Initial commit: watch-together phases 0-4 + presence hardening, internet-tested

packages/server/lib/src/session.dart

@@ -0,0 +1,95 @@
+import 'dart:io';
+import 'dart:math';
+
+import 'package:sync_relay_core/core.dart';
+
+enum MediaGate { ok, gone, unauthorized, forbidden, offline }
+
+class ViewerToken {
+  final String token;
+  final String name;
+  final String avatar;
+  bool kicked = false;
+  int bytesServed = 0;
+  DateTime lastSeen;
+  Future<void> Function(String reason)? onKick;
+  ViewerToken({required this.token, required this.name, this.avatar = ''})
+      : lastSeen = DateTime.now().toUtc();
+
+  bool isStale(Duration timeout, [DateTime? now]) =>
+      (now ?? DateTime.now().toUtc()).difference(lastSeen) > timeout;
+
+  void touch([DateTime? now]) => lastSeen = now ?? DateTime.now().toUtc();
+}
+
+class SessionMedia {
+  final String name;
+  final int size;
+  final double duration;
+  final String? url;
+  final File? file;
+  final int mediaId;
+  const SessionMedia({
+    required this.name,
+    required this.size,
+    required this.duration,
+    this.url,
+    this.file,
+    this.mediaId = 1,
+  });
+}
+
+class Session {
+  final String id;
+  final String secret;
+  final Map<String, ViewerToken> tokens = {};
+  SessionMedia? media;
+  final _random = Random.secure();
+
+  Session({required this.id, required this.secret});
+
+  String issueToken(String name, String avatar) {
+    if (avatar.length > RelayConstants.maxAvatarBytes) {
+      throw const AuthException('avatar too large');
+    }
+    final trimmed = name.trim();
+    final cleanName = trimmed.isEmpty
+        ? '?'
+        : trimmed.substring(
+            0, trimmed.length.clamp(0, RelayConstants.maxNameLength));
+    final bytes = List<int>.generate(16, (_) => _random.nextInt(256));
+    final token = bytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join();
+    tokens[token] = ViewerToken(token: token, name: cleanName, avatar: avatar);
+    return token;
+  }
+
+  MediaGate gate(String? token) {
+    if (token == null || !tokens.containsKey(token)) return MediaGate.unauthorized;
+    if (tokens[token]!.kicked) return MediaGate.forbidden;
+    return MediaGate.ok;
+  }
+
+  Future<void> kick(String token, {String reason = ''}) async {
+    final viewer = tokens[token];
+    if (viewer == null) throw const AuthException('unknown token');
+    viewer.kicked = true;
+    await viewer.onKick?.call(reason);
+  }
+
+  void addBytes(String? token, int n) {
+    if (token != null) tokens[token]?.bytesServed += n;
+  }
+
+  int get totalBytesServed => tokens.values.fold(0, (a, v) => a + v.bytesServed);
+}
+
+class SessionMap {
+  final Map<String, Session> _sessions = {};
+
+  Session getOrCreate(String id, String secret) =>
+      _sessions.putIfAbsent(id, () => Session(id: id, secret: secret));
+
+  Session? get(String id) => _sessions[id];
+
+  void drop(String id) => _sessions.remove(id);
+}