Add gateway realtime fanout and cursor pagination docs

lib/server.dart

@@ -3,6 +3,7 @@ import 'package:relic/relic.dart';
 
 import 'config/config.dart';
 import 'src/auth/auth_middleware.dart';
+import 'src/gateway/gateway_handlers.dart';
 import 'src/handlers/auth_handlers.dart';
 import 'src/handlers/channel_handlers.dart';
 import 'src/handlers/message_handlers.dart';
@@ -26,6 +27,7 @@ Future<void> startServer() async {
     ..get('/.well-known/users/:username', publicUserHandler)
     ..get('/.well-known/verify/:userId', publicVerifyHandler)
     ..get('/.well-known/server', publicServerInfoHandler)
+    ..get('/gateway', gatewayHandler)
 
     // ============ PROTECTED ENDPOINTS (requires auth) ============
     ..use('/api', jwtMiddleware)

lib/src/gateway/gateway_handlers.dart

@@ -0,0 +1,442 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:relic/relic.dart';
+import 'package:web_socket/web_socket.dart';
+
+import '../auth/crypto_service.dart';
+import '../state/app_state.dart';
+
+final _gatewayRegistry = _GatewayRegistry();
+
+/// WebSocket gateway with JWT auth and channel subscriptions.
+Result gatewayHandler(Request req) {
+  final token = _extractGatewayToken(req);
+  if (token == null) {
+    return Response.unauthorized(
+      body: Body.fromString('Bearer token required'),
+    );
+  }
+
+  final payload = AuthService.verifyToken(token);
+  if (payload == null) {
+    return Response.forbidden(
+      body: Body.fromString('Invalid or expired token'),
+    );
+  }
+
+  final userId = payload['sub'] as String?;
+  final username = payload['username'] as String?;
+  if (userId == null || userId.isEmpty) {
+    return Response.forbidden(
+      body: Body.fromString('Invalid token payload'),
+    );
+  }
+
+  return WebSocketUpgrade((webSocket) {
+    webSocket.pingInterval = const Duration(seconds: 30);
+
+    final connection = _gatewayRegistry.register(
+      socket: webSocket,
+      userId: userId,
+      username: username,
+    );
+
+    _sendGatewayPayload(
+      connection.id,
+      {
+        'op': 'ready',
+        'connectionId': connection.id,
+        'userId': connection.userId,
+        if (connection.username != null) 'username': connection.username,
+      },
+    );
+
+    webSocket.events.listen(
+      (event) {
+        switch (event) {
+          case TextDataReceived(text: final text):
+            _handleGatewayTextMessage(connection.id, text);
+          case BinaryDataReceived():
+            _sendProtocolError(
+              connection.id,
+              'Binary payloads are not supported',
+            );
+          case CloseReceived():
+            _gatewayRegistry.unregister(connection.id);
+        }
+      },
+      onError: (_, __) {
+        _gatewayRegistry.unregister(connection.id);
+      },
+      onDone: () {
+        _gatewayRegistry.unregister(connection.id);
+      },
+    );
+  });
+}
+
+void broadcastMessageCreated({
+  required int channelId,
+  required Map<String, dynamic> message,
+}) {
+  _gatewayRegistry.broadcastToChannel(channelId, {
+    'op': 'event',
+    'event': 'message.created',
+    'channelId': channelId,
+    'message': message,
+    'emittedAt': DateTime.now().toUtc().toIso8601String(),
+  });
+}
+
+void broadcastMessageUpdated({
+  required int channelId,
+  required Map<String, dynamic> message,
+}) {
+  _gatewayRegistry.broadcastToChannel(channelId, {
+    'op': 'event',
+    'event': 'message.updated',
+    'channelId': channelId,
+    'message': message,
+    'emittedAt': DateTime.now().toUtc().toIso8601String(),
+  });
+}
+
+void broadcastMessageDeleted({
+  required int channelId,
+  required int messageId,
+}) {
+  _gatewayRegistry.broadcastToChannel(channelId, {
+    'op': 'event',
+    'event': 'message.deleted',
+    'channelId': channelId,
+    'messageId': messageId,
+    'emittedAt': DateTime.now().toUtc().toIso8601String(),
+  });
+}
+
+String? _extractGatewayToken(Request req) {
+  final authHeader = req.headers.authorization;
+  if (authHeader is BearerAuthorizationHeader) {
+    final token = authHeader.token.trim();
+    if (token.isNotEmpty) {
+      return token;
+    }
+  }
+
+  final rawAuthorization = req.headers[Headers.authorizationHeader];
