using System.Diagnostics;
using System.Net;
using System.Net.Sockets;
using FinalFactory.Rendezvous.Client;
using FinalFactory.Rendezvous.Contracts;
using FinalFactory.Rendezvous.Server.Abuse;
using FinalFactory.Rendezvous.Server.Browser;
using FinalFactory.Rendezvous.Server.Http;
using FinalFactory.Rendezvous.Server.Provisioning;
using FinalFactory.Rendezvous.Server.Sessions;
using FinalFactory.Rendezvous.Server.State;
using FinalFactory.Rendezvous.Tests.Provisioning;
using FinalFactory.Rendezvous.Tests.State;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Hosting.Server;
using Microsoft.AspNetCore.Hosting.Server.Features;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;

namespace FinalFactory.Rendezvous.Tests.Client;

public sealed class RendezvousClientIntegrationTests
{
    [Fact]
    public async Task RestartReturnsTypedUnavailabilityThenAllowsHostReregistration()
    {
        int port = ReserveTcpPort();
        string address = $"http://127.0.0.1:{port}";
        using HttpClient client = new() { BaseAddress = new Uri(address) };
        RendezvousClientOptions noRetry = new()
        {
            MaximumSafeRetries = 0,
            RequestTimeout = TimeSpan.FromSeconds(1),
        };
        ClientTestHost first = await ClientTestHost.StartAsync(address);
        RendezvousPublisherClient publisher = new(client, noRetry);
        RendezvousClientResult<PublishedSession> registered = await publisher.RegisterAsync(
            CreateRegistration(100),
            first.PublisherCredential);
        PublishedSession initialSession = AssertSuccess(registered);
        BindPresence(first, initialSession, 41_100);
        RendezvousSessionBrowserClient browser = new(client, noRetry);
        BrowseSessionsResponse beforeRestart = AssertSuccess(await browser.BrowseAsync(BrowseRequest()));
        Assert.Equal(initialSession.ListingId, Assert.Single(beforeRestart.Items).ListingId);
        Stopwatch restart = Stopwatch.StartNew();
        await first.DisposeAsync();

        RendezvousClientResult<BrowseSessionsResponse> unavailable = await browser.BrowseAsync(BrowseRequest());
        Assert.False(unavailable.IsSuccess);
        Assert.Equal(RendezvousErrorCode.ServiceUnavailable, unavailable.Error);

        await using ClientTestHost second = await ClientTestHost.StartAsync(address);
        RendezvousClientResult<PublishedSession> reregistered = await publisher.RegisterAsync(
            CreateRegistration(101),
            second.PublisherCredential);
        PublishedSession replacementSession = AssertSuccess(reregistered);
        Assert.NotEqual(initialSession.ListingId, replacementSession.ListingId);
        BindPresence(second, replacementSession, 41_101);
        BrowseSessionsResponse afterRestart = AssertSuccess(await browser.BrowseAsync(BrowseRequest()));
        Assert.Equal(replacementSession.ListingId, Assert.Single(afterRestart.Items).ListingId);
        Assert.DoesNotContain(afterRestart.Items, item => item.ListingId == initialSession.ListingId);
        Assert.True(
            restart.Elapsed < TimeSpan.FromSeconds(5),
            $"Local restart and host re-registration took {restart.Elapsed}.");
    }

    [Fact]
    public async Task PublisherAndBrowserClientsCompleteTheRealSessionLifecycleAndPaging()
    {
        await using ClientTestHost host = await ClientTestHost.StartAsync();
        RendezvousPublisherClient publisher = new(host.HttpClient);
        RendezvousSessionBrowserClient browser = new(host.HttpClient);
        List<PublishedSession> sessions = [];

        for (int index = 0; index < 3; index++)
        {
            RendezvousClientResult<PublishedSession> registered = await publisher.RegisterAsync(
                CreateRegistration(index),
                host.PublisherCredential);
            PublishedSession session = AssertSuccess(registered);
            sessions.Add(session);
            Assert.True(host.Capabilities.TryFingerprint(
                session.HostPresenceCapability,
                out SecretFingerprint fingerprint));
            StoreResult<StoredListing> bound = host.Store.BindHostPresence(new(
                session.HostPresenceHandle,
                fingerprint,
                new(AddressFamilyKind.Ipv4, $"203.0.113.{80 + index}", 41_000 + index),
                null));
            Assert.Equal(StoreResultCode.Success, bound.Code);
        }

