From f82282367efd41192716fbb89e5a8756ff73bd5a Mon Sep 17 00:00:00 2001
From: Jacky Zhao <j.zhao2k19@gmail.com>
Date: Sat, 15 Jul 2023 23:33:06 -0700
Subject: [PATCH] treat _index as index

---
 content/features/upcoming features.md |  1 -
 quartz/path.test.ts                   |  1 +
 quartz/path.ts                        | 28 ++++++++++++++++++---------
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/content/features/upcoming features.md b/content/features/upcoming features.md
index b93afce7..86200fed 100644
--- a/content/features/upcoming features.md	
+++ b/content/features/upcoming features.md	
@@ -1,6 +1,5 @@
 
 - fixes
-	- changing `_index` files
 	- typography
 - CLI    
     - update
diff --git a/quartz/path.test.ts b/quartz/path.test.ts
index c0ceacc3..674f683f 100644
--- a/quartz/path.test.ts
+++ b/quartz/path.test.ts
@@ -122,6 +122,7 @@ describe('transforms', () => {
   describe('slugifyFilePath', () => {
     asserts([
       ["content/index.md", "content/index"],
+      ["content/_index.md", "content/index"],
       ["/content/index.md", "content/index"],
       ["content/cool.png", "content/cool"],
       ["index.md", "index"],
diff --git a/quartz/path.ts b/quartz/path.ts
index 24144d85..5e1feb22 100644
--- a/quartz/path.ts
+++ b/quartz/path.ts
@@ -134,12 +134,17 @@ export function slugifyFilePath(fp: FilePath): ServerSlug {
   conditionCheck(slugifyFilePath.name, 'pre', fp, isFilePath)
   fp = _stripSlashes(fp) as FilePath
   const withoutFileExt = fp.replace(new RegExp(_getFileExtension(fp) + '$'), '')
-  const slug = withoutFileExt
+  let slug = withoutFileExt
     .split('/')
     .map((segment) => segment.replace(/\s/g, '-')) // slugify all segments
     .join('/') // always use / as sep
     .replace(/\/$/, '') // remove trailing slash
 
+  // treat _index as index
+  if (_endsWith(slug, "_index")) {
+    slug = slug.replace(/_index$/, "index")
+  }
+
   conditionCheck(slugifyFilePath.name, 'post', slug, isServerSlug)
   return slug as ServerSlug
 }
@@ -156,10 +161,7 @@ export function transformInternalLink(link: string): RelativeURL {
   }
 
   fp = canonicalizeServer(slugifyFilePath(fp as FilePath))
-
-  if (fp.endsWith("index")) {
-    fp = fp.slice(0, -"index".length)
-  }
+  fp = _trimSuffix(fp, "index")
 
   let joined = joinSegments(_stripSlashes(prefix), _stripSlashes(fp))
   const res = _addRelativeToStart(joined) + anchor as RelativeURL
@@ -202,13 +204,21 @@ export function joinSegments(...args: string[]): string {
 export const QUARTZ = "quartz"
 
 function _canonicalize(fp: string): string {
-  if (fp.endsWith("index")) {
-    fp = fp.slice(0, -"index".length)
-  }
-
+  fp = _trimSuffix(fp, "index")
   return _stripSlashes(fp) 
 }
 
+function _endsWith(s: string, suffix: string): boolean {
+  return s === suffix || s.endsWith("/" + suffix) 
+}
+
+function _trimSuffix(s: string, suffix: string): string {
+  if (_endsWith(s, suffix)) {
+    s = s.slice(0, -(suffix.length))
+  }
+  return s
+}
+
 function _containsForbiddenCharacters(s: string): boolean {
   return s.includes(" ") || s.includes("#") || s.includes("?")
 }