+  if (rawAuthorization != null && rawAuthorization.isNotEmpty) {
+    final value = rawAuthorization.first.trim();
+    if (value.toLowerCase().startsWith('bearer ')) {
+      final token = value.substring(7).trim();
+      if (token.isNotEmpty) {
+        return token;
+      }
+    }
+  }
+
+  final queryToken = req.url.queryParameters['token']?.trim();
+  if (queryToken != null && queryToken.isNotEmpty) {
+    return queryToken;
+  }
+
+  final queryAccessToken = req.url.queryParameters['access_token']?.trim();
+  if (queryAccessToken != null && queryAccessToken.isNotEmpty) {
+    return queryAccessToken;
+  }
+
+  return null;
+}
+
+void _handleGatewayTextMessage(String connectionId, String text) {
+  final connection = _gatewayRegistry.getConnection(connectionId);
+  if (connection == null) {
+    return;
+  }
+
+  final payload = _decodePayload(text);
+  if (payload == null) {
+    _sendProtocolError(connectionId, 'Invalid JSON payload');
+    return;
+  }
+
+  final rawOp = payload['op'];
+  if (rawOp is! String || rawOp.trim().isEmpty) {
+    _sendProtocolError(connectionId, '`op` is required');
+    return;
+  }
+
+  switch (rawOp.trim().toLowerCase()) {
+    case 'subscribe':
+      _handleSubscribe(connectionId, payload);
+    case 'unsubscribe':
+      _handleUnsubscribe(connectionId, payload);
+    case 'ping':
+    case 'heartbeat':
+      _sendGatewayPayload(connectionId, {
+        'op': 'pong',
+        'ts': DateTime.now().toUtc().toIso8601String(),
+      });
+    case 'pong':
+      return;
+    default:
+      _sendProtocolError(connectionId, 'Unsupported op `$rawOp`');
+  }
+}
+
+void _handleSubscribe(String connectionId, Map<String, dynamic> payload) {
+  final channelIds = _parseChannelIds(payload);
+  if (channelIds.isEmpty) {
+    _sendProtocolError(
+      connectionId,
+      'subscribe requires `channelId` or `channelIds`',
+    );
+    return;
+  }
+
+  final knownChannelIds = <int>[];
+  final unknownChannelIds = <int>[];
+  for (final channelId in channelIds) {
+    if (channelBox.get(channelId) == null) {
+      unknownChannelIds.add(channelId);
+    } else {
+      knownChannelIds.add(channelId);
+    }
+  }
+
+  final subscribed = _gatewayRegistry.subscribe(connectionId, knownChannelIds);
+
+  _sendGatewayPayload(connectionId, {
+    'op': 'subscribed',
+    'channelIds': subscribed,
+    'subscriptions': _gatewayRegistry.subscriptions(connectionId),
+    if (unknownChannelIds.isNotEmpty) 'unknownChannelIds': unknownChannelIds,
+  });
+}
+
+void _handleUnsubscribe(String connectionId, Map<String, dynamic> payload) {
+  final channelIds = _parseChannelIds(payload);
+  if (channelIds.isEmpty) {
+    _sendProtocolError(
+      connectionId,
+      'unsubscribe requires `channelId` or `channelIds`',
+    );
+    return;
+  }
+
+  final unsubscribed = _gatewayRegistry.unsubscribe(connectionId, channelIds);
+
+  _sendGatewayPayload(connectionId, {
+    'op': 'unsubscribed',
+    'channelIds': unsubscribed,
+    'subscriptions': _gatewayRegistry.subscriptions(connectionId),
+  });
+}
+
+Map<String, dynamic>? _decodePayload(String text) {
+  try {
+    final decoded = jsonDecode(text);
+    if (decoded is Map<String, dynamic>) {
+      return decoded;
+    }
+    if (decoded is Map) {
+      return decoded.map(
+        (key, value) => MapEntry(key.toString(), value),
+      );
+    }
+    return null;
+  } catch (_) {
+    return null;
+  }
+}
+
+Set<int> _parseChannelIds(Map<String, dynamic> payload) {
+  final channelIds = <int>{};
+
+  void parseAndAdd(Object? value) {
+    final parsed = switch (value) {
+      int id when id > 0 => id,
+      String id => int.tryParse(id),
+      _ => null,
+    };
+    if (parsed != null && parsed > 0) {
+      channelIds.add(parsed);
+    }
+  }
+
+  parseAndAdd(payload['channelId']);
+  final channelIdList = payload['channelIds'];
+  if (channelIdList is List) {
+    for (final value in channelIdList) {
+      parseAndAdd(value);
+    }
+  }
+
+  return channelIds;
+}
+
+void _sendProtocolError(String connectionId, String message) {
+  _sendGatewayPayload(connectionId, {
+    'op': 'error',
+    'message': message,
+  });
+}
+
+void _sendGatewayPayload(String connectionId, Map<String, dynamic> payload) {