        PublishedSession first = sessions[0];
        RendezvousClientResult<RenewLeaseResponse> renewed = await publisher.RenewAsync(
            first,
            host.PublisherCredential);
        Assert.True(renewed.IsSuccess, renewed.Message);
        Assert.Equal(renewed.Value!.ExpiresAt, first.ExpiresAt);

        UpdateSessionRequest update = new()
        {
            BuildVersion = "2.0.0",
            DisplayName = "SDK host updated",
            Capacity = new() { CurrentPlayers = 2, MaximumPlayers = 8 },
            Metadata = new() { ["mode"] = "online-coop" },
        };
        RendezvousClientResult<bool> updated = await publisher.UpdateAsync(
            first,
            update,
            host.PublisherCredential);
        Assert.True(updated.IsSuccess, updated.Message);

        BrowseSessionsRequest browseRequest = new()
        {
            GameId = new("space-game"),
            EnvironmentId = new("production"),
            RegionId = new("eu-central"),
            ProtocolVersion = 7,
            PageSize = 1,
            ExcludeFull = true,
        };
        IReadOnlyList<SessionListing> listings = AssertSuccess(
            await browser.BrowseAllAsync(browseRequest));
        Assert.Equal(3, listings.Count);
        Assert.Equal("SDK host updated", listings.Single(item => item.ListingId == first.ListingId).DisplayName);

        GetSessionResponse direct = AssertSuccess(await browser.GetAsync(
            first.ListingId,
            new("space-game"),
            new("production"),
            7));
        Assert.Equal("2.0.0", direct.Session.BuildVersion);

        foreach (PublishedSession session in sessions)
        {
            RendezvousClientResult<bool> deregistered = await publisher.DeregisterAsync(
                session,
                host.PublisherCredential);
            Assert.True(deregistered.IsSuccess, deregistered.Message);
            Assert.Equal(StoreResultCode.NotFound, host.Store.GetListing(session.ListingId, false).Code);
        }
    }

    [Fact]
    public async Task BrowserStreamResetsInvalidCursorReplaysReconnectAndReleasesConnections()
    {
        await using ClientTestHost host = await ClientTestHost.StartAsync();
        RendezvousPublisherClient publisher = new(host.HttpClient);
        RendezvousSessionBrowserClient browser = new(host.HttpClient);
        PublishedSession session = AssertSuccess(await publisher.RegisterAsync(
            CreateRegistration(200),
            host.PublisherCredential));
        BindPresence(host, session, 41_200);
        BrowseSessionsRequest request = BrowseRequest();
        BrowseSessionsResponse snapshot = AssertSuccess(await browser.BrowseAsync(request));
        Assert.False(string.IsNullOrWhiteSpace(snapshot.StreamCursor));

