From 062ded9e6daf5c4a76ab57aaad05391de163050d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?R=C3=A2u=20Cao?= <raucao@kosmos.org>
Date: Wed, 23 Oct 2024 14:54:01 +0200
Subject: [PATCH] Remove generated anchor links from feed content

---
 feeds.ts                          |  10 +-
 tests/feeds_test.ts               |  17 +++
 tests/fixtures/gfm-content-1.html | 165 ++++++++++++++++++++++++++++++
 3 files changed, 191 insertions(+), 1 deletion(-)
 create mode 100644 tests/feeds_test.ts
 create mode 100644 tests/fixtures/gfm-content-1.html

diff --git a/feeds.ts b/feeds.ts
index bef4c6a..031ade8 100644
--- a/feeds.ts
+++ b/feeds.ts
@@ -18,7 +18,7 @@ export function profileAtomFeed(profile: Profile, articles: Article[]) {
         <updated>${isoDate(article.updatedAt)}</updated>
         <summary>${article.summary}</summary>
         <content type="html"><![CDATA[
-          ${article.html}
+          ${cleanContentHtml(article.html)}
         ]]></content>
       </entry>
     `;
@@ -38,3 +38,11 @@ export function profileAtomFeed(profile: Profile, articles: Article[]) {
     </feed>
   `.trim();
 }
+
+export function cleanContentHtml(html: string) {
+  const cleanHtml = html.replace(
+    /<a class="anchor" aria-hidden="true"[^>]*>.*?<\/a>/gs,
+    "",
+  );
+  return cleanHtml;
+}
diff --git a/tests/feeds_test.ts b/tests/feeds_test.ts
new file mode 100644
index 0000000..b629d92
--- /dev/null
+++ b/tests/feeds_test.ts
@@ -0,0 +1,17 @@
+import { describe, it } from "@std/testing/bdd";
+import { expect } from "@std/expect";
+import { cleanContentHtml } from "../feeds.ts";
+
+describe("Feeds", () => {
+  describe("#cleanContentHtml", () => {
+    let articleHtml = Deno.readTextFileSync(
+      "tests/fixtures/gfm-content-1.html",
+    );
+
+    it("removes the anchor links for headlines", () => {
+      const cleanHtml = cleanContentHtml(articleHtml);
+      expect(cleanHtml).not.toMatch(/<a class="anchor" aria-hidden="true"/);
+      expect(cleanHtml).not.toMatch(/<svg class="octicon octicon-link"/);
+    });
+  });
+});
diff --git a/tests/fixtures/gfm-content-1.html b/tests/fixtures/gfm-content-1.html
new file mode 100644
index 0000000..fc8dc1d
--- /dev/null
+++ b/tests/fixtures/gfm-content-1.html
@@ -0,0 +1,165 @@
+<p>
+  This week, it finally happened: I still had a Lightning channel open with a
+  node that hadn't been online for the better part of a year now, so I decided
+  to close the channel unilaterally. But force-closing a channel means you have
+  to broadcast the latest commitment transaction, the pre-set fee of which was
+  only ~1 sat/vB for this one.
+</p>
+<p>
+  With LND, if the channel is created as an <a
+    href="https://lightning.engineering/posts/2021-01-28-lnd-v0.12/"
+    rel="noopener noreferrer"
+  >anchor channel</a> (by default only since version 0.12), then the commitment
+  transaction contains small extra outputs (currently 330 sats), which let
+  either channel partner spend one of them into a child transaction that can be
+  created with higher fees to pay for the parent transaction (CPFP). LND even
+  has a built-in command for that: <code>lncli wallet bumpclosefee</code>
+</p>
+<p>
+  However, this channel was created in the old-school way, and was thus stuck
+  with its low fee. In fact, even the local bitcoin node refused to accept the
+  transaction into its own mempool, so the bitcoin p2p network didn't even know
+  it existed. So how do we get out of this pickle?
