using System;
using System.Threading;
using System.Threading.Tasks;
using NUnit.Framework;
using Opc.Ua.Server.TestFramework;
using Opc.Ua.Tests;
using Quickstarts.ReferenceServer;

namespace Opc.Ua.Server.Tests
{
    /// <summary>
    /// Test <see cref="CustomNodeManager2"/>
    /// </summary>
    [TestFixture]
    [Category("CustomNodeManager")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    [Parallelizable]
    public class CustomNodeManagerTests
    {
        /// <summary>
        /// Tests the componentCache methods with multiple threads
        /// </summary>
        [Test]
        public async Task TestComponentCacheAsync()
        {
            ITelemetryContext telemetry = NUnitTelemetryContext.Create();
            var fixture = new ServerFixture<StandardServer>(t => new ReferenceServer(t));

            try
            {
                // Arrange
                const string ns = "http://test.org/UA/Data/";
                StandardServer server = await fixture.StartAsync()
                    .ConfigureAwait(false);

                using var nodeManager = new TestableCustomNodeManger2(server.CurrentInstance, ns);

                var baseObject = new BaseObjectState(null);
                var nodeHandle = new NodeHandle(
                    CommonTestWorkers.NodeIdTestSetStatic[0]
                        .WithNamespaceIndex(0)
                        .InnerNodeId,
                    baseObject);

                //Act
                await RunTaskInParallelAsync(
                    () => UseComponentCacheAsync(nodeManager, baseObject, nodeHandle),
                    100)
                    .ConfigureAwait(false);

                //Assert, that entry was deleted from cache after parallel operations on the same node
                NodeState handleFromCache = nodeManager.LookupNodeInComponentCache(
                    nodeManager.SystemContext,
                    nodeHandle);

                Assert.That(handleFromCache, Is.Null);
            }
            finally
            {
                await fixture.StopAsync().ConfigureAwait(false);
            }
        }

        /// <summary>
        /// Part 4 §5.12.2.2: a Call whose methodId is the Method declaration of the
        /// ObjectType resolves to the Method of the Object, so the RolePermissions
        /// of the Object's Method are verified and that Method is invoked.
        /// </summary>
        [Test]
        public async Task FindMethodStateResolvesTypeDeclarationToObjectMethodAsync()
        {
            var fixture = new ServerFixture<StandardServer>(t => new ReferenceServer(t));

            try
            {
                const string ns = "http://test.org/UA/MethodResolution/";
                StandardServer server = await fixture.StartAsync()
                    .ConfigureAwait(false);

                using var nodeManager = new TestableCustomNodeManger2(server.CurrentInstance, ns);
                ushort index = (ushort)server.CurrentInstance.NamespaceUris.GetIndex(ns);
                ServerSystemContext context = nodeManager.SystemContext;

                var objectType = new BaseObjectTypeState
                {
                    NodeId = new NodeId("ResolveType", index),
                    BrowseName = new QualifiedName("ResolveType", index),
                    SuperTypeId = ObjectTypeIds.BaseObjectType
                };
                var declaration = new MethodState(objectType)
                {
                    NodeId = new NodeId("ResolveType.Reset", index),
                    BrowseName = new QualifiedName("Reset", index)
                };
                objectType.AddChild(declaration);

                var instance = new BaseObjectState(null)
                {
                    NodeId = new NodeId("ResolveInstance", index),
                    BrowseName = new QualifiedName("ResolveInstance", index),
                    TypeDefinitionId = objectType.NodeId
                };
                var instanceMethod = new MethodState(instance)
                {
                    NodeId = new NodeId("ResolveInstance.Reset", index),
                    BrowseName = new QualifiedName("Reset", index)
                };
                instance.AddChild(instanceMethod);

                nodeManager.AddPredefinedNode(context, objectType);
                nodeManager.AddPredefinedNode(context, instance);
                server.CurrentInstance.TypeTree.AddSubtype(
                    objectType.NodeId,
                    ObjectTypeIds.BaseObjectType);

                var operationContext = new OperationContext(
                    new RequestHeader(),
                    null,
                    RequestType.Call,
                    RequestLifetime.None);

                MethodState resolved = nodeManager.FindMethodState(
                    operationContext,
                    new CallMethodRequest
                    {
                        ObjectId = instance.NodeId,
                        MethodId = declaration.NodeId
                    });

                Assert.That(resolved, Is.SameAs(instanceMethod));
            }
            finally
            {
                await fixture.StopAsync().ConfigureAwait(false);
            }
        }

        /// <summary>
        /// Tests the Predefined Nodes methods with multiple threads
        /// </summary>
        [Test]
        public async Task TestPredefinedNodesAsync()
        {
            ITelemetryContext telemetry = NUnitTelemetryContext.Create();
            var fixture = new ServerFixture<StandardServer>(t => new ReferenceServer(t));

            try
            {
                // Arrange
                const string ns = "http://test.org/UA/Data/";
                StandardServer server = await fixture.StartAsync()
                    .ConfigureAwait(false);

                using var nodeManager = new TestableCustomNodeManger2(server.CurrentInstance, ns);
                int index = server.CurrentInstance.NamespaceUris.GetIndex(ns);

                var baseObject = new DataItemState(null);
                NodeId nodeId =
                    CommonTestWorkers.NodeIdTestSetStatic[0]
                    .WithNamespaceIndex((ushort)index)
                    .InnerNodeId;
                baseObject.NodeId = nodeId;

                //single threaded test
                nodeManager.AddPredefinedNode(nodeManager.SystemContext, baseObject);

