module Mutant
  class Matcher
    class Method
      # Matcher for singleton methods
      class Singleton < self
        SUBJECT_CLASS = Subject::Method::Singleton

        # Return identification
        #
        # @return [String]
        #
        # @api private
        #
        def identification
          "#{scope.name}.#{method_name}"
        end
        memoize :identification

        RECEIVER_INDEX   = 0
        NAME_INDEX       = 1

      private

        # Test for node match
        #
        # @param [Parser::AST::Node] node
        #
        # @return [Boolean]
        #
        # @api private
        #
        def match?(node)
          line?(node) && name?(node) && receiver?(node)
        end

        # Test for line match
        #
        # @param [Parser::AST::Node] node
        #
        # @return [Boolean]
        #
        # @api private
        #
        def line?(node)
          expression = node.location.expression
          return false unless expression
          expression.line.equal?(source_line)
        end

        # Test for name match
        #
        # @param [Parser::AST::Node] node
        #
        # @return [Boolean]
        #
        # @api private
        #
        def name?(node)
          node.children[NAME_INDEX].equal?(method_name)
        end

        # Test for receiver match
        #
        # @param [Parser::AST::Node] node
        #
        # @return [Boolean]
        #
        # @api private
        #
        def receiver?(node)
          receiver = node.children[RECEIVER_INDEX]
          case receiver.type
          when :self
            true
          when :const
            receiver_name?(receiver)
          else
            env.warn(format('Can only match :defs on :self or :const got %s unable to match', receiver.type.inspect))
            false
          end
        end

        # Test if receiver name matches context
        #
        # @param [Parser::AST::Node] node
        #
        # @return [Boolean]
        #
        # @api private
        #
        def receiver_name?(node)
          name = node.children[NAME_INDEX]
          name.to_s.eql?(context.unqualified_name)
        end

      end # Singleton
    end # Method
  end # Matcher
end # Mutant