docs: add guide on integrating user comments with Giscus

src/content/blog/how-to-integrate-giscus-comments.md

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+---
+author: FjellOverflow
+pubDatetime: 2024-07-25T11:11:53Z
+title: How to integrate Giscus comments into AstroPaper
+slug: how-to-integrate-giscus-comments
+featured: true
+draft: false
+tags:
+  - astro
+  - blog
+  - docs
+description: Comment function on a static blog hosted on GitHub Pages with Giscus.
+---
+
+Hosting a thin static blog on a platform like [GitHub Pages](https://docs.github.com/en/pages/getting-started-with-github-pages/creating-a-github-pages-site) has numerous advantages, but also takes away some interactivity. Fortunately, [Giscus](https://giscus.app/) exists and offers a way to embed user comments on static sites.
+
+## Table of contents
+
+## How _Giscus_ works
+
+[Giscus uses the GitHub API](https://github.com/giscus/giscus?tab=readme-ov-file#how-it-works) to read and store comments made by _GitHub_ users in the `Discussions` associated with a repository.
+
+Embed the _Giscus_ client-side script bundle on your site, configure it with the correct repository URL, and users can view and write comments (when logged into _GitHub_).
+
+The approach is serverless, as the comments are stored on _GitHub_ and dynamically loaded from there on client side, hence perfect for a static blog, like _AstroPaper_.
+
+## Setting up _Giscus_
+
+_Giscus_ can be set up easily on [giscus.app](https://giscus.app/), but I will outline the process shortly still.
+
+### Prequisites
+
+Prequisites to get _Giscus_ working are
+
+- the repository is [public](https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/managing-repository-settings/setting-repository-visibility#making-a-repository-public)
+- the [Giscus app](https://github.com/apps/giscus) is installed
+- the [Discussions](https://docs.github.com/en/github/administering-a-repository/managing-repository-settings/enabling-or-disabling-github-discussions-for-a-repository) feature is turned on for your repository
+
+If any of these conditions cannot be fulfilled for any reason, unfortunately, _Giscus_ cannot be integrated.
+
+### Configuring _Giscus_
+
+Next, configuring _Giscus_ is necessary. In most cases, the preselected defaults are suitable, and you should only modify them if you have a specific reason and know what you are doing. Don't worry too much about making the wrong choices; you can always adjust the configuration later on.
+
+However you need to
+
+- select the right language for the UI
+- specify the _GitHub_ repository you want to connect, typically the repository containing your statically hosted _AstroPaper_ blog on _GitHub Pages_
+- create and set an `Announcement` type discussion on _GitHub_ if you want to ensure nobody can create random comments directly on _GitHub_
+- define the color scheme
+
+After configuring the settings, _Giscus_ provides you with a generated `<script>` tag, which you will need in the next steps.
+
+## Simple script tag
+
+You should now have a script tag that looks like this:
+
+```html
+<script
+  src="https://giscus.app/client.js"
+  data-repo="[ENTER REPO HERE]"
+  data-repo-id="[ENTER REPO ID HERE]"
+  data-category="[ENTER CATEGORY NAME HERE]"
+  data-category-id="[ENTER CATEGORY ID HERE]"
+  data-mapping="pathname"
+  data-strict="0"
+  data-reactions-enabled="1"
+  data-emit-metadata="0"
+  data-input-position="bottom"
+  data-theme="preferred_color_scheme"
+  data-lang="en"
+  crossorigin="anonymous"
+  async
+></script>
+```
+
+Simply add that to the source code of the site. Most likely, if you're using _AstroPaper_ and want to enable comments on posts, navigate to `src/layouts/PostDetails.astro` and paste it into the desired location where you want the comments to appear, perhaps underneath the `Share this post on:` buttons.
+
+```diff
+      <ShareLinks />
+    </div>
+
++    <script src="https://giscus.app/client.js"
++        data-repo="[ENTER REPO HERE]"
++        data-repo-id="[ENTER REPO ID HERE]"
++        data-category="[ENTER CATEGORY NAME HERE]"
++        data-category-id="[ENTER CATEGORY ID HERE]"
++        ...
