Add more RSS feeds

Summary:
* Add separate feeds for notes and articles
* Add feed with articles excerpt only
* Add feed with articles excerpts and complete notes
* Add new feeds to `size-limit`

.size-limit.json

@@ -29,6 +29,6 @@
   },
   {
       "name": "Feeds",
-      "path": ["public/feed.xml"]
+      "path": ["public/feed.xml", "public/feed-*.xml"]
   }
 ]

vitepress/.vitepress/rss.mjs

@@ -1,49 +1,99 @@
-import path from 'path'
-import { writeFileSync } from 'fs'
 import { Feed } from 'feed'
 import { createContentLoader } from 'vitepress'
+import { isArticle, isNote } from './utils/content-type.mjs'
 import { comparePublicationDate, isPublished } from './utils/frontmatter.mjs'
+import { baseFeedOptions, compareItemsDates, feedItem, writeFeed } from './utils/rss.mjs'
 
 /** @todo: should come from .env */
 const APP_URL = `https://blog.mehdi.cc`
 
 /** @param {import('vitepress').SiteConfig} config */
 export async function rss(config) {
+  const feedOptions = baseFeedOptions(config)
+
+  // Load content and turn it into feed items.
+
+  /** @type {import('vitepress').ContentData[]} */
+  const content = (await createContentLoader(['articles/*.md', 'notes/*.md'], { excerpt: true, render: true }).load())
+    .filter(isPublished)
+    .toSorted(comparePublicationDate)
+
+  const notesItems = content.filter(isNote).map(feedItem)
+  const articlesItems = content.filter(isArticle).map(feedItem)
+  const articlesItemsExcerptOnly = content
+    .filter(isArticle)
+    .map(content => feedItem(content, { content: content.excerpt }))
+
   /**
-   * https://www.rssboard.org/rss-profile
-   * https://github.com/jpmonette/feed
+   * Generate all feeds and store them on disk.
+   *
+   * - spec: https://www.rssboard.org/rss-specification
+   * - spec best practices: https://www.rssboard.org/rss-profile
+   * - `feed` package: https://github.com/jpmonette/feed
    */
-  const feed = new Feed({
-    docs: 'https://www.rssboard.org/rss-specification',
-    link: APP_URL + 'link',
-    title: config.site.title,
+
+  // Feed 1: full content
+
+  const feedWithEverything = new Feed({
+    title: 'Mehdi’s notes and articles',
     description: config.site.description,
-    language: config.site.lang,
-    // image: 'https://blog.mehdi.cc/file.png',
-    // favicon: `${APP_URL}/favicon.ico`,
-    copyright: 'Copyright © 2023-present, Mehdi Merah',
     feed: `${APP_URL}/feed.xml`,
-    ttl: 2880, // 1 day,
-  });
+    ...feedOptions,
+  })
 
-  (await createContentLoader(['articles/*.md', 'notes/*.md'], { excerpt: true, render: true }).load())
-    .filter(isPublished)
-    .toSorted(comparePublicationDate)
-    .forEach(({ url, excerpt, frontmatter, html }) =>
-      feed.addItem({
-        title: frontmatter.title,
-        id: `${APP_URL}${url}`,
-        link: `${APP_URL}${url}`,
-        description: frontmatter.description || excerpt,
-        content: html,
-        date: frontmatter.publishedAt,
-        author: [{
-          name: 'Mehdi Merah',
-          link: 'https://mehdi.cc',
-          email: ' ', // hack, otherwise <author> is missing in RSS
-        }],
-      })
-    )
-
-  writeFileSync(path.join(config.outDir, 'feed.xml'), feed.rss2())
+  feedWithEverything.items = [...notesItems, ...articlesItems].toSorted(compareItemsDates)
+
+  writeFeed('feed', feedWithEverything)
+
+  // Feed 2: notes
+
+  const feedWithNotes = new Feed({
+    title: 'Mehdi’s notes',
+    description: 'A chronological gathering of… notes.',
+    feed: `${APP_URL}/feed-notes-only.xml`,
+    ...feedOptions,
+  })
+
+  feedWithNotes.items = notesItems
+
+  writeFeed('feed-notes-only', feedWithNotes)
+
+  // Feed 3: articles
+
+  const feedWithArticles = new Feed({
+    title: 'Mehdi’s articles',
+    description: 'A chronological gathering of… articles.',
+    feed: `${APP_URL}/feed-articles-only.xml`,
+    ...feedOptions,
+  })
+
+  feedWithArticles.items = articlesItems
+
+  writeFeed('feed-articles-only', feedWithArticles)
+
+  // Feed 4: articles excerpts
+
+  const feedWithArticlesExcerpts = new Feed({
+    title: 'Mehdi’s articles (excerpts only)',
+    description: 'Excerpt of my articles.',
+    feed: `${APP_URL}/feed-articles-excerpts-only.xml`,
+    ...feedOptions,
+  })
+
+  feedWithArticlesExcerpts.items = articlesItemsExcerptOnly
+
+  writeFeed('feed-articles-excerpts-only', feedWithArticlesExcerpts)
+
+  // Feed 5: articles excerpts and notes
+
+  const feedWithArticlesExcerptsAndNotes = new Feed({
+    title: 'Mehdi’s light feed',
+    description: 'Articles excerpts and notes.',
+    feed: `${APP_URL}/feed-articles-excerpts-and-notes.xml`,
+    ...feedOptions,
+  })
+
+  feedWithArticlesExcerptsAndNotes.items = [...notesItems, ...articlesItemsExcerptOnly].toSorted(compareItemsDates)
+
+  writeFeed('feed-articles-excerpts-and-notes', feedWithArticlesExcerptsAndNotes)
 }

