Add LNURL-pay server for donations

.gitignore

@@ -2,6 +2,7 @@
 .vscode
 .aleph
 dist
+addinvoice_payload.json
 
 config/config.ts
 pageviews.json

api.ts

@@ -1,5 +1,8 @@
 import { Router } from "https://deno.land/x/oak/mod.ts";
 import { exec, OutputMode } from "https://deno.land/x/exec/mod.ts";
+import { ensureFile } from "https://deno.land/std/fs/mod.ts";
+import * as base64 from "https://denopkg.com/chiefbiiko/base64/mod.ts";
+import { sha256 } from "https://denopkg.com/chiefbiiko/sha256/mod.ts";
 
 import { getBlocks } from "./blocks.ts";
 import { getblockchaininfo, getblockcount, getblockhash } from "./jsonrpc/index.ts";
@@ -41,7 +44,8 @@ router.get("/blocks", (context) => {
   context.response.body = blocks;
 });
 
-router.get("/invoice", async (context) => {
+const responseMetadata = JSON.stringify([["text/plain", "Donation on taproot.watch"]]);
+router.get("/invoice", (context) => {
   if (!config.donation) {
     context.response.status = 400;
     context.response.body = JSON.stringify({
@@ -51,14 +55,60 @@ router.get("/invoice", async (context) => {
     return;
   }
 
+  context.response.body = JSON.stringify({
+    tag: "payRequest",
+    callback: `${config.donation.lnurlPayUrl}/callback`,
+    maxSendable: 100000,
+    minSendable: 1000,
+    metadata: responseMetadata,
+    // commentAllowed: 200,
+  });
+});
+
+await ensureFile("./addinvoice_payload.json");
+router.get("/invoice/callback", async (context) => {
+  if (!config.donation) {
+    context.response.status = 400;
+    context.response.body = JSON.stringify({
+      status: "ERROR",
+      reason: "Donation is not configured",
+    });
+    return;
+  }
+
+  const amountString = context.request.url.searchParams.get("amount");
+  if (amountString === null) {
+    context.response.body = JSON.stringify({
+      status: "ERROR",
+      reason: "Missing amount parameter",
+    });
+    return;
+  }
+  const amount = Number.parseInt(amountString);
+
+  await Deno.writeTextFile(
+    "./addinvoice_payload.json",
+    JSON.stringify({
+      memo: "Donation",
+      value_msat: amount,
+      description_hash: sha256(responseMetadata, "utf8", "base64"),
+    })
+  );
+
   const macaroonHeader = bytesToHexString(await Deno.readFile(config.donation.data.macaroon));
-  // -d '{"memo":"Donation"}'
-  const command = `curl -X POST --cacert ${config.donation.data.cert} --header "Grpc-Metadata-macaroon: ${macaroonHeader}" ${config.donation.data.server}/v1/invoices`;
+  const command = `curl -X POST --cacert ${config.donation.data.cert} --header "Grpc-Metadata-macaroon: ${macaroonHeader}" -d @addinvoice_payload.json ${config.donation.data.server}/v1/invoices`;
 
   const result = await exec(command, {
     output: OutputMode.Capture,
   });
-  context.response.body = JSON.parse(result.output).payment_request;
+  const paymentRequest = JSON.parse(result.output).payment_request;
+  context.response.body = JSON.stringify({
+    pr: paymentRequest,
+    successAction: {
+      tag: "message",
+      message: "Cheers!",
+    },
+    disposable: true,
+  });
 });
-
 export default router;

config/config.ts_TEMPLATE

@@ -43,6 +43,8 @@ interface Config {
       // Path to invoice.macaroon
       macaroon: string;
     };
+    // URL to the LNURL-pay endpoint
+    lnurlPayUrl: string;
   };
 }
 
@@ -73,6 +75,7 @@ const config: Config = {
   //     macaroon: "/path/to/invoice.macaroon",
   //   },
   // },
+  // lnurlPayUrl: "https://domain.com/invoice",
 };
 
 export default config;

frontend/components/Donation.tsx

@@ -1,37 +1,101 @@
 import React, { useState } from "https://esm.sh/react@17.0.2";
 import styled from "https://esm.sh/styled-components";
 import { QRCode } from "https://esm.sh/react-qr-svg";
+import { bech32 } from "https://esm.sh/bech32";
+
+import config from "../back/config/config.ts";
+import { bytesToString } from "../back/utils.ts";
 
 export const DonateContainer = styled.div`
+  margin: 0 auto 100px;
+  width: 400px;
   text-align: center;
-  margin-bottom: 100px;
 `;
 
 export const DonateText = styled.a`
+  display: block;
   text-align: center;
   color: #404040;
   text-shadow: #000 1px 1px 0px;
   cursor: pointer;
 `;
 