+  final connection = _gatewayRegistry.getConnection(connectionId);
+  if (connection == null) {
+    return;
+  }
+
+  final sent = _safeSend(connection, payload);
+  if (!sent) {
+    _gatewayRegistry.unregister(connectionId);
+  }
+}
+
+bool _safeSend(_GatewayConnection connection, Map<String, dynamic> payload) {
+  try {
+    return connection.socket.trySendText(jsonEncode(payload));
+  } catch (_) {
+    return false;
+  }
+}
+
+class _GatewayRegistry {
+  final Map<String, _GatewayConnection> _connections = {};
+  final Map<int, Set<String>> _subscribersByChannel = {};
+  int _nextConnectionId = 1;
+
+  _GatewayConnection register({
+    required RelicWebSocket socket,
+    required String userId,
+    String? username,
+  }) {
+    final id = 'gw_${_nextConnectionId++}';
+    final connection = _GatewayConnection(
+      id: id,
+      socket: socket,
+      userId: userId,
+      username: username,
+    );
+    _connections[id] = connection;
+    return connection;
+  }
+
+  _GatewayConnection? getConnection(String connectionId) {
+    return _connections[connectionId];
+  }
+
+  List<int> subscriptions(String connectionId) {
+    final connection = _connections[connectionId];
+    if (connection == null) {
+      return const <int>[];
+    }
+    return connection.subscriptions.toList()..sort();
+  }
+
+  List<int> subscribe(String connectionId, Iterable<int> channelIds) {
+    final connection = _connections[connectionId];
+    if (connection == null) {
+      return const <int>[];
+    }
+
+    for (final channelId in channelIds) {
+      connection.subscriptions.add(channelId);
+      _subscribersByChannel.putIfAbsent(channelId, () => <String>{}).add(
+            connectionId,
+          );
+    }
+
+    return channelIds.toSet().toList()..sort();
+  }
+
+  List<int> unsubscribe(String connectionId, Iterable<int> channelIds) {
+    final connection = _connections[connectionId];
+    if (connection == null) {
+      return const <int>[];
+    }
+
+    final removed = <int>[];
+    for (final channelId in channelIds) {
+      final didRemove = connection.subscriptions.remove(channelId);
+      if (didRemove) {
+        removed.add(channelId);
+      }
+
+      final subscribers = _subscribersByChannel[channelId];
+      if (subscribers != null) {
+        subscribers.remove(connectionId);
+        if (subscribers.isEmpty) {
+          _subscribersByChannel.remove(channelId);
+        }
+      }
+    }
+
+    removed.sort();
+    return removed;
+  }
+
+  void unregister(String connectionId) {
+    final connection = _connections.remove(connectionId);
+    if (connection == null) {
+      return;
+    }
+
+    for (final channelId in connection.subscriptions) {
+      final subscribers = _subscribersByChannel[channelId];
+      if (subscribers == null) {
+        continue;
+      }
+      subscribers.remove(connectionId);
+      if (subscribers.isEmpty) {
+        _subscribersByChannel.remove(channelId);
+      }
+    }
+
+    if (!connection.socket.isClosed) {
+      unawaited(connection.socket.tryClose(1000, 'Disconnected'));
+    }
+  }
+
+  void broadcastToChannel(int channelId, Map<String, dynamic> payload) {
+    final subscribers = _subscribersByChannel[channelId];
+    if (subscribers == null || subscribers.isEmpty) {
+      return;
+    }
+
+    final deadConnections = <String>[];
+    final subscriberIds = subscribers.toList(growable: false);
+    for (final connectionId in subscriberIds) {
+      final connection = _connections[connectionId];
+      if (connection == null) {
+        deadConnections.add(connectionId);
+        continue;
+      }
+
+      final sent = _safeSend(connection, payload);
+      if (!sent) {
+        deadConnections.add(connectionId);
+      }
+    }
+
+    for (final connectionId in deadConnections) {
+      unregister(connectionId);
+    }
+  }
+}
+
+class _GatewayConnection {
+  final String id;
+  final RelicWebSocket socket;
+  final String userId;
+  final String? username;
+  final Set<int> subscriptions = <int>{};
+
+  _GatewayConnection({
+    required this.id,
+    required this.socket,
+    required this.userId,
+    required this.username,
+  });
+}

