using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config;
using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Runtime;
using ZB.MOM.WW.Secrets.Abstractions;

namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests.Runtime;

/// <summary>
///     lmxopcua#765 item 3 — a keyed session whose API key has no Galaxy ack identity is refused synchronously
///     (<c>BadUserAccessDenied</c> via <see cref="ZB.MOM.WW.OtOpcUa.Core.Abstractions.IAlarmAcknowledgePreflight"/>)
///     from a cached, periodically refreshed set read without I/O, and everything the set is not certain about
///     fails open to the Good-then-revert path.
/// </summary>
public sealed class GalaxyAckIdentityDirectoryTests
{
    private const string WithIdentity = "0a1b2c3d4e5f6071";
    private const string WithoutIdentity = "ffeeddccbbaa0099";
    private static readonly TimeSpan Interval = TimeSpan.FromSeconds(30);
    private static readonly TimeSpan StaleAfter = TimeSpan.FromSeconds(90);

    // ------------------------------------------------------------------ driver pre-check

    [Fact]
    public async Task Keyed_session_without_an_identity_is_refused_synchronously()
    {
        var (directory, _, _) = await RefreshedDirectoryAsync();
        using var driver = NewDriver(directory);

        var refusal = driver.GetAcknowledgeRefusal(WithoutIdentity);

        refusal.ShouldNotBeNull();
        refusal.ShouldContain(WithoutIdentity);
        refusal.ShouldContain("no Galaxy ack identity");
        refusal.ShouldContain("drv");
    }

    [Fact]
    public async Task Keyed_session_with_an_identity_proceeds()
    {
        var (directory, _, _) = await RefreshedDirectoryAsync();
        using var driver = NewDriver(directory);

        driver.GetAcknowledgeRefusal(WithIdentity).ShouldBeNull();
        driver.GetAcknowledgeRefusal(WithIdentity.ToUpperInvariant()).ShouldBeNull("key ids are case-insensitive");
    }

    [Fact]
    public async Task A_fallback_account_lets_a_keyed_session_without_an_identity_through()
    {
        var (directory, _, _) = await RefreshedDirectoryAsync();
        using var driver = NewDriver(directory, Opts() with
        {
            AlarmAck = new GalaxyAlarmAckOptions("ack-svc", "PLANT", "secret:otopcua/galaxy/ack-fallback"),
        });

        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldBeNull();
    }

    [Fact]
    public void Without_a_directory_a_keyed_session_is_never_pre_refused()
    {
        using var driver = NewDriver(directory: null);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldBeNull();
        driver.GetAcknowledgeRefusal(apiKeyId: null).ShouldNotBeNull("the #760 anonymous refusal is unchanged");
    }

    [Fact]
    public async Task A_refusal_asks_for_a_refresh_so_a_retry_sees_an_identity_set_out_of_band()
    {
        var (directory, store, _) = await RefreshedDirectoryAsync(TimeSpan.FromHours(1));
        using var driver = NewDriver(directory);
        using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));
        var loop = directory.RunAsync(cts.Token);
        await WaitForAsync(() => store.ListCalls >= 2, cts.Token); // RunAsync's own initial refresh

        // Set by the `secret` CLI: nothing in this process is told.
        store.AddIdentity(WithoutIdentity);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldNotBeNull();

        // The refusal kicked a refresh well inside the one-hour interval.
        await WaitForAsync(() => driver.GetAcknowledgeRefusal(WithoutIdentity) is null, cts.Token);

        await cts.CancelAsync();
        await loop;
    }

    // ------------------------------------------------------------------ fail open

    [Fact]
    public void Before_the_first_refresh_every_key_is_Unknown_and_proceeds()
    {
        using var directory = new GalaxyAckIdentityDirectory(new FakeSecretStore(), Interval, StaleAfter);
        using var driver = NewDriver(directory);

        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Unknown);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldBeNull();
    }

    [Fact]
    public async Task A_stale_snapshot_is_Unknown_and_proceeds()
    {
        var (directory, store, clock) = await RefreshedDirectoryAsync();
        using var driver = NewDriver(directory);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldNotBeNull("positive control: fresh snapshot refuses");

        // The store starts failing: the old snapshot is kept, and ages out.
        store.Fail = true;
        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeFalse();
        clock.Advance(StaleAfter - TimeSpan.FromSeconds(1));
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Absent);

        clock.Advance(TimeSpan.FromSeconds(2));
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Unknown);
        directory.GetPresence(WithIdentity).ShouldBe(GalaxyAckIdentityPresence.Unknown);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldBeNull();
    }

