using System.Reflection;
using System.Security.Claims;
using Bunit;
using Microsoft.AspNetCore.Components.Authorization;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
using NSubstitute;
using ZB.MOM.WW.ScadaBridge.CentralUI.Auth;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Instances;
using ZB.MOM.WW.ScadaBridge.Commons.Entities.Sites;
using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories;
using ZB.MOM.WW.ScadaBridge.Commons.Types.Enums;
using ZB.MOM.WW.ScadaBridge.Communication;
using ZB.MOM.WW.ScadaBridge.Communication.Grpc;
using DebugViewPage = ZB.MOM.WW.ScadaBridge.CentralUI.Components.Pages.Deployment.DebugView;

namespace ZB.MOM.WW.ScadaBridge.CentralUI.Tests.Deployment;

/// <summary>
/// bUnit tests for the Debug View's instance selector after it moved from a flat
/// <c>&lt;select&gt;</c> to the shared <c>InstancePicker</c> area-tree combobox
/// (design 2026-09-08). Pins that the page hands the picker the site's areas and
/// its Enabled-only instance list, that drilling down the tree selects an instance,
/// that the selection still enables <em>Connect</em>, and that a live connection
/// locks the picker down.
/// </summary>
public class DebugViewInstancePickerTests : BunitContext
{
    private const int SiteId = 1;

    private readonly ITemplateEngineRepository _repo = Substitute.For<ITemplateEngineRepository>();

    private void RegisterServices()
    {
        // DebugView touches localStorage on render; let bUnit answer loosely.
        JSInterop.Mode = JSRuntimeMode.Loose;

        _repo.GetInstancesBySiteIdAsync(SiteId).Returns(new List<Instance>
        {
            new("Sim01") { Id = 7, SiteId = SiteId, AreaId = 2, State = InstanceState.Enabled },
            new("Off01") { Id = 8, SiteId = SiteId, State = InstanceState.Disabled },
        });
        _repo.GetAreasBySiteIdAsync(SiteId).Returns(new List<Area>
        {
            new("Line1") { Id = 1, SiteId = SiteId },
            new("Cell A") { Id = 2, SiteId = SiteId, ParentAreaId = 1 },
        });
        Services.AddSingleton(_repo);

        var siteRepo = Substitute.For<ISiteRepository>();
        siteRepo.GetAllSitesAsync().Returns(new List<Site>
        {
            new("Site One", "site-a") { Id = SiteId },
        });
        Services.AddSingleton(siteRepo);

        var comms = new CommunicationService(
            Options.Create(new CommunicationOptions()),
            NullLogger<CommunicationService>.Instance);
        Services.AddSingleton(comms);

        var grpcFactory = new SiteStreamGrpcClientFactory(NullLoggerFactory.Instance);
        // An empty throwaway provider — these tests never call StartStreamAsync,
        // so the provider is unused. (Services.BuildServiceProvider() would leak
        // an undisposed provider.)
        var debugStream = new DebugStreamService(
            comms, new ServiceCollection().BuildServiceProvider(), grpcFactory,
            NullLogger<DebugStreamService>.Instance);
        Services.AddSingleton(debugStream);

        // No SiteId claim => system-wide, so site 1 passes the scope re-check.
        var identity = new ClaimsIdentity(
            new[] { new Claim(ClaimTypes.Name, "deployer") }, "TestCookie");
        var authState = new AuthenticationState(new ClaimsPrincipal(identity));
        var stubAuth = new StubAuthStateProvider(authState);
        Services.AddSingleton<AuthenticationStateProvider>(stubAuth);
        Services.AddScoped(_ => new SiteScopeService(stubAuth));
    }

    private sealed class StubAuthStateProvider : AuthenticationStateProvider
    {
        private readonly AuthenticationState _state;
        public StubAuthStateProvider(AuthenticationState state) => _state = state;
        public override Task<AuthenticationState> GetAuthenticationStateAsync()
            => Task.FromResult(_state);
    }

    /// <summary>Renders the page, selects the seeded site and opens the picker panel.</summary>
    private IRenderedComponent<DebugViewPage> RenderWithOpenPicker()
    {
        RegisterServices();
        var cut = Render<DebugViewPage>();
        cut.Find("[data-test='debug-site-select']").Change(SiteId.ToString());
        cut.Find("[data-test='debug-instance-toggle']").Click();
        return cut;
    }

    private static void ClickRow(IRenderedComponent<DebugViewPage> cut, string text) =>
        cut.FindAll("[data-test='debug-instance-row']")
            .First(r => r.TextContent.Trim() == text)
            .Click();

    [Fact]
    public void InstanceSelector_IsThePicker_NotAFlatSelect()
    {
        RegisterServices();
        var cut = Render<DebugViewPage>();

        Assert.Single(cut.FindAll("[data-test='debug-instance-picker']"));
        Assert.Empty(cut.FindAll("select[data-test='debug-instance-select']"));
    }

    [Fact]
    public void OpeningThePicker_ShowsOnlyTheRootArea()
    {
        var cut = RenderWithOpenPicker();

        var rows = cut.FindAll("[data-test='debug-instance-row']");
        Assert.Single(rows);
        Assert.Equal("Line1", rows[0].TextContent.Trim());
        Assert.False(rows[0].HasAttribute("data-instance-id"));
    }