+</p>
+<h2 id="the-solution">
+  <a class="anchor" aria-hidden="true" tabindex="-1" href="#the-solution"><svg
+      class="octicon octicon-link"
+      viewBox="0 0 16 16"
+      width="16"
+      height="16"
+      aria-hidden="true"
+    >
+      <path
+        fill-rule="evenodd"
+        d="M7.775 3.275a.75.75 0 001.06 1.06l1.25-1.25a2 2 0 112.83 2.83l-2.5 2.5a2 2 0 01-2.83 0 .75.75 0 00-1.06 1.06 3.5 3.5 0 004.95 0l2.5-2.5a3.5 3.5 0 00-4.95-4.95l-1.25 1.25zm-4.69 9.64a2 2 0 010-2.83l2.5-2.5a2 2 0 012.83 0 .75.75 0 001.06-1.06 3.5 3.5 0 00-4.95 0l-2.5 2.5a3.5 3.5 0 004.95 4.95l1.25-1.25a.75.75 0 00-1.06-1.06l-1.25 1.25a2 2 0 01-2.83 0z"
+      >
+      </path>
+    </svg></a>The solution
+</h2>
+<p>
+  Enter the <a
+    href="https://mempool.space/accelerator"
+    rel="noopener noreferrer"
+  >mempool.space Accelerator</a>. It is essentially an automated way to create
+  agreements with various mining pools to mine your low-fee transaction in
+  exchange for an out-of-band payment. Mempool.space coordinates these
+  agreements and out-of-band payments with miners and gets a share from the
+  overall fee for that.
+</p>
+<p>
+  Now, if you're in the same situation as I was, you might search for the ID of
+  your closing transaction and find that mempool.space cannot find it. Remember
+  how the local bitcoin node (with mostly default settings) didn't accept it in
+  the first place?
+</p>
+<h3 id="1-get-the-transaction-to-be-broadcast">
+  <a
+    class="anchor"
+    aria-hidden="true"
+    tabindex="-1"
+    href="#1-get-the-transaction-to-be-broadcast"
+  ><svg
+      class="octicon octicon-link"
+      viewBox="0 0 16 16"
+      width="16"
+      height="16"
+      aria-hidden="true"
+    >
+      <path
+        fill-rule="evenodd"
+        d="M7.775 3.275a.75.75 0 001.06 1.06l1.25-1.25a2 2 0 112.83 2.83l-2.5 2.5a2 2 0 01-2.83 0 .75.75 0 00-1.06 1.06 3.5 3.5 0 004.95 0l2.5-2.5a3.5 3.5 0 00-4.95-4.95l-1.25 1.25zm-4.69 9.64a2 2 0 010-2.83l2.5-2.5a2 2 0 012.83 0 .75.75 0 001.06-1.06 3.5 3.5 0 00-4.95 0l-2.5 2.5a3.5 3.5 0 004.95 4.95l1.25-1.25a.75.75 0 00-1.06-1.06l-1.25 1.25a2 2 0 01-2.83 0z"
+      >
+      </path>
+    </svg></a>1. Get the transaction to be broadcast
+</h3>
+<p>In your <code>bitcoin.conf</code>, add the following line:</p>
+<pre><code>minrelaytxfee=0</code></pre><p>
+  This sets the minimum fee to 0, meaning it will accept and broadcast your
+  transactions, no matter how low the fee is. Restart <code>bitcoind</code> and
+  wait a little bit. LND will retry broadcasting the closing transaction every
+  minute or so until it succeeds. At some point you should be able to find it on
+  mempool.space.
