From 9dbc1ff66d9aba6b62cc3a113440593d5992e22b Mon Sep 17 00:00:00 2001
From: Egge <egge24@protonmail.com>
Date: Wed, 17 Jan 2024 11:27:31 +0100
Subject: [PATCH] added decodeInvoice util

---
 src/model/types/index.ts | 10 ++++++++++
 src/utils.ts             | 29 ++++++++++++++++++++++++++++-
 test/utils.test.ts       | 16 ++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/src/model/types/index.ts b/src/model/types/index.ts
index 1fd13cdcb..3b6422271 100644
--- a/src/model/types/index.ts
+++ b/src/model/types/index.ts
@@ -341,3 +341,13 @@ export type AmountPreference = {
 	amount: number;
 	count: number;
 };
+
+export type InvoiceData = {
+	paymentRequest: string;
+	amountInSats: number;
+	amountInMSats: number;
+	timestamp: number;
+	paymentHash: string;
+	memo: string;
+	expiry: number;
+};
diff --git a/src/utils.ts b/src/utils.ts
index 541a94f64..b25bde53d 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,6 +1,8 @@
+import { decode } from '@gandlaf21/bolt11-decode';
 import { encodeBase64ToJson, encodeJsonToBase64 } from './base64.js';
 import {
 	AmountPreference,
+	InvoiceData,
 	MintKeys,
 	Proof,
 	Token,
@@ -184,10 +186,35 @@ export function checkResponse(data: { error?: string; detail?: string }) {
 	}
 }
 
-export function joinUrls(...parts: string[]): string {
+export function joinUrls(...parts: Array<string>): string {
 	return parts.map((part) => part.replace(/(^\/+|\/+$)/g, '')).join('/');
 }
 
+export function decodeInvoice(bolt11Invoice: string): InvoiceData {
+	const invoiceData: InvoiceData = {} as InvoiceData;
+	const decodeResult = decode(bolt11Invoice);
+	for (let i = 0; i < decodeResult.sections.length; i++) {
+		const decodedSection = decodeResult.sections[i];
+		if (decodedSection.name === 'amount') {
+			invoiceData.amountInSats = Number(decodedSection.value) / 1000;
+			invoiceData.amountInMSats = Number(decodedSection.value);
+		}
+		if (decodedSection.name === 'timestamp') {
+			invoiceData.timestamp = decodedSection.value;
+		}
+		if (decodedSection.name === 'description') {
+			invoiceData.memo = decodedSection.value;
+		}
+		if (decodedSection.name === 'expiry') {
+			invoiceData.expiry = decodedSection.value;
+		}
+		if (decodedSection.name === 'payment_hash') {
+			invoiceData.paymentHash = decodedSection.value.toString('hex');
+		}
+	}
+	return invoiceData;
+}
+
 export {
 	bigIntStringify,
 	bytesToNumber,
diff --git a/test/utils.test.ts b/test/utils.test.ts
index 3795a91a0..ba8948e82 100644
--- a/test/utils.test.ts
+++ b/test/utils.test.ts
@@ -298,3 +298,19 @@ describe('test cleanToken', () => {
 		expect(mint_info_url).toBe('https://8333.space:3338/info');
 	});
 });
+
+describe('test decodeInvoice', () => {
+	test('decoding a lightning invoice', async () => {
+		const invoice =
+			'lnbc15u1p3xnhl2pp5jptserfk3zk4qy42tlucycrfwxhydvlemu9pqr93tuzlv9cc7g3sdqsvfhkcap3xyhx7un8cqzpgxqzjcsp5f8c52y2stc300gl6s4xswtjpc37hrnnr3c9wvtgjfuvqmpm35evq9qyyssqy4lgd8tj637qcjp05rdpxxykjenthxftej7a2zzmwrmrl70fyj9hvj0rewhzj7jfyuwkwcg9g2jpwtk3wkjtwnkdks84hsnu8xps5vsq4gj5hs';
+		const invoiceData = utils.decodeInvoice(invoice);
+		expect(invoiceData.timestamp).toStrictEqual(1651105770);
+		expect(invoiceData.amountInMSats).toStrictEqual(1500000);
+		expect(invoiceData.amountInSats).toStrictEqual(1500);
+		expect(invoiceData.paymentHash).toStrictEqual(
+			'90570c8d3688ad5012aa5ff982606971ae46b3f9df0a100cb15f05f61718f223'
+		);
+		expect(invoiceData.expiry).toStrictEqual(600);
+		expect(invoiceData.memo).toStrictEqual('bolt11.org');
+	});
+});