bbatsov/rubocop

# frozen_string_literal: true

module RuboCop
  module Cop
    module Style
      # Detects the use of the `public_send` method with a literal method name argument.
      # Since the `send` method can be used to call private methods, by default,
      # only the `public_send` method is detected.
      #
      # @safety
      #   This cop is not safe because it can incorrectly detect based on the receiver.
      #   Additionally, when `AllowSend` is set to `true`, it cannot determine whether
      #   the `send` method being detected is calling a private method.
      #
      # @example
      #   # bad
      #   obj.public_send(:method_name)
      #   obj.public_send('method_name')
      #
      #   # good
      #   obj.method_name
      #
      # @example AllowSend: true (default)
      #   # good
      #   obj.send(:method_name)
      #   obj.send('method_name')
      #   obj.__send__(:method_name)
      #   obj.__send__('method_name')
      #
      # @example AllowSend: false
      #   # bad
      #   obj.send(:method_name)
      #   obj.send('method_name')
      #   obj.__send__(:method_name)
      #   obj.__send__('method_name')
      #
      #   # good
      #   obj.method_name
      #
      class SendWithLiteralMethodName < Base
        extend AutoCorrector

        MSG = 'Use `%<method_name>s` method call directly instead.'
        RESTRICT_ON_SEND = %i[public_send send __send__].freeze
        STATIC_METHOD_NAME_NODE_TYPES = %i[sym str].freeze
        METHOD_NAME_PATTERN = /\A[a-zA-Z_][a-zA-Z0-9_]*[!?=]?\z/.freeze
        RESERVED_WORDS = %i[
          BEGIN END alias and begin break case class def defined? do else elsif end ensure
          false for if in module next nil not or redo rescue retry return self super then true
          undef unless until when while yield
        ].freeze

        # rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
        def on_send(node)
          return if allow_send? && !node.method?(:public_send)
          return unless (first_argument = node.first_argument)
          return unless STATIC_METHOD_NAME_NODE_TYPES.include?(first_argument.type)

          offense_range = offense_range(node)
          method_name = first_argument.value
          return if !METHOD_NAME_PATTERN.match?(method_name) || RESERVED_WORDS.include?(method_name)

          add_offense(offense_range, message: format(MSG, method_name: method_name)) do |corrector|
            if node.arguments.one?
              corrector.replace(offense_range, method_name)
            else
              corrector.replace(node.loc.selector, method_name)
              corrector.remove(removal_argument_range(first_argument, node.arguments[1]))
            end
          end
        end
        # rubocop:enable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity

        private

        def allow_send?
          !!cop_config['AllowSend']
        end

        def offense_range(node)
          node.loc.selector.join(node.source_range.end)
        end

        def removal_argument_range(first_argument, second_argument)
          first_argument.source_range.begin.join(second_argument.source_range.begin)
        end
      end
    end
  end
end