From 2fa59f14d63404493d914c9b5038ba9acb3385a5 Mon Sep 17 00:00:00 2001
From: Bauke <me@bauke.xyz>
Date: Sat, 15 Jul 2023 15:54:21 +0200
Subject: [PATCH] Factor out the Intercooler HTTP request into a utility
 function.

---
 .../features/group-list-subscribe-button.tsx  | 35 ++++---------
 source/utilities/exports.ts                   |  1 +
 source/utilities/http.ts                      | 50 +++++++++++++++++++
 3 files changed, 60 insertions(+), 26 deletions(-)
 create mode 100644 source/utilities/http.ts

diff --git a/source/content-scripts/features/group-list-subscribe-button.tsx b/source/content-scripts/features/group-list-subscribe-button.tsx
index ee5c9ad..7887b12 100644
--- a/source/content-scripts/features/group-list-subscribe-button.tsx
+++ b/source/content-scripts/features/group-list-subscribe-button.tsx
@@ -1,5 +1,10 @@
 import {Component, render} from "preact";
-import {log, pluralize, querySelectorAll} from "../../utilities/exports.js";
+import {
+  log,
+  makeIntercoolerRequest,
+  pluralize,
+  querySelectorAll,
+} from "../../utilities/exports.js";
 
 export function runGroupListSubscribeButtonFeature(): void {
   const count = addSubscribeButtonsToGroupList();
@@ -14,14 +19,6 @@ function addSubscribeButtonsToGroupList(): number {
     return 0;
   }
 
-  const csrfToken = document.querySelector<HTMLMetaElement>(
-    'meta[name="csrftoken"]',
-  )?.content;
-  if (csrfToken === undefined) {
-    log("No CSRF token found", true);
-    return 0;
-  }
-
   let count = 0;
   for (const listItem of querySelectorAll<HTMLLIElement>(
     ".group-list li:not(.trx-group-list-subscribe-button)",
@@ -34,14 +31,7 @@ function addSubscribeButtonsToGroupList(): number {
     }
 
     const button = document.createDocumentFragment();
-    render(
-      <SubscribeButton
-        csrfToken={csrfToken}
-        group={group}
-        listItem={listItem}
-      />,
-      button,
-    );
+    render(<SubscribeButton group={group} listItem={listItem} />, button);
 
     const activity =
       listItem.querySelector(".group-list-activity") ?? undefined;
@@ -59,7 +49,6 @@ function addSubscribeButtonsToGroupList(): number {
 }
 
 type Props = {
-  csrfToken: string;
   listItem: HTMLLIElement;
   group: string;
 };
@@ -80,21 +69,15 @@ class SubscribeButton extends Component<Props, State> {
   }
 
   clickHandler = async () => {
-    const {csrfToken, group} = this.props;
+    const {group} = this.props;
     const {isSubscribed} = this.state;
 
-    const response = await window.fetch(
+    const response = await makeIntercoolerRequest(
       `https://tildes.net/api/web/group/${group}/subscribe`,
       {
-        headers: {
-          "X-CSRF-Token": csrfToken,
-          "X-IC-Request": "true",
-        },
         method: isSubscribed ? "DELETE" : "PUT",
-        referrer: "https://tildes.net",
       },
     );
-
     if (response.status !== 200) {
       log(`Unexpected status code: ${response.status}`, true);
       return;
diff --git a/source/utilities/exports.ts b/source/utilities/exports.ts
index 3294472..bd997ce 100644
--- a/source/utilities/exports.ts
+++ b/source/utilities/exports.ts
@@ -3,6 +3,7 @@ export * from "./components/link.js";
 export * from "./elements.js";
 export * from "./globals.js";
 export * from "./groups.js";
+export * from "./http.js";
 export * from "./logging.js";
 export * from "./query-selectors.js";
 export * from "./report-a-bug.js";
diff --git a/source/utilities/http.ts b/source/utilities/http.ts
new file mode 100644
index 0000000..fd7f005
--- /dev/null
+++ b/source/utilities/http.ts
@@ -0,0 +1,50 @@
+import {log} from "./logging.js";
+
+/**
+ * Make an HTTP request to the Tildes API that is normally used by Intercooler.
+ * This should only be used when using HTML elements from Tildes itself isn't
+ * feasible.
+ * @param url The API URL to call.
+ * @param request Any extra request details, note that some of these values will
+ * be overridden by the ones required to make a proper Intercooler request.
+ */
+export async function makeIntercoolerRequest(
+  url: string,
+  request: RequestInit,
+): Promise<Response> {
+  if (!url.startsWith("https://tildes.net")) {
+    throw new Error(`Can't make Intercooler request to non-Tildes URL: ${url}`);
+  }
+
+  const csrfToken = document.querySelector<HTMLMetaElement>(
+    'meta[name="csrftoken"]',
+  )!.content;
+
+  const ic: RequestInit = {
+    headers: {
+      "X-CSRF-Token": csrfToken,
+      "X-IC-Request": "true",
+      // Include this header so it's clear this isn't a request actually sent by
+      // Intercooler but by Tildes ReExtended.
+      "X-TRX-Request": "true",
+    },
+    referrer: "https://tildes.net",
+  };
+
+  request.headers =
+    request.headers === undefined
+      ? ic.headers
+      : {
+          ...request.headers,
+          // Apply the Intercooler headers last so they can't be overridden.
+          ...ic.headers,
+        };
+
+  request.referrer = request.referrer ?? ic.referrer;
+
+  // Explicitly log the request because content script HTTP calls don't show up
+  // in the Network DevTools.
+  log("Making Intercooler request:");
+  log(request);
+  return window.fetch(url, request);
+}