using Akka.Actor;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Mvc.Testing;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using ZB.MOM.WW.ScadaBridge.ConfigurationDatabase;

namespace ZB.MOM.WW.ScadaBridge.Host.Tests;

/// <summary>
/// The guard's own self-tests. These are what make the production scans below trustworthy:
/// a reflection guard that silently matches nothing passes just as green as one that works,
/// so the positive controls are permanent fixtures, not scaffolding.
/// </summary>
public class CaptiveDependencyGuardSelfTests
{
    /// <summary>A stand-in for any service the container registers <c>Scoped</c>.</summary>
    private interface IPretendScopedService;

    /// <summary>
    /// POSITIVE CONTROL — the pre-row-45 shape, preserved permanently. An actor that caches a
    /// scoped-typed service for its lifetime is exactly what <c>NotificationOutboxActor</c>
    /// looked like before 9e769735, and the guard must report it.
    /// </summary>
    private sealed class CachesScopedServiceActor : ReceiveActor
    {
#pragma warning disable CS0169, IDE0051, CA1823 // the unused field IS the fixture
        private readonly IPretendScopedService? _captive;
#pragma warning restore CS0169, IDE0051, CA1823
    }

    /// <summary>POSITIVE CONTROL — caching the scope itself, the other half of row 45.</summary>
    private sealed class CachesScopeActor : ReceiveActor
    {
#pragma warning disable CS0169, IDE0051, CA1823
        private readonly IServiceScope? _scope;
#pragma warning restore CS0169, IDE0051, CA1823
    }

    /// <summary>POSITIVE CONTROL — an EF context held for the actor's lifetime.</summary>
    private sealed class CachesDbContextActor : ReceiveActor
    {
#pragma warning disable CS0169, IDE0051, CA1823
        private readonly ScadaBridgeDbContext? _db;
#pragma warning restore CS0169, IDE0051, CA1823
    }

    /// <summary>
    /// NEGATIVE CONTROL — the correct pattern. Holding the root provider and/or the scope
    /// factory for the actor's lifetime must NOT be flagged; every production actor does this.
    /// </summary>
    private sealed class CreatesScopePerOperationActor : ReceiveActor
    {
#pragma warning disable CS0169, IDE0051, CA1823
        private readonly IServiceProvider? _services;
        private readonly IServiceScopeFactory? _scopeFactory;
#pragma warning restore CS0169, IDE0051, CA1823
    }

    /// <summary>POSITIVE CONTROL — an auto-property backing field must be caught too.</summary>
    private sealed class ScopedAutoPropertyActor : ReceiveActor
    {
        private IPretendScopedService? Captive { get; init; }
    }

    private static readonly IReadOnlySet<Type> PretendScopedSet =
        new HashSet<Type> { typeof(IPretendScopedService) };

    [Fact]
    public void Guard_Flags_ActorCachingAScopedService()
    {
        var violations = CaptiveDependencyGuard.Scan(
            [typeof(CachesScopedServiceActor)], PretendScopedSet);

        var violation = Assert.Single(violations);
        Assert.Equal("_captive", violation.FieldName);
        Assert.Equal(typeof(IPretendScopedService), violation.FieldType);
    }

    [Fact]
    public void Guard_Flags_ActorCachingAServiceScope_EvenWhenTheScopedSetIsEmpty()
    {
        // An IServiceScope field is wrong whatever the container says, so this must not
        // depend on the derived scoped set having caught anything.
        var violations = CaptiveDependencyGuard.Scan(
            [typeof(CachesScopeActor)], new HashSet<Type>());

        var violation = Assert.Single(violations);
        Assert.Equal("_scope", violation.FieldName);
    }

    [Fact]
    public void Guard_Flags_ActorCachingADbContext()
    {
        var violations = CaptiveDependencyGuard.Scan(
            [typeof(CachesDbContextActor)], new HashSet<Type>());

        var violation = Assert.Single(violations);
        Assert.Equal(typeof(ScadaBridgeDbContext), violation.FieldType);
    }

    [Fact]
    public void Guard_Flags_ScopedAutoPropertyBackingField()
    {
        var violations = CaptiveDependencyGuard.Scan(
            [typeof(ScopedAutoPropertyActor)], PretendScopedSet);

        var violation = Assert.Single(violations);
        Assert.Contains("Captive", violation.FieldName, StringComparison.Ordinal);
    }

