using Microsoft.AspNetCore.SignalR;

namespace ZB.MOM.WW.MxGateway.Server.Dashboard.Hubs;

/// <summary>
/// Time-bounded SignalR send shared by the dashboard hub publishers. A group or
/// broadcast send completes only once every target connection has accepted the
/// frame, so one remote viewer with a full transport buffer would otherwise hold
/// the publisher's single drain loop for as long as that viewer stays slow.
/// </summary>
internal static class BoundedHubSend
{
    /// <summary>
    /// Sends <paramref name="argument"/> as <paramref name="method"/> and waits at most
    /// <paramref name="timeout"/> for it. The timeout cancels the send's own token, so
    /// the lifetime manager abandons the pending write to the slow connection, and the
    /// wait itself is bounded too, so a proxy that ignores the token cannot stall the
    /// caller either.
    /// </summary>
    /// <param name="proxy">Target client proxy (a group or all connections).</param>
    /// <param name="method">Client method name.</param>
    /// <param name="argument">The single message argument.</param>
    /// <param name="timeout">Upper bound on the send.</param>
    /// <param name="stoppingToken">Host shutdown token; its cancellation propagates.</param>
    /// <returns>
    /// <see langword="true"/> when the send completed in time; <see langword="false"/>
    /// when it was abandoned at the timeout.
    /// </returns>
    /// <exception cref="OperationCanceledException"><paramref name="stoppingToken"/> was cancelled.</exception>
    public static async Task<bool> SendAsync(
        IClientProxy proxy,
        string method,
        object argument,
        TimeSpan timeout,
        CancellationToken stoppingToken)
    {
        using CancellationTokenSource bounded = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken);
        bounded.CancelAfter(timeout);

        try
        {
            await proxy.SendAsync(method, argument, bounded.Token)
                .WaitAsync(bounded.Token)
                .ConfigureAwait(false);
            return true;
        }
        catch (OperationCanceledException) when (!stoppingToken.IsCancellationRequested)
        {
            return false;
        }
    }
}