module RuboCop::Cop::StatementModifier

def indentation_multiplier
  return 1 if config.for_cop('Layout/Tab')['Enabled']
  default_configuration = RuboCop::ConfigLoader.default_configuration
  config.for_cop('Layout/Tab')['IndentationWidth'] ||
    config.for_cop('Layout/IndentationWidth')['Width'] ||
    default_configuration.for_cop('Layout/Tab')['IndentationWidth'] ||
    default_configuration.for_cop('Layout/IndentationWidth')['Width']
end

def length_in_modifier_form(node, cond, body_length)
  indentation = node.loc.keyword.column * indentation_multiplier
  kw_length = node.loc.keyword.size
  cond_length = cond.source_range.size
  space = 1
  indentation + body_length + space + kw_length + space + cond_length
end

def max_line_length
  return unless config.for_cop('Metrics/LineLength')['Enabled']
  config.for_cop('Metrics/LineLength')['Max']
end

def modifier_fits_on_single_line?(node)
  return true unless max_line_length
  modifier_length = length_in_modifier_form(node, node.condition,
                                            node.body.source_length)
  modifier_length <= max_line_length
end

def non_eligible_body?(body)
  body.nil? ||
    body.empty_source? ||
    body.begin_type? ||
    processed_source.commented?(body.source_range)
end

def non_eligible_condition?(condition)
  condition.each_node.any?(&:lvasgn_type?)
end

def non_eligible_node?(node)
  node.nonempty_line_count > 3 ||
    !node.modifier_form? &&
      processed_source.commented?(node.loc.end)
end

def single_line_as_modifier?(node)
  return false if non_eligible_node?(node) ||
                  non_eligible_body?(node.body) ||
                  non_eligible_condition?(node.condition)
  modifier_fits_on_single_line?(node)
end