/* ========================================================================
 * Copyright (c) 2005-2025 The OPC Foundation, Inc. All rights reserved.
 *
 * OPC Foundation MIT License 1.00
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * The complete license agreement can be found here:
 * http://opcfoundation.org/License/MIT/1.00/
 * ======================================================================*/

using System.Collections.Generic;

namespace Opc.Ua.Server
{
    /// <summary>
    /// Calculates the value of an aggregate.
    /// </summary>
    public class StatusAggregateCalculator : 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 StatusAggregateCalculator(
            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_DurationGood:
                    return ComputeDurationGoodBad(slice, false, false);
                case Objects.AggregateFunction_DurationBad:
                    return ComputeDurationGoodBad(slice, true, false);
                case Objects.AggregateFunction_PercentGood:
                    return ComputeDurationGoodBad(slice, false, true);
                case Objects.AggregateFunction_PercentBad:
                    return ComputeDurationGoodBad(slice, true, true);
                case Objects.AggregateFunction_WorstQuality:
                    return ComputeWorstQuality(slice, false);
                case Objects.AggregateFunction_WorstQuality2:
                    return ComputeWorstQuality(slice, true);
                default:
                    return base.ComputeValue(slice);
            }
        }

        /// <summary>
        /// Calculates the DurationGood and DurationBad aggregates for the timeslice.
        /// </summary>
        protected DataValue ComputeDurationGoodBad(TimeSlice slice, bool isBad, bool usePercent)
        {
            // get the values in the slice.
            List<DataValue>? values = GetValuesWithSimpleBounds(slice);

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

            // get the regions.
            List<SubRegion>? regions = GetRegionsInValueSet(values, false, true);

            double duration = 0;
            double total = 0;

            for (int ii = 0; ii < regions!.Count; ii++)
            {
                total += regions[ii].Duration;

                if (isBad)
                {
                    if (StatusCode.IsBad(regions[ii].StatusCode))
                    {
                        duration += regions[ii].Duration;
                    }
                }
                else if (StatusCode.IsGood(regions[ii].StatusCode))
                {
                    duration += regions[ii].Duration;
                }
            }

            if (usePercent)
            {
                duration = duration / total * 100;
            }

            // set the timestamp and status.
            var value = new DataValue(
                Variant.From(duration),
                StatusCodes.Good,
                GetTimestamp(slice),
                GetTimestamp(slice));

            // return result.
            return value.WithStatus(value.StatusCode.WithAggregateBits(AggregateBits.Calculated));
        }

        /// <summary>
        /// Calculates the DurationGood and DurationBad aggregates for the timeslice.
        /// </summary>
        protected DataValue ComputeWorstQuality(TimeSlice slice, bool includeBounds)
        {
            // get the values in the slice.
            List<DataValue>? values;
            if (!includeBounds)
            {
                values = GetValues(slice);
            }
            else
            {
                values = GetValuesWithSimpleBounds(slice);
            }

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

            // get the regions.
            _ = GetRegionsInValueSet(values, false, true);

            StatusCode worstQuality = StatusCodes.Good;
            int badQualityCount = 0;
            int uncertainQualityCount = 0;

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

                if (StatusCode.IsBad(quality))
                {
                    badQualityCount++;

                    if (StatusCode.IsNotBad(worstQuality))
                    {
                        worstQuality = quality.CodeBits;
                    }

                    continue;
                }

                if (StatusCode.IsUncertain(quality))
                {
                    uncertainQualityCount++;

                    if (StatusCode.IsGood(worstQuality))
                    {
                        worstQuality = quality.CodeBits;
                    }
                }
            }

            // set the timestamp and status.
            var value = new DataValue(
                Variant.From(worstQuality),
                StatusCodes.Good,
                GetTimestamp(slice),
                GetTimestamp(slice));
            value = value.WithStatus(value.StatusCode.WithAggregateBits(AggregateBits.Calculated));

            if ((StatusCode.IsBad(worstQuality) && badQualityCount > 1) ||
                (StatusCode.IsUncertain(worstQuality) && uncertainQualityCount > 1))
            {
                value = value.WithStatus(value.StatusCode.WithAggregateBits(
                    value.StatusCode.AggregateBits | AggregateBits.MultipleValues));
            }

            // return result.
            return value;
        }
    }
}