class RBS::Annotate::Formatter

def self.each_part(doc, &block)
  if block
    document =
      case doc
      when String
        raise
      when RDoc::Comment
        document = doc.parse
      when RDoc::Markup::Document
        document = doc
      end
    if document.file
      yield document
    else
      document.each do |d|
        each_part(d, &block)
      end
    end
  else
    enum_for :each_part, doc
  end
end

def self.translate(doc)
  if doc.file
    formatter = RDoc::Markup::ToMarkdown.new
    doc.accept(formatter).strip.lines.map(&:rstrip).join("\n")
  end
end

def <<(s)
  if s
    if s.is_a?(RDoc::Markup::Document)
      s = self.class.translate(s) or raise
    end
    s = s.rstrip
    unless s.empty?
      if ss = @pending_separator
        buffer << ss
        buffer << "\n"
        @pending_separator = nil
      end
      buffer << s
      buffer << "\n"
    end
  end
  self
end

def empty?
  buffer.empty?
end

def format(newline_at_end:)
  unless buffer.empty?
    if newline_at_end
      buffer.strip + "\n\n"
    else
      buffer.strip + "\n"
    end
  else
    buffer
  end
end

def initialize()
  @buffer = +""
  @pending_separator = nil
end

def margin(separator: "")
  unless buffer.empty?
    @pending_separator = separator
  end
  self
end