troessner/reek

# frozen_string_literal: true

require_relative 'base_detector'

module Reek
  module SmellDetectors
    #
    # A Long Parameter List occurs when a method has more than one
    # or two parameters, or when a method yields more than one or
    # two objects to an associated block.
    #
    # Currently +LongParameterList+ reports any method or block with too
    # many parameters.
    #
    # See {file:docs/Long-Parameter-List.md} for details.
    class LongParameterList < BaseDetector
      # The name of the config field that sets the maximum number of
      # parameters permitted in any method or block.
      MAX_ALLOWED_PARAMS_KEY = 'max_params'
      DEFAULT_MAX_ALLOWED_PARAMS = 3

      def self.default_config
        super.merge(
          MAX_ALLOWED_PARAMS_KEY => DEFAULT_MAX_ALLOWED_PARAMS,
          SmellConfiguration::OVERRIDES_KEY => {
            'initialize' => { MAX_ALLOWED_PARAMS_KEY => 5 }
          })
      end

      #
      # Checks the number of parameters in the given method.
      #
      # @return [Array<SmellWarning>]
      #
      def sniff
        count = expression.arg_names.length
        return [] if count <= max_allowed_params

        [smell_warning(
          lines: [source_line],
          message: "has #{count} parameters",
          parameters: { count: count })]
      end

      private

      def max_allowed_params
        value(MAX_ALLOWED_PARAMS_KEY, context)
      end
    end
  end
end