func main() {
    l, err := zap.NewDevelopment()
    if err != nil {
        panic(err)
    }
    logger = otelzap.New(l, WithDatadogFields())
    
    ctx, span := tracer.Start(context.Background(), "root")
    defer span.End()

    logger.Ctx(ctx).Error("hello from zap")
}

func WithDatadogFields() otelzap.Option {
	convertTraceId := func(id string) string {
		if len(id) < 16 {
			return ""
		}
		if len(id) > 16 {
			id = id[16:]
		}
		intValue, err := strconv.ParseUint(id, 16, 64)
		if err != nil {
			return ""
		}
		return strconv.FormatUint(intValue, 10)
	}

	return otelzap.WithDynamicFields(func(ctx context.Context) []zap.Field {
		fields := make([]zap.Field, 0)
		span := trace.SpanFromContext(ctx)
		if span.IsRecording() {
			fields = append(fields, zap.String("dd.trace_id", convertTraceId(span.SpanContext().TraceID().String())))
			fields = append(fields, zap.String("dd.span_id", convertTraceId(span.SpanContext().SpanID().String())))
		}
		return fields
	})
}