Arkade provides seamless integration with the Lightning Network through Boltz submarine swaps, allowing users to move funds between Arkade and Lightning channels. This integration leverages Hash Time-Locked Contracts (HTLCs) to ensure trustless and secure cross-chain atomic swaps.

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Overview

The BoltzSwapProvider library extends Arkade’s functionality by enabling:
  1. Lightning to Arkade swaps - Receive funds from Lightning payments into your Arkade wallet
  2. Arkade to Lightning swaps - Send funds from your Arkade wallet to Lightning invoices
This integration is built on top of the Boltz submarine swap protocol, providing a reliable and secure way to bridge the gap between Arkade and the Lightning Network.

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Installation

npm install @arkade-os/sdk @arkade-os/boltz-swap

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Basic Usage

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Initializing the Lightning Swap Provider

import { Wallet } from '@arkade-os/wallet-sdk';
import { ArkadeLightning, BoltzSwapProvider } from '@arkade-os/boltz-swap';

// Initialize your Arkade wallet
const wallet = await Wallet.create({
  identity,
  arkServerUrl: 'https://mutinynet.arkade.sh',
});

// Initialize the Lightning swap provider
const swapProvider = new BoltzSwapProvider({
  apiUrl: 'https://api.boltz.exchange',
  network: 'mainnet'
});

// Create the ArkadeLightning instance
const arkadeLightning = new ArkadeLightning({
  wallet,
  swapProvider
});

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Receiving Lightning Payments

To receive a Lightning payment into your Arkade wallet: 
// Create a Lightning invoice that will deposit funds to your Arkade wallet
const result = await arkadeLightning.createLightningInvoice({
  amountSats: 50000, // 50,000 sats
  description: 'Payment to my Arkade wallet'
});

console.log('Lightning Invoice:', result.invoice);
console.log('Payment Hash:', result.paymentHash);
console.log('Expiry (seconds):', result.expirySeconds);

// The invoice can now be shared with the payer
// When paid, funds will appear in your Arkade wallet

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Monitoring Incoming Lightning Payments

You can monitor the status of incoming Lightning payments: 
// Monitor the payment by payment hash
const subscription = arkadeLightning.monitorIncomingPayment(result.paymentHash);

subscription.on('pending', () => {
  console.log('Payment detected but not yet confirmed');
});

subscription.on('confirmed', (txDetails) => {
  console.log('Payment confirmed!');
  console.log('Transaction ID:', txDetails.txid);
  console.log('Amount received:', txDetails.amountSats, 'sats');
  
  // Update your UI or notify the user
  updateBalanceDisplay();
});

subscription.on('failed', (error) => {
  console.error('Payment failed:', error.message);
});

// Don't forget to clean up when done
subscription.unsubscribe();

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Sending Lightning Payments

To send a payment from your Arkade wallet to a Lightning invoice: 
// Parse a Lightning invoice
const invoiceDetails = await arkadeLightning.decodeInvoice(
  'lnbc500u1pj...'  // Lightning invoice string
);

console.log('Invoice amount:', invoiceDetails.amountSats, 'sats');
console.log('Description:', invoiceDetails.description);
console.log('Destination:', invoiceDetails.destination);

// Pay the Lightning invoice from your Arkade wallet
try {
  const paymentResult = await arkadeLightning.sendLightningPayment({
    invoice: 'lnbc500u1pj...',  // Lightning invoice string
    // Optional: Specify which VTXOs to use
    sourceVtxos: await wallet.getVtxos(),
    // Optional: Maximum fee you're willing to pay (in sats)
    maxFeeSats: 1000
  });
  
  console.log('Payment successful!');
  console.log('Preimage:', paymentResult.preimage);
  console.log('Transaction ID:', paymentResult.txid);
} catch (error) {
  console.error('Payment failed:', error.message);
}

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Handling Refunds

In case a Lightning payment fails after the swap has been initiated, the library provides a refund mechanism: 
// Set up a refund handler when initializing
const arkadeLightning = new ArkadeLightning({
  wallet,
  swapProvider,
  refundHandler: {
    onRefundNeeded: async (swapData) => {
      console.log('Initiating refund for swap:', swapData.id);
      
      // You can implement custom logic here, such as:
      // - Notifying the user
      // - Automatically claiming the refund
      // - Logging the event
      
      // Claim the refund automatically
      return await arkadeLightning.claimRefund(swapData);
    }
  }
});

// Or handle refunds manually
const pendingSwaps = await arkadeLightning.getPendingSwaps();
for (const swap of pendingSwaps) {
  if (swap.status === 'refundable') {
    const refundResult = await arkadeLightning.claimRefund(swap);
    console.log('Refund claimed:', refundResult.txid);
  }
}

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Advanced Configuration

The library supports advanced configuration options for more specific use cases: 
const arkadeLightning = new ArkadeLightning({
  wallet,
  swapProvider,
  
  // Configure timeouts
  timeoutConfig: {
    swapExpiryBlocks: 144, // Number of blocks until swap expires
    invoiceExpirySeconds: 3600, // Invoice expiry in seconds
    claimDelayBlocks: 10 // Blocks to wait before claiming
  },
  
  // Configure fee limits
  feeConfig: {
    maxMinerFeeSats: 5000, // Maximum miner fee in sats
    maxSwapFeeSats: 1000, // Maximum swap fee in sats
  },
  
  // Configure retry logic
  retryConfig: {
    maxAttempts: 3,
    delayMs: 1000
  }
});

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Error Handling

The library provides detailed error types to help you handle different failure scenarios: 
import { 
  SwapError, 
  InvoiceExpiredError,
  InsufficientFundsError,
  NetworkError 
} from '@arkade-os/lightning-swap';

try {
  await arkadeLightning.sendLightningPayment({
    invoice: 'lnbc500u1pj...'
  });
} catch (error) {
  if (error instanceof InvoiceExpiredError) {
    console.error('The invoice has expired. Please request a new one.');
  } else if (error instanceof InsufficientFundsError) {
    console.error('Not enough funds available:', error.message);
  } else if (error instanceof NetworkError) {
    console.error('Network issue. Please try again later:', error.message);
  } else if (error instanceof SwapError) {
    console.error('Swap failed:', error.message);
    
    // You might be able to claim a refund
    if (error.isRefundable) {
      const refundResult = await arkadeLightning.claimRefund(error.swapData);
      console.log('Refund claimed:', refundResult.txid);
    }
  } else {
    console.error('Unknown error:', error);
  }
}

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Security Considerations

When working with Lightning swaps, keep these security considerations in mind:
  1. Timeouts: Always ensure that your HTLCs have appropriate timeouts to prevent funds from being locked indefinitely.
  2. Fee Management: Set reasonable fee limits to prevent excessive fees during network congestion.
  3. Refund Monitoring: Implement proper monitoring for failed swaps to ensure refunds are claimed promptly.
  4. Invoice Validation: Always validate Lightning invoices before initiating payments.
  5. Backup Management: Keep proper backups of swap data to be able to claim refunds if needed.