feat: add sendMultiPayment function and example

examples/nwc/send-multi-payment.js

@@ -0,0 +1,45 @@
+import * as crypto from "node:crypto"; // required in node.js
+global.crypto = crypto; // required in node.js
+import "websocket-polyfill"; // required in node.js
+
+import { LightningAddress } from "@getalby/lightning-tools";
+
+import * as readline from "node:readline/promises";
+import { stdin as input, stdout as output } from "node:process";
+
+import { webln as providers } from "../../dist/index.module.js";
+
+const rl = readline.createInterface({ input, output });
+
+const ln = new LightningAddress(process.env.LN_ADDRESS || "[email protected]");
+// fetch the LNURL data
+await ln.fetch();
+
+// generate 2 invoices to pay
+const invoices = (
+  await Promise.all(
+    [1, 2].map((v) =>
+      ln.requestInvoice({
+        satoshi: 1,
+        comment: `Multi-pay invoice #${v}`,
+      }),
+    ),
+  )
+).map((invoice) => invoice.paymentRequest);
+
+console.info("Generated two invoices", invoices);
+
+const nwcUrl =
+  process.env.NWC_URL ||
+  (await rl.question("Nostr Wallet Connect URL (nostr+walletconnect://...): "));
+rl.close();
+
+const webln = new providers.NostrWebLNProvider({
+  nostrWalletConnectUrl: nwcUrl,
+});
+await webln.enable();
+const response = await webln.sendMultiPayment(invoices);
+
+console.info(response);
+
+webln.close();

package.json

@@ -38,8 +38,9 @@
     "prepare": "husky install"
   },
   "dependencies": {
-    "nostr-tools": "^1.17.0",
-    "events": "^3.3.0"
+    "@getalby/lightning-tools": "^5.0.1",
+    "events": "^3.3.0",
+    "nostr-tools": "^1.17.0"
   },
   "devDependencies": {
     "@commitlint/cli": "^17.7.1",

src/webln/NostrWeblnProvider.ts

@@ -9,7 +9,6 @@ import {
   Event,
   UnsignedEvent,
   finishEvent,
-  Kind,
 } from "nostr-tools";
 import {
   GetBalanceResponse,
@@ -26,6 +25,7 @@ import {
 } from "@webbtc/webln-types";
 import { GetInfoResponse } from "@webbtc/webln-types";
 import { NWCAuthorizationUrlOptions } from "../types";
+import { Invoice } from "@getalby/lightning-tools";
 
 const NWCs: Record<string, NostrWebLNOptions> = {
   alby: {
@@ -47,6 +47,12 @@ export type ListTransactionsResponse = {
 // TODO: consider moving to webln-types package
 export type ListTransactionsArgs = Nip47ListTransactionsArgs;
 
+// TODO: consider moving to webln-types package
+export type SendMultiPaymentResponse = {
+  payments: ({ paymentRequest: string } & SendPaymentResponse)[];
+  errors: { paymentRequest: string; message: string }[];
+};
+
 interface Nip47ListTransactionsArgs {
   from?: number;
   until?: number;
@@ -110,6 +116,9 @@ const nip47ToWeblnRequestMap = {
   lookup_invoice: "lookupInvoice",
   list_transactions: "listTransactions",
 };
+const nip47ToWeblnMultiRequestMap = {
+  multi_pay_invoice: "sendMultiPayment",
+};
 
 export class NostrWebLNProvider implements WebLNProvider, Nip07Provider {
   relay: Relay;
@@ -338,6 +347,51 @@ export class NostrWebLNProvider implements WebLNProvider, Nip07Provider {
     );
   }
 