vitepress/.vitepress/utils/content-type.mjs

@@ -0,0 +1,23 @@
+/** @typedef {import('vitepress').ContentData} ContentData */
+
+/**
+ * Check the type of content based on URL.
+ *
+ * @param {ContentData} content
+ * @param {string} type
+ */
+const isContentType = ({ url }, type) => url.startsWith(`/${type}s/`)
+
+/**
+ * The content is an article.
+ *
+ * @param {ContentData} content
+ */
+export const isArticle = content => isContentType(content, 'article')
+
+/**
+ * The content is a note.
+ *
+ * @param {ContentData} content
+ */
+export const isNote = content => isContentType(content, 'note')

vitepress/.vitepress/utils/rss.mjs

@@ -0,0 +1,74 @@
+import path from 'path'
+import { writeFileSync } from 'fs'
+import { Feed } from 'feed'
+
+/** @typedef {import('feed').FeedOptions} FeedOptions */
+/** @typedef {import('feed').Item} Item */
+/** @typedef {import('vitepress').ContentData} ContentData */
+/** @typedef {import('vitepress').SiteConfig} SiteConfig */
+
+/** @todo: should come from .env */
+const APP_URL = `https://blog.mehdi.cc`
+
+/** @type SiteConfig */
+let config = null
+
+/**
+ * Compare frontmatter publication date
+ * @param {Item} a
+ * @param {Item} b
+ */
+export const compareItemsDates = (a, b) => new Date(b.date) - new Date(a.date)
+
+/**
+ * @param {SiteConfig} config
+ * @returns {FeedOptions}
+ */
+export const baseFeedOptions = siteConfig => {
+  if (!config) {
+    config = { ...siteConfig }
+  }
+
+  return {
+    docs: 'https://www.rssboard.org/rss-specification',
+    link: APP_URL,
+    language: config.site.lang,
+    // image: 'https://blog.mehdi.cc/file.png',
+    // favicon: `${APP_URL}/favicon.ico`,
+    copyright: 'Copyright © 2023-present, Mehdi Merah',
+    ttl: 2880, // 1 day,
+  }
+}
+
+/**
+ * @param {ContentData} content
+ * @param {Item?} overrides
+ * @returns {Item}
+ */
+export const feedItem = ({ url, excerpt, frontmatter, html }, { content } = null) => ({
+  title: frontmatter.title,
+  id: `${APP_URL}${url}`,
+  link: `${APP_URL}${url}`,
+  description: frontmatter.description || excerpt,
+  content: content ?? html,
+  date: frontmatter.publishedAt,
+  author,
+})
+
+/** @type {import('feed').Author[]} */
+export const author = [{
+  name: 'Mehdi Merah',
+  link: 'https://mehdi.cc',
+  email: '[email protected]',
+}]
+
+/**
+ * Save a feed on the file system.
+ *
+ * @param {string} filename The name of the feed without file extension.
+ * @param {Feed} feed
+ */
+export const writeFeed = (filename, feed) => writeFileSync(
+  path.join(config.outDir, `${filename}.xml`),
+  feed.rss2(),
+)