using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Opc.Ua;
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
{
    public class IncrementalSyncTests
    {
        /// <summary>
        /// Verifies that adding a new Galaxy object and attribute causes the corresponding OPC UA node subtree to appear after sync.
        /// </summary>
        [Fact]
        public async Task Sync_AddObject_NewNodeAppears()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Verify initial state
                var children = await client.BrowseAsync(client.MakeNodeId("TestArea"));
                children.Select(c => c.Name).ShouldContain("TestMachine_001");
                children.Select(c => c.Name).ShouldNotContain("NewObject");

                // Add a new object
                fixture.GalaxyRepository!.Hierarchy.Add(new GalaxyObjectInfo
                {
                    GobjectId = 100, TagName = "NewObject_001", ContainedName = "NewObject",
                    BrowseName = "NewObject", ParentGobjectId = 2, IsArea = false
                });
                fixture.GalaxyRepository.Attributes.Add(new GalaxyAttributeInfo
                {
                    GobjectId = 100, TagName = "NewObject_001", AttributeName = "Status",
                    FullTagReference = "NewObject_001.Status", MxDataType = 5
                });

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

                // Reconnect in case session was disrupted during rebuild
                using var client2 = new OpcUaTestClient();
                await client2.ConnectAsync(fixture.EndpointUrl);

                // New object should appear when browsing parent
                children = await client2.BrowseAsync(client2.MakeNodeId("TestArea"));
                children.Select(c => c.Name).ShouldContain("NewObject",
                    $"Browse returned: [{string.Join(", ", children.Select(c => c.Name))}]");

                // Original object should still be there
                children.Select(c => c.Name).ShouldContain("TestMachine_001");
            }
            finally { await fixture.DisposeAsync(); }
        }

        /// <summary>
        /// Verifies that removing a Galaxy object tears down the corresponding OPC UA subtree without affecting siblings.
        /// </summary>
        [Fact]
        public async Task Sync_RemoveObject_NodeDisappears()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

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

                // Remove MESReceiver (gobject_id 5) and its attributes
                fixture.GalaxyRepository!.Hierarchy.RemoveAll(h => h.GobjectId == 5);
                fixture.GalaxyRepository.Attributes.RemoveAll(a => a.GobjectId == 5);

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

                // MESReceiver should be gone
                children = await client.BrowseAsync(client.MakeNodeId("TestMachine_001"));
                children.Select(c => c.Name).ShouldNotContain("MESReceiver");

                // DelmiaReceiver should still be there
                children.Select(c => c.Name).ShouldContain("DelmiaReceiver");
            }
            finally { await fixture.DisposeAsync(); }
        }

        /// <summary>
        /// Verifies that adding a Galaxy attribute creates a new OPC UA variable during incremental rebuild.
        /// </summary>
        [Fact]
        public async Task Sync_AddAttribute_NewVariableAppears()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Add a new attribute to TestMachine_001
                fixture.GalaxyRepository!.Attributes.Add(new GalaxyAttributeInfo
                {
                    GobjectId = 3, TagName = "TestMachine_001", AttributeName = "NewAttr",
                    FullTagReference = "TestMachine_001.NewAttr", MxDataType = 5
                });

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

                var children = await client.BrowseAsync(client.MakeNodeId("TestMachine_001"));
                children.Select(c => c.Name).ShouldContain("NewAttr");
                children.Select(c => c.Name).ShouldContain("MachineID");
            }
            finally { await fixture.DisposeAsync(); }
        }

        /// <summary>
        /// Verifies that subscriptions on unchanged objects continue receiving data after unrelated subtree rebuilds.
        /// </summary>
        [Fact]
        public async Task Sync_UnchangedObject_SubscriptionSurvives()
        {
            var mxClient = new FakeMxAccessClient();
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient(mxClient: mxClient);
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Subscribe to MachineID on TestMachine_001
                var nodeId = client.MakeNodeId("TestMachine_001.MachineID");
                var (sub, item) = await client.SubscribeAsync(nodeId, 250);
                await Task.Delay(500);

                // Modify a DIFFERENT object (MESReceiver) — TestMachine_001 should be unaffected
                var mesAttr = fixture.GalaxyRepository!.Attributes
                    .First(a => a.GobjectId == 5 && a.AttributeName == "MoveInBatchID");
                mesAttr.SecurityClassification = 2; // change something

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

                // Push a value change through MXAccess — subscription should still deliver
                mxClient.SimulateDataChange("TestMachine_001.MachineID", Vtq.Good("UPDATED"));
                await Task.Delay(1000);

                var lastValue = (item.LastValue as MonitoredItemNotification)?.Value?.Value;
                lastValue.ShouldBe("UPDATED");
            }
            finally { await fixture.DisposeAsync(); }
        }

        /// <summary>
        /// Verifies that a rebuild request with no repository changes leaves the published namespace intact.
        /// </summary>
        [Fact]
        public async Task Sync_NoChanges_NothingHappens()
        {
            var fixture = OpcUaServerFixture.WithFakeMxAccessClient();
            await fixture.InitializeAsync();
            try
            {
                using var client = new OpcUaTestClient();
                await client.ConnectAsync(fixture.EndpointUrl);

                // Trigger rebuild with no changes
                fixture.Service.TriggerRebuild();
                await Task.Delay(500);

                // Everything should still work
                var children = await client.BrowseAsync(client.MakeNodeId("TestMachine_001"));
                children.Select(c => c.Name).ShouldContain("MachineID");
            }
            finally { await fixture.DisposeAsync(); }
        }
    }
}