lib/src/handlers/message_handlers.dart

@@ -3,14 +3,20 @@ import 'package:chat_server/objectbox.g.dart';
 import 'package:relic/relic.dart';
 
 import '../auth/auth_middleware.dart';
+import '../gateway/gateway_handlers.dart';
 import '../state/app_state.dart';
 import '../utils/extensions.dart';
 
+const _defaultMessageLimit = 50;
+const _maxMessageLimit = 100;
+
 /// Get messages for a channel
-/// Query params: channelId (required), limit, before
+/// Query params: channelId (required), limit, before, after
 Future<Response> getMessagesHandler(Request req) async {
   final channelIdStr = req.url.queryParameters['channelId'];
-  final limitStr = req.url.queryParameters['limit'] ?? '50';
+  final limitStr = req.url.queryParameters['limit'];
+  final beforeStr = req.url.queryParameters['before'];
+  final afterStr = req.url.queryParameters['after'];
 
   if (channelIdStr == null) {
     return Response.badRequest(
@@ -18,8 +24,17 @@ Future<Response> getMessagesHandler(Request req) async {
     );
   }
 
+  if (beforeStr != null && afterStr != null) {
+    return Response.badRequest(
+      body: Body.fromString('Use either `before` or `after`, not both'),
+    );
+  }
+
   final channelId = int.tryParse(channelIdStr);
-  final limit = int.tryParse(limitStr) ?? 50;
+  final parsedLimit =
+      limitStr == null ? _defaultMessageLimit : int.tryParse(limitStr);
+  int? before;
+  int? after;
 
   if (channelId == null) {
     return Response.badRequest(
@@ -27,6 +42,32 @@ Future<Response> getMessagesHandler(Request req) async {
     );
   }
 
+  if (parsedLimit == null || parsedLimit <= 0) {
+    return Response.badRequest(
+      body: Body.fromString('Invalid limit'),
+    );
+  }
+
+  final limit = parsedLimit > _maxMessageLimit ? _maxMessageLimit : parsedLimit;
+
+  if (beforeStr != null) {
+    before = int.tryParse(beforeStr);
+    if (before == null || before <= 0) {
+      return Response.badRequest(
+        body: Body.fromString('Invalid `before` cursor'),
+      );
+    }
+  }
+
+  if (afterStr != null) {
+    after = int.tryParse(afterStr);
+    if (after == null || after <= 0) {
+      return Response.badRequest(
+        body: Body.fromString('Invalid `after` cursor'),
+      );
+    }
+  }
+
   // Check channel exists
   final channel = channelBox.get(channelId);
   if (channel == null) {
@@ -35,33 +76,50 @@ Future<Response> getMessagesHandler(Request req) async {
     );
   }
 