+export const Bolt11Text = styled.a`
+  display: block;
+  overflow-wrap: anywhere;
+  font-size: 11px;
+  color: #aaa;
+  cursor: pointer;
+  margin-top: 5px;
+  margin-bottom: 15px;
+`;
+
+export const InvoiceText = styled.p`
+  text-align: center;
+  color: #aaa;
+  text-shadow: #000 1px 1px 0px;
+`;
+
+export const ChangeToBolt11 = styled.a`
+  display: block;
+  text-align: center;
+  color: #aaa;
+  text-shadow: #000 1px 1px 0px;
+  cursor: pointer;
+  text-decoration: underline;
+  font-size: 14px;
+`;
+
+const lnurlPayBech32 = bech32.encode(
+  "lnurl",
+  bech32.toWords(new TextEncoder().encode(config.donation?.lnurlPayUrl)),
+  1024
+);
+
 export function Donation() {
+  const [type, setType] = useState<"lnurl-pay" | "bolt11">("lnurl-pay");
   const [invoice, setInvoice] = useState<string | undefined>(undefined);
 
-  const fetchInvoice = async () => {
-    const result = await fetch("/invoice");
-    setInvoice(await result.text());
+  const showLnUrlPay = () => {
+    setType("lnurl-pay");
+    setInvoice(lnurlPayBech32);
+  };
+
+  const decodeLnUrlPay = async () => {
+    const decodedBech32 = bech32.decode(invoice!, 1024);
+    const decodedUrl = bytesToString(bech32.fromWords(decodedBech32.words));
+
+    const result = await fetch(decodedUrl);
+    const resultJson = await result.json();
+
+    const amount = prompt(
+      `Choose an amount between ${resultJson.minSendable} sats and ${resultJson.maxSendable} sats`,
+      resultJson.minSendable
+    );
+
+    const callback = resultJson.callback;
+
+    const resultCallback = await fetch(callback + "?amount=" + amount);
+    const resultCallbackJson = await resultCallback.json();
+
+    setType("bolt11");
+    setInvoice(resultCallbackJson.pr);
+  };
+
+  const onClickInvoice = () => {
+    window.location.replace("lightning:" + invoice);
   };
 
   return (
     <DonateContainer>
-      {!invoice && <DonateText onClick={fetchInvoice}>Donate via Lightning Network</DonateText>}
+      {!invoice && <DonateText onClick={showLnUrlPay}>Donate via Lightning Network</DonateText>}
       {invoice && (
-        <div
-          style={{ cursor: "pointer" }}
-          onClick={() => {
-            window.location.replace("lightning:" + invoice);
-          }}
-        >
+        <>
+          <InvoiceText>
+            {type === "lnurl-pay" && <>LNURL-pay</>}
+            {type === "bolt11" && <>LN Invoice</>} QR code:
+          </InvoiceText>
+          <div style={{ cursor: "pointer" }} onClick={onClickInvoice}>
             <QRCode
               bgColor="#FFFFFF"
               fgColor="#000000"
@@ -39,6 +103,13 @@ export function Donation() {
               style={{ border: "8px solid #fff", width: 200 }}
             />
           </div>
+          <Bolt11Text onClick={onClickInvoice}>{invoice}</Bolt11Text>
+          {type == "lnurl-pay" && (
+            <ChangeToBolt11 onClick={decodeLnUrlPay}>
+              Unsupported wallet? Click to change to normal BOLT11 invoice
+            </ChangeToBolt11>
+          )}
+        </>
       )}
     </DonateContainer>
   );

frontend/pages/index.tsx

@@ -114,7 +114,7 @@ export default function Blocks() {
             <Block key={i} height={block.height} signals={block.signals} />
           ))}
         </BlockContainer>
-        <Donation />
+        {config.donation && <Donation />}
       </Content>
     </Container>
   );

utils.ts

@@ -3,3 +3,7 @@ export const bytesToHexString = (bytes: Uint8Array) => {
     return memo + ("0" + i.toString(16)).slice(-2); //padd with leading 0 if <16
   }, "");
 };
+
+export const bytesToString = (bytes: number[]) => {
+  return String.fromCharCode.apply(null, bytes);
+};