                Assert.That(nodeManager.PredefinedNodes.ContainsKey(nodeId), Is.True);

                NodeState nodeState = nodeManager.Find(nodeId)!;
                Assert.That(nodeState, Is.Not.Null);

                var handle = nodeManager.GetManagerHandle(nodeId) as NodeHandle;
                Assert.That(handle, Is.Not.Null);

                nodeManager.DeleteNode(nodeManager.SystemContext, nodeId);

                Assert.That(nodeManager.PredefinedNodes, Is.Empty);

                nodeState = nodeManager.Find(nodeId)!;
                Assert.That(nodeState, Is.Null);

                handle = nodeManager.GetManagerHandle(nodeId) as NodeHandle;
                Assert.That(handle, Is.Null);

                nodeManager.AddPredefinedNode(nodeManager.SystemContext, baseObject);

                nodeManager.DeleteAddressSpace();

                Assert.That(nodeManager.PredefinedNodes, Is.Empty);

                //Act
                await RunTaskInParallelAsync(
                    () => UsePredefinedNodesAsync(nodeManager, baseObject, nodeId),
                    100)
                    .ConfigureAwait(false);

                //last operation added the Node back into the dictionary
                Assert.That(nodeManager.PredefinedNodes.ContainsKey(nodeId), Is.True);

                //delete full adress space
                nodeManager.DeleteAddressSpace();
                Assert.That(nodeManager.PredefinedNodes, Is.Empty);
            }
            finally
            {
                await fixture.StopAsync().ConfigureAwait(false);
            }
        }

        private static Task UsePredefinedNodesAsync(
            TestableCustomNodeManger2 nodeManager,
            DataItemState baseObject,
            NodeId nodeId)
        {
            nodeManager.AddPredefinedNode(nodeManager.SystemContext, baseObject);
            _ = nodeManager.Find(nodeId);
            _ = nodeManager.GetManagerHandle(nodeId) as NodeHandle;

            nodeManager.DeleteNode(nodeManager.SystemContext, nodeId);

            _ = nodeManager.Find(nodeId);

            _ = nodeManager.GetManagerHandle(nodeId) as NodeHandle;

            nodeManager.AddPredefinedNode(nodeManager.SystemContext, baseObject);

            return Task.CompletedTask;
        }

        /// <summary>
        /// Test Methods  AddNodeToComponentCache,  RemoveNodeFromComponentCache & LookupNodeInComponentCache & verify the node is added to the cache
        /// </summary>
        private static async Task UseComponentCacheAsync(
            TestableCustomNodeManger2 nodeManager,
            BaseObjectState baseObject,
            NodeHandle nodeHandle)
        {
            //-- Act
            nodeManager.AddNodeToComponentCache(nodeManager.SystemContext, nodeHandle, baseObject);
            nodeManager.AddNodeToComponentCache(nodeManager.SystemContext, nodeHandle, baseObject);

            NodeState handleFromCache = nodeManager.LookupNodeInComponentCache(
                nodeManager.SystemContext,
                nodeHandle);

            //-- Assert

            Assert.That(handleFromCache, Is.Not.Null);

            nodeManager.RemoveNodeFromComponentCache(nodeManager.SystemContext, nodeHandle);

            handleFromCache = nodeManager.LookupNodeInComponentCache(
                nodeManager.SystemContext,
                nodeHandle);

            Assert.That(handleFromCache, Is.Not.Null);

            nodeManager.RemoveNodeFromComponentCache(nodeManager.SystemContext, nodeHandle);

            await Task.CompletedTask.ConfigureAwait(false);
        }

        private static async Task<(bool IsSuccess, Exception? Error)> RunTaskInParallelAsync(
            Func<Task> task,
            int iterations)
        {
            using var cancellationTokenSource = new CancellationTokenSource();
            Exception? error = null;
            int tasksCompletedCount = 0;
            ParallelLoopResult result = Parallel.For(
                0,
                iterations,
                new ParallelOptions(),
                async _ =>
                {
                    try
                    {
                        await task().ConfigureAwait(false);
                    }
                    catch (Exception ex)
                    {
                        error = ex;
                        cancellationTokenSource.Cancel();
                    }
                    finally
                    {
                        tasksCompletedCount++;
                    }
                });

            int spinWaitCount = 0;
            const int maxSpinWaitCount = 100;
            while (iterations > tasksCompletedCount &&
                error is null &&
                spinWaitCount < maxSpinWaitCount)
            {
                await Task.Delay(TimeSpan.FromMilliseconds(100)).ConfigureAwait(false);
                spinWaitCount++;
            }

            return (error == null, error);
        }
    }

    public class TestableCustomNodeManger2 : CustomNodeManager2
    {
        public TestableCustomNodeManger2(IServerInternal server, params string[] namespaceUris)
            : base(server, namespaceUris)
        {
        }

        public new NodeState AddNodeToComponentCache(
            ISystemContext context,
            NodeHandle handle,
            NodeState node)
        {
            return base.AddNodeToComponentCache(context, handle, node);
        }

        public new void RemoveNodeFromComponentCache(ISystemContext context, NodeHandle handle)
        {
            base.RemoveNodeFromComponentCache(context, handle);
        }

        public new NodeState LookupNodeInComponentCache(ISystemContext context, NodeHandle handle)
        {
            return base.LookupNodeInComponentCache(context, handle)!;
        }

        public new NodeIdDictionary<NodeState> PredefinedNodes => base.PredefinedNodes;

        public new virtual void AddPredefinedNode(ISystemContext context, NodeState node)
        {
            base.AddPredefinedNode(context, node);
        }
    }
}