rails_next_cop.rb

# Cleans up branches like:
# if Shopify.rails_next?
#   # Rails 5 login
# else 
#   # Rails 4 login
# end
module RuboCop
  module Cop
    module ShopifyRails
      class RailsNextUnless < Cop
        MSG = 'Rails_next'.freeze

        def on_if(node)
          loc = node.loc

          ifst = node.child_nodes[0]
          if loc.respond_to?(:keyword) && loc.keyword.is?('unless'.freeze) && ifst.method_name == :rails_next? && ifst.receiver.source == "Shopify"
            add_offense(node, :expression)
          end
        end

        private

        def autocorrect(node)
          ->(corrector) {
            found_indent = node.source_range.source_line =~ /^( +)/
            if found_indent
              whitespaces = $1.size

              # the range has to include indentation
              r = node.source_range
              line_range = r.class.new(r.source_buffer, r.begin_pos - whitespaces, r.end_pos + 1)
              corrector.remove(line_range)
            else
              corrector.remove(node.source_range)
            end
          }
        end
      end

      class RailsNextIfElse < Cop
        MSG = 'Rails_next'.freeze

        def on_if(node)
          ifst = node.child_nodes[0]
          if ifst.method_name == :rails_next? && ifst.receiver.source == "Shopify"
            add_offense(node, :expression)
          end
        end

        private

        def autocorrect(node)
          if_content = node.child_nodes[1]
          ->(corrector) {
            new_source = String.new
            if_content.source.each_line do |line|
              if line =~ /^( +)/
                line = line[2..-1]
              end
              new_source << line
            end
            corrector.insert_before(node.source_range, new_source)
            corrector.remove(node.source_range)
          }
        end
      end
    end
  end
end