        using CancellationTokenSource timeout = new(TimeSpan.FromSeconds(10));
        await using (IAsyncEnumerator<RendezvousClientResult<SessionStreamEvent>> invalid = browser
                         .StreamAsync(request, CorruptCursor(snapshot.StreamCursor), timeout.Token)
                         .GetAsyncEnumerator(timeout.Token))
        {
            Assert.True(await invalid.MoveNextAsync());
            Assert.Equal(SessionStreamEventKind.Reset, AssertSuccess(invalid.Current).Kind);
            Assert.False(await invalid.MoveNextAsync());
        }
        await using IAsyncEnumerator<RendezvousClientResult<SessionStreamEvent>> events = browser
            .StreamAsync(request, snapshot.StreamCursor, timeout.Token)
            .GetAsyncEnumerator(timeout.Token);
        Task<bool> upsertPending = events.MoveNextAsync().AsTask();
        Assert.True((await publisher.UpdateAsync(
            session,
            new UpdateSessionRequest
            {
                BuildVersion = "2.0.0",
                DisplayName = "Live update",
                Capacity = new() { CurrentPlayers = 3, MaximumPlayers = 8 },
                Metadata = new() { ["mode"] = "online-coop" },
            },
            host.PublisherCredential,
            timeout.Token)).IsSuccess);
        Assert.True(await upsertPending);
        SessionStreamEvent upsert = AssertSuccess(events.Current);
        Assert.Equal(SessionStreamEventKind.SessionUpsert, upsert.Kind);
        Assert.Equal("Live update", upsert.Session!.DisplayName);

        await using (IAsyncEnumerator<RendezvousClientResult<SessionStreamEvent>> replay = browser
                         .StreamAsync(request, snapshot.StreamCursor, timeout.Token)
                         .GetAsyncEnumerator(timeout.Token))
        {
            Assert.True(await replay.MoveNextAsync());
            SessionStreamEvent replayed = AssertSuccess(replay.Current);
            Assert.Equal(SessionStreamEventKind.SessionUpsert, replayed.Kind);
            Assert.Equal(upsert.Cursor, replayed.Cursor);
            Assert.Equal("Live update", replayed.Session!.DisplayName);
        }

        Task<bool> removePending = events.MoveNextAsync().AsTask();
        Assert.True((await publisher.DeregisterAsync(
            session,
            host.PublisherCredential,
            timeout.Token)).IsSuccess);
        Assert.True(await removePending);
        SessionStreamEvent remove = AssertSuccess(events.Current);
        Assert.Equal(SessionStreamEventKind.SessionRemove, remove.Kind);
        Assert.Equal(session.ListingId, remove.ListingId);
    }

    private static string CorruptCursor(string cursor)
    {
        char replacement = cursor[^1] == 'a' ? 'b' : 'a';
        return cursor[..^1] + replacement;
    }

    private static T AssertSuccess<T>(RendezvousClientResult<T> result)
    {
        Assert.True(result.IsSuccess, result.Message);
        return Assert.IsAssignableFrom<T>(result.Value);
    }

    private static void BindPresence(ClientTestHost host, PublishedSession session, int port)
    {
        Assert.True(host.Capabilities.TryFingerprint(
            session.HostPresenceCapability,
            out SecretFingerprint fingerprint));
        Assert.Equal(StoreResultCode.Success, host.Store.BindHostPresence(new(
            session.HostPresenceHandle,
            fingerprint,
            new(AddressFamilyKind.Ipv4, "203.0.113.80", port),
            null)).Code);
    }

    private static BrowseSessionsRequest BrowseRequest() => new()
    {
        GameId = new("space-game"),
        EnvironmentId = new("production"),
        RegionId = new("eu-central"),
        ProtocolVersion = 7,
        PageSize = 10,
    };

    private static RegisterSessionRequest CreateRegistration(int index) => new()
    {
        IdempotencyKey = $"sdk-integration-{index}",
        GameId = new("space-game"),
        EnvironmentId = new("production"),
        RegionId = new("eu-central"),
        ProtocolVersion = 7,
        BuildVersion = "1.0.0",
        DisplayName = $"SDK host {index}",
        Visibility = ListingVisibility.Public,
        Capacity = new() { CurrentPlayers = 1, MaximumPlayers = 8 },
        Metadata = new() { ["mode"] = "online-coop" },
    };

    private sealed class ClientTestHost : IAsyncDisposable
    {
        private readonly WebApplication _application;

