From 51f63559863383aecc86bb6eb9eb909bd2618ffc Mon Sep 17 00:00:00 2001
From: Alex Kotov <git@kotovalexarian.com>
Date: Thu, 17 Oct 2024 23:47:58 +0400
Subject: [PATCH] Add chapter title anchors

---
 examples/config.yml            | 1 +
 examples/full.chapters.json    | 4 ++--
 examples/full.html             | 4 ++--
 examples/full.repub            | 4 ++--
 lib/repubmark/config.rb        | 1 +
 lib/repubmark/elems/chapter.rb | 4 +++-
 6 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/examples/config.yml b/examples/config.yml
index ace7f8d..f7d45fb 100644
--- a/examples/config.yml
+++ b/examples/config.yml
@@ -61,6 +61,7 @@ http:
   <<: *css_classes
   format: html
   relative_urls: true
+  chapter_anchor_prefix: 'chapter-'
 
 rss:
   <<: *paths
diff --git a/examples/full.chapters.json b/examples/full.chapters.json
index 634cbed..c1fdff8 100644
--- a/examples/full.chapters.json
+++ b/examples/full.chapters.json
@@ -1,13 +1,13 @@
 [
   {
-    "slug": "chapter-1",
+    "slug": "1",
     "title": "Chapter 1",
     "chapters": [
 
     ]
   },
   {
-    "slug": "chapter-2",
+    "slug": "2",
     "title": "Chapter 2",
     "chapters": [
 
diff --git a/examples/full.html b/examples/full.html
index fdc3e33..1192053 100644
--- a/examples/full.html
+++ b/examples/full.html
@@ -63,13 +63,13 @@ The Rty
 </div>
 </div>
 </div>
-<h2>Chapter 1</h2>
+<h2 id="chapter-1">Chapter 1</h2>
 <p>
 <span>
 Chapter 1 paragraph text
 </span>
 </p>
-<h2>Chapter 2</h2>
+<h2 id="chapter-2">Chapter 2</h2>
 <p>
 <span>
 Chapter 2 paragraph text
diff --git a/examples/full.repub b/examples/full.repub
index 81bf7d2..c4f91d4 100644
--- a/examples/full.repub
+++ b/examples/full.repub
@@ -33,7 +33,7 @@ end
 
 
 
-article.chapter 'chapter-1', 'Chapter 1' do |chapter|
+article.chapter '1', 'Chapter 1' do |chapter|
   chapter.paragraph do |paragraph|
     paragraph.text 'Chapter 1 paragraph text'
   end
@@ -41,7 +41,7 @@ end
 
 
 
-article.chapter 'chapter-2', 'Chapter 2' do |chapter|
+article.chapter '2', 'Chapter 2' do |chapter|
   chapter.paragraph do |paragraph|
     paragraph.text 'Chapter 2 paragraph text'
   end
diff --git a/lib/repubmark/config.rb b/lib/repubmark/config.rb
index b278af3..1f0553e 100644
--- a/lib/repubmark/config.rb
+++ b/lib/repubmark/config.rb
@@ -4,6 +4,7 @@ module Repubmark
   class Config
     OPTIONAL_KEYS = %i[
       base_url
+      chapter_anchor_prefix
       css_class_annotation
       css_class_blockquote_figure
       css_class_blockquote_blockquote
diff --git a/lib/repubmark/elems/chapter.rb b/lib/repubmark/elems/chapter.rb
index 308a5eb..1cb8a34 100644
--- a/lib/repubmark/elems/chapter.rb
+++ b/lib/repubmark/elems/chapter.rb
@@ -118,7 +118,9 @@ module Repubmark
       end
 
       def build_title_html
-        "<h#@level>#@title</h#@level>\n" if @level != 1
+        anchor_prefix = String(config[:chapter_anchor_prefix]).strip
+        anchor = %( id="#{anchor_prefix}#@slug") unless anchor_prefix.empty?
+        "<h#@level#{anchor}>#@title</h#@level>\n" if @level != 1
       end
 
       def build_title_gemtext