A small script to convert WP-Footnotes style footnotes to PHP Markdown Extra style footnotes.

convertnotes.rb

#!/usr/bin/env ruby

# A small script to convert WP-Footnotes style footnotes to PHP Markdown Extra
# style footnotes.
#
# Possibly useful for those who are migrating from Wordpress to Jekyll, were
# using WP-Footnotes, and wish to render their new Markdown pages with Kramdown
# (which supports PHP Markdown Extra style footnotes).
#
# For example, you might first run https://github.com/thomasf/exitwp and then run
# this in your _posts directory.
#
# - Outputs changed files with extension "new.markdown".
# - Not very well tested. In fact, not really tested at all.
# - USE AT YOUR OWN RISK.

def convertnotes(directory,files)
  Dir.chdir(directory)
  puts "Processing directory: " << Dir.pwd
  Dir.glob(files).each do |filename|
    File.open(filename,'r+') do |file|
      newtext = ""
      footnotes = []

      # Replace ((footnote)) with [^n]
      # (If the footnote text finishes with a series of brackets, we
      # carry them into the footnote itself)
      newtext << file.read.gsub(/\s\(\((.*?)\)\)(\)*)/m) { |s| 
        retain = $1 + $2
        footnotes << retain
        "[^" << footnotes.length.to_s << "]"
      }

      unless footnotes.empty?
        puts "File " << filename << " had " << footnotes.length.to_s << " footnotes."

        # Append list of "[^n]: footnote" lines
        newtext << "\n"
        footnotes.each_index { |i|
          # First we strip any inherited blockquotes markup
          footnotes[i].gsub!(/\n\s*>/,"")
          # The we strip out remaining newlines, replacing with a space if it
          # is in between non-whitespace characters
          footnotes[i].gsub!(/(\S)\n(\S)/,'\\1 \\2')
          footnotes[i].gsub!(/\n/,"")
          # Then we output the footnote
          newtext << "[^" << (i+1).to_s << "]: " << footnotes[i] << "\n"
        }

        # Write to file
        puts "Writing to file: " << filename << ".new.markdown"
        newfile = File.new(filename << ".new.markdown",'a')
        newfile.write(newtext)
      end
    end
  end
end

convertnotes('.','*.markdown')