+  async sendMultiPayment(
+    paymentRequests: string[],
+  ): Promise<SendMultiPaymentResponse> {
+    await this.checkConnected();
+
+    // get payment hashes of the payment requests
+    const paymentHashToPaymentRequestMap: Record<string, string> = {};
+    for (const paymentRequest of paymentRequests) {
+      paymentHashToPaymentRequestMap[
+        new Invoice({ pr: paymentRequest }).paymentHash
+      ] = paymentRequest;
+    }
+
+    const results = await this.executeMultiNip47Request<
+      { preimage: string; paymentRequest: string },
+      Nip47PayResponse
+    >(
+      "multi_pay_invoice",
+      {
+        invoices: paymentRequests.map((paymentRequest) => ({
+          invoice: paymentRequest,
+        })),
+      },
+      paymentRequests.length,
+      (result) => !!result.preimage,
+      (result) => {
+        const paymentRequest = paymentHashToPaymentRequestMap[result.dTag];
+        if (!paymentRequest) {
+          throw new Error(
+            "Could not find paymentRequest matching response d tag",
+          );
+        }
+        return {
+          paymentRequest,
+          preimage: result.preimage,
+        };
+      },
+    );
+
+    return {
+      payments: results,
+      errors: [],
+    };
+  }
+
   async keysend(args: KeysendArgs) {
     await this.checkConnected();
 
@@ -559,7 +613,7 @@ export class NostrWebLNProvider implements WebLNProvider, Nip07Provider {
           JSON.stringify(command),
         );
         const unsignedEvent: UnsignedEvent = {
-          kind: 23194 as Kind,
+          kind: 23194,
           created_at: Math.floor(Date.now() / 1000),
           tags: [["p", this.walletPubkey]],
           content: encryptedCommand,
@@ -604,7 +658,6 @@ export class NostrWebLNProvider implements WebLNProvider, Nip07Provider {
             reject({ error: "invalid response", code: "INTERNAL" });
             return;
           }
-          // @ts-ignore // event is still unknown in nostr-tools
           if (event.kind == 23195 && response.result) {
             // console.info("NIP-47 result", response.result);
             if (resultValidator(response.result)) {
@@ -644,6 +697,141 @@ export class NostrWebLNProvider implements WebLNProvider, Nip07Provider {
       })();
     });
   }
+
+  // TODO: this method currently fails if any payment fails.
+  // this could be improved in the future.
+  // TODO: reduce duplication between executeNip47Request and executeMultiNip47Request
+  private executeMultiNip47Request<T, R>(
+    nip47Method: keyof typeof nip47ToWeblnMultiRequestMap,
+    params: unknown,
+    numPayments: number,
+    resultValidator: (result: R) => boolean,
+    resultMapper: (result: R & { dTag: string }) => T,
+  ) {
+    const weblnMethod = nip47ToWeblnMultiRequestMap[nip47Method];
+    let numPaymentsReceived = 0;
+    const results: (R & { dTag: string })[] = [];
+    return new Promise<T[]>((resolve, reject) => {
+      (async () => {
+        const command = {
+          method: nip47Method,
+          params,
+        };
+        const encryptedCommand = await this.encrypt(
+          this.walletPubkey,
+          JSON.stringify(command),
+        );
+        const unsignedEvent: UnsignedEvent = {
+          kind: 23194,
+          created_at: Math.floor(Date.now() / 1000),
+          tags: [["p", this.walletPubkey]],
+          content: encryptedCommand,
+          pubkey: this.publicKey,
+        };
+
+        const event = await this.signEvent(unsignedEvent);
+        // subscribe to NIP_47_SUCCESS_RESPONSE_KIND and NIP_47_ERROR_RESPONSE_KIND
+        // that reference the request event (NIP_47_REQUEST_KIND)
+        const sub = this.relay.sub([
+          {
+            kinds: [23195],
+            authors: [this.walletPubkey],
+            "#e": [event.id],
+          },
+        ]);
+
+        function replyTimeout() {
+          sub.unsub();
+          //console.error(`Reply timeout: event ${event.id} `);
+          reject({
+            error: `reply timeout: event ${event.id}`,
+            code: "INTERNAL",
+          });
+        }
+
+        const replyTimeoutCheck = setTimeout(replyTimeout, 60000);
+
+        sub.on("event", async (event) => {
+          ++numPaymentsReceived;
+          // console.log(`Received reply event: `, event);
+
+          const decryptedContent = await this.decrypt(
+            this.walletPubkey,
+            event.content,
+          );
+          // console.log(`Decrypted content: `, decryptedContent);
+          let response;
+          try {
+            response = JSON.parse(decryptedContent);
+          } catch (e) {
+            console.error(e);
+            clearTimeout(replyTimeoutCheck);
+            sub.unsub();
+            reject({ error: "invalid response", code: "INTERNAL" });
+            return;
+          }
+          if (event.kind == 23195 && response.result) {
+            // console.info("NIP-47 result", response.result);
+            try {
+              if (!resultValidator(response.result)) {
+                throw new Error(
+                  "Response from NWC failed validation: " +
+                    JSON.stringify(response.result),
+                );
+              }
+              const dTag = event.tags.find((tag) => tag[0] === "d")?.[1];
+              if (!dTag) {
+                throw new Error("No d tag found in response event");
+              }
+              // console.info("dTag", dTag);
+              results.push({
+                ...response.result,
+                dTag,
+              });
+              if (numPaymentsReceived === numPayments) {
+                clearTimeout(replyTimeoutCheck);
+                sub.unsub();
+                //console.log("Received results", results);
+                resolve(results.map(resultMapper));
+                this.notify(weblnMethod, response.result);
+              }
+            } catch (error) {
+              console.error(error);
+              clearTimeout(replyTimeoutCheck);
+              sub.unsub();
+              reject({
+                error: (error as Error).message,
+                code: "INTERNAL",
+              });
+            }
+          } else {
+            clearTimeout(replyTimeoutCheck);
+            sub.unsub();
+            reject({
+              error: response.error?.message,
+              code: response.error?.code,
+            });
+          }
+        });
+
+        function publishTimeout() {
+          //console.error(`Publish timeout: event ${event.id}`);
+          reject({ error: `Publish timeout: event ${event.id}` });
+        }
+        const publishTimeoutCheck = setTimeout(publishTimeout, 5000);
+
+        try {
+          await this.relay.publish(event);
+          clearTimeout(publishTimeoutCheck);
+          //console.debug(`Event ${event.id} for ${invoice} published`);
+        } catch (error) {
+          //console.error(`Failed to publish to ${this.relay.url}`, error);
+          clearTimeout(publishTimeoutCheck);
+          reject({ error: `Failed to publish request: ${error}` });
+        }
+      })();
+    });
+  }
 }
 