    [Fact]
    public void Guard_Allows_RootProviderAndScopeFactoryFields()
    {
        var violations = CaptiveDependencyGuard.Scan(
            [typeof(CreatesScopePerOperationActor)], PretendScopedSet);

        Assert.Empty(violations);
    }

    /// <summary>
    /// The scoped set must be derived from real registrations rather than hand-listed, and it
    /// must pick up BOTH sides of a descriptor — row 45 cached the interface, but caching the
    /// concrete adapter would have been the same bug.
    /// </summary>
    [Fact]
    public void ScopedTypes_CollectsServiceAndImplementationTypes()
    {
        var services = new ServiceCollection();
        services.AddScoped<IPretendScopedService, PretendScopedService>();
        services.AddSingleton<PretendSingleton>();

        var scoped = CaptiveDependencyGuard.ScopedTypes(services);

        Assert.Contains(typeof(IPretendScopedService), scoped);
        Assert.Contains(typeof(PretendScopedService), scoped);
        Assert.DoesNotContain(typeof(PretendSingleton), scoped);
    }

    private sealed class PretendScopedService : IPretendScopedService;

    private sealed class PretendSingleton;

    /// <summary>
    /// The assembly walk must actually find the production actors. Without this floor a
    /// broken loader would make every scan below vacuously green — the classic way a
    /// reflection guard rots into a no-op.
    /// </summary>
    [Fact]
    public void ProductionActorTypes_FindsTheShippedActors()
    {
        var actorTypes = CaptiveDependencyGuard.ProductionActorTypes();

        // 28 actor classes ship today; the floor is deliberately loose so adding or
        // consolidating an actor does not fail this, while a loader that finds nothing does.
        Assert.True(
            actorTypes.Count >= 20,
            $"Expected the ScadaBridge assembly walk to find at least 20 actors, found {actorTypes.Count}. " +
            "A guard that scans no types passes vacuously.");

        // Spot-check one actor from a site assembly and one from a central assembly, so a
        // walk that only reached the Host assembly's own actors cannot satisfy the floor.
        Assert.Contains(actorTypes, t => t.Name == "InstanceActor");
        Assert.Contains(actorTypes, t => t.Name == "NotificationOutboxActor");
    }

    /// <summary>
    /// Register row 61: the allowlist is now EMPTY and must stay that way.
    ///
    /// <para>
    /// This replaces the former staleness self-test, which checked that each entry still named
    /// a field the scanner would flag. Its two entries — <c>AuditLogIngestActor</c> and
    /// <c>SiteCallAuditActor</c>'s <c>_injectedRepository</c> — covered repository fields
    /// assigned only by test-mode constructors; those constructors have been deleted and the
    /// fixtures fold onto the <c>IServiceProvider</c> overload, so there is no longer a field
    /// to exempt. An empty allowlist is a strictly stronger statement than a correct one:
    /// nothing is exempt, so nothing can rot.
    /// </para>
    /// </summary>
    [Fact]
    public void Allowlist_IsEmpty_NoActorExemptFromTheCaptiveDependencyScan()
    {
        Assert.True(
            CaptiveDependencyGuard.Allowlist.Count == 0,
            "The captive-dependency allowlist must stay empty (register row 61). Entries present: " +
            string.Join(", ", CaptiveDependencyGuard.Allowlist) +
            ". An entry means an actor caches a scoped service on a field — fix the actor " +
            "(fold test fixtures onto the IServiceProvider overload) rather than exempting it.");
    }

    /// <summary>
    /// Register row 61 (the other half of the pin): with the allowlist empty, the two actors
    /// that used to need exemptions must now scan CLEAN against the scoped repository types
    /// they resolve. This is what makes the empty allowlist meaningful — it proves the entries
    /// were removed because the fields are gone, not because the scan stopped looking.
    /// </summary>
    [Fact]
    public void FormerlyAllowlistedActors_NowScanClean()
    {
        var actorTypes = CaptiveDependencyGuard.ProductionActorTypes();
        var everyScopedType = CaptiveDependencyGuard.ScopedTypes(BuildCentralishScopedProbe());

        // Allowlist disabled, so a surviving _injectedRepository-shaped field would still show.
        var unfiltered = CaptiveDependencyGuard.Scan(actorTypes, everyScopedType, applyAllowlist: false);

        var offenders = unfiltered
            .Where(v => v.ActorType.Name is "AuditLogIngestActor" or "SiteCallAuditActor")
            .Select(v => v.ToString())
            .ToList();

