using System.Net;
using System.Text.Json;
using FinalFactory.Rendezvous.Client;
using FinalFactory.Rendezvous.Contracts;

namespace FinalFactory.Rendezvous.Tests.Client;

public sealed class RendezvousJoinClientTests
{
    [Fact]
    public async Task JoinIssuanceRetriesTheSameIdempotentPayloadAndCancellationUsesCapability()
    {
        CreateJoinAttemptResponse created = CreateAttempt();
        RecordingHandler handler = new(
            new HttpResponseMessage(HttpStatusCode.ServiceUnavailable),
            JsonResponse(HttpStatusCode.Created, created),
            new HttpResponseMessage(HttpStatusCode.NoContent));
        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
        RendezvousJoinClient client = new(
            http,
            new RendezvousClientOptions { JitterRatio = 0 },
            new ImmediateDelay());
        CreateJoinAttemptRequest request = new()
        {
            IdempotencyKey = "stable-join-key",
            GameId = new("space-game"),
            EnvironmentId = new("production"),
            ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000201")),
            ProtocolVersion = 7,
        };

        RendezvousClientResult<CreateJoinAttemptResponse> result = await client.CreateAsync(request);
        RendezvousClientResult<bool> cancelled = await client.CancelAsync(created);

        Assert.True(result.IsSuccess, result.Message);
        Assert.True(cancelled.IsSuccess, cancelled.Message);
        Assert.Equal(handler.Requests[0].Body, handler.Requests[1].Body);
        Assert.Contains("stable-join-key", handler.Requests[0].Body, StringComparison.Ordinal);
        RecordedRequest cancellation = handler.Requests[2];
        Assert.Equal(HttpMethod.Delete, cancellation.Method);
        Assert.Equal(
            created.ClientPunchCapability,
            cancellation.Headers["X-Rendezvous-Client-Punch-Capability"]);
    }

    [Fact]
    public async Task HostInvitationPollingFollowsCursorsWithTheLeaseToken()
    {
        HostJoinAttempt first = CreateHostAttempt("00000000-0000-0000-0000-000000000211");
        HostJoinAttempt second = CreateHostAttempt("00000000-0000-0000-0000-000000000212");
        RecordingHandler handler = new(
            JsonResponse(HttpStatusCode.OK, new BrowseHostJoinAttemptsResponse
            {
                Items = [first],
                NextCursor = "next page+cursor",
            }),
            JsonResponse(HttpStatusCode.OK, new BrowseHostJoinAttemptsResponse
            {
                Items = [second],
            }));
        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
        RendezvousJoinClient client = new(http);
        PublishedSession session = new(new RegisterSessionResponse
        {
            ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000220")),
            LeaseId = new(Guid.Parse("00000000-0000-0000-0000-000000000221")),
            LeaseToken = "lease-secret",
            HostPresenceHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000222")),
            HostPresenceCapability = Credential('P'),
            ExpiresAt = new DateTimeOffset(2030, 1, 1, 0, 0, 0, TimeSpan.Zero),
            LeaseRenewAfterSeconds = 15,
            HostPresenceRefreshAfterSeconds = 10,
        });

        RendezvousClientResult<IReadOnlyList<HostJoinAttempt>> result =
            await client.BrowseAllForHostAsync(session);

        Assert.True(result.IsSuccess, result.Message);
        Assert.Equal([first.AttemptId, second.AttemptId], result.Value!.Select(item => item.AttemptId));
        Assert.Equal(2, handler.Requests.Count);
        Assert.All(handler.Requests, request =>
            Assert.Equal("lease-secret", request.Headers["X-Rendezvous-Lease-Token"]));
        Assert.Contains("cursor=next%20page%2Bcursor", handler.Requests[1].Uri.Query, StringComparison.Ordinal);
    }