    [Fact]
    public async Task A_signalled_identity_change_makes_the_snapshot_Unknown_until_the_next_refresh()
    {
        var (directory, store, _) = await RefreshedDirectoryAsync();
        using var driver = NewDriver(directory);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldNotBeNull("positive control");

        // AdminUI sets the identity: the write invalidates the secret, the directory is told.
        store.AddIdentity(WithoutIdentity);
        directory.NotifySecretChanged(new SecretName(GalaxyAckIdentitySecrets.UserSecretName(WithoutIdentity)));

        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Unknown);
        driver.GetAcknowledgeRefusal(WithoutIdentity).ShouldBeNull("never refuse in the window before the refresh");

        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeTrue();
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Present);
    }

    [Fact]
    public async Task A_change_signalled_during_a_refresh_leaves_that_snapshot_untrusted()
    {
        var (directory, store, _) = await RefreshedDirectoryAsync();
        store.OnList = () => directory.NotifySecretChanged(
            new SecretName(GalaxyAckIdentitySecrets.PasswordSecretName(WithoutIdentity)));

        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeTrue();

        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Unknown);
    }

    [Fact]
    public async Task An_unrelated_secret_change_does_not_untrust_the_snapshot()
    {
        var (directory, _, _) = await RefreshedDirectoryAsync();
        directory.NotifySecretChanged(new SecretName("otopcua/galaxy/ack-fallback"));
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Absent);
    }

    [Fact]
    public async Task A_directory_without_a_store_is_always_Unknown()
    {
        using var directory = new GalaxyAckIdentityDirectory(store: null, Interval, StaleAfter);
        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeFalse();
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Unknown);
    }

    [Fact]
    public async Task A_key_id_the_resolver_could_not_look_up_is_Unknown()
    {
        var (directory, _, _) = await RefreshedDirectoryAsync();
        directory.GetPresence("../etc").ShouldBe(GalaxyAckIdentityPresence.Unknown);
        directory.GetPresence(" ").ShouldBe(GalaxyAckIdentityPresence.Unknown);
        directory.GetPresence(null).ShouldBe(GalaxyAckIdentityPresence.Unknown);
    }

    // ------------------------------------------------------------------ refresh

    [Fact]
    public async Task Refresh_picks_up_added_and_removed_identities()
    {
        var (directory, store, _) = await RefreshedDirectoryAsync();
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Absent);

        store.AddIdentity(WithoutIdentity);
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Absent, "a cache, until refreshed");
        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeTrue();
        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Present);

        store.RemoveIdentity(WithIdentity, softDelete: true);
        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeTrue();
        directory.GetPresence(WithIdentity).ShouldBe(GalaxyAckIdentityPresence.Absent, "a deleted user secret is no identity");
    }

    [Fact]
    public async Task Only_user_secrets_count_as_an_identity()
    {
        var store = new FakeSecretStore();
        store.Add(GalaxyAckIdentitySecrets.PasswordSecretName(WithoutIdentity)); // password without user
        store.Add("otopcua/galaxy/ack-fallback");
        using var directory = new GalaxyAckIdentityDirectory(store, Interval, StaleAfter);

        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeTrue();

        directory.GetPresence(WithoutIdentity).ShouldBe(GalaxyAckIdentityPresence.Absent);
    }

    [Fact]
    public async Task The_loop_refreshes_on_its_interval()
    {
        var store = new FakeSecretStore();
        using var directory = new GalaxyAckIdentityDirectory(store, TimeSpan.FromMilliseconds(50), TimeSpan.FromMinutes(1));
        using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));
        var loop = directory.RunAsync(cts.Token);

        await WaitForAsync(() => directory.GetPresence(WithIdentity) == GalaxyAckIdentityPresence.Absent, cts.Token);
        store.AddIdentity(WithIdentity);
        await WaitForAsync(() => directory.GetPresence(WithIdentity) == GalaxyAckIdentityPresence.Present, cts.Token);

        await cts.CancelAsync();
        await loop; // completes cleanly on cancellation
    }

    [Fact]
    public async Task The_loop_refreshes_early_on_a_signalled_change()
    {
        var store = new FakeSecretStore();
        using var directory = new GalaxyAckIdentityDirectory(store, TimeSpan.FromHours(1), TimeSpan.FromHours(3));
        using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30));
        var loop = directory.RunAsync(cts.Token);
        await WaitForAsync(() => directory.GetPresence(WithIdentity) == GalaxyAckIdentityPresence.Absent, cts.Token);

        store.AddIdentity(WithIdentity);
        directory.NotifySecretChanged(new SecretName(GalaxyAckIdentitySecrets.UserSecretName(WithIdentity)));

        await WaitForAsync(() => directory.GetPresence(WithIdentity) == GalaxyAckIdentityPresence.Present, cts.Token);
        await cts.CancelAsync();
        await loop;
    }