        Assert.True(offenders.Count == 0,
            "AuditLogIngestActor / SiteCallAuditActor must hold no scoped repository field " +
            "(register row 61). Found: " + string.Join(" | ", offenders));

        // Sanity: the scan really did examine those two actors, so the clean result above is
        // evidence rather than an empty walk.
        Assert.Contains(actorTypes, t => t.Name == "AuditLogIngestActor");
        Assert.Contains(actorTypes, t => t.Name == "SiteCallAuditActor");
    }

    /// <summary>
    /// A minimal descriptor set naming the two repository types the deleted test-mode
    /// constructors used to cache, so <see cref="FormerlyAllowlistedActors_NowScanClean"/> does
    /// not need to boot a host. Both are registered <c>Scoped</c> by
    /// <c>AddConfigurationDatabase</c>; the role-scan tests below verify that against the real
    /// container.
    /// </summary>
    /// <returns>The probe descriptors.</returns>
    private static IServiceCollection BuildCentralishScopedProbe()
    {
        var services = new ServiceCollection();
        services.AddScoped<
            ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories.IAuditLogRepository>(
            _ => throw new NotSupportedException("registration shape only"));
        services.AddScoped<
            ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories.ISiteCallAuditRepository>(
            _ => throw new NotSupportedException("registration shape only"));
        return services;
    }
}

/// <summary>
/// Runs the guard against every shipped actor using the CENTRAL composition root's real
/// scoped registrations.
/// </summary>
[Collection(HostBootCollection.Name)]
public class CentralCaptiveDependencyGuardTests : IDisposable
{
    private readonly WebApplicationFactory<Program> _factory;
    private readonly string? _previousEnv;
    private readonly CentralDbTestEnvironment _dbEnv;
    private readonly List<ServiceDescriptor> _descriptors = [];

    public CentralCaptiveDependencyGuardTests()
    {
        _previousEnv = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
        Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", "Central");
        _dbEnv = new CentralDbTestEnvironment();

        _factory = new WebApplicationFactory<Program>()
            .WithWebHostBuilder(builder =>
            {
                builder.ConfigureAppConfiguration((_, config) =>
                {
                    config.AddInMemoryCollection(new Dictionary<string, string?>
                    {
                        ["ScadaBridge:Node:NodeName"] = "central-a",
                        ["ScadaBridge:Node:NodeHostname"] = "localhost",
                        ["ScadaBridge:Node:RemotingPort"] = "0",
                        ["ScadaBridge:Cluster:SeedNodes:0"] = "akka.tcp://scadabridge@localhost:2551",
                        ["ScadaBridge:Cluster:SeedNodes:1"] = "akka.tcp://scadabridge@localhost:2552",
                        ["ScadaBridge:Database:SkipMigrations"] = "true",
                        ["ScadaBridge:Security:JwtSigningKey"] = "test-signing-key-must-be-at-least-32-chars-long!",
                        ["ScadaBridge:Security:Ldap:Server"] = "localhost",
                        ["ScadaBridge:Security:Ldap:Port"] = "3893",
                        ["ScadaBridge:Security:Ldap:Transport"] = "None",
                        ["ScadaBridge:Security:Ldap:AllowInsecure"] = "true",
                        ["ScadaBridge:Security:Ldap:SearchBase"] = "dc=zb,dc=local",
                        ["ScadaBridge:Security:Ldap:ServiceAccountDn"] = "cn=admin,dc=zb,dc=local",
                        ["ScadaBridge:InboundApi:ApiKeyPepper"] = "test-inbound-api-key-pepper-at-least-32-chars!",
                    });
                });
                builder.UseSetting("ScadaBridge:Node:Role", "Central");
                builder.UseSetting("ScadaBridge:Database:SkipMigrations", "true");
                builder.ConfigureServices(services =>
                {
                    var descriptorsToRemove = services
                        .Where(d =>
                            d.ServiceType == typeof(DbContextOptions<ScadaBridgeDbContext>) ||
                            d.ServiceType == typeof(DbContextOptions) ||
                            d.ServiceType == typeof(ScadaBridgeDbContext) ||
                            d.ServiceType.FullName?.Contains("EntityFrameworkCore") == true)
                        .ToList();
                    foreach (var d in descriptorsToRemove)
                        services.Remove(d);

                    services.AddDbContext<ScadaBridgeDbContext>(options =>
                        options.UseInMemoryDatabase($"CaptiveGuard_{Guid.NewGuid()}"));

