feat: basic invoice decoding

README.md

@@ -215,6 +215,20 @@ await l402.fetchWithL402(
 );
 ```
 
+### Basic invoice decoding
+
+You can initialize an `Invoice` to decode a payment request.
+
+```js
+const { Invoice } = require("alby-tools");
+
+const invoice = new Invoice({ pr });
+
+const { paymentHash, satoshi, description, createdDate, expiryDate } = invoice;
+```
+
+> If you need more details about the invoice, use a dedicated BOLT11 decoding library.
+
 ### 💵 Fiat conversions
 
 Helpers to convert sats values to fiat and fiat values to sats.

src/invoice.test.ts

@@ -0,0 +1,30 @@
+import Invoice from "./invoice";
+
+const paymentRequestWithoutMemo =
+  "lnbc10n1pj4xmazpp5ns890al37jpreen4rlpl6fsw2hlp9n9hm0ts4dvwvcxq8atf4v6qhp50kncf9zk35xg4lxewt4974ry6mudygsztsz8qn3ar8pn3mtpe50scqzzsxqyz5vqsp5k508kdmvfpuac6lvn9wumr9x4mcpnh2t6jyp5kkxcjhueq4xjxqq9qyyssq0m88mwgknhkqfsa9u8e9dp8v93xlm0lqggslzj8mpsnx3mdzm8z5k9ns7g299pfm9zwm4crs00a364cmpraxr54jw5cf2qx9vycucggqz2ggul";
+
+const paymentRequestWithMemo =
+  "lnbc10u1pj4t6w0pp54wm83znxp8xly6qzuff2z7u6585rnlcw9uduf2haa42qcz09f5wqdq023jhxapqd4jk6mccqzzsxqyz5vqsp5mlvjs8nktpz98s5dcrhsuelrz94kl2vjukvu789yzkewast6m00q9qyyssqupynqdv7e5y8nlul0trva5t97g7v3gwx7akhu2dvu4pn66eu2pr5zkcnegp8myz3wrpj9ht06pwyfn4dvpmnr96ejq6ygex43ymaffqq3gud4d";
+
+describe("Invoice", () => {
+  test("decode invoice without description", () => {
+    const decodedInvoice = new Invoice({ pr: paymentRequestWithoutMemo });
+    expect(decodedInvoice.paymentHash).toBe(
+      "9c0e57f7f1f4823ce6751fc3fd260e55fe12ccb7dbd70ab58e660c03f569ab34",
+    );
+    expect(decodedInvoice.satoshi).toBe(1);
+    expect(decodedInvoice.expiry).toBe(86400);
+    expect(decodedInvoice.timestamp).toBe(1699966882);
+    expect(decodedInvoice.createdDate.toISOString()).toBe(
+      "2023-11-14T13:01:22.000Z",
+    );
+    expect(decodedInvoice.expiryDate.toISOString()).toBe(
+      "2023-11-15T13:01:22.000Z",
+    );
+    expect(decodedInvoice.description).toBeNull();
+  });
+  test("decode invoice with description", () => {
+    const decodedInvoice = new Invoice({ pr: paymentRequestWithMemo });
+    expect(decodedInvoice.description).toBe("Test memo");
+  });
+});

src/invoice.ts

@@ -1,4 +1,4 @@
-import { getHashFromInvoice } from "./utils/invoice";
+import { decodeInvoice } from "./utils/invoice";
 import Hex from "crypto-js/enc-hex.js";
 import sha256 from "crypto-js/sha256.js";
 import { InvoiceArgs } from "./types";
@@ -8,10 +8,29 @@ export default class Invoice {
   paymentHash: string;
   preimage: string | null;
   verify: string | null;
+  satoshi: number;
+  expiry: number; // expiry in seconds (not a timestamp)
+  timestamp: number; // created date in seconds
+  createdDate: Date;
+  expiryDate: Date;
+  description: string | null;
 
   constructor(args: InvoiceArgs) {
     this.paymentRequest = args.pr;
-    this.paymentHash = getHashFromInvoice(this.paymentRequest) as string;
+    if (!this.paymentRequest) {
+      throw new Error("Invalid payment request");
+    }
+    const decodedInvoice = decodeInvoice(this.paymentRequest);
+    if (!decodedInvoice) {
+      throw new Error("Failed to decode payment request");
+    }
+    this.paymentHash = decodedInvoice.paymentHash;
+    this.satoshi = decodedInvoice.satoshi;
+    this.timestamp = decodedInvoice.timestamp;
+    this.expiry = decodedInvoice.expiry;
+    this.createdDate = new Date(this.timestamp * 1000);
+    this.expiryDate = new Date((this.timestamp + this.expiry) * 1000);
+    this.description = decodedInvoice.description ?? null;
     this.verify = args.verify ?? null;
     this.preimage = args.preimage ?? null;
   }

src/utils/invoice.ts

@@ -1,18 +1,68 @@
 import { decode } from "light-bolt11-decoder";
 
-export const getHashFromInvoice = (invoice) => {
-  if (!invoice) return null;
+type DecodedInvoice = {
+  paymentHash: string;
+  satoshi: number;
+  timestamp: number;
+  expiry: number;
+  description: string | undefined;
+};
+
+export const decodeInvoice = (
+  paymentRequest: string,
+): DecodedInvoice | null => {
