[PATCH 20/23] doc: asciidoctor: add hack to improve links

[Felipe Contreras <felipe.contreras@gmail.com>]

The way asciidoctor handles links is very primitive compared to docbook.
Links are simply presented in the format "#{text} <#{target}>", which
may not be all that bad for the future, but pollutes the doc-diff.

By adding another modification to convert_inline_anchor() we can present
links in a form very similar to docbook, diminishing the doc-diff.

This significantly reduces the doc-diff:

From:

        abysmal performance). These safety and performance issues cannot be
        backward compatibly fixed and as such, its use is not recommended.
        Please use an alternative history filtering tool such as git
-       filter-repo[1]. If you still need to use git filter-branch, please
-       carefully read the section called “SAFETY” (and the section called
-       “PERFORMANCE”) to learn about the land mines of filter-branch, and then
-       vigilantly avoid as many of the hazards listed there as reasonably
-       possible.
+       <https://github.com/newren/git-filter-repo/> filter-repo" . If you
+       still need to use git filter-branch, please carefully read the section
+       called “SAFETY” (and the section called “PERFORMANCE”) to learn about
+       the land mines of filter-branch, and then vigilantly avoid as many of
+       the hazards listed there as reasonably possible.

-NOTES
-        1. git filter-repo
-           https://github.com/newren/git-filter-repo/
-
-        2. filter-lamely
-           https://github.com/newren/git-filter-repo/blob/master/contrib/filter-repo-demos/filter-lamely
-

To:

 NOTES
-        1. git filter-repo
+       [1]    git filter-repo
               https://github.com/newren/git-filter-repo/

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
---
 Documentation/asciidoctor-extensions.rb | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/asciidoctor-extensions.rb b/Documentation/asciidoctor-extensions.rb
index 7561973df6..914e6f64c8 100644
--- a/Documentation/asciidoctor-extensions.rb
+++ b/Documentation/asciidoctor-extensions.rb
@@ -10,6 +10,19 @@ module Asciidoctor
         return node.text if node.text
         refid = node.attributes['refid']
         'the section called &#8220;%s&#8221;' % refid.gsub('_', ' ')
+      when :link
+        return node.target if node.text == node.target
+        doc = node.document
+
+        footnote = doc.footnotes.find { |e| e.id == node.target }
+        if !footnote
+          footnote_text = "%s\n\e.RS\n\e\\%%%s\n\e.RE" % [node.text, node.target]
+          index = doc.counter('footnote-number')
+          footnote = Document::Footnote.new(index, node.target, footnote_text)
+          doc.register(:footnotes, footnote)
+        end
+
+        "\e\\fB%s\e\\fR[%d]" % [node.text, footnote.index]
       else
         orig_convert_inline_anchor(node)
       end
-- 
2.32.0