class SimpleCov::Formatter::LcovFormatter

def create_output_directory!
  return if Dir.exist?(self.class.output_directory)
  FileUtils.mkdir_p(self.class.output_directory)
end

def filtered_lines(file)
  file.lines.reject(&:never?).reject(&:skipped?)
end

def format(result)
  create_output_directory!
  if self.class.report_with_single_file?
    write_lcov_to_single_file!(result.files)
  else
    result.files.each { |file| write_lcov!(file) }
  end
  puts "Lcov style coverage report generated for #{result.command_name} to #{SimpleCov::Formatter::LcovFormatter.output_directory}."
end

def format_file(file)
  "SF:#{file.filename}\n#{format_lines(file)}\nend_of_record\n"
end

def format_line(line)
  "DA:#{line.number},#{line.coverage}"
end

def format_lines(file)
  filtered_lines(file)
    .map { |line| format_line(line) }
    .join("\n")
end

def output_directory
  File.join(SimpleCov.coverage_path, 'lcov')
end

def output_filename(filename)
  filename.gsub("#{SimpleCov.root}/", '').gsub('/', '-')
    .tap { |name| name << '.lcov' }
end

def report_with_single_file?
  !!@report_with_single_file
end

def single_report_path
  basename = Pathname.new(SimpleCov.root).basename.to_s
  File.join(output_directory, "#{basename}.lcov")
end

def write_lcov!(file)
  File.open(File.join(self.class.output_directory, output_filename(file.filename)), 'w') do |f|
    f.write format_file(file)
  end
end

def write_lcov_to_single_file!(files)
  File.open(self.class.single_report_path, 'w') do |f|
    files.each { |file| f.write format_file(file) }
  end
end