js-sdk

Here’s a complete integration example for a web-based bitcoin tipping app called *TipBit* that allows users to send payments via Lightning Network using the Alby OAuth2 Wallet API and Nostr Wallet Connect. The app leverages the `@getalby/js-sdk` library to handle authentication, payment requests, and transaction broadcasting.

**Step 1: Setup and Authentication**
First, we initialize the SDK with the Alby OAuth2 client credentials and Nostr Wallet Connect configuration. The user authenticates via Alby’s OAuth2 flow, granting the app permission to interact with their wallet. We store the access token securely in the browser’s `localStorage` for subsequent requests.

```javascript
import { AlbyWallet } from '@getalby/sdk';
import { NostrWalletConnect } from '@getalby/nostr-wallet-connect';

const albyWallet = new AlbyWallet({
  clientId: 'tipbit-app-client-id',
  clientSecret: 'tipbit-app-client-secret',
  scopes: ['invoices:read', 'invoices:create', 'payments:send']
});

// Redirect user to Alby OAuth2 authorization page
const authUrl = albyWallet.getAuthorizationUrl({
  redirectUri: 'https://tipbit.app/auth/callback'
});
window.location.href = authUrl;
```

**Step 2: Nostr Wallet Connect Integration**
Once authenticated, we establish a Nostr Wallet Connect session to interact with the user’s Lightning wallet. This allows us to send payments without custody of the user’s funds. We subscribe to payment events to track transaction status in real-time.

```javascript
const nwc = new NostrWalletConnect({
  nostrWalletConnectUrl: 'nostrwalletconnect://...',
  appName: 'TipBit'
});

// Listen for payment events
nwc.on('payment', (event) => {
  console.log('Payment event:', event);
  if (event.status === 'paid') {
    alert(`Payment of ${event.amount} sats received!`);
  }
});
```

**Step 3: Sending a Payment**
The app now allows users to send a tip of 10,000 sats to a content creator’s Lightning address. The SDK constructs the payment request, signs it with the user’s Nostr key, and broadcasts it to the Lightning Network. We handle potential errors, such as insufficient balance or network issues, and provide user feedback.

```javascript
async function sendTip(lnAddress, amountSats) {
  try {
    const paymentRequest = await nwc.makeInvoice({
      amount: amountSats,
      description: 'Tip for great content!'
    });
    
    const paymentResult = await nwc.payInvoice({
      invoice: paymentRequest.invoice,
      amount: amountSats
    });
    
    console.log('Payment successful:', paymentResult);
    return paymentResult;
  } catch (error) {
    console.error('Payment failed:', error);
    alert('Failed to send tip. Please try again.');
  }
}

// Example usage
sendTip('creator@lnaddress.com', 10000);
```

**Step 4: Error Handling and User Feedback**
The integration includes robust error handling to manage scenarios like expired invoices, network failures, or insufficient funds. For example, if the user’s wallet balance is too low, the app displays a friendly message and suggests alternative payment methods, such as connecting a different wallet.

```javascript
nwc.on('error', (error) => {
  console.error('NWC Error:', error);
  if (error.message.includes('insufficient_balance')) {
    alert('Your wallet balance is too low. Please add funds or connect another wallet.');
  }
});
```

This implementation ensures that TipBit users can send and receive bitcoin payments in a non-custodial manner, with seamless integration into their existing Lightning wallets. The SDK handles the complexities of OAuth2 authentication, Nostr Wallet Connect, and Lightning Network interactions, allowing developers to focus on building user-friendly features.