From d7ebfdb85cf73c027fb928518004533e428f3893 Mon Sep 17 00:00:00 2001
From: Silvio Rhatto <rhatto@riseup.net>
Date: Thu, 4 Mar 2021 15:29:27 -0300
Subject: Feat: MathJax setup

---
 lib/IkiWiki/Plugin/mathjax.pm | 74 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100755 lib/IkiWiki/Plugin/mathjax.pm

(limited to 'lib')

diff --git a/lib/IkiWiki/Plugin/mathjax.pm b/lib/IkiWiki/Plugin/mathjax.pm
new file mode 100755
index 0000000..99b74c3
--- /dev/null
+++ b/lib/IkiWiki/Plugin/mathjax.pm
@@ -0,0 +1,74 @@
+package IkiWiki::Plugin::mathjax;
+
+use warnings;
+use strict;
+use IkiWiki 3.00;
+use MIME::Base64;
+
+# Strategy:
+## - filter replaces normal TeX delimiters with imath and dmath directives
+##   (perhaps while considering a mathconf directive); also, it adds a script
+##   block if there is any math on the page relevant.
+## - preprocess handles the directives themselves.
+##
+## Later: config hooks for mathjax script tag and mathjax config block
+##
+
+sub import {
+    hook(type => "filter", id => "mathjax", call => \&filter);
+    hook(type => "format", id=>"mathjax", call=> \&format);
+}
+
+sub format {
+    my %params = @_;
+    my $content = $params{content};
+    return $content unless $content =~ /\!\!mathjaxbegin/; #]/{{
+    $content =~ s{\!\!mathjaxbegin-i!! (.*?)\s\!\!mathjaxend-i\!\!}{'\('.decode_base64($1).'\)'}ges; #{
+    $content =~ s{\!\!mathjaxbegin-d!! (.*?)\s\!\!mathjaxend-d\!\!}{'\['.decode_base64($1).'\]'}ges; #{
+    my $scripttag = _scripttag();
+    $content =~ s{(</body>)}{$scripttag\n$1}i; #}{
+    return $content;
+}
+
+sub filter (@) {
+    my %params=@_;
+    my $content = $params{content};
+    return $content unless $content =~ /\$[^\$]+\$|\\[\(\[][\s\S]+\\[\)\]]/;
+    # first, handle display math...
+    $content =~ s{(?<!\\)\\\[(.+?)(?<!\\)\\\]}{_escape_mathjax('d', $1)}ges; #};[}
+    $content =~ s{(?<!\\)\$\$(.+?)(?<!\\)\$\$}{_escape_mathjax('d', $1)}ges; #};[}
+    # then, the inline math -- note that it must stay on one line
+    $content =~ s{(?<!\\)\\\((.+?)(?<!\\)\\\)}{_escape_mathjax('i', $1)}ge; #};[}
+    # note that the 'parsing' of $..$ is extremely fragile
+    $content =~ s{(?<!\\)\$(.+?)(?<!\\)\$}{_escape_mathjax('i', $1)}ge; #};[}
+    return $content;
+}
+
+sub _escape_mathjax {
+    my ($mode, $formula) = @_;
+    my %modes = qw/i inline d display/;
+    my $directive = "!!mathjaxbegin-$mode!! ";
+    $formula =~ s/"/&quot;/g;
+    $formula =~ s/&/&amp;/g; #"/}[{
+    $formula =~ s/</&lt;/g;
+    $formula =~ s/>/&gt;/g; #{"
+    $directive .= encode_base64($formula, " ");
+    $directive .= "!!mathjaxend-$mode!!";
+    return $directive;
+}
+
+sub _scripttag {
+    my $config = 'TeX-AMS_HTML'; # another possibility: TeX-AMS-MML_HTMLorMML
+    return '<script type="text/x-mathjax-config">'
+      . 'MathJax.Hub.Config({ TeX: { equationNumbers: {autoNumber: "AMS"} } });'
+      . '</script>'
+      . '<script async="async" type="text/javascript" '
+      # Serving MathJax script locally
+      #. 'src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.9/MathJax.js?config='
+      #. 'src="/js/MathJax.js?config='
+      . 'src="/vendor/MathJax/es5/tex-chtml.js?config='
+      . $config
+      . '"></script>';
+}
+
+1;
-- 
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