From 13cf6263b0d55870d83138506cc9091675eeaa80 Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Tue, 7 Apr 2020 15:53:56 -0700
Subject: [PATCH] Update blog builder to use KaTeX and statically render math.

---
 blog/convert.rb | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 blog/convert.rb

diff --git a/blog/convert.rb b/blog/convert.rb
new file mode 100644
index 0000000..cd6602e
--- /dev/null
+++ b/blog/convert.rb
@@ -0,0 +1,33 @@
+require "open3"
+require "nokogiri"
+
+def perform_katex_sub(content)
+  rendered = content.gsub /\\\(((?:[^\\]|\\[^\)])*)\\\)/ do |match|
+    puts "  Rendering #{$~[1]}"
+    Open3.popen3("$(npm bin)/katex") do |i, o, e, t|
+      i.write $~[1]
+      i.close
+      o.read.force_encoding(Encoding::UTF_8).strip
+    end
+  end
+  rendered = rendered.gsub /\$\$((?:[^\$]|$[^\$])*)\$\$/ do |match|
+    puts "  Rendering display #{$~[1][0..30].strip}"
+    Open3.popen3("$(npm bin)/katex -d") do |i, o, e, t|
+      i.write $~[1]
+      i.close
+      o.read.force_encoding(Encoding::UTF_8).strip
+    end
+  end
+  return rendered
+end
+
+files = ARGV[0..-1]
+
+files.each do |file|
+  puts "Rendering file: #{file}"
+  document = Nokogiri::HTML.parse(File.open(file))
+  document.search('//text()').each do |t|
+    t.replace(perform_katex_sub(t.content))
+  end
+  File.write(file, document.to_html)
+end