namespace ChessCubing.Server.Social;

public sealed class CollaborativeMatchCoordinator
{
    private readonly object _sync = new();
    private readonly Dictionary<string, CollaborativeSessionState> _sessions = new(StringComparer.Ordinal);

    public void RegisterSession(PlaySessionResponse session)
    {
        lock (_sync)
        {
            _sessions[session.SessionId] = new CollaborativeSessionState(
                session.SessionId,
                new HashSet<string>(StringComparer.Ordinal)
                {
                    session.WhiteSubject,
                    session.BlackSubject,
                    session.InitiatorSubject,
                    session.RecipientSubject,
                },
                null,
                0);
        }
    }

    public bool CanAccessSession(string sessionId, string subject)
    {
        lock (_sync)
        {
            return _sessions.TryGetValue(sessionId, out var session)
                && session.ParticipantSubjects.Contains(subject);
        }
    }

    public CollaborativeMatchStateMessage? GetLatestState(string sessionId, string subject)
    {
        lock (_sync)
        {
            if (!_sessions.TryGetValue(sessionId, out var session) ||
                !session.ParticipantSubjects.Contains(subject))
            {
                throw new SocialValidationException("Cette session de partie est introuvable ou n'est pas accessible.");
            }

            return session.LatestState;
        }
    }

    public CollaborativeMatchStateMessage PublishState(
        string sessionId,
        string subject,
        string? matchJson,
        string route)
    {
        lock (_sync)
        {
            if (!_sessions.TryGetValue(sessionId, out var session) ||
                !session.ParticipantSubjects.Contains(subject))
            {
                throw new SocialValidationException("Cette session de partie est introuvable ou n'est pas accessible.");
            }

            var revision = session.Revision + 1;
            var message = new CollaborativeMatchStateMessage
            {
                SessionId = sessionId,
                MatchJson = matchJson,
                Route = string.IsNullOrWhiteSpace(route) ? "/application.html" : route.Trim(),
                SenderSubject = subject,
                Revision = revision,
                UpdatedUtc = DateTime.UtcNow,
            };

            _sessions[sessionId] = session with
            {
                Revision = revision,
                LatestState = message,
            };

            return message;
        }
    }

    private sealed record CollaborativeSessionState(
        string SessionId,
        HashSet<string> ParticipantSubjects,
        CollaborativeMatchStateMessage? LatestState,
        long Revision);
}