                    AkkaHostedServiceRemover.RemoveAkkaHostedServiceOnly(services);

                    // ConfigureServices runs after Program.cs has added everything, so this
                    // snapshot IS the Central composition root's registration set.
                    _descriptors.AddRange(services);
                });
            });

        _ = _factory.Server;
    }

    public void Dispose()
    {
        try
        {
            _factory.Dispose();
        }
        finally
        {
            Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", _previousEnv);
            _dbEnv.Dispose();
        }
    }

    [Fact]
    public void Central_NoActorHoldsCaptiveScopedState()
    {
        var scopedTypes = CaptiveDependencyGuard.ScopedTypes(_descriptors);
        Assert.NotEmpty(scopedTypes);

        var violations = CaptiveDependencyGuard.Scan(
            CaptiveDependencyGuard.ProductionActorTypes(), scopedTypes);

        Assert.True(
            violations.Count == 0,
            "Actors holding captive scope state (register row 45's bug class):\n  "
            + string.Join("\n  ", violations));
    }
}

/// <summary>
/// The same scan against the SITE composition root's real scoped registrations. Both roles
/// are checked because the scoped set differs between them — a type that is a singleton on
/// central can be scoped on a site, and only the role that registers it scoped can catch an
/// actor caching it.
/// </summary>
public class SiteCaptiveDependencyGuardTests : IDisposable
{
    private readonly string _tempDbPath;
    private readonly string _tempTrackingDbPath;
    private readonly string _tempLocalDbPath;
    private readonly string _tempAuditDbPath;
    private readonly IServiceCollection _services;

    public SiteCaptiveDependencyGuardTests()
    {
        _tempDbPath = Path.Combine(Path.GetTempPath(), $"sb_guard_{Guid.NewGuid()}.db");
        _tempTrackingDbPath = Path.Combine(Path.GetTempPath(), $"sb_guard_track_{Guid.NewGuid()}.db");
        _tempLocalDbPath = Path.Combine(Path.GetTempPath(), $"sb_guard_localdb_{Guid.NewGuid()}.db");
        _tempAuditDbPath = Path.Combine(Path.GetTempPath(), $"sb_guard_audit_{Guid.NewGuid()}.db");

        var builder = WebApplication.CreateBuilder();
        builder.Configuration.Sources.Clear();
        builder.Configuration.AddInMemoryCollection(new Dictionary<string, string?>
        {
            ["ScadaBridge:Node:Role"] = "Site",
            ["ScadaBridge:Node:NodeName"] = "node-a",
            ["ScadaBridge:Node:NodeHostname"] = "test-site",
            ["ScadaBridge:Node:SiteId"] = "TestSite",
            ["ScadaBridge:Node:RemotingPort"] = "0",
            ["ScadaBridge:Node:GrpcPort"] = "0",
            ["ScadaBridge:Database:SiteDbPath"] = _tempDbPath,
            ["ScadaBridge:OperationTracking:ConnectionString"] = $"Data Source={_tempTrackingDbPath}",
            ["LocalDb:Path"] = _tempLocalDbPath,
            ["AuditLog:SiteWriter:DatabasePath"] = _tempAuditDbPath,
            ["ScadaBridge:Cluster:SeedNodes:0"] = "akka.tcp://scadabridge@localhost:2551",
            ["ScadaBridge:Cluster:SeedNodes:1"] = "akka.tcp://scadabridge@localhost:2552",
        });

        builder.Services.AddGrpc();
        SiteServiceRegistration.Configure(builder.Services, builder.Configuration);

        // Registration only — the provider is never built here, so nothing resolves and no
        // site database file is opened.
        _services = builder.Services;
    }

    public void Dispose()
    {
        foreach (var path in new[] { _tempDbPath, _tempTrackingDbPath, _tempLocalDbPath, _tempAuditDbPath })
        {
            try { File.Delete(path); } catch { /* best effort */ }
        }
    }

    [Fact]
    public void Site_NoActorHoldsCaptiveScopedState()
    {
        var scopedTypes = CaptiveDependencyGuard.ScopedTypes(_services);
        Assert.NotEmpty(scopedTypes);

        var violations = CaptiveDependencyGuard.Scan(
            CaptiveDependencyGuard.ProductionActorTypes(), scopedTypes);

        Assert.True(
            violations.Count == 0,
            "Actors holding captive scope state (register row 45's bug class):\n  "
            + string.Join("\n  ", violations));
    }
}