HellionChat/ChatTwo/Http/EventServer.cs

using System.Text;
using ChatTwo.Http.MessageProtocol;
using Newtonsoft.Json;
using WatsonWebserver.Core;

namespace ChatTwo.Http;

public class EventServer
{
    private bool Stopping;
    private bool Finished;
    private readonly CancellationToken Token;

    public readonly Stack<BaseMessage> OutboundStack = new();

    private long Index;

    public EventServer(CancellationToken token)
    {
        Token = token;
    }

    public async Task HandleEventLoop(HttpContextBase ctx)
    {
        try
        {
            ctx.Response.Headers.Add("Content-Type", "text/event-stream");
            ctx.Response.Headers.Add("Cache-Control", "no-cache");
            ctx.Response.Headers.Add("Connection", "keep-alive");

            ctx.Response.ChunkedTransfer = true;
            while (!Token.IsCancellationRequested && !Stopping)
            {
                await Task.Delay(10, Token);
                if (Token.IsCancellationRequested)
                    return;

                if (!OutboundStack.TryPop(out var message))
                    continue;

                var data = JsonConvert.SerializeObject(message);
                await ctx.Response.SendChunk(Encoding.UTF8.GetBytes($"id: {Index}\ndata: {data}\n\n"), Token);
                Index++;
            }
        }
        catch (TaskCanceledException)
        {
            // Ignore
        }
        catch (Exception ex)
        {
            Plugin.Log.Error(ex, "Event queued failed to continue");
        }
        finally
        {
            // No Content (204) didn't work for Firefox, so manually closing the connection on client side
            await ctx.Response.SendFinalChunk("data: closing\nevent: close\n\n"u8.ToArray());

            Finished = true;
        }
    }

    public async ValueTask DisposeAsync()
    {
        Stopping = true;

        var timeout = 1000; // 1000ms
        while (timeout > 0)
        {
            if (Finished)
                break;

            timeout -= 100;
            await Task.Delay(100);
            Plugin.Log.Debug("Sleeping because EventServer still alive");
        }
    }
}