+</p>
+<h3 id="2-use-the-accelerator-to-confirm-it">
+  <a
+    class="anchor"
+    aria-hidden="true"
+    tabindex="-1"
+    href="#2-use-the-accelerator-to-confirm-it"
+  ><svg
+      class="octicon octicon-link"
+      viewBox="0 0 16 16"
+      width="16"
+      height="16"
+      aria-hidden="true"
+    >
+      <path
+        fill-rule="evenodd"
+        d="M7.775 3.275a.75.75 0 001.06 1.06l1.25-1.25a2 2 0 112.83 2.83l-2.5 2.5a2 2 0 01-2.83 0 .75.75 0 00-1.06 1.06 3.5 3.5 0 004.95 0l2.5-2.5a3.5 3.5 0 00-4.95-4.95l-1.25 1.25zm-4.69 9.64a2 2 0 010-2.83l2.5-2.5a2 2 0 012.83 0 .75.75 0 001.06-1.06 3.5 3.5 0 00-4.95 0l-2.5 2.5a3.5 3.5 0 004.95 4.95l1.25-1.25a.75.75 0 00-1.06-1.06l-1.25 1.25a2 2 0 01-2.83 0z"
+      >
+      </path>
+    </svg></a>2. Use the Accelerator to confirm it
+</h3>
+<p>
+  Once you can see the transaction on <a
+    href="https://mempool.space"
+    rel="noopener noreferrer"
+  >mempool.space</a>, you can just click the "Accelerate" button next to the
+  ETA. This will bring you to a page that shows you the estimated share of
+  miners that will include your transaction in their blocks, as well as some
+  acceleration fee options for various transaction fee levels, which you can pay
+  for via the Lightning Network, of course.
+</p>
+<p>
+  If you haven't looked into this service before (which I had), then the fees
+  might be a bit of a surprise to you. This thing is <strong>not</strong> cheap!
+  Bumping my fee from 1 sat/vB to <del>9 sats/vB cost a whopping 51,500 sats
+    (</del>31 USD that day). Bumping it higher only seemed to add the difference
+  in the transaction fee itself, so the service seems to have cost a flat 50K
+  sats at the time.
+</p>
+<p>
+  Unfortunately, this channel wasn't particularly large, so the acceleration fee
+  amounted to ~9% of my remaining channel balance. But 91% of something is
+  better than 100% of nothing, so I actually felt pretty good about it.
+</p>
+<p>Next, you will see something like this:</p>
+<p>
+  <img
+    src="https://image.nostr.build/76151cc2ae06a93a8fcd97102bf4fa63541f8f3bd19800b96ff1070c9450945c.png"
+    alt="Screenshot of an accelerated transaction on mempool.space"
+  />
+</p>
+<p>
+  Time to lean back and let the miners work for you. In my case, the ETA was
+  eerily precise. It told me that it would take ~56 minutes to confirm the
+  transaction, and almost exactly an hour later it was mined.
+</p>
+<h3 id="3-wait">
+  <a class="anchor" aria-hidden="true" tabindex="-1" href="#3-wait"><svg
+      class="octicon octicon-link"
+      viewBox="0 0 16 16"
+      width="16"
+      height="16"
+      aria-hidden="true"
+    >
+      <path
+        fill-rule="evenodd"
+        d="M7.775 3.275a.75.75 0 001.06 1.06l1.25-1.25a2 2 0 112.83 2.83l-2.5 2.5a2 2 0 01-2.83 0 .75.75 0 00-1.06 1.06 3.5 3.5 0 004.95 0l2.5-2.5a3.5 3.5 0 00-4.95-4.95l-1.25 1.25zm-4.69 9.64a2 2 0 010-2.83l2.5-2.5a2 2 0 012.83 0 .75.75 0 001.06-1.06 3.5 3.5 0 00-4.95 0l-2.5 2.5a3.5 3.5 0 004.95 4.95l1.25-1.25a.75.75 0 00-1.06-1.06l-1.25 1.25a2 2 0 01-2.83 0z"
+      >
+      </path>
+    </svg></a>3. Wait
+</h3>
+<p>
+  Now that our transaction is confirmed, our channel is not closed immediately,
+  of course. The <a
+    href="https://docs.lightning.engineering/the-lightning-network/multihop-payments/hash-time-lock-contract-htlc"
+    rel="noopener noreferrer"
+  >time lock of the HTLC</a> protects our channel partner from us broadcasting
+  an old channel state in which our balance might be higher than in the latest
+  state.
+</p>
+<p>
+  In my case, it was set to 144 blocks, i.e. ~24 hours. So I checked back the
+  next day, et voilá: channel closed and balance restored. 🥳
+</p>