Opc.Ua.Server.StartEndAggregateCalculator.ComputeDelta C# (CSharp) Method

        protected DataValue ComputeDelta(TimeSlice slice)
        {
            // get the values in the slice.
            List<DataValue> values = GetValues(slice);

            // check for empty slice.
            if (values == null || values.Count == 0)
            {
                return GetNoDataValue(slice);
            }

            // find start value.
            DataValue start = null;
            double startValue = 0;
            TypeInfo originalType = null;
            bool badDataSkipped = false;

            for (int ii = 0; ii < values.Count; ii++)
            {
                start = values[ii];

                if (StatusCode.IsGood(start.StatusCode))
                {
                    try
                    {
                        startValue = CastToDouble(start);
                        originalType = start.WrappedValue.TypeInfo;
                        break;
                    }
                    catch (Exception)
                    {
                        startValue = Double.NaN;
                    }
                }

                start = null;
                badDataSkipped = true;
            }

            // find end value.
            DataValue end = null;
            double endValue = 0;

            for (int ii = values.Count - 1; ii >= 0; ii--)
            {
                end = values[ii];

                if (StatusCode.IsGood(end.StatusCode))
                {
                    try
                    {
                        endValue = CastToDouble(end);
                        break;
                    }
                    catch (Exception)
                    {
                        endValue = Double.NaN;
                    }

                    break;
                }

                end = null;
                badDataSkipped = true;
            }

            // check if no good data.
            if (Double.IsNaN(startValue) || Double.IsNaN(endValue))
            {
                return GetNoDataValue(slice);
            }
            
            DataValue value = new DataValue();
            value.SourceTimestamp = GetTimestamp(slice);
            value.ServerTimestamp = GetTimestamp(slice);

            // set status code.
            if (badDataSkipped)
            {
                value.StatusCode = StatusCodes.UncertainDataSubNormal;
            }
            
            value.StatusCode = value.StatusCode.SetAggregateBits(AggregateBits.Calculated);
            
            // calculate delta.
            double delta = endValue - startValue;

            if (originalType != null && originalType.BuiltInType != BuiltInType.Double)
            {
                object delta2 = TypeInfo.Cast(delta, TypeInfo.Scalars.Double, originalType.BuiltInType);
                value.WrappedValue = new Variant(delta2, originalType);
            }
            else
            {
                value.WrappedValue = new Variant(delta, TypeInfo.Scalars.Double);
            }

            // return result.
            return value;
        }