    [Fact]
    public async Task OutcomeReportingUsesTheAttemptCapabilityAndCoarseElapsedBucket()
    {
        CreateJoinAttemptResponse attempt = CreateAttempt();
        RecordingHandler handler = new(JsonResponse(HttpStatusCode.OK, new ReportConnectionOutcomeResponse
        {
            Accepted = true,
            IsDuplicate = false,
        }));
        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
        RendezvousJoinClient client = new(http);
        RendezvousConnectionOutcome outcome = RendezvousConnectionOutcome.Create(
            ConnectionOutcomeKind.DirectConnectTimedOut,
            RendezvousConnectionOutcomeSource.LocalTraversal,
            RendezvousConnectionFailureCategory.DirectConnection,
            RendezvousConnectionPhase.DirectConnection,
            TimeSpan.FromSeconds(6));

        RendezvousClientResult<ReportConnectionOutcomeResponse> result =
            await client.ReportOutcomeAsync(attempt, outcome);

        Assert.True(result.IsSuccess, result.Message);
        RecordedRequest request = Assert.Single(handler.Requests);
        Assert.Equal(HttpMethod.Post, request.Method);
        Assert.Equal(
            attempt.ClientPunchCapability,
            request.Headers["X-Rendezvous-Client-Punch-Capability"]);
        Assert.Contains("\"outcome\":\"directConnectTimedOut\"", request.Body, StringComparison.Ordinal);
        Assert.Contains("\"elapsedBucket\":\"fiveToFifteenSeconds\"", request.Body, StringComparison.Ordinal);
        Assert.DoesNotContain("diagnostic", request.Body, StringComparison.OrdinalIgnoreCase);
    }

    [Fact]
    public async Task ConnectionStartReturnsATypedServiceOutcomeInsteadOfAnUnboundedFailure()
    {
        RecordingHandler handler = new(JsonResponse(HttpStatusCode.NotFound, new ApiError
        {
            Code = RendezvousErrorCode.NotFound,
            Message = "listing unavailable",
        }));
        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
        RendezvousJoinClient client = new(http);
        NetworkEndpoint fallback = new()
        {
            AddressFamily = AddressFamilyKind.Ipv4,
            Address = "203.0.113.93",
            Port = 9_063,
        };

        RendezvousConnectionStartResult result = await client.CreateConnectionAttemptAsync(
            new CreateJoinAttemptRequest
            {
                IdempotencyKey = "typed-start",
                GameId = new("space-game"),
                EnvironmentId = new("production"),
                ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000230")),
                ProtocolVersion = 7,
            },
            fallback);

        Assert.True(result.IsCompleted);
        Assert.False(result.IsReadyForTraversal);
        Assert.Null(result.Attempt);
        Assert.Equal(ConnectionOutcomeKind.DirectoryNotFound, result.Outcome!.Kind);
        Assert.Equal("203.0.113.93", result.Outcome.DedicatedFallback!.Address);
    }

    [Fact]
    public async Task ConnectionStartReturnsCancelledForAPrecancelledCallerToken()
    {
        RecordingHandler handler = new();
        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
        RendezvousJoinClient client = new(http);
        using CancellationTokenSource cancellation = new();
        cancellation.Cancel();

        RendezvousConnectionStartResult result = await client.CreateConnectionAttemptAsync(
            CreateRequest("cancelled-before-send"),
            new NetworkEndpoint
            {
                AddressFamily = AddressFamilyKind.Ipv4,
                Address = "203.0.113.90",
                Port = 7777,
            },
            cancellationToken: cancellation.Token);

        Assert.Empty(handler.Requests);
        Assert.Equal(ConnectionOutcomeKind.Cancelled, result.Outcome!.Kind);
        Assert.True(result.Outcome.HasDedicatedFallback);
        Assert.Equal(RendezvousConnectionOutcomeSource.Caller, result.Outcome.Source);
    }

