From bcb5b2df09cb8c8fc0736ec476b2486f9b4643be Mon Sep 17 00:00:00 2001
From: Emile Bangma <ewjbangma@hotmail.com>
Date: Mon, 4 Mar 2024 18:52:28 +0100
Subject: [PATCH] feat(frontmatter): configure max length for description
 (#946)

* Sentence length check

* Replace external links with domain name.

* Updated documentation.

* Updated replacement values.

* Updated Regex based on feedback.

* Check description for undefined

* Updated external url transform regex.

* Updated formatting
---
 docs/plugins/Description.md                |  1 +
 quartz/plugins/transformers/description.ts | 43 ++++++++++++++++++----
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/docs/plugins/Description.md b/docs/plugins/Description.md
index 6849b3c..526bb01 100644
--- a/docs/plugins/Description.md
+++ b/docs/plugins/Description.md
@@ -14,6 +14,7 @@ If the frontmatter contains a `description` property, it is used (see [[authorin
 This plugin accepts the following configuration options:
 
 - `descriptionLength`: the maximum length of the generated description. Default is 150 characters. The cut off happens after the first _sentence_ that ends after the given length.
+- `replaceExternalLinks`: If `true` (default), replace external links with their domain and path in the description (e.g. `https://domain.tld/some_page/another_page?query=hello&target=world` is replaced with `domain.tld/some_page/another_page`).
 
 ## API
 
diff --git a/quartz/plugins/transformers/description.ts b/quartz/plugins/transformers/description.ts
index 884d5b1..0f8cd8d 100644
--- a/quartz/plugins/transformers/description.ts
+++ b/quartz/plugins/transformers/description.ts
@@ -5,12 +5,19 @@ import { escapeHTML } from "../../util/escape"
 
 export interface Options {
   descriptionLength: number
+  replaceExternalLinks: boolean
 }
 
 const defaultOptions: Options = {
   descriptionLength: 150,
+  replaceExternalLinks: true,
 }
 
+const urlRegex = new RegExp(
+  /(https?:\/\/)?(?<domain>([\da-z\.-]+)\.([a-z\.]{2,6})(:\d+)?)(?<path>[\/\w\.-]*)(\?[\/\w\.=&;-]*)?/,
+  "g",
+)
+
 export const Description: QuartzTransformerPlugin<Partial<Options> | undefined> = (userOpts) => {
   const opts = { ...defaultOptions, ...userOpts }
   return {
@@ -19,19 +26,39 @@ export const Description: QuartzTransformerPlugin<Partial<Options> | undefined>
       return [
         () => {
           return async (tree: HTMLRoot, file) => {
-            const frontMatterDescription = file.data.frontmatter?.description
-            const text = escapeHTML(toString(tree))
+            let frontMatterDescription = file.data.frontmatter?.description
+            let text = escapeHTML(toString(tree))
+
+            if (opts.replaceExternalLinks) {
+              frontMatterDescription = frontMatterDescription?.replace(
+                urlRegex,
+                "$<domain>" + "$<path>",
+              )
+              text = text.replace(urlRegex, "$<domain>" + "$<path>")
+            }
 
             const desc = frontMatterDescription ?? text
-            const sentences = desc.replace(/\s+/g, " ").split(".")
+            const sentences = desc.replace(/\s+/g, " ").split(/\.\s/)
             let finalDesc = ""
             let sentenceIdx = 0
             const len = opts.descriptionLength
-            while (finalDesc.length < len) {
-              const sentence = sentences[sentenceIdx]
-              if (!sentence) break
-              finalDesc += sentence + "."
-              sentenceIdx++
+
+            if (sentences[0] !== undefined && sentences[0].length >= len) {
+              const firstSentence = sentences[0].split(" ")
+              while (finalDesc.length < len) {
+                const sentence = firstSentence[sentenceIdx]
+                if (!sentence) break
+                finalDesc += sentence + " "
+                sentenceIdx++
+              }
+              finalDesc = finalDesc.trimEnd() + "..."
+            } else {
+              while (finalDesc.length < len) {
+                const sentence = sentences[sentenceIdx]
+                if (!sentence) break
+                finalDesc += sentence.endsWith(".") ? sentence : sentence + "."
+                sentenceIdx++
+              }
             }
 
             file.data.description = finalDesc