module ActionArgs
  module ParamsHandler
    # converts the request params Hash into an Array to be passed into the target Method
    def self.extract_method_arguments_from_params(method_parameters, params)
      kwargs, missing_required_params = {}, []
      parameter_names = method_parameters.map(&:last)
      method_parameters.reverse_each do |type, key|
        case type
        when :req
          missing_required_params << key unless params.has_key? key
          next
        when :keyreq
          if params.has_key? key
            kwargs[key] = params[key]
          else
            missing_required_params << key
          end
        when :key
          kwargs[key] = params[key] if params.has_key? key
        when :opt
          break if params.has_key? key
        end
        # omitting parameters that are :block, :rest, :opt without a param, and :key without a param
        parameter_names.delete key
      end
      if missing_required_params.any?
        if defined? ActionController::BadRequest
          raise ActionController::BadRequest.new(:required, ArgumentError.new("Missing required parameters: #{missing_required_params.join(', ')}"))
        else
          raise ArgumentError, "Missing required parameters: #{missing_required_params.join(', ')}"
        end
      end

      values = parameter_names.map {|k| params[k]}
      values << kwargs if kwargs.any?
      values
    end

    # permits declared model attributes in the params Hash
    # note that this method mutates the given params Hash
    def self.strengthen_params!(controller_class, method_parameters, params)
      target_model_name = (controller_class.instance_variable_get(:'@permitting_model_name') || controller_class.name.sub(/.+::/, '').sub(/Controller$/, '')).singularize.underscore.tr('/', '_').to_sym
      permitted_attributes = controller_class.instance_variable_get :'@permitted_attributes'

      method_parameters.each do |type, key|
        if (key == target_model_name) && permitted_attributes
          params[key] = params.require(key).try :permit, *permitted_attributes
        end
      end
    end
  end
end