using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using ZB.MOM.WW.OtOpcUa.Cluster;
using ZB.MOM.WW.OtOpcUa.Configuration;
using ZB.MOM.WW.OtOpcUa.Core.Authorization;
using ZB.MOM.WW.OtOpcUa.Host.OpcUa;
using ZB.MOM.WW.OtOpcUa.OpcUaServer.Security;

namespace ZB.MOM.WW.OtOpcUa.Host.Configuration;

/// <summary>
///     Composition of the OPC UA data-plane authentication + authorization seams, extracted from
///     <c>Program.cs</c> so the role-conditional branches are reachable from a test.
/// </summary>
/// <remarks>
///     A store decorator registered in one branch of a role conditional is exactly the
///     "built but never wired" shape, and <c>Program.cs</c>'s top-level statements cannot be driven by a
///     test — so the wiring moved here rather than the guard being written against a comment. The
///     branches are unchanged from the ones that lived inline; see <c>ApiKeyStoreRegistrationTests</c>.
/// </remarks>
public static class DataPlaneAuthRegistration
{
    /// <summary>
    ///     Registers the shared clock, the node-scoped ACL gate and the role-appropriate API-key store +
    ///     user authenticator.
    /// </summary>
    /// <param name="services">The service collection.</param>
    /// <param name="hasAdmin">Whether this node carries the <c>admin</c> role (and therefore a ConfigDb).</param>
    /// <param name="hasDriver">Whether this node carries the <c>driver</c> role.</param>
    /// <returns>The same collection, for chaining.</returns>
    public static IServiceCollection AddOtOpcUaDataPlaneAuth(
        this IServiceCollection services, bool hasAdmin, bool hasDriver)
    {
        ArgumentNullException.ThrowIfNull(services);

        // ONE clock for the whole authorization surface. The authorizer, the key-store bound and the
        // revalidation timer all read time, and DataPlaneAuthorizer already documents what a second,
        // diverging clock costs: every request denied, with a verdict indistinguishable from "no grant
        // matched". TryAdd so a test (or a future host) can substitute one before this runs.
        services.TryAddSingleton(TimeProvider.System);

        // the node-scoped ACL gate. Registered on EVERY node, not just driver ones, because
        // OtOpcUaServerHostedService takes it as a constructor parameter and the built-in container resolves
        // constructors by whether every parameter is registered, not by whether the parameter type is nullable.
        // That is the same trap the IOpcUaUserAuthenticator and IDataPlaneAuthoritySource registrations below
        // both carry a comment about; an absent registration is a node that will not start.
        services.AddSingleton<IPermissionEvaluator>(sp =>
            new TriePermissionEvaluator(sp.GetRequiredService<PermissionTrieCache>()));
        services.AddSingleton(sp => new DataPlaneAuthorizer(
            sp.GetRequiredService<IDataPlaneAuthoritySource>(),
            sp.GetRequiredService<IPermissionEvaluator>(),
            sp.GetRequiredService<IOptions<AclOptions>>().Value.Enabled,
            sp.GetRequiredService<ILoggerFactory>().CreateLogger<DataPlaneAuthorizer>(),
            sp.GetRequiredService<TimeProvider>()));

        if (hasAdmin)
        {
            // A node WITH a ConfigDb reads keys straight from it, which is what makes revocation take effect
            // on the very next activation rather than on the next deployment. Preferred wherever it is
            // available, including on a fused admin+driver node.
            // The ClusterId confines the grants this node honours to its OWN cluster — the ConfigDb holds
            // the whole fleet's ACL rows, unlike the artifact a driver-only node reads, which
            // ParseDataPlaneAuthority already scoped. Taken from AkkaClusterOptions (pure configuration),
            // NOT from IClusterRoleInfo: that depends on the ActorSystem, and the same options-not-services
            // rule is what keeps the redundancy-singleton registration in Program.cs from recursing into
            // ActorSystem construction. Null on a node with no cluster-{ClusterId} role ⇒ no filter.
            //
            // arch-review 03/S18 — and it is WRAPPED. The lookup runs inline in the SDK's synchronous
            // impersonation callback, under a SessionManager-wide lock, with CancellationToken.None: an
            // unanswered ConfigDb query therefore stalls every session activation in the server. The
            // decorator adds the deadline that bounds that, plus a short TTL that turns a burst of
            // activations into one round trip. It cannot admit anything the inner store did not.
            services.AddSingleton<IApiKeyStore>(sp => new BoundedApiKeyStore(
                new ConfigDbApiKeyStore(
                    sp.GetRequiredService<IDbContextFactory<OtOpcUaConfigDbContext>>(),
                    ConfigDbApiKeyStore.ResolveClusterId(
                        sp.GetRequiredService<IOptions<AkkaClusterOptions>>().Value)),
                sp.GetRequiredService<IOptions<ApiKeyOptions>>(),
                sp.GetRequiredService<ILoggerFactory>().CreateLogger<BoundedApiKeyStore>(),
                sp.GetRequiredService<TimeProvider>(),
                // R03:3.3 — the known-id set + miss budget in front of the SQL lookup; same section as
                // ApiKeyOptions, Host-owned knobs.
                ApiKeyStoreGuardOptions.Bind(sp.GetService<IConfiguration>())));
            services.AddSingleton<IOpcUaUserAuthenticator, ApiKeyOpcUaUserAuthenticator>();

            // Minting surface for the AdminUI. Same node condition as the store above: both need a ConfigDb.
            services.AddSingleton<IApiKeyAdminService>(sp => new ApiKeyAdminService(
                sp.GetRequiredService<IDbContextFactory<OtOpcUaConfigDbContext>>(),
                sp.GetRequiredService<IOptions<ApiKeyOptions>>().Value.Pepper));
        }
        else if (hasDriver)
        {
            // Phase 4 left a driver-only node with no ConfigDb, so its keys ride the deployment artifact.
            // Before stage 4 this node fell through to NullOpcUaUserAuthenticator and denied EVERY UserName
            // token — safe, but it meant no machine client could authenticate against a site node at all.
            // Deliberately NOT wrapped by the S18 bound: the artifact store is two dictionary probes on an
            // in-memory snapshot, so it can neither hang nor be worth caching.
            services.AddSingleton<IApiKeyStore, ArtifactApiKeyStore>();
            services.AddSingleton<IOpcUaUserAuthenticator, ApiKeyOpcUaUserAuthenticator>();
        }
        else
        {
            // Neither role: nothing serves a data plane here. MUST be registered explicitly, not left absent —
            // OtOpcUaServerHostedService takes IOpcUaUserAuthenticator as a REQUIRED constructor parameter, so
            // an unregistered seam is not a quiet fallback to deny-all; it fails DI and the node does not start.
            services.AddSingleton<IOpcUaUserAuthenticator>(NullOpcUaUserAuthenticator.Instance);
        }

        return services;
    }
}