Setup new services required for change

RelayClient/Services/RelaySocketClient.cs

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+using System.Text.Json;
+using RelayClient.Crypto;
+using RelayShared.Services;
+using WebSocketSharp;
+
+namespace RelayClient.Services;
+
+public sealed class RelaySocketClient
+{
+    private readonly string _username;
+    private readonly WebSocket _socket;
+
+    public string? ServerPublicKey { get; private set; }
+
+    public event Action<string>? RawMessageReceived;
+    public event Action<SocketChannelList>? ChannelListReceived;
+    public event Action<SocketEncryptedMessage>? EncryptedChatReceived;
+    public event Action<SocketRtcSignalMessage>? EncryptedRtcSignalReceived;
+    public event Action<string>? ServerPublicKeyReceived;
+    public event Action<string>? Log;
+
+    public RelaySocketClient(string username, string url = "ws://localhost:1337/")
+    {
+        _username = username;
+        _socket = new WebSocket(url);
+        _socket.OnMessage += OnMessage;
+    }
+
+    public void Connect()
+    {
+        _socket.Connect();
+
+        var publicKey = KeyStorage.LoadPublicKey(_username);
+
+        SendRaw($"REGISTER_KEY|{_username}|{publicKey}");
+        SendRaw("GET_SERVER_KEY");
+        SendRaw("GET_CHANNELS");
+    }
+
+    public void SendRaw(string message)
+    {
+        if (_socket.ReadyState == WebSocketState.Open)
+            _socket.Send(message);
+    }
+
+    public void SendJson<T>(T payload)
+    {
+        SendRaw(JsonSerializer.Serialize(payload));
+    }
+
+    public void Disconnect()
+    {
+        _socket.OnMessage -= OnMessage;
+
+        if (_socket.ReadyState == WebSocketState.Open)
+            _socket.Close();
+    }
+
+    private void OnMessage(object? sender, MessageEventArgs e)
+    {
+        if (e.Data.StartsWith("SERVER:REGISTERED_KEY:"))
+        {
+            Log?.Invoke(e.Data);
+            return;
+        }
+
+        RawMessageReceived?.Invoke(e.Data);
+        Log?.Invoke($"[{_username}] RAW WS DATA: {e.Data}");
+
+        try
+        {
+            using var doc = JsonDocument.Parse(e.Data);
+            var root = doc.RootElement;
+
+            if (!root.TryGetProperty("Type", out var typeElement))
+                return;
+
+            var type = (SignalType)typeElement.GetInt32();
+
+            switch (type)
+            {
+                case SignalType.ChannelList:
+                {
+                    var channelList = JsonSerializer.Deserialize<SocketChannelList>(e.Data);
+                    if (channelList is not null)
+                        ChannelListReceived?.Invoke(channelList);
+
+                    return;
+                }
+
+                case SignalType.ServerPublicKey:
+                {
+                    var serverKeyMessage = JsonSerializer.Deserialize<ServerPublicKeyMessage>(e.Data);
+                    if (serverKeyMessage is not null)
+                    {
+                        ServerPublicKey = serverKeyMessage.PublicKey;
+                        ServerPublicKeyReceived?.Invoke(serverKeyMessage.PublicKey);
+                    }
+
+                    return;
+                }
+
+                case SignalType.EncryptedSignal:
+                {
+                    var payload = JsonSerializer.Deserialize<SocketRtcSignalMessage>(e.Data);
+                    if (payload is not null)
+                        EncryptedRtcSignalReceived?.Invoke(payload);
+
+                    return;
+                }
+
+                case SignalType.EncryptedChat:
+                {
+                    var payload = JsonSerializer.Deserialize<SocketEncryptedMessage>(e.Data);
+                    if (payload is not null)
+                        EncryptedChatReceived?.Invoke(payload);
+
+                    return;
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            Log?.Invoke($"[{_username}] failed to process websocket message: {ex.Message}");
+        }
+    }
+}

