module RuboCop::Cop::Documentation

def base_url_for(cop_class, config)
  if config
    department_name = cop_class.department.to_s
    url = config.for_department(department_name)['DocumentationBaseURL']
    return url if url
  end
  default_base_url if builtin?(cop_class)
end

def builtin?(cop_class)
  # any custom method will do
  return false unless (m = cop_class.instance_methods(false).first)
  path, _line = cop_class.instance_method(m).source_location
  path.start_with?(__dir__)
end

def default_base_url
  'https://docs.rubocop.org/rubocop'
end

def default_extension
  '.html'
end

def department_to_basename(department)
  "cops_#{department.to_s.downcase.tr('/', '_')}"
end

def extension_for(cop_class, config)
  if config
    department_name = cop_class.department
    extension = config.for_department(department_name)['DocumentationExtension']
    return extension if extension
  end
  default_extension
end

def url_for(cop_class, config = nil)
  base = department_to_basename(cop_class.department)
  fragment = cop_class.cop_name.downcase.gsub(/[^a-z]/, '')
  base_url = base_url_for(cop_class, config)
  extension = extension_for(cop_class, config)
  "#{base_url}/#{base}#{extension}##{fragment}" if base_url
end