++    </script>
+
+  </main>
+  <Footer />
+</Layout>
+```
+
+And it's done! You have successfully integrated comments in _AstroPaper_!
+
+## React component with light/dark theme
+
+The embedded script tag in the layout is quite static, with the _Giscus_ configuration, including `theme`, hardcoded into the layout. Given that _AstroPaper_ features a light/dark theme toggle, it would be nice for the comments to seamlessly transition between light and dark themes along with the rest of the site. To achieve this, a more sophisticated approach to embedding _Giscus_ is required.
+
+Firstly, we are going to install the [React component](https://www.npmjs.com/package/@giscus/react) for _Giscus_:
+
+```bash
+npm i @giscus/react
+```
+
+Then we create a new `Comments.tsx` React component in `src/components`:
+
+```tsx
+import Giscus, { type Theme } from "@giscus/react";
+import { GISCUS } from "@config";
+import { useEffect, useState } from "react";
+
+interface CommentsProps {
+  lightTheme?: Theme;
+  darkTheme?: Theme;
+}
+
+export default function Comments({
+  lightTheme = "light",
+  darkTheme = "dark",
+}: CommentsProps) {
+  const [theme, setTheme] = useState(() => {
+    const currentTheme = localStorage.getItem("theme");
+    const browserTheme = window.matchMedia("(prefers-color-scheme: dark)")
+      .matches
+      ? "dark"
+      : "light";
+
+    return currentTheme || browserTheme;
+  });
+
+  useEffect(() => {
+    const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)");
+    const handleChange = ({ matches }: MediaQueryListEvent) => {
+      setTheme(matches ? "dark" : "light");
+    };
+
+    mediaQuery.addEventListener("change", handleChange);
+
+    return () => mediaQuery.removeEventListener("change", handleChange);
+  }, []);
+
+  useEffect(() => {
+    const themeButton = document.querySelector("#theme-btn");
+    const handleClick = () => {
+      setTheme(prevTheme => (prevTheme === "dark" ? "light" : "dark"));
+    };
+
+    themeButton?.addEventListener("click", handleClick);
+
+    return () => themeButton?.removeEventListener("click", handleClick);
+  }, []);
+
+  return (
+    <div className="mt-8">
+      <Giscus theme={theme === "light" ? lightTheme : darkTheme} {...GISCUS} />
+    </div>
+  );
+}
+```
+
+This _React_ component not only wraps the native _Giscus_ component, but also introduces additional props, namely `lightTheme` and `darkTheme`. Leveraging two event listeners, the _Giscus_ comments will align with the site's theme, dynamically switching between dark and light themes whenever the site or browser theme is changed.
+
+We also need to define the `GISCUS` config, for which the optimal location is in `src/config.ts`:
+
+```ts
+import type { GiscusProps } from "@giscus/react";
+
+...
+
+export const GISCUS: GiscusProps = {
+  repo: "[ENTER REPO HERE]",
+  repoId: "[ENTER REPO ID HERE]",
+  category: "[ENTER CATEGORY NAME HERE]",
+  categoryId: "[ENTER CATEGORY ID HERE]",
+  mapping: "pathname",
+  reactionsEnabled: "0",
+  emitMetadata: "0",
+  inputPosition: "bottom",
+  lang: "en",
+  loading: "lazy",
+};
+```
+
+Note that specifying a `theme` here will override the `lightTheme` and `darkTheme` props, resulting in a static theme setting, similar to the previous approach of embedding _Giscus_ with the `<script>` tag.
+
+To complete the process, add the new Comments component to `src/layouts/PostDetails.astro` (replacing the `script` tag from the previous step).
+
+```diff
+      <ShareLinks />
+    </div>
+
++    <Comments client:only />
+
+  </main>
+  <Footer />
+</Layout>
+```
+
+And that's it!