RelayClient/Services/RtcBridgeService.cs

@@ -0,0 +1,228 @@
+using System.Text.Json;
+using RelayClient.Crypto;
+using RelayShared.Rtc;
+using RelayShared.Services;
+
+namespace RelayClient.Services;
+
+public sealed class RtcBridgeService
+{
+    private readonly string _username;
+    private readonly RelaySocketClient _socket;
+    private readonly HybridWebView _hybridWebView;
+    private readonly Func<string?> _getCurrentChannelId;
+    private readonly Action<string> _sendRawToWebView;
+
+    public RtcBridgeService(
+        string username,
+        RelaySocketClient socket,
+        HybridWebView hybridWebView,
+        Func<string?> getCurrentChannelId,
+        Action<string> sendRawToWebView)
+    {
+        _username = username;
+        _socket = socket;
+        _hybridWebView = hybridWebView;
+        _getCurrentChannelId = getCurrentChannelId;
+        _sendRawToWebView = sendRawToWebView;
+    }
+
+    public Task JoinRtcChannel()
+    {
+        var channelId = _getCurrentChannelId();
+
+        if (string.IsNullOrWhiteSpace(channelId))
+            return Task.CompletedTask;
+
+        _socket.SendRaw($"RTC_JOIN_CHANNEL|{_username}|{channelId}");
+        return Task.CompletedTask;
+    }
+
+    public void LeaveRtcChannel()
+    {
+        var channelId = _getCurrentChannelId();
+
+        if (string.IsNullOrWhiteSpace(channelId))
+            return;
+
+        _socket.SendRaw($"RTC_LEAVE_CHANNEL|{_username}|{channelId}");
+    }
+
+    public void SendRtcSignal(string json)
+    {
+        if (string.IsNullOrWhiteSpace(_socket.ServerPublicKey))
+        {
+            _sendRawToWebView("SendRtcSignal failed: server public key not loaded.");
+            return;
+        }
+
+        RtcSignalMessage? rtcSignal;
+
+        try
+        {
+            rtcSignal = JsonSerializer.Deserialize<RtcSignalMessage>(json);
+        }
+        catch (Exception ex)
+        {
+            _sendRawToWebView("SendRtcSignal failed to parse RTC signal: " + ex.Message);
+            return;
+        }
+
+        if (rtcSignal is null)
+            return;
+
+        rtcSignal.ChannelId ??= _getCurrentChannelId();
+        rtcSignal.From ??= _username;
+
+        if (string.IsNullOrWhiteSpace(rtcSignal.ChannelId))
+        {
+            _sendRawToWebView("SendRtcSignal failed: missing channel id.");
+            return;
+        }
+
+        var outgoingJson = JsonSerializer.Serialize(rtcSignal);
+
+        try
+        {
+            var encrypted = E2EeHelper.EncryptForRecipient(outgoingJson, _socket.ServerPublicKey);
+
+            var payload = new SocketRtcSignalMessage
+            {
+                Type = SignalType.EncryptedSignal,
+                SenderUsername = _username,
+                ChannelId = rtcSignal.ChannelId,
+                CipherText = encrypted.CipherText,
+                Nonce = encrypted.Nonce,
+                Tag = encrypted.Tag,
+                EncryptedKey = encrypted.EncryptedKey
+            };
+
+            _socket.SendJson(payload);
+
+            _sendRawToWebView($"SendRtcSignal sent: {rtcSignal.Type} -> {rtcSignal.To}");
+        }
+        catch (Exception ex)
+        {
+            _sendRawToWebView("SendRtcSignal failed: " + ex.Message);
+        }
+    }
+
+    public async Task<string> GetRtcParticipants()
+    {
+        var channelId = _getCurrentChannelId();
+
+        if (string.IsNullOrWhiteSpace(channelId))
+            return "[]";
+
+        var participants = await ServerAPI.GetRtcParticipantsAsync(channelId);
+        return JsonSerializer.Serialize(participants ?? []);
+    }
+
+    public async Task HandleIncomingRtcSignalAsync(SocketRtcSignalMessage payload)
+    {
+        var currentChannelId = _getCurrentChannelId();
+
+        if (payload.ChannelId != currentChannelId)
+            return;
+
+        if (payload.SenderUsername == _username)
+            return;
+
+        string decryptedJson;
+
+        try
+        {
+            var privateKey = KeyStorage.LoadPrivateKey(_username);
+
+            decryptedJson = E2EeHelper.DecryptForRecipient(
+                new EncryptedPayload
+                {
+                    CipherText = payload.CipherText,
+                    Nonce = payload.Nonce,
+                    Tag = payload.Tag,
+                    EncryptedKey = payload.EncryptedKey
+                },
+                privateKey
+            );
+        }
+        catch (Exception ex)
+        {
+            _sendRawToWebView("RTC decrypt failed: " + ex.Message);
+            return;
+        }
+
+        RtcSignalMessage? rtcSignal;
+
+        try
+        {
+            rtcSignal = JsonSerializer.Deserialize<RtcSignalMessage>(decryptedJson);
+        }
+        catch (Exception ex)
+        {
+            _sendRawToWebView("RTC signal parse failed: " + ex.Message);
+            return;
+        }
+
+        if (rtcSignal is null)
+            return;
+
+        if (!string.IsNullOrWhiteSpace(rtcSignal.To) &&
+            !string.Equals(rtcSignal.To, _username, StringComparison.OrdinalIgnoreCase))
+        {
+            _sendRawToWebView($"Ignoring RTC signal meant for {rtcSignal.To}");
+            return;
+        }
+
+        _sendRawToWebView("Received encrypted RTC signal: " + decryptedJson);
+
+        await SendRtcSignalToJsAsync(decryptedJson);
+    }
+
+    public Task PushRtcContextToJsAsync()
+    {
+        MainThread.BeginInvokeOnMainThread(async () =>
+        {
+            var usernameJson = JsonSerializer.Serialize(_username);
+            var channelIdJson = JsonSerializer.Serialize(_getCurrentChannelId());
+
+            await _hybridWebView.EvaluateJavaScriptAsync($"window.setUsername({usernameJson})");
+            await _hybridWebView.EvaluateJavaScriptAsync($"window.setChannelId({channelIdJson})");
+        });
+
+        return Task.CompletedTask;
+    }
+
+    private Task SendRtcSignalToJsAsync(string rawJson)
+    {
+        MainThread.BeginInvokeOnMainThread(async () =>
+        {
+            try
+            {
+                var jsArg = JsonSerializer.Serialize(rawJson);
+
+                await _hybridWebView.EvaluateJavaScriptAsync($@"
+                    try {{
+                        window.HybridWebView.SendRawMessage('C# eval entered');
+
+                        if (!window.RelaySocket) {{
+                            window.HybridWebView.SendRawMessage('window.RelaySocket missing');
+                        }} else if (typeof window.RelaySocket.receiveRtcSignal !== 'function') {{
+                            window.HybridWebView.SendRawMessage('RelaySocket.receiveRtcSignal missing');
+                        }} else {{
+                            window.HybridWebView.SendRawMessage('Calling RelaySocket.receiveRtcSignal');
+                            window.RelaySocket.receiveRtcSignal({jsArg});
+                        }}
+                    }} catch (err) {{
+                        window.HybridWebView.SendRawMessage('RTC JS dispatch failed: ' + err);
+                    }}
+                ");
+            }
+            catch (Exception ex)
+            {
+                _sendRawToWebView("SendRtcSignalToJsAsync failed: " + ex.Message);
+            }
+        });
+
+        return Task.CompletedTask;
+    }
+}