    // ------------------------------------------------------------------ helpers

    private static async Task<(GalaxyAckIdentityDirectory Directory, FakeSecretStore Store, ManualClock Clock)>
        RefreshedDirectoryAsync(TimeSpan? interval = null)
    {
        var store = new FakeSecretStore();
        store.AddIdentity(WithIdentity);
        var clock = new ManualClock();
        var directory = new GalaxyAckIdentityDirectory(
            store, interval ?? Interval, interval is { } i ? i * 3 : StaleAfter, clock);
        (await directory.RefreshAsync(CancellationToken.None)).ShouldBeTrue();
        return (directory, store, clock);
    }

    private static async Task WaitForAsync(Func<bool> condition, CancellationToken ct)
    {
        while (!condition())
        {
            ct.ThrowIfCancellationRequested();
            await Task.Delay(10, ct);
        }
    }

    private static GalaxyDriverOptions Opts() => new(
        new GalaxyGatewayOptions("https://mxgw.test:5001", "dev:key"),
        new GalaxyMxAccessOptions("OtOpcUa-A"),
        new GalaxyRepositoryOptions(),
        new GalaxyReconnectOptions());

    private static GalaxyDriver NewDriver(IGalaxyAckIdentityDirectory? directory, GalaxyDriverOptions? options = null) =>
        new("drv", options ?? Opts(), hierarchySource: null, ackIdentityDirectory: directory);

    private sealed class ManualClock : TimeProvider
    {
        private DateTimeOffset _now = new(2026, 11, 9, 12, 0, 0, TimeSpan.Zero);

        public void Advance(TimeSpan by) => _now += by;

        public override DateTimeOffset GetUtcNow() => _now;
    }

    /// <summary>Metadata-only store: <see cref="ListAsync"/> is all the directory may call.</summary>
    private sealed class FakeSecretStore : ISecretStore
    {
        private readonly Dictionary<string, bool> _rows = new(StringComparer.Ordinal); // name → deleted
        private readonly Lock _lock = new();
        private int _listCalls;

        public bool Fail { get; set; }

        public Action? OnList { get; set; }

        public int ListCalls => Volatile.Read(ref _listCalls);

        public void Add(string name)
        {
            lock (_lock) _rows[name] = false;
        }

        public void AddIdentity(string keyId)
        {
            Add(GalaxyAckIdentitySecrets.PasswordSecretName(keyId));
            Add(GalaxyAckIdentitySecrets.UserSecretName(keyId));
        }

        public void RemoveIdentity(string keyId, bool softDelete)
        {
            lock (_lock)
            {
                foreach (var name in new[]
                         {
                             GalaxyAckIdentitySecrets.UserSecretName(keyId), GalaxyAckIdentitySecrets.PasswordSecretName(keyId),
                         })
                {
                    if (softDelete) _rows[name] = true;
                    else _rows.Remove(name);
                }
            }
        }

        public Task<IReadOnlyList<SecretMetadata>> ListAsync(bool includeDeleted, CancellationToken ct)
        {
            Interlocked.Increment(ref _listCalls);
            OnList?.Invoke();
            if (Fail) throw new InvalidOperationException("store unavailable");
            lock (_lock)
            {
                // Deleted rows are returned regardless, to prove the directory filters them itself.
                IReadOnlyList<SecretMetadata> rows = _rows.Select(r => new SecretMetadata
                {
                    Name = new SecretName(r.Key),
                    ContentType = SecretContentType.Text,
                    KekId = "k",
                    Revision = 1,
                    IsDeleted = r.Value,
                    CreatedUtc = DateTimeOffset.UnixEpoch,
                    UpdatedUtc = DateTimeOffset.UnixEpoch,
                }).ToList();
                return Task.FromResult(rows);
            }
        }

        public Task<StoredSecret?> GetAsync(SecretName name, CancellationToken ct) => throw Unexpected();

        public Task UpsertAsync(StoredSecret row, CancellationToken ct) => throw Unexpected();

        public Task<bool> DeleteAsync(SecretName name, string? actor, CancellationToken ct) => throw Unexpected();

        public Task<IReadOnlyList<SecretManifestEntry>> GetManifestAsync(CancellationToken ct) => throw Unexpected();

        public Task ApplyReplicatedAsync(StoredSecret row, CancellationToken ct) => throw Unexpected();

        public Task<bool> ApplyRewrapAsync(StoredSecret rewrappedRow, byte[] expectedCurrentWrappedDek, CancellationToken ct) =>
            throw Unexpected();

        // The directory must read metadata only — never a row (that would decrypt-adjacent I/O per key).
        private static InvalidOperationException Unexpected() => new("the directory may only list metadata");
    }
}