feat: add support for backlinks

Enabled by default in right sidebar. Can be disabled with `backlinks: false` in front matter.

See https://github.com/gohugoio/hugo/issues

modules/blox-tailwind/assets/css/components/page.css

@@ -80,3 +80,7 @@
   z-index: -1;
   display: block;
 }
+
+.backlink {
+  @apply text-xs font-medium text-gray-500 hover:text-gray-900 dark:text-gray-400 dark:hover:text-gray-100 contrast-more:text-gray-800 contrast-more:dark:text-gray-50;
+}

modules/blox-tailwind/hugo.yaml

@@ -1,13 +1,20 @@
 markup:
   defaultMarkdownHandler: goldmark
   goldmark:
+    renderHooks:
+      link:
+        # Process backlinks hook
+        enableDefault: true
     renderer:
+      # Render HTML in Markdown
       unsafe: true
     parser:
+      # Support Latex math(?)
       attribute:
         block: true
         title: true
     extensions:
+      # Support Latex math
       passthrough:
         enable: true
         delimiters:
@@ -21,7 +28,18 @@ markup:
               - \)
             - - $
               - $
+      extras:
+        # Enable subscript, superscript, and highlighting with ~,^, and == wrappers
+        insert:
+          enable: false
+        mark:
+          enable: true
+        subscript:
+          enable: true
+        superscript:
+          enable: true
   highlight:
+    # Enable code highlighting
     codeFences: true
     noHl: false
     lineNumbersInTable: false
@@ -31,14 +49,16 @@ markup:
     startLevel: 2
     endLevel: 3
 minify:
+  minifyOutput: true
   tdewolff:
     html:
       keepComments: true
+      keepSpecialComments: true
 sitemap:
   changefreq: weekly
 module:
   hugoVersion:
-    min: '0.122.0'
+    min: '0.126.0'
     extended: true
   imports:
     - path: github.com/HugoBlox/hugo-blox-builder/modules/blox-analytics
@@ -62,6 +82,14 @@ security:
     getenv:
       - ^HUGO_
       - ^WC_
+      - ^HB_
+outputFormats:
+  backlinks:
+    mediaType: application/json
+    baseName: backlinks
+    isPlainText: true
+    notAlternative: true
+    weight: 1
 params:
   locale:
     date_format: 'Jan 2, 2006'

modules/blox-tailwind/i18n/en.yaml

@@ -26,6 +26,9 @@
 - id: related
   translation: Related
 
+- id: backlinks
+  translation: Backlinks
+
 - id: minute_read
   translation: min read
 

modules/blox-tailwind/layouts/_default/_markup/render-link.backlinks.json

@@ -0,0 +1,18 @@
+{{- $u := urls.Parse .Destination -}}
+{{- if or $u.IsAbs (strings.HasPrefix $u.String "#") }}
+  {{- /* do nothing */}}
+{{- else }}
+  {{- with .PageInner.GetPage (strings.TrimPrefix "./" $u.Path) }}
+    {{- $source := dict
+      "date" ($.Page.Date.UTC.Format "2006-01-02T15:04:05-07:00")
+      "linkTitle" $.Page.LinkTitle
+      "permalink" $.Page.Permalink
+      "relPermalink" $.Page.RelPermalink
+      "section" $.Page.Section
+      "title" $.Page.Title
+      "type" $.Page.Type
+    }}
+    {{- $el := dict "source" $source "target" .RelPermalink }}
+    {{- site.Home.Store.Add "backlinks" (slice $el) }}
+  {{- end }}
+{{- end }}

modules/blox-tailwind/layouts/_default/home.backlinks.json

@@ -0,0 +1,9 @@
+{{- $debug := false }}
+{{- range site.Pages }}
+  {{- $noop := .WordCount }}
+{{- end }}
+{{- if $debug }}
+  {{- jsonify (dict "indent" "  ") (.Store.Get "backlinks") }}
+{{- else }}
+  {{- jsonify (dict "indent" "  ") (dict "comment" "This file is intentionally empty.") }}
+{{- end }}

modules/blox-tailwind/layouts/partials/components/backlinks.html

@@ -0,0 +1,20 @@
+{{ $show_backlinks := .Params.backlinks | default true }}
+{{ if $show_backlinks }}
+  {{- $debug := false }}
+  {{- $backlinks := site.Home.Store.Get "backlinks" | uniq  }}
+  {{- with (where $backlinks "target" .RelPermalink) }}
+  <div class="backlinks">
+    <div class="mb-1 font-semibold tracking-tight">
+      {{ or (T "backlinks") "Backlinks" }}
+    </div>
+    <ul>
+      {{- range (sort . "source.linkTitle" "asc") }}
+      <li><a href="{{ .source.relPermalink }}" class="backlink">{{ .source.linkTitle }}</a></li>
+      {{- end }}
+    </ul>
+  </div>
+  {{- end }}
+  {{- if $debug }}
+  <pre>{{ jsonify (dict "indent" "  ") $backlinks }}</pre>
+  {{- end }}
+{{ end }}

modules/blox-tailwind/layouts/partials/components/toc.html

@@ -38,6 +38,8 @@
     </div>
     {{- end -}}
 
+    {{ partial "components/backlinks" . }}
+
     {{ partial "functions/get_hook" (dict "hook" "toc-end" "context" .) }}
 
   </div>