UA-.NETStandard/Libraries/Opc.Ua.Server/Aggregates/StartEndAggregateCalculator.cs

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 *
 * OPC Foundation MIT License 1.00
 *
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 * obtaining a copy of this software and associated documentation
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using System;
using System.Collections.Generic;

namespace Opc.Ua.Server
{
    /// <summary>
    /// Calculates the value of an aggregate.
    /// </summary>
    public class StartEndAggregateCalculator : AggregateCalculator
    {
        /// <summary>
        /// Initializes the aggregate calculator.
        /// </summary>
        /// <param name="aggregateId">The aggregate function to apply.</param>
        /// <param name="startTime">The start time.</param>
        /// <param name="endTime">The end time.</param>
        /// <param name="processingInterval">The processing interval.</param>
        /// <param name="stepped">Whether to use stepped interpolation.</param>
        /// <param name="configuration">The aggregate configuration.</param>
        /// <param name="telemetry">The telemetry context to use to create obvservability instruments</param>
        public StartEndAggregateCalculator(
            NodeId aggregateId,
            DateTimeUtc startTime,
            DateTimeUtc endTime,
            double processingInterval,
            bool stepped,
            AggregateConfiguration configuration,
            ITelemetryContext telemetry)
            : base(aggregateId, startTime, endTime, processingInterval, stepped, configuration, telemetry)
        {
            SetPartialBit = true;
        }

        /// <summary>
        /// Computes the value for the timeslice.
        /// </summary>
        protected override DataValue ComputeValue(TimeSlice slice)
        {
            if (!AggregateId.TryGetValue(out uint numericId))
            {
                return base.ComputeValue(slice);
            }
            switch (numericId)
            {
                case Objects.AggregateFunction_Start:
                    return ComputeStartEnd(slice, false);
                case Objects.AggregateFunction_End:
                    return ComputeStartEnd(slice, true);
                case Objects.AggregateFunction_Delta:
                    return ComputeDelta(slice);
                case Objects.AggregateFunction_StartBound:
                    return ComputeStartEnd2(slice, false);
                case Objects.AggregateFunction_EndBound:
                    return ComputeStartEnd2(slice, true);
                case Objects.AggregateFunction_DeltaBounds:
                    return ComputeDelta2(slice);
                default:
                    return base.ComputeValue(slice);
            }
        }

        /// <summary>
        /// Calculate the Start and End aggregates for the timeslice.
        /// </summary>
        protected DataValue ComputeStartEnd(TimeSlice slice, bool returnEnd)
        {
            // get the values in the slice.
            List<DataValue>? values = GetValues(slice);

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

            // return start value.
            if (!returnEnd)
            {
                return values[0];
            }

            return values[^1];
        }

        /// <summary>
        /// Calculates the Delta aggregate for the timeslice.
        /// </summary>
        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);
            }

            double startValue = double.NaN;
            TypeInfo originalType = default;
            bool badDataSkipped = false;

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

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

                badDataSkipped = true;
            }

            double endValue = double.NaN;

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

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

                    break;
                }

                badDataSkipped = true;
            }

            // check if no good data.
            if (double.IsNaN(startValue) || double.IsNaN(endValue))
            {
                return GetNoDataValue(slice);
            }

            var value = new DataValue(
                Variant.Null,
                StatusCodes.Good,
                GetTimestamp(slice),
                GetTimestamp(slice));

            // set status code.
            if (badDataSkipped)
            {
                value = value.WithStatus(StatusCodes.UncertainDataSubNormal);
            }

            value = value.WithStatus(value.StatusCode.WithAggregateBits(AggregateBits.Calculated));

            // calculate delta.
            double delta = endValue - startValue;
            if (originalType.IsUnknown)
            {
                originalType = TypeInfo.Scalars.Double;
            }

            // return result.
            return value.WithWrappedValue(new Variant(delta).ConvertTo(originalType.BuiltInType));
        }

        /// <summary>
        /// Calculate the Start2 and End2 aggregates for the timeslice.
        /// </summary>
        protected DataValue ComputeStartEnd2(TimeSlice slice, bool returnEnd)
        {
            // get the values in the slice.
            List<DataValue>? values = GetValuesWithSimpleBounds(slice);

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

            DataValue value;

            // return start bound.
            if ((!returnEnd && !TimeFlowsBackward) || (returnEnd && TimeFlowsBackward))
            {
                value = values[0];
            }
            // return end bound.
            else
            {
                value = values[^1];
            }

            if (!IsGood(value))
            {
                value = value.WithStatus(StatusCodes.BadNoData);
            }

            if (returnEnd)
            {
                DateTimeUtc sliceStamp = GetTimestamp(slice);
                value = value
                    .WithSourceTimestamp(sliceStamp)
                    .WithServerTimestamp(sliceStamp);

                if (StatusCode.IsNotBad(value.StatusCode))
                {
                    value = value.WithStatus(
                        value.StatusCode.WithAggregateBits(AggregateBits.Calculated));
                }
            }

            return value;
        }

        /// <summary>
        /// Calculates the Delta2 aggregate for the timeslice.
        /// </summary>
        protected DataValue ComputeDelta2(TimeSlice slice)
        {
            // get the values in the slice.
            List<DataValue>? values = GetValuesWithSimpleBounds(slice);

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

            DataValue start = values[0];
            DataValue end = values[^1];

            // check for bad bounds.
            if (!IsGood(start) || !IsGood(end))
            {
                return GetNoDataValue(slice);
            }

            TypeInfo originalType = default;

            // convert to doubles.
            double startValue;
            try
            {
                startValue = CastToDouble(start);
                originalType = start.WrappedValue.TypeInfo;
            }
            catch (Exception)
            {
                startValue = double.NaN;
            }

            double endValue;
            try
            {
                endValue = CastToDouble(end);
            }
            catch (Exception)
            {
                endValue = double.NaN;
            }

            // check for bad bounds.
            if (double.IsNaN(startValue) || double.IsNaN(endValue))
            {
                return GetNoDataValue(slice);
            }

            var value = new DataValue(
                Variant.Null,
                StatusCodes.Good,
                GetTimestamp(slice),
                GetTimestamp(slice));

            if (!IsGood(start) || !IsGood(end))
            {
                value = value.WithStatus(StatusCodes.UncertainDataSubNormal);
            }

            value = value.WithStatus(value.StatusCode.WithAggregateBits(AggregateBits.Calculated));

            // calculate delta.
            double delta = endValue - startValue;

            if (originalType.IsUnknown)
            {
                originalType = TypeInfo.Scalars.Double;
            }

            // return result.
            return value.WithWrappedValue(new Variant(delta).ConvertTo(originalType.BuiltInType));
        }
    }
}