        private ClientTestHost(
            WebApplication application,
            HttpClient httpClient,
            InMemoryEphemeralRendezvousStore store,
            EphemeralCapabilityIssuer capabilities,
            string publisherCredential)
        {
            _application = application;
            HttpClient = httpClient;
            Store = store;
            Capabilities = capabilities;
            PublisherCredential = publisherCredential;
        }

        internal HttpClient HttpClient { get; }
        internal InMemoryEphemeralRendezvousStore Store { get; }
        internal EphemeralCapabilityIssuer Capabilities { get; }
        internal string PublisherCredential { get; }

        internal static async Task<ClientTestHost> StartAsync(string? bindAddress = null)
        {
            ManualRendezvousClock clock = new(ProvisioningTestData.Now);
            EphemeralStoreOptions stateOptions = new();
            SessionChangeJournal changes = new(new SessionChangeJournalOptions());
            InMemoryEphemeralRendezvousStore store = new(stateOptions, clock, clock, changes);
            EphemeralCapabilityIssuer capabilities = new();
            ProvisioningRuntime provisioning = ProvisioningRuntime.Create(
                ProvisioningTestData.CreateOptions(),
                ProvisioningTestData.CreateSecrets("secret-1"),
                clock.UtcNow);
            DedicatedPublisherPrincipal principal = ProvisioningTestData.CreateDedicatedPublisher();
            string credential = provisioning.Credentials.Issue(principal, clock.UtcNow);

            WebApplicationBuilder builder = WebApplication.CreateBuilder();
            builder.WebHost.UseUrls(bindAddress ?? "http://127.0.0.1:0");
            builder.Services.ConfigureHttpJsonOptions(static options =>
                ContractJson.Configure(options.SerializerOptions));
            builder.Services.Configure<RouteHandlerOptions>(static options =>
                options.ThrowOnBadRequest = true);
            builder.Services.AddProblemDetails();
            builder.Services.AddExceptionHandler<RendezvousExceptionHandler>();
            builder.Services.AddOptions<AbuseProtectionOptions>();
            builder.Services.AddSingleton<AbuseProtectionService>();
            builder.Services.AddSingleton(provisioning);
            builder.Services.AddSingleton(provisioning.Credentials);
            builder.Services.AddSingleton(provisioning.PublisherAuthorization);
            builder.Services.AddSingleton<IEphemeralRendezvousStore>(store);
            builder.Services.AddSingleton<IWallClock>(clock);
            builder.Services.AddSingleton(capabilities);
            builder.Services.AddSingleton<ISessionCapabilityService>(capabilities);
            builder.Services.AddSingleton(SessionLeaseTiming.From(stateOptions));
            builder.Services.AddSingleton<SessionLeaseService>();
            builder.Services.AddSingleton<SessionBrowserCursorCodec>();
            builder.Services.AddSingleton<SessionStreamCursorCodec>();
            builder.Services.AddSingleton(changes);
            builder.Services.AddSingleton<SessionBrowserService>();
            builder.Services.AddSingleton<SessionStreamService>();

            WebApplication app = builder.Build();
            app.UseExceptionHandler();
            app.UseMiddleware<HttpAbuseProtectionMiddleware>();
            app.MapRendezvousContractEndpoints();
            await app.StartAsync();
            IServer server = app.Services.GetRequiredService<IServer>();
            string serviceAddress = Assert.Single(server.Features.Get<IServerAddressesFeature>()!.Addresses);
            return new(
                app,
                new HttpClient { BaseAddress = new Uri(serviceAddress) },
                store,
                capabilities,
                credential);
        }

        public async ValueTask DisposeAsync()
        {
            HttpClient.Dispose();
            await _application.StopAsync();
            await _application.DisposeAsync();
        }
    }

    private static int ReserveTcpPort()
    {
        TcpListener listener = new(IPAddress.Loopback, 0);
        listener.Start();
        int port = ((IPEndPoint)listener.LocalEndpoint).Port;
        listener.Stop();
        return port;
    }
}