Integrate BTCPay Server: auto-settling invoice deposits

- lib/btcpay.ts: Greenfield API client (createBtcPayInvoice, getBtcPayInvoiceStatus)
- /api/btcpay/invoice: creates per-deposit invoice (USD amount + handle in metadata)
- /api/btcpay/status/[id]: polls invoice status + returns BTC address/amount
- add-funds page: BTCPay tab with amount picker, live address display,
  10s auto-poll, settlement auto-credits localStorage ledger
- WalletContext: creditBtcPayInvoice() with duplicate-invoice guard
- .env.example: BTCPAY_URL, BTCPAY_API_KEY, BTCPAY_STORE_ID, NEXT_PUBLIC_BTCPAY_ENABLED

Made-with: Cursor

lib/btcpay.ts

@@ -0,0 +1,149 @@
+/**
+ * BTCPay Server Greenfield API v1 client.
+ *
+ * Env vars required (set in .env.local):
+ *   BTCPAY_URL       e.g. http://10.30.20.237
+ *   BTCPAY_API_KEY   generated in BTCPay → Account → Manage account → API keys
+ *   BTCPAY_STORE_ID  found in BTCPay → Settings → General (the alphanumeric ID in the URL)
+ */
+
+export type BtcPayInvoiceStatus =
+  | "New"
+  | "Processing"
+  | "Expired"
+  | "Invalid"
+  | "Settled";
+
+export type BtcPayInvoice = {
+  id: string;
+  status: BtcPayInvoiceStatus;
+  amount: string;
+  currency: string;
+  checkoutLink: string;
+  createdTime: number;
+  expirationTime: number;
+  metadata?: Record<string, string>;
+};
+
+export type BtcPayPaymentMethod = {
+  paymentMethod: string;       // "BTC"
+  destination: string;         // bc1q... address
+  paymentLink: string;         // bitcoin:... URI
+  rate: string;                // BTC/USD rate at time of invoice
+  due: string;                 // BTC amount customer must send
+  amount: string;              // total BTC amount
+  totalPaid: string;           // BTC paid so far
+};
+
+function btcPayConfig() {
+  const url = (process.env.BTCPAY_URL ?? "").replace(/\/$/, "");
+  const apiKey = process.env.BTCPAY_API_KEY ?? "";
+  const storeId = process.env.BTCPAY_STORE_ID ?? "";
+  return { url, apiKey, storeId };
+}
+
+export function isBtcPayConfigured(): boolean {
+  const { url, apiKey, storeId } = btcPayConfig();
+  return Boolean(url && apiKey && storeId);
+}
+
+function authHeaders(apiKey: string) {
+  return {
+    "Content-Type": "application/json",
+    Authorization: `token ${apiKey}`,
+  };
+}
+
+/**
+ * Create a new BTCPay invoice.
+ * `usdAmount` is the dollar amount the customer wants to deposit.
+ * BTCPay converts this to the BTC equivalent at current rate.
+ */
+export async function createBtcPayInvoice(
+  usdAmount: number,
+  handle: string,
+): Promise<{ ok: true; invoice: BtcPayInvoice } | { ok: false; error: string }> {
+  const { url, apiKey, storeId } = btcPayConfig();
+  if (!url || !apiKey || !storeId) {
+    return { ok: false, error: "BTCPay not configured — set BTCPAY_URL, BTCPAY_API_KEY, BTCPAY_STORE_ID" };
+  }
+
+  try {
+    const res = await fetch(`${url}/api/v1/stores/${storeId}/invoices`, {
+      method: "POST",
+      headers: authHeaders(apiKey),
+      body: JSON.stringify({
+        amount: usdAmount.toFixed(2),
+        currency: "USD",
+        metadata: {
+          cyberlux_handle: handle,
+          source: "cyberlux-deposit-desk",
+        },
+        checkout: {
+          speedPolicy: "LowSpeed",   // 1 confirmation required
+          paymentMethods: ["BTC"],
+          defaultPaymentMethod: "BTC",
+          expirationMinutes: 60,
+        },
+      }),
+      cache: "no-store",
+    });
+
+    if (!res.ok) {
+      const text = await res.text().catch(() => "");
+      return { ok: false, error: `BTCPay error ${res.status}: ${text.slice(0, 120)}` };
+    }
+
+    const invoice = (await res.json()) as BtcPayInvoice;
+    return { ok: true, invoice };
+  } catch (err) {
+    return { ok: false, error: `Network error reaching BTCPay: ${String(err).slice(0, 100)}` };
+  }
+}
+
+/**
+ * Fetch current status and payment method details for an invoice.
+ */
+export async function getBtcPayInvoiceStatus(invoiceId: string): Promise<{
+  ok: true;
+  status: BtcPayInvoiceStatus;
+  usdAmount: number;
+  paymentMethod?: BtcPayPaymentMethod;
+} | { ok: false; error: string }> {
+  const { url, apiKey, storeId } = btcPayConfig();
+  if (!url || !apiKey || !storeId) {
+    return { ok: false, error: "BTCPay not configured" };
+  }
+
+  try {
+    // Fetch invoice
+    const invRes = await fetch(`${url}/api/v1/stores/${storeId}/invoices/${invoiceId}`, {
+      headers: authHeaders(apiKey),
+      cache: "no-store",
+    });
+    if (!invRes.ok) {
+      return { ok: false, error: `Invoice not found (${invRes.status})` };
+    }
+    const invoice = (await invRes.json()) as BtcPayInvoice;
+
+    // Fetch payment methods to get the BTC address
+    const pmRes = await fetch(
+      `${url}/api/v1/stores/${storeId}/invoices/${invoiceId}/payment-methods`,
+      { headers: authHeaders(apiKey), cache: "no-store" },
+    );
+    let paymentMethod: BtcPayPaymentMethod | undefined;
+    if (pmRes.ok) {
+      const methods = (await pmRes.json()) as BtcPayPaymentMethod[];
+      paymentMethod = methods.find((m) => m.paymentMethod === "BTC");
+    }
+
+    return {
+      ok: true,
+      status: invoice.status,
+      usdAmount: parseFloat(invoice.amount),
+      paymentMethod,
+    };
+  } catch (err) {
+    return { ok: false, error: `Network error: ${String(err).slice(0, 100)}` };
+  }
+}