    [Fact]
    public void DrillingDown_RevealsTheEnabledInstanceOnly()
    {
        var cut = RenderWithOpenPicker();

        ClickRow(cut, "Line1");
        ClickRow(cut, "Cell A");

        var instanceRow = cut.Find("[data-instance-id='7']");
        Assert.Equal("Sim01 (Enabled)", instanceRow.TextContent.Trim());

        // Off01 is Disabled, so the page filters it out before the picker sees it.
        Assert.DoesNotContain(
            cut.FindAll("[data-test='debug-instance-row']"),
            r => r.TextContent.Contains("Off01"));
    }

    [Fact]
    public void PickingAnInstance_FillsTheField_AndEnablesConnect()
    {
        var cut = RenderWithOpenPicker();

        ClickRow(cut, "Line1");
        ClickRow(cut, "Cell A");
        cut.Find("[data-instance-id='7']").Click();

        Assert.Equal(
            "Sim01 (Enabled)",
            cut.Find("[data-test='debug-instance-input']").GetAttribute("value"));

        var connect = cut.FindAll("button.btn.btn-primary.btn-sm")
            .First(b => b.TextContent.Contains("Connect"));
        Assert.False(connect.HasAttribute("disabled"));
    }

    /// <summary>
    /// The picker must stay disabled for the WHOLE site load, not just until the site id lands.
    /// Blazor renders as soon as <c>LoadInstancesForSite</c> hits its first await, and at that point
    /// the page is not <c>_connected</c> — so the field was already enabled while the site's lists
    /// were still loading. Typing into it then (an operator, or Playwright's <c>FillAsync</c>, which
    /// waits only for "enabled") lost the text: the picker reads the freshly-assigned lists as
    /// "the site changed" and clears the field and closes the panel.
    /// </summary>
    [Fact]
    public void PickerStaysDisabled_UntilTheSitesInstancesHaveLoaded()
    {
        RegisterServices();
        // Hold the instance load open so the render that follows the first await is observable.
        var gate = new TaskCompletionSource<IReadOnlyList<Instance>>();
        _repo.GetInstancesBySiteIdAsync(SiteId).Returns(gate.Task);

        var cut = Render<DebugViewPage>();
        cut.Find("[data-test='debug-site-select']").Change(SiteId.ToString());

        Assert.True(cut.Find("[data-test='debug-instance-input']").HasAttribute("disabled"));
        Assert.True(cut.Find("[data-test='debug-instance-toggle']").HasAttribute("disabled"));

        cut.InvokeAsync(() => gate.SetResult(
            [new Instance("Sim01") { Id = 7, SiteId = SiteId, AreaId = 2, State = InstanceState.Enabled }]));

        cut.WaitForAssertion(() =>
            Assert.False(cut.Find("[data-test='debug-instance-input']").HasAttribute("disabled")));
    }

    /// <summary>
    /// The localStorage auto-reconnect must apply the same membership guard the
    /// <c>?instanceId=</c> deep link does. Off01 is Disabled, so the page filters it out of the
    /// list the picker is handed — restoring it anyway left the field blank while the page held
    /// a non-zero id and auto-connected to it. The stored id is dropped instead, and the site
    /// stays selected and loaded so the operator can pick again.
    /// </summary>
    [Fact]
    public void AutoReconnect_FromStorage_SkipsAnInstanceThatIsNoLongerAvailable()
    {
        RegisterServices();
        JSInterop.Setup<string>("localStorage.getItem", "debugView.siteId").SetResult(SiteId.ToString());
        JSInterop.Setup<string>("localStorage.getItem", "debugView.instanceId").SetResult("8");

        var cut = Render<DebugViewPage>();

        cut.WaitForAssertion(() =>
            Assert.Equal(string.Empty, cut.Find("[data-test='debug-instance-input']").GetAttribute("value")));

        // Nothing is selected, so Connect stays disabled — and the stale id is forgotten.
        var connect = cut.FindAll("button.btn.btn-primary.btn-sm").First(b => b.TextContent.Contains("Connect"));
        Assert.True(connect.HasAttribute("disabled"));
        JSInterop.VerifyInvoke("localStorage.removeItem");
    }

    [Fact]
    public void WhileConnected_ThePickerIsDisabled()
    {
        RegisterServices();
        var cut = Render<DebugViewPage>();
        cut.Find("[data-test='debug-site-select']").Change(SiteId.ToString());

        // Mark the page connected the way the other DebugView page tests do —
        // driving the real gRPC stream is not available to a bUnit render.
        cut.InvokeAsync(() => typeof(DebugViewPage)
            .GetField("_connected", BindingFlags.Instance | BindingFlags.NonPublic)!
            .SetValue(cut.Instance, true));
        cut.Render();

        Assert.True(cut.Find("[data-test='debug-instance-input']").HasAttribute("disabled"));
        Assert.True(cut.Find("[data-test='debug-instance-toggle']").HasAttribute("disabled"));
    }
}