/* ========================================================================
 * 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;
using System.Threading;
using System.Threading.Tasks;

namespace Opc.Ua.Server
{
    /// <summary>
    /// An object that manages aggregate factories supported by the server.
    /// </summary>
    public class AggregateManager : IDisposable
    {
        /// <summary>
        /// Initilizes the manager.
        /// </summary>
        public AggregateManager(IServerInternal server)
        {
            m_server = server;
            m_factories = [];
            m_minimumProcessingInterval = 1000;
        }

        /// <summary>
        /// Frees any unmanaged resources.
        /// </summary>
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        /// <summary>
        /// An overrideable version of the Dispose.
        /// </summary>
        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                // TBD
            }
        }

        /// <summary>
        /// Checks if the aggregate is supported by the server.
        /// </summary>
        /// <param name="aggregateId">The id of the aggregate function.</param>
        /// <returns>True if the aggregate is supported.</returns>
        public bool IsSupported(NodeId aggregateId)
        {
            if (aggregateId.IsNull)
            {
                return false;
            }

            lock (m_lock)
            {
                return m_factories.ContainsKey(aggregateId);
            }
        }

        /// <summary>
        /// The minimum processing interval for any aggregate calculation.
        /// </summary>
        public double MinimumProcessingInterval
        {
            get
            {
                lock (m_lock)
                {
                    return m_minimumProcessingInterval;
                }
            }
            set
            {
                lock (m_lock)
                {
                    m_minimumProcessingInterval = value;
                }
            }
        }

        /// <summary>
        /// Returns the default configuration for the specified variable id.
        /// </summary>
        /// <param name="variableId">The id of history data node.</param>
        /// <returns>The configuration.</returns>
        public AggregateConfiguration GetDefaultConfiguration(NodeId variableId)
        {
            lock (m_lock)
            {
                m_defaultConfiguration ??= new AggregateConfiguration
                {
                    PercentDataBad = 100,
                    PercentDataGood = 100,
                    // Part 13 v1.05.07 §4.2.1.2: the TreatUncertainAsBad default is True.
                    TreatUncertainAsBad = true,
                    UseSlopedExtrapolation = false,
                    UseServerCapabilitiesDefaults = false
                };

                return m_defaultConfiguration;
            }
        }

        /// <summary>
        /// Sets the default aggregate configuration.
        /// </summary>
        /// <param name="configuration">The default aggregate configuration..</param>
        public void SetDefaultConfiguration(AggregateConfiguration configuration)
        {
            lock (m_lock)
            {
                m_defaultConfiguration = configuration;
            }
        }

        /// <summary>
        /// Creates a new aggregate calculator.
        /// </summary>
        /// <param name="aggregateId">The id of the aggregate function.</param>
        /// <param name="startTime">When to start processing.</param>
        /// <param name="endTime">When to stop processing.</param>
        /// <param name="processingInterval">The processing interval.</param>
        /// <param name="stepped">Whether stepped interpolation should be used.</param>
        /// <param name="configuration">The configuration to use.</param>
        public IAggregateCalculator? CreateCalculator(
            NodeId aggregateId,
            DateTimeUtc startTime,
            DateTimeUtc endTime,
            double processingInterval,
            bool stepped,
            AggregateConfiguration configuration)
        {
            if (aggregateId.IsNull)
            {
                return null;
            }

            AggregatorFactory? factory;
            lock (m_lock)
            {
                if (!m_factories.TryGetValue(aggregateId, out factory))
                {
                    return null;
                }
            }

            if (configuration.UseServerCapabilitiesDefaults)
            {
                // ensure the configuration is initialized
                configuration = GetDefaultConfiguration(default);
            }

            return factory!(
                aggregateId,
                startTime,
                endTime,
                processingInterval,
                stepped,
                configuration,
                m_server.Telemetry);
        }

        /// <summary>
        /// Registers an aggregate factory.
        /// </summary>
        /// <param name="aggregateId">The id of the aggregate function.</param>
        /// <param name="aggregateName">The id of the aggregate name.</param>
        /// <param name="factory">The factory used to create calculators.</param>
        /// <param name="cancellationToken">A cancellation token.</param>
        public async ValueTask RegisterFactoryAsync(
            NodeId aggregateId,
            string aggregateName,
            AggregatorFactory factory,
            CancellationToken cancellationToken = default)
        {
            lock (m_lock)
            {
                m_factories[aggregateId] = factory;
            }

            await m_server.DiagnosticsNodeManager.AddAggregateFunctionAsync(aggregateId, aggregateName, true, cancellationToken).ConfigureAwait(false);
        }

        /// <summary>
        /// Unregisters an aggregate factory.
        /// </summary>
        /// <param name="aggregateId">The id of the aggregate function.</param>
        public void RegisterFactory(NodeId aggregateId)
        {
            lock (m_lock)
            {
                m_factories.Remove(aggregateId);
            }
        }

        private readonly Lock m_lock = new();
        private readonly IServerInternal m_server;
        private AggregateConfiguration? m_defaultConfiguration;
        private readonly NodeIdDictionary<AggregatorFactory> m_factories;
        private double m_minimumProcessingInterval;
    }
}