[Indiekit] Adapt inbound hashtags

indiekit/packages/indiekit-preset-byjp/lib/post-template.js

@@ -52,6 +52,7 @@ const getFrontMatter = (properties, frontMatterFormat) => {
     }),
     ...properties,
   };
+  // TODO: move photos
 
   delete properties.content; // Shown below front matter
   delete properties.deleted; // Use `expiryDate`
@@ -93,8 +94,29 @@ const getFrontMatter = (properties, frontMatterFormat) => {
  * @returns {string} Rendered template
  */
 export const getPostTemplate = (properties, frontMatterFormat = "yaml") => {
-  const content = getContent(properties);
+  const { content, tags } = replaceTags(getContent(properties));
+  if (tags.length > 0) {
+    properties.tags = tags;
+  }
   const frontMatter = getFrontMatter(properties, frontMatterFormat);
 
   return frontMatter + content;
 };
+
+const tagFinder = /(?<=\s|^)#[a-z0-9]+\b/ig;
+
+/**
+ * Replaces all #HashTags with [HashTags](/tags/hashtags) and returns a compact array of the tags used
+ * @param {string} content - Post content
+ * @returns {{content: string, tags: Array<string>}} The replaced content, and found tags
+ */
+const replaceTags = (content) => {
+  let tags = [];
+  content = content.replace(tagFinder, (tag) => {
+    tag = tag.substring(1);
+    tags.push(tag);
+    return `[${tag}](/tags/${tag.toLowerCase()})`;
+  });
+
+  return { content, tags }
+}

indiekit/packages/indiekit-preset-byjp/test/unit/post-template.js

@@ -210,6 +210,28 @@ syndication: https://website.example/post/12345
 ---
 
 I ate a [cheese](https://en.wikipedia.org/wiki/Cheese) sandwich, which was nice.
+`,
+    );
+  });
+
+  it("Renders posts with hashtags correctly", () => {
+    const result = getPostTemplate({
+      published: "2024-10-02",
+      content: "#some posts might have #hashtags, even #MultiCasedOnes but [fragment URLs](#heading) must be left alone.",
+    });
+
+    assert.equal(
+      result,
+      `---
+date: 2024-10-02
+publishDate: 2024-10-02
+tags:
+  - some
+  - hashtags
+  - MultiCasedOnes
+---
+
+[some](/tags/some) posts might have [hashtags](/tags/hashtags), even [MultiCasedOnes](/tags/multicasedones) but [fragment URLs](#heading) must be left alone.
 `,
     );
   });