using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Opc.Ua;
using Opc.Ua.Client;
using Shouldly;
using Xunit;
using ZB.MOM.WW.LmxOpcUa.Host.Domain;
using ZB.MOM.WW.LmxOpcUa.Tests.Helpers;

namespace ZB.MOM.WW.LmxOpcUa.Tests.Integration
{
    /// <summary>
    /// Integration tests verifying dynamic address space changes via a real OPC UA client.
    /// Tests browse, subscribe, add/remove nodes at runtime, and subscription quality changes.
    /// </summary>
    public class AddressSpaceRebuildTests
    {
        /// <summary>
        /// Confirms that the initial browsed hierarchy matches the seeded Galaxy model.
        /// </summary>
        [Fact]
        public async Task Browse_ReturnsInitialHierarchy()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Browse from ZB root
                var zbNode = client.MakeNodeId("ZB");
                var children = await client.BrowseAsync(zbNode);

                children.ShouldContain(c => c.Name == "DEV");
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that adding a Galaxy object and rebuilding exposes the new node to OPC UA clients.
        /// </summary>
        [Fact]
        public async Task Browse_AfterAddingObject_NewNodeAppears()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Verify initial state — browse TestMachine_001
                var machineNode = client.MakeNodeId("TestMachine_001");
                var initialChildren = await client.BrowseAsync(machineNode);
                initialChildren.ShouldNotContain(c => c.Name == "NewReceiver");

                // Add a new object to the hierarchy
                fixture.GalaxyRepository!.Hierarchy.Add(new GalaxyObjectInfo
                {
                    GobjectId = 100, TagName = "NewReceiver_001",
                    ContainedName = "NewReceiver", BrowseName = "NewReceiver",
                    ParentGobjectId = 3, IsArea = false // parent = TestMachine_001
                });
                fixture.GalaxyRepository.Attributes.Add(new GalaxyAttributeInfo
                {
                    GobjectId = 100, TagName = "NewReceiver_001",
                    AttributeName = "NewAttr", FullTagReference = "NewReceiver_001.NewAttr",
                    MxDataType = 5, IsArray = false
                });

                // Trigger rebuild
                fixture.Service.TriggerRebuild();
                await Task.Delay(500); // allow rebuild to complete

                // Browse again — new node should appear
                var updatedChildren = await client.BrowseAsync(machineNode);
                updatedChildren.ShouldContain(c => c.Name == "NewReceiver");
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that removing a Galaxy object and rebuilding removes the node from the OPC UA hierarchy.
        /// </summary>
        [Fact]
        public async Task Browse_AfterRemovingObject_NodeDisappears()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Verify MESReceiver exists initially
                var machineNode = client.MakeNodeId("TestMachine_001");
                var initialChildren = await client.BrowseAsync(machineNode);
                initialChildren.ShouldContain(c => c.Name == "MESReceiver");

                // Remove MESReceiver and its attributes from hierarchy
                fixture.GalaxyRepository!.Hierarchy.RemoveAll(h => h.TagName == "MESReceiver_001");
                fixture.GalaxyRepository.Attributes.RemoveAll(a => a.TagName == "MESReceiver_001");

                // Trigger rebuild
                fixture.Service.TriggerRebuild();
                await Task.Delay(500);

                // Browse again — MESReceiver should be gone
                var updatedChildren = await client.BrowseAsync(machineNode);
                updatedChildren.ShouldNotContain(c => c.Name == "MESReceiver");
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that subscriptions on deleted nodes receive a bad-quality notification after rebuild.
        /// </summary>
        [Fact]
        public async Task Subscribe_RemovedNode_PublishesBadQuality()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Subscribe to an attribute that will be removed
                var nodeId = client.MakeNodeId("MESReceiver_001.MoveInBatchID");
                var (sub, item) = await client.SubscribeAsync(nodeId, intervalMs: 100);

                // Collect notifications
                var notifications = new List<MonitoredItemNotification>();
                item.Notification += (_, e) =>
                {
                    if (e.NotificationValue is MonitoredItemNotification n)
                        notifications.Add(n);
                };

                await Task.Delay(500); // let initial subscription settle

                // Remove MESReceiver and its attributes
                fixture.GalaxyRepository!.Hierarchy.RemoveAll(h => h.TagName == "MESReceiver_001");
                fixture.GalaxyRepository.Attributes.RemoveAll(a => a.TagName == "MESReceiver_001");

                // Trigger rebuild — nodes get deleted
                fixture.Service.TriggerRebuild();

                // Wait for publish cycle to deliver Bad status
                await Task.Delay(2000);

                // The subscription should have received a Bad quality notification
                // after the node was deleted during rebuild
                notifications.ShouldContain(n => StatusCode.IsBad(n.Value.StatusCode));

                await sub.DeleteAsync(true);
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that subscriptions on surviving nodes continue to work after a partial rebuild.
        /// </summary>
        [Fact]
        public async Task Subscribe_SurvivingNode_StillWorksAfterRebuild()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Subscribe to an attribute that will survive the rebuild
                var nodeId = client.MakeNodeId("TestMachine_001.MachineID");
                var (sub, item) = await client.SubscribeAsync(nodeId, intervalMs: 100);

                await Task.Delay(500);

