours).
• Monitor Transactions: Regularly sync your wallet to stay updated on incoming and outgoing payments.
• Zero Amount Invoices: When paying zero amount invoices, always specify the amount_sats parameter.
• Payment Status: Always check the payment status using getLightningPaymentRequest to confirm successful completion.
• Fee Estimation: Always estimate fees before sending or receiving payments to avoid surprises.

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Next Steps

Proceed to Send & Receive on Spark for direct transactions within Spark.