Rendezvous/src/FinalFactory.Rendezvous.Client/RendezvousClientAbstractions.cs

using FinalFactory.Rendezvous.Contracts;

namespace FinalFactory.Rendezvous.Client;

public sealed class RendezvousClientResult<T>
{
    internal RendezvousClientResult(
        RendezvousErrorCode error,
        T? value,
        string message,
        int? retryAfterSeconds)
    {
        Error = error;
        Value = value;
        Message = message;
        RetryAfterSeconds = retryAfterSeconds;
    }

    public bool IsSuccess => Error == RendezvousErrorCode.None;
    public RendezvousErrorCode Error { get; }
    public T? Value { get; }
    public string Message { get; }
    public int? RetryAfterSeconds { get; }

}

public static class RendezvousClientResult
{
    public static RendezvousClientResult<T> Success<T>(T value) =>
        value is null
            ? throw new ArgumentNullException(nameof(value))
            : new(RendezvousErrorCode.None, value, string.Empty, null);

    public static RendezvousClientResult<T> Failure<T>(
        RendezvousErrorCode error,
        string message,
        int? retryAfterSeconds = null) =>
        error == RendezvousErrorCode.None
            ? throw new ArgumentException("A failure requires a non-success error.", nameof(error))
            : new(error, default, message ?? string.Empty, retryAfterSeconds);
}

public sealed class PublishedSession
{
    private readonly object _timingGate = new();
    private DateTimeOffset _expiresAt;
    private int _leaseRenewAfterSeconds;

    internal PublishedSession(RegisterSessionResponse response)
    {
        ListingId = response.ListingId;
        LeaseId = response.LeaseId;
        LeaseToken = response.LeaseToken;
        HostPresenceHandle = response.HostPresenceHandle;
        HostPresenceCapability = response.HostPresenceCapability;
        _expiresAt = response.ExpiresAt;
        _leaseRenewAfterSeconds = response.LeaseRenewAfterSeconds;
        HostPresenceRefreshAfterSeconds = response.HostPresenceRefreshAfterSeconds;
    }

    public SessionListingId ListingId { get; }
    public LeaseId LeaseId { get; }
    public string LeaseToken { get; }
    public MediationHandle HostPresenceHandle { get; }
    public string HostPresenceCapability { get; }
    public DateTimeOffset ExpiresAt
    {
        get
        {
            lock (_timingGate)
            {
                return _expiresAt;
            }
        }
        internal set
        {
            lock (_timingGate)
            {
                _expiresAt = value;
            }
        }
    }

    public int LeaseRenewAfterSeconds
    {
        get
        {
            lock (_timingGate)
            {
                return _leaseRenewAfterSeconds;
            }
        }
        internal set
        {
            lock (_timingGate)
            {
                _leaseRenewAfterSeconds = value;
            }
        }
    }
    public int HostPresenceRefreshAfterSeconds { get; }

    public override string ToString() => $"[PublishedSession {ListingId}; credentials redacted]";
}

public interface IRendezvousPublisherClient
{
    Task<RendezvousClientResult<PublishedSession>> RegisterAsync(
        RegisterSessionRequest request,
        string publisherCredential,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<RenewLeaseResponse>> RenewAsync(
        PublishedSession session,
        string publisherCredential,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<bool>> UpdateAsync(
        PublishedSession session,
        UpdateSessionRequest request,
        string publisherCredential,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<bool>> DeregisterAsync(
        PublishedSession session,
        string publisherCredential,
        CancellationToken cancellationToken = default);
}

public interface IRendezvousSessionBrowserClient
{
    Task<RendezvousClientResult<BrowseSessionsResponse>> BrowseAsync(
        BrowseSessionsRequest request,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<IReadOnlyList<SessionListing>>> BrowseAllAsync(
        BrowseSessionsRequest request,
        int maximumPages = 100,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<GetSessionResponse>> GetAsync(
        SessionListingId listingId,
        GameId gameId,
        EnvironmentId environmentId,
        uint protocolVersion,
        CancellationToken cancellationToken = default);
}

public interface IRendezvousJoinClient
{
    Task<RendezvousConnectionStartResult> CreateConnectionAttemptAsync(
        CreateJoinAttemptRequest request,
        NetworkEndpoint? dedicatedFallback = null,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<CreateJoinAttemptResponse>> CreateAsync(
        CreateJoinAttemptRequest request,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<bool>> CancelAsync(
        CreateJoinAttemptResponse attempt,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<BrowseHostJoinAttemptsResponse>> BrowseForHostAsync(
        PublishedSession session,
        int pageSize = ContractLimits.BrowserPageMaxItems,
        string? cursor = null,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<IReadOnlyList<HostJoinAttempt>>> BrowseAllForHostAsync(
        PublishedSession session,
        int maximumPages = 100,
        CancellationToken cancellationToken = default);

    Task<RendezvousClientResult<ReportConnectionOutcomeResponse>> ReportOutcomeAsync(
        CreateJoinAttemptResponse attempt,
        RendezvousConnectionOutcome outcome,
        CancellationToken cancellationToken = default);
}

public interface IRendezvousDelay
{
    Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken);
}

public sealed class RendezvousClientOptions
{
    public int MaximumSafeRetries { get; set; } = 2;
    public TimeSpan RequestTimeout { get; set; } = TimeSpan.FromSeconds(5);
    public TimeSpan InitialRetryDelay { get; set; } = TimeSpan.FromMilliseconds(200);
    public TimeSpan MaximumRetryDelay { get; set; } = TimeSpan.FromSeconds(2);
    public double JitterRatio { get; set; } = 0.2;

    internal void Validate()
    {
        if (MaximumSafeRetries is < 0 or > 5
            || RequestTimeout <= TimeSpan.Zero
            || RequestTimeout > TimeSpan.FromSeconds(30)
            || InitialRetryDelay < TimeSpan.Zero
            || MaximumRetryDelay < InitialRetryDelay
            || MaximumRetryDelay > TimeSpan.FromSeconds(30)
            || JitterRatio is < 0 or > 1)
        {
            throw new ArgumentOutOfRangeException(nameof(RendezvousClientOptions));
        }
    }
}

internal sealed class SystemRendezvousDelay : IRendezvousDelay
{
    public Task DelayAsync(TimeSpan delay, CancellationToken cancellationToken) =>
        Task.Delay(delay, cancellationToken);
}

internal static class RendezvousEndpoint
{
    internal static NetworkEndpoint? Copy(NetworkEndpoint? endpoint) => endpoint is null
        ? null
        : new NetworkEndpoint
        {
            AddressFamily = endpoint.AddressFamily,
            Address = endpoint.Address,
            Port = endpoint.Port,
        };
}