refactor: update backlinks section in post.html and add backlinks gen…

…erator plugin

- Update the backlinks section in the post.html layout file to include a conditional check for displaying backlinks.
- Add a new backlinks generator plugin in the _plugins directory to identify and add backlinks to each document.
- Modify the post.html layout file to include the generated backlinks in a styled box.

Related to cotes2020#123

_layouts/post.html

@@ -171,3 +171,19 @@ <h1 data-toc-skip>{{ page.title }}</h1>
   crossorigin="anonymous"
   async>
 </script>
+
+ <!-- Backlinks Section -->
+  {% assign home = site.html_pages | where: 'url', '/' | first %}
+  {% if page.url != home.url %}
+      {% if page.showbacklinks == true %}
+          {% if page.backlinks.size > 0 %}
+              <div class="backlink-box">
+                  <ul>
+                  {% for backlink in page.backlinks %}
+                      <li><a href="{{ site.url }}{{ backlink.url }}">{{ backlink.title }}</a></li>
+                  {% endfor %}
+                  </ul>
+              </div>
+          {% endif %}
+      {% endif %}
+  {% endif %}

_plugins/backlinks_generator.rb

@@ -0,0 +1,19 @@
+module Jekyll
+    class BacklinksGenerator < Generator
+        def generate(site)
+            all_notes = site.collections['docs'].docs
+            all_posts = site.posts.docs
+            all_pages = site.pages
+
+            all_docs = all_notes + all_posts + all_pages
+
+            # Identify backlinks and add them to each doc
+            all_docs.each do |current_doc|
+                backlinks = all_docs.select do |doc|
+                    doc.content.include?(current_doc.url)
+                end
+                current_doc.data['backlinks'] = backlinks
+            end
+        end
+    end
+end

_posts/2020-03-20-introduction-to-pytrhon.md

@@ -70,6 +70,5 @@ Feel free to explore these resources as you begin your journey with Python!
 ---
 
 [^footnote]: **Next Steps**: In the next post, we'll dive into {% raw %}
-[**Python variables**](_posts/2020-03-20-introduction-to-pytrhon.md)
+[**Python variables**](_posts/2020-03-20-python-variables.md)
 {% endraw %} to get you familiar with manipulating data using Python. Stay tuned and happy coding!
-

assets/css/jekyll-theme-chirpy.scss

@@ -8,3 +8,17 @@
 ';
 
 /* append your custom style below */
+
+/* Backlink Box Styles */
+.backlink-box {
+    background-color: #fffdf7;
+}
+
+.backlink-box:before {
+    content: "What links here";
+    font-style: italic;
+}
+
+.backlink-box li {
+    line-height: 1em;
+}