From 5a233e738466464493b4ba516a4e05d39edd0c2f Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 20 Jul 2024 17:24:21 +0100
Subject: [PATCH] layouts: add Mermaid support

Similar to Graphviz and TikZ support.
---
 content/posts/2020-07-14-hello-world/index.md | 14 ++++++++++++++
 layouts/partials/head-extra.html              |  7 +++++++
 layouts/shortcodes/mermaid.html               | 16 ++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 layouts/shortcodes/mermaid.html

diff --git a/content/posts/2020-07-14-hello-world/index.md b/content/posts/2020-07-14-hello-world/index.md
index 9eb06e8..d430add 100644
--- a/content/posts/2020-07-14-hello-world/index.md
+++ b/content/posts/2020-07-14-hello-world/index.md
@@ -9,6 +9,7 @@ categories:
 favorite: false
 tikz: true
 graphviz: true
+mermaid: true
 ---
 
 ## Test post please ignore
@@ -51,6 +52,19 @@ echo hello world | cut -d' ' -f 1
   }
 {{% /graphviz %}}
 
+### Mermaid support
+
+{{% mermaid %}}
+  graph TD
+  A[Enter Chart Definition] --> B(Preview)
+  B --> C{decide}
+  C --> D[Keep]
+  C --> E[Edit Definition]
+  E --> B
+  D --> F[Save Image and Code]
+  F --> B
+{{% /graphviz %}}
+
 ### Spoilers
 
 {{% spoiler "Don't open me" %}}
diff --git a/layouts/partials/head-extra.html b/layouts/partials/head-extra.html
index f0a049d..dc97efa 100644
--- a/layouts/partials/head-extra.html
+++ b/layouts/partials/head-extra.html
@@ -20,6 +20,13 @@
     })();
     </script>
 {{ end }}
+<!-- Mermaid support -->
+{{ if (.Params.mermaid) }}
+    <script type="module" async>
+        import mermaid from "https://cdn.jsdelivr.net/npm/mermaid@latest/dist/mermaid.esm.min.mjs";
+        mermaid.initialize({ startOnLoad: true });
+    </script>
+{{ end }}
 {{ with .OutputFormats.Get "atom" -}}
     {{ printf `<link rel="%s" type="%s" href="%s" title="%s" />` .Rel .MediaType.Type .Permalink $.Site.Title | safeHTML }}
 {{ end -}}
diff --git a/layouts/shortcodes/mermaid.html b/layouts/shortcodes/mermaid.html
new file mode 100644
index 0000000..80cf0a5
--- /dev/null
+++ b/layouts/shortcodes/mermaid.html
@@ -0,0 +1,16 @@
+<pre class="mermaid">
+    {{ with .Get "file" }}
+        {{ if eq (. | printf "%.1s") "/" }}
+            {{/* Absolute path are from root of site. */}}
+            {{ $.Scratch.Set "filepath" . }}
+        {{ else }}
+            {{/* Relative paths are from page directory. */}}
+            {{ $.Scratch.Set "filepath" $.Page.File.Dir }}
+            {{ $.Scratch.Add "filepath" . }}
+        {{ end }}
+
+        {{ $.Scratch.Get "filepath" | readFile }}
+    {{ else }}
+        {{.Inner}}
+    {{ end }}
+</pre>