// .NET (System.Net.WebSockets) subscription to CodeB Signal WebSocket events.
// European Digital Identity Wallet-enabled tenants use the same signalling.
// [realtime-events-cookbook 2026-07-23]
//
// Endpoint: wss://<tenant>/signal.ashx?room=<room>&name=<peerName>
// Server-emitted event names verified in signal.ashx: welcome, peer-joined,
// peer-left, mode-changed, ring, ring-cancelled, ring-cleared, dial-result,
// office-call-result, office-call-answered, office-call-timeout,
// office-registered, sfu-answer, sfu-subscribe-answer, sfu-offer-failed,
// sfu-subscribe-failed, signal, breakout-list, breakout-assigned,
// breakout-end, breakout-rejected, knock, knock-pending, dup-ip-warning,
// denied, pong, error.

using System;
using System.Net.WebSockets;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

class SignalWs
{
    static async Task Main()
    {
        var host = Environment.GetEnvironmentVariable("CODEB_TENANT_HOST") ?? "phone.example.tld";
        var room = Environment.GetEnvironmentVariable("ROOM") ?? "lobby";
        var name = Environment.GetEnvironmentVariable("NAME") ?? "ops-dashboard";
        var uri  = new Uri("wss://" + host + "/signal.ashx?room=" + Uri.EscapeDataString(room) +
                           "&name=" + Uri.EscapeDataString(name));

        var backoff = TimeSpan.FromSeconds(1);
        while (true)
        {
            using var ws = new ClientWebSocket();
            try
            {
                await ws.ConnectAsync(uri, CancellationToken.None);
                backoff = TimeSpan.FromSeconds(1);
                Console.WriteLine("[ws] open " + uri);
                var buf = new byte[64 * 1024];
                while (ws.State == WebSocketState.Open)
                {
                    var sb = new StringBuilder();
                    WebSocketReceiveResult r;
                    do {
                        r = await ws.ReceiveAsync(buf, CancellationToken.None);
                        if (r.MessageType == WebSocketMessageType.Close) break;
                        sb.Append(Encoding.UTF8.GetString(buf, 0, r.Count));
                    } while (!r.EndOfMessage);
                    if (sb.Length == 0) continue;
                    using var doc = JsonDocument.Parse(sb.ToString());
                    var type = doc.RootElement.TryGetProperty("type", out var t) ? t.GetString() : "";
                    Console.WriteLine("[event] " + type);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("[ws] " + e.Message + "; retry in " + backoff.TotalSeconds + "s");
                await Task.Delay(backoff);
                if (backoff < TimeSpan.FromSeconds(30)) backoff = backoff + backoff;
            }
        }
    }
}