    [Fact]
    public async Task ConnectionStartReturnsCancelledWhenCallerStopsASilentRequest()
    {
        CancellingHandler handler = new();
        using HttpClient http = new(handler) { BaseAddress = new("http://rendezvous.test/") };
        RendezvousJoinClient client = new(http);
        using CancellationTokenSource cancellation = new();
        Task<RendezvousConnectionStartResult> pending = client.CreateConnectionAttemptAsync(
            CreateRequest("cancelled-in-flight"),
            cancellationToken: cancellation.Token);
        await handler.Started.Task.WaitAsync(TimeSpan.FromSeconds(2));

        await cancellation.CancelAsync();
        RendezvousConnectionStartResult result = await pending;

        Assert.Equal(ConnectionOutcomeKind.Cancelled, result.Outcome!.Kind);
        Assert.Equal(RendezvousConnectionOutcomeSource.Caller, result.Outcome.Source);
    }

    private static CreateJoinAttemptResponse CreateAttempt() => new()
    {
        AttemptId = new(Guid.Parse("00000000-0000-0000-0000-000000000202")),
        MediationHandle = new(Guid.Parse("00000000-0000-0000-0000-000000000203")),
        ClientPunchCapability = Credential('C'),
        ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
            NatIntroductionTokenCodec.Encode(
                new JoinAttemptId(Guid.Parse("00000000-0000-0000-0000-000000000202")),
                Credential('T'))),
        ExpiresAt = new DateTimeOffset(2030, 1, 1, 0, 0, 30, TimeSpan.Zero),
    };

    private static CreateJoinAttemptRequest CreateRequest(string idempotencyKey) => new()
    {
        IdempotencyKey = idempotencyKey,
        GameId = new("space-game"),
        EnvironmentId = new("production"),
        ListingId = new(Guid.Parse("00000000-0000-0000-0000-000000000230")),
        ProtocolVersion = 7,
    };

    private static HostJoinAttempt CreateHostAttempt(string id) => new()
    {
        AttemptId = new(Guid.Parse(id)),
        MediationHandle = new(Guid.NewGuid()),
        HostPunchCapability = Credential('H'),
        ConnectionTicketDigest = NatIntroductionTokenCodec.ComputeDigest(
            NatIntroductionTokenCodec.Encode(new JoinAttemptId(Guid.Parse(id)), Credential('T'))),
        ExpiresAt = new DateTimeOffset(2030, 1, 1, 0, 0, 30, TimeSpan.Zero),
    };

    private static string Credential(char value) => new(value, ContractLimits.DerivedCredentialCharacters);

    private static HttpResponseMessage JsonResponse<T>(HttpStatusCode status, T value) => new(status)
    {
        Content = new ByteArrayContent(JsonSerializer.SerializeToUtf8Bytes(value, ContractJson.Options)),
    };

    private sealed class RecordingHandler(params HttpResponseMessage[] responses) : HttpMessageHandler
    {
        private readonly Queue<HttpResponseMessage> _responses = new(responses);

        internal List<RecordedRequest> Requests { get; } = [];

        protected override async Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request,
            CancellationToken cancellationToken)
        {
            Dictionary<string, string> headers = request.Headers.ToDictionary(
                static item => item.Key,
                static item => string.Join(",", item.Value),
                StringComparer.OrdinalIgnoreCase);
            Requests.Add(new(
                request.Method,
                request.RequestUri!,
                headers,
                request.Content is null
                    ? string.Empty
                    : await request.Content.ReadAsStringAsync(cancellationToken)));
            return _responses.Dequeue();
        }
    }

    private sealed class CancellingHandler : HttpMessageHandler
    {
        internal TaskCompletionSource Started { get; } = new(
            TaskCreationOptions.RunContinuationsAsynchronously);

        protected override async Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request,
            CancellationToken cancellationToken)
        {
            _ = request;
            Started.TrySetResult();
            await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
            throw new InvalidOperationException("The silent request unexpectedly completed.");
        }
    }

    private sealed record RecordedRequest(
        HttpMethod Method,
        Uri Uri,
        IReadOnlyDictionary<string, string> Headers,
        string Body);

    private sealed class ImmediateDelay : IRendezvousDelay
    {
        public Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            return Task.CompletedTask;
        }
    }
}