Improve plugin interface (#545)

lib/src/client.dart

@@ -18,13 +18,19 @@ import 'package:oauth2/oauth2.dart';
 
 /// A helper function to nest and execute calls to plugin connect methods.
 Future<T> _doConnect<T extends Nyxx>(ApiOptions apiOptions, ClientOptions clientOptions, Future<T> Function() connect, List<NyxxPlugin> plugins) {
-  connect = plugins.fold(connect, (previousConnect, plugin) => () => plugin.connect(apiOptions, clientOptions, previousConnect));
+  connect = plugins.fold(
+    connect,
+    (previousConnect, plugin) => () async => (await plugin.doConnect(apