func castTemporal()

in arrow/scalar/temporal.go [154:223]
62 lines of code
23 McCabe index (conditional complexity)

func castTemporal(from TemporalScalar, to arrow.DataType) (Scalar, error) {
	if arrow.TypeEqual(from.DataType(), to) {
		return from, nil
	}

	if !from.IsValid() {
		return MakeNullScalar(to), nil
	}

	if r, ok := numericMap[to.ID()]; ok {
		return convertToNumeric(reflect.ValueOf(from.value()), r.valueType, r.scalarFunc), nil
	}

	if to.ID() == arrow.STRING {
		return NewStringScalar(temporalToString(from)), nil
	}

	switch s := from.(type) {
	case DateScalar:
		if to.ID() == arrow.TIMESTAMP {
			var newValue int64
			switch s := s.(type) {
			case *Date32:
				newValue = int64(s.Value) * int64(millisecondsInDay)
			case *Date64:
				newValue = int64(s.Value)
			}
			return NewTimestampScalar(arrow.Timestamp(ConvertTimestampValue(arrow.Millisecond, to.(*arrow.TimestampType).Unit, newValue)), to), nil
		}

		switch s := s.(type) {
		case *Date32:
			if to.ID() == arrow.DATE64 {
				return NewDate64Scalar(arrow.Date64(s.Value) * arrow.Date64(millisecondsInDay)), nil
			}
		case *Date64:
			if to.ID() == arrow.DATE32 {
				return NewDate32Scalar(arrow.Date32(s.Value / arrow.Date64(millisecondsInDay))), nil
			}
		}
	case *Timestamp:
		switch to := to.(type) {
		case *arrow.TimestampType:
			return NewTimestampScalar(arrow.Timestamp(ConvertTimestampValue(s.Unit(), to.Unit, int64(s.Value))), to), nil
		case *arrow.Date32Type:
			millis := ConvertTimestampValue(s.Unit(), arrow.Millisecond, int64(s.Value))
			return NewDate32Scalar(arrow.Date32(millis / int64(millisecondsInDay))), nil
		case *arrow.Date64Type:
			millis := ConvertTimestampValue(s.Unit(), arrow.Millisecond, int64(s.Value))
			return NewDate64Scalar(arrow.Date64(millis - millis%int64(millisecondsInDay))), nil
		}
	case TimeScalar:
		switch to := to.(type) {
		case *arrow.Time32Type:
			return NewTime32Scalar(arrow.Time32(ConvertTimestampValue(s.Unit(), to.Unit, int64(s.value().(arrow.Time64)))), to), nil
		case *arrow.Time64Type:
			return NewTime64Scalar(arrow.Time64(ConvertTimestampValue(s.Unit(), to.Unit, int64(s.value().(arrow.Time32)))), to), nil
		}

	case *Duration:
		switch to := to.(type) {
		case *arrow.StringType:

		case *arrow.DurationType:
			return NewDurationScalar(arrow.Duration(ConvertTimestampValue(s.Unit(), to.Unit, int64(s.Value))), to), nil
		}
	}

	return nil, xerrors.Errorf("")
}