class GitHub::Markup::CommandImplementation

def call_block(rendered, content)
  if block && block.arity == 2
    block.call(rendered, content)
  elsif block
    block.call(rendered)
  else
    rendered
  end
end

def execute(command, target)
  # capture3 blocks until both buffers are written to and the process terminates, but
  # it won't allow either buffer to fill up
  stdout, stderr, status = Open3.capture3(*command, stdin_data: target)
  raise CommandError.new(stderr) unless status.success?
  sanitize(stdout, target.encoding)
end

def initialize(regexp, languages, command, name, &block)
  super(regexp, languages)
  @command = command.to_s
  @block = block
  @name = name
end

def render(filename, content, options: {})
  rendered = execute(command, content)
  rendered = rendered.to_s.empty? ? content : rendered
  call_block(rendered, content)
end

def sanitize(input, encoding)
  input.gsub("\r", '').force_encoding(encoding)
end