Extract fenced code blocks from markdown into separate files

mdunfence.rb

#!/usr/bin/env ruby
# coding: utf-8
#
# mdunfence - Extract fenced code blocks from markdown into separate files.
#
# All files with the markdown extension under the current working directory are
# handled and the new files will be named after their parent markdown filename
# with a count appended to keep track of multiple extracted code blocks. The
# optional language identifier will be used as the new file extension.
#
# For example, two files hello0.cs and hello1.ext are produced when given a
# markdown file named "hello.md" with the contents below:
#
##*Hello World Examples*
##
##```cs
##Console.WriteLine("Hello World!");
##```
##
##```
##int main(void) {
##  puts("Hello World!");
##
##  return 0;
##}
##```
#
#
# Written by Derek Callaway <[email protected]>
#

Dir.glob('**/*.md').each do |f|
  STDOUT.puts(f) if ENV['MDUNFENCE_DEBUG']

  aflag, anumb, afile = false, 0, nil

  File.readlines(f).each do |l|
    if l.start_with?('```')
      if !aflag
        aflag = true
        anext = l.split('`').last
        anext = '' if !anext

        anext.strip!

        if anext.empty?
          anext = 'ext'
        else
          anext.downcase!

          anext = 'cs' if anext.eql?('c#') or anext.eql?('csharp')
        end

        abase = File.basename(f)
        aname = abase.split('.').first
        afnam = "#{aname}#{anumb}.#{anext}"
        anumb += 1
        afile = File.open(afnam, 'w')

        STDOUT.puts(afnam) if ENV['MDUNFENCE_DEBUG']
        STDERR.puts(afile) if ENV['MDUNFENCE_DEBUG']
      else
        aflag = false

        afile.close
      end
    else
      if aflag
        afile.write(l)
      end
    end
  end
end

exit 0