Add id links to the headers and tweak link formatting

lib/Pandoc.rakumod

@@ -100,10 +100,21 @@ sub markdown-first-paragraph(IO::Path:D $file --> Str:D) is export {
     $para
 }
 
+my regex header { '<h' $<level>=(\d) \s+ 'id="' $<id>=(<-["]>+) '">' $<content>=(<-[<]>+) '</h' $<level> '>'};
+
 #| Use pandoc to render a markdown document to html
 sub markdown-to-html(IO::Path:D $file --> Str:D) is export {
-    # Remove the header, we'll regenerate it later
+    # Have pandoc do its thing
     my $output = pandoc <-f gfm>, $file;
+    # Remove the header, we'll regenerate it later
     $output ~~ s:g/'<h1' .* '</h1>'//;
+    # Make all headers links to themselves
+    $output ~~ s:g[<header>] =
+            do given $<header> {
+                  my $link = "<a href=\"#$_<id>\">{$_<content>}</a>";
+                  my $header ="<h{$_<level>} class=\"heading-id-link\">{$link}</h{$_<level>}>";
+                  $header
+            };
     $output
 }
+