 function mapNip47TransactionToTransaction(

yarn.lock

@@ -1470,6 +1470,11 @@
   resolved "https://registry.yarnpkg.com/@eslint/js/-/js-8.47.0.tgz#5478fdf443ff8158f9de171c704ae45308696c7d"
   integrity sha512-P6omY1zv5MItm93kLM8s2vr1HICJH8v0dvddDhysbIuZ+vcjOHg5Zbkf1mTkcmi2JA9oBG2anOkRnW8WJTS8Og==
 
+"@getalby/lightning-tools@^5.0.1":
+  version "5.0.1"
+  resolved "https://registry.yarnpkg.com/@getalby/lightning-tools/-/lightning-tools-5.0.1.tgz#08a974bcdf3d98a86ff9909df838360ee67174c8"
+  integrity sha512-xoBfBYMQrJqwryU9fAYGIW6dzWRpdsAw8rroqTROba2bHdYT0ZvGnt4tjqXUhRswopR2X+wp1QeeWHZNL9A0Kg==
+
 "@humanwhocodes/config-array@^0.11.10":
   version "0.11.10"
   resolved "https://registry.yarnpkg.com/@humanwhocodes/config-array/-/config-array-0.11.10.tgz#5a3ffe32cc9306365fb3fd572596cd602d5e12d2"