module ActiveModel
  module Type
    class DateTime < Value # :nodoc:
      include Helpers::TimeValue
      include Helpers::AcceptsMultiparameterTime.new(
        defaults: { 4 => 0, 5 => 0 }
      )

      def type
        :datetime
      end

      private

        def cast_value(value)
          return apply_seconds_precision(value) unless value.is_a?(::String)
          return if value.empty?

          fast_string_to_time(value) || fallback_string_to_time(value)
        end

        # '0.123456' -> 123456
        # '1.123456' -> 123456
        def microseconds(time)
          time[:sec_fraction] ? (time[:sec_fraction] * 1_000_000).to_i : 0
        end

        def fallback_string_to_time(string)
          time_hash = ::Date._parse(string)
          time_hash[:sec_fraction] = microseconds(time_hash)

          new_time(*time_hash.values_at(:year, :mon, :mday, :hour, :min, :sec, :sec_fraction, :offset))
        end

        def value_from_multiparameter_assignment(values_hash)
          missing_parameter = (1..3).detect { |key| !values_hash.key?(key) }
          if missing_parameter
            raise ArgumentError, missing_parameter
          end
          super
        end
    end
  end
end
