From b4577a130159c2638b51318cb5645c39ec85ff46 Mon Sep 17 00:00:00 2001
From: EuAndreh <eu@euandre.org>
Date: Fri, 16 Oct 2020 06:31:28 -0300
Subject: Add GraphvizBlock plugin

---
 .gitignore                 |  3 ++-
 _config.yml                |  1 +
 _plugins/graphviz-block.rb | 36 ++++++++++++++++++++++++++++++++++++
 default.nix                |  1 +
 4 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 _plugins/graphviz-block.rb

diff --git a/.gitignore b/.gitignore
index 476620d..94fc6b7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,4 +4,5 @@
 # Jekyll
 /.bundle/
 /_site/
-/.jekyll-cache/
\ No newline at end of file
+/.jekyll-cache/
+/images/graphviz/
\ No newline at end of file
diff --git a/_config.yml b/_config.yml
index b8467f5..3eceb93 100644
--- a/_config.yml
+++ b/_config.yml
@@ -32,6 +32,7 @@ exclude:
   - drafts/
   - description
   - result
+  - images/graphviz/
 
 collections:
   articles:
diff --git a/_plugins/graphviz-block.rb b/_plugins/graphviz-block.rb
new file mode 100644
index 0000000..4ddd2ee
--- /dev/null
+++ b/_plugins/graphviz-block.rb
@@ -0,0 +1,36 @@
+require 'tempfile'
+require 'digest'
+
+OUTPUT_DIR = '/images/graphviz'
+
+module Jekyll
+  class GraphvizBlock < Liquid::Block
+    def initialize(tag_name, options, tokens)
+      super
+      opts_list = options.split('|').map { |s| s.strip }
+      @name = opts_list[0]
+      @alt = opts_list[1]
+    end
+
+    def render(context)
+      source = super
+      site = context.registers[:site]
+      FileUtils.mkdir_p(File.join(site.source, OUTPUT_DIR))
+
+      filename = "#{@name}-#{Digest::SHA256.hexdigest(source + @alt)}.svg"
+      site_path = File.join(OUTPUT_DIR, filename)
+      os_path = File.join(site.source, site_path)
+
+      f = Tempfile.new('graphviz-input')
+      f.write(source)
+      f.close
+      `dot -Tsvg #{f.path} > #{os_path}`
+      f.unlink
+
+      site.static_files << Jekyll::StaticFile.new(site, site.source, OUTPUT_DIR, filename)
+      "<img src=\"#{site_path}\" alt=\"#{@alt}\" />"
+    end
+  end
+end
+
+Liquid::Template.register_tag('graphviz', Jekyll::GraphvizBlock)
diff --git a/default.nix b/default.nix
index f52c6a6..10d7ef0 100644
--- a/default.nix
+++ b/default.nix
@@ -13,6 +13,7 @@ let
   projectBuildInputs = with pkgs; [
     jekyllEnv
 
+    graphviz
     nixfmt
     git
     shellcheck
-- 
cgit v1.3