-  // Get messages
-  final query = messageBox
-      .query(ChatMessage_.channelId.equals(channelId))
-      .order(ChatMessage_.createdAt, flags: Order.descending)
-      .build();
+  var condition = ChatMessage_.channelId.equals(channelId);
+  if (before != null) {
+    condition = condition & ChatMessage_.id.lessThan(before);
+  } else if (after != null) {
+    condition = condition & ChatMessage_.id.greaterThan(after);
+  }
 
-  query.limit = limit;
-  final messages = query.find();
+  final queryBuilder = messageBox.query(condition);
+  if (after != null) {
+    queryBuilder.order(ChatMessage_.id);
+  } else {
+    queryBuilder.order(ChatMessage_.id, flags: Order.descending);
+  }
+
+  final query = queryBuilder.build();
+  query.limit = limit + 1;
+
+  final fetchedMessages = query.find();
   query.close();
 
+  final hasMore = fetchedMessages.length > limit;
+  final messages =
+      hasMore ? fetchedMessages.sublist(0, limit) : fetchedMessages;
+
+  int? nextBefore;
+  int? nextAfter;
+  if (messages.isNotEmpty) {
+    if (after != null) {
+      nextBefore = messages.first.id;
+      nextAfter = messages.last.id;
+    } else {
+      nextBefore = messages.last.id;
+      nextAfter = messages.first.id;
+    }
+  }
+
   return Response.ok(
     body: {
-      'messages': messages
-          .map((m) => {
-                'id': m.id,
-                'content': m.content,
-                'authorId': m.authorUserId,
-                'authorUsername': m.authorUsername,
-                'authorAvatarUrl': m.authorAvatarUrl,
-                'authorHomeServer': m.authorHomeServer,
-                'channelId': m.channelId,
-                'createdAt': m.createdAt.toIso8601String(),
-                'editedAt': m.editedAt?.toIso8601String(),
-              })
-          .toList(),
+      'messages': messages.map(_messageToMap).toList(),
       'channelId': channelId,
       'limit': limit,
+      'hasMore': hasMore,
+      'nextBefore': nextBefore,
+      'nextAfter': nextAfter,
     }.toBody,
   );
 }
@@ -123,6 +181,12 @@ Future<Response> sendMessageHandler(Request req) async {
   );
 
   final id = messageBox.put(message);
+  message.id = id;
+
+  broadcastMessageCreated(
+    channelId: channelId,
+    message: _messageToMap(message),
+  );
 
   return Response.ok(
     body: {
@@ -192,6 +256,11 @@ Future<Response> editMessageHandler(Request req) async {
   message.editedAt = DateTime.now();
   messageBox.put(message);
 
+  broadcastMessageUpdated(
+    channelId: message.channelId,
+    message: _messageToMap(message),
+  );
+
   return Response.ok(
     body: {
       'id': message.id,
@@ -243,8 +312,14 @@ Future<Response> deleteMessageHandler(Request req) async {
     );
   }
 
+  final channelId = message.channelId;
   messageBox.remove(messageId);
 
+  broadcastMessageDeleted(
+    channelId: channelId,
+    messageId: messageId,
+  );
+
   return Response.ok(
     body: {
       'deleted': true,
@@ -252,3 +327,17 @@ Future<Response> deleteMessageHandler(Request req) async {
     }.toBody,
   );
 }
+
+Map<String, dynamic> _messageToMap(ChatMessage message) {
+  return {
+    'id': message.id,
+    'content': message.content,
+    'authorId': message.authorUserId,
+    'authorUsername': message.authorUsername,
+    'authorAvatarUrl': message.authorAvatarUrl,
+    'authorHomeServer': message.authorHomeServer,
+    'channelId': message.channelId,
+    'createdAt': message.createdAt.toIso8601String(),
+    'editedAt': message.editedAt?.toIso8601String(),
+  };
+}