                // Remove only MESReceiver (MachineID on TestMachine_001 survives)
                fixture.GalaxyRepository!.Hierarchy.RemoveAll(h => h.TagName == "MESReceiver_001");
                fixture.GalaxyRepository.Attributes.RemoveAll(a => a.TagName == "MESReceiver_001");

                fixture.Service.TriggerRebuild();
                await Task.Delay(1000);

                // The surviving node should still be browsable
                var machineNode = client.MakeNodeId("TestMachine_001");
                var children = await client.BrowseAsync(machineNode);
                children.ShouldContain(c => c.Name == "MachineID");

                await sub.DeleteAsync(true);
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that adding a Galaxy attribute and rebuilding exposes a new OPC UA variable.
        /// </summary>
        [Fact]
        public async Task Browse_AddAttribute_NewVariableAppears()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                var machineNode = client.MakeNodeId("TestMachine_001");
                var initialChildren = await client.BrowseAsync(machineNode);
                initialChildren.ShouldNotContain(c => c.Name == "NewSensor");

                // Add a new attribute
                fixture.GalaxyRepository!.Attributes.Add(new GalaxyAttributeInfo
                {
                    GobjectId = 3, TagName = "TestMachine_001",
                    AttributeName = "NewSensor", FullTagReference = "TestMachine_001.NewSensor",
                    MxDataType = 4, IsArray = false // Double
                });

                fixture.Service.TriggerRebuild();
                await Task.Delay(500);

                var updatedChildren = await client.BrowseAsync(machineNode);
                updatedChildren.ShouldContain(c => c.Name == "NewSensor");
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that removing a Galaxy attribute and rebuilding removes the OPC UA variable.
        /// </summary>
        [Fact]
        public async Task Browse_RemoveAttribute_VariableDisappears()
        {
            var fixture = OpcUaServerFixture.WithFakes();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                var machineNode = client.MakeNodeId("TestMachine_001");
                var initialChildren = await client.BrowseAsync(machineNode);
                initialChildren.ShouldContain(c => c.Name == "MachineCode");

                // Remove MachineCode attribute
                fixture.GalaxyRepository!.Attributes.RemoveAll(
                    a => a.TagName == "TestMachine_001" && a.AttributeName == "MachineCode");

                fixture.Service.TriggerRebuild();
                await Task.Delay(500);

                var updatedChildren = await client.BrowseAsync(machineNode);
                updatedChildren.ShouldNotContain(c => c.Name == "MachineCode");
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that rebuilds preserve subscription bookkeeping for nodes that survive the metadata refresh.
        /// </summary>
        [Fact]
        public async Task Rebuild_PreservesSubscriptionBookkeeping_ForSurvivingNodes()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                var nodeManager = fixture.Service.NodeManagerInstance!;
                var mxClient = fixture.MxAccessClient!;

                nodeManager.SubscribeTag("TestMachine_001.MachineID");
                mxClient.ActiveSubscriptionCount.ShouldBe(1);

                fixture.Service.TriggerRebuild();
                await Task.Delay(200);

                mxClient.ActiveSubscriptionCount.ShouldBe(1);

                nodeManager.UnsubscribeTag("TestMachine_001.MachineID");
                mxClient.ActiveSubscriptionCount.ShouldBe(0);
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that transferred monitored items recreate MXAccess subscriptions when the service has no local subscription state.
        /// </summary>
        [Fact]
        public async Task TransferSubscriptions_RestoresMxAccessSubscriptionState_WhenLocalStateIsMissing()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                var nodeManager = fixture.Service.NodeManagerInstance!;
                var mxClient = fixture.MxAccessClient!;

                nodeManager.RestoreTransferredSubscriptions(new[]
                {
                    "TestMachine_001.MachineID",
                    "TestMachine_001.MachineID"
                });

                await Task.Delay(100);

                mxClient.ActiveSubscriptionCount.ShouldBe(1);

                nodeManager.UnsubscribeTag("TestMachine_001.MachineID");
                mxClient.ActiveSubscriptionCount.ShouldBe(1);

                nodeManager.UnsubscribeTag("TestMachine_001.MachineID");
                mxClient.ActiveSubscriptionCount.ShouldBe(0);
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }

        /// <summary>
        /// Confirms that transferring monitored items does not double-count subscriptions already tracked in memory.
        /// </summary>
        [Fact]
        public async Task TransferSubscriptions_DoesNotDoubleCount_WhenSubscriptionAlreadyTracked()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                var nodeManager = fixture.Service.NodeManagerInstance!;
                var mxClient = fixture.MxAccessClient!;

                nodeManager.SubscribeTag("TestMachine_001.MachineID");
                mxClient.ActiveSubscriptionCount.ShouldBe(1);

                nodeManager.RestoreTransferredSubscriptions(new[]
                {
                    "TestMachine_001.MachineID"
                });

                await Task.Delay(100);

                mxClient.ActiveSubscriptionCount.ShouldBe(1);

                nodeManager.UnsubscribeTag("TestMachine_001.MachineID");
                mxClient.ActiveSubscriptionCount.ShouldBe(0);
            }
            finally
            {
                await fixture.DisposeAsync();
            }
        }
    }
}