+  if (!paymentRequest) return null;
 
   try {
-    const decoded = decode(invoice);
+    const decoded = decode(paymentRequest);
     if (!decoded || !decoded.sections) return null;
 
     const hashTag = decoded.sections.find(
       (value) => value.name === "payment_hash",
     );
-    if (!hashTag || !hashTag.value) return null;
 
-    return hashTag.value.toString();
+    if (hashTag?.name !== "payment_hash" || !hashTag.value) return null;
+
+    const paymentHash = hashTag.value;
+
+    const amountTag = decoded.sections.find((value) => value.name === "amount");
+
+    if (amountTag?.name !== "amount" || amountTag.value === undefined)
+      return null;
+
+    const satoshi = parseInt(amountTag.value) / 1000; // millisats
+
+    const expiryTag = decoded.sections.find((value) => value.name === "expiry");
+
+    const timestampTag = decoded.sections.find(
+      (value) => value.name === "timestamp",
+    );
+
+    if (timestampTag?.name !== "timestamp" || !timestampTag.value) return null;
+
+    const timestamp = timestampTag.value;
+
+    if (expiryTag?.name !== "expiry" || expiryTag.value === undefined)
+      return null;
+
+    const expiry = expiryTag.value;
+
+    const descriptionTag = decoded.sections.find(
+      (value) => value.name === "description",
+    );
+
+    const description =
+      descriptionTag?.name === "description"
+        ? descriptionTag?.value
+        : undefined;
+
+    return {
+      paymentHash,
+      satoshi,
+      timestamp,
+      expiry,
+      description,
+    };
   } catch {
     return null;
   }

src/utils/light-bolt11-decoder.d.ts

@@ -0,0 +1,90 @@
+// TODO: remove when https://github.com/nbd-wtf/light-bolt11-decoder/pull/4 is merged
+declare module "light-bolt11-decoder" {
+  type NetworkSection = {
+    name: "coin_network";
+    letters: string;
+    value?: {
+      bech32: string;
+      pubKeyHash: number;
+      scriptHash: number;
+      validWitnessVersions: number[];
+    };
+  };
+
+  type FeatureBits = {
+    option_data_loss_protect: string;
+    initial_routing_sync: string;
+    option_upfront_shutdown_script: string;
+    gossip_queries: string;
+    var_onion_optin: string;
+    gossip_queries_ex: string;
+    option_static_remotekey: string;
+    payment_secret: string;
+    basic_mpp: string;
+    option_support_large_channel: string;
+    extra_bits: {
+      start_bit: number;
+      bits: unknown[];
+      has_required: boolean;
+    };
+  };
+
+  type RouteHint = {
+    pubkey: string;
+    short_channel_id: string;
+    fee_base_msat: number;
+    fee_proportional_millionths: number;
+    cltv_expiry_delta: number;
+  };
+
+  type RouteHintSection = {
+    name: "route_hint";
+    tag: "r";
+    letters: string;
+    value: RouteHint[];
+  };
+
+  type FeatureBitsSection = {
+    name: "feature_bits";
+    tag: "9";
+    letters: string;
+    value: FeatureBits;
+  };
+
+  type Section =
+    | { name: "paymentRequest"; value: string }
+    | { name: "expiry"; value: number }
+    | { name: "checksum"; letters: string }
+    | NetworkSection
+    | { name: "amount"; letters: string; value: string }
+    | { name: "separator"; letters: string }
+    | { name: "timestamp"; letters: string; value: number }
+    | { name: "payment_hash"; tag: "p"; letters: string; value: string }
+    | { name: "description"; tag: "d"; letters: string; value: string }
+    | { name: "payment_secret"; tag: "s"; letters: string; value: string }
+    | {
+        name: "min_final_cltv_expiry";
+        tag: "c";
+        letters: string;
+        value: number;
+      }
+    | FeatureBitsSection
+    | RouteHintSection
+    | { name: "signature"; letters: string; value: string };
+
+  type PaymentJSON = {
+    paymentRequest: string;
+    sections: Section[];
+    expiry: number;
+    route_hints: RouteHint[][];
+  };
+
+  type DecodedInvoice = {
+    paymentRequest: string;
+    sections: Section[];
+    expiry: number;
+    route_hints: RouteHint[][];
+  };
+
+  function decode(invoice: string): DecodedInvoice;
+}