feat(payments): implement payInvoice for LND nodes

TODO.md

@@ -2,7 +2,6 @@
 
 Small Stuff
 
-- add Copy & Close button to CreateInvoiceModal
 - refactor: add redraw param to designer.syncChart()
 - fix pasting text in terminal
 - display bitcoin rpc user/pass in sidebar

electron/lnd/lndProxyServer.ts

@@ -101,6 +101,22 @@ const createInvoice = async (args: {
   return await rpc.addInvoice(args.req);
 };
 
+const payInvoice = async (args: {
+  node: LndNode;
+  req: LND.SendRequest;
+}): Promise<LND.SendResponse> => {
+  const rpc = await getRpc(args.node);
+  return await rpc.sendPaymentSync(args.req);
+};
+
+const decodeInvoice = async (args: {
+  node: LndNode;
+  req: LND.PayReqString;
+}): Promise<LND.PayReq> => {
+  const rpc = await getRpc(args.node);
+  return await rpc.decodePayReq(args.req);
+};
+
 /**
  * A mapping of electron IPC channel names to the functions to execute when
  * messages are recieved
@@ -118,6 +134,8 @@ const listeners: {
   [ipcChannels.listChannels]: listChannels,
   [ipcChannels.pendingChannels]: pendingChannels,
   [ipcChannels.createInvoice]: createInvoice,
+  [ipcChannels.payInvoice]: payInvoice,
+  [ipcChannels.decodeInvoice]: decodeInvoice,
 };
 
 /**

src/lib/lightning/lnd/lndProxyClient.ts

@@ -55,6 +55,14 @@ class LndProxyClient {
   async createInvoice(node: LndNode, req: LND.Invoice): Promise<LND.AddInvoiceResponse> {
     return await this.ipc(ipcChannels.createInvoice, { node, req });
   }
+
+  async payInvoice(node: LndNode, req: LND.SendRequest): Promise<LND.SendResponse> {
+    return await this.ipc(ipcChannels.payInvoice, { node, req });
+  }
+
+  async decodeInvoice(node: LndNode, req: LND.PayReqString): Promise<LND.PayReq> {
+    return await this.ipc(ipcChannels.decodeInvoice, { node, req });
+  }
 }
 
 export default new LndProxyClient();

src/lib/lightning/lnd/lndService.ts

@@ -120,14 +120,26 @@ class LndService implements LightningService {
     return res.paymentRequest;
   }
 
-  payInvoice(
+  async payInvoice(
     node: LightningNode,
     invoice: string,
     amount?: number,
   ): Promise<PLN.LightningNodePayReceipt> {
-    throw new Error(
-      `payInvoice is not implemented for ${node.implementation} nodes ${invoice} ${amount}`,
-    );
+    const req: LND.SendRequest = {
+      paymentRequest: invoice,
+      amt: amount ? amount.toString() : undefined,
+    };
+    const res = await proxy.payInvoice(this.cast(node), req);
+    // handle errors manually
+    if (res.paymentError) throw new Error(res.paymentError);
+
+    const payReq = await proxy.decodeInvoice(this.cast(node), { payReq: invoice });
+
+    return {
+      amount: parseInt(payReq.numSatoshis),
+      preimage: res.paymentPreimage.toString(),
+      destination: payReq.destination,
+    };
   }
 
   /**

src/shared/ipcChannels.ts

@@ -13,4 +13,6 @@ export default {
   listChannels: 'list-channels',
   pendingChannels: 'pending-channels',
   createInvoice: 'create-invoice',
+  payInvoice: 'pay-invoice',
+  decodeInvoice: 'decode-invoice',
 };