Add YAML headers and rename files according to Jekyll format

main.rb

# frozen_string_literal: true

def main
  dir = if ARGV.empty?
          '**/*'
        elsif ARGV.first.end_with?('/')
          "#{ARGV.first}**/*"
        else
          "#{ARGV.first}/**/*"
        end

  Dir.glob(dir) do |original_file|
    if original_file.end_with?('.md')
      new_file = original_file.gsub(/.md$/, '-.md')

      File.open(new_file, 'w') do |new_file_io|
        new_file_io.puts "---\n---\n\n"

        File.foreach(original_file) do |original_file_io|
          new_file_io.puts original_file_io
        end
      end

      File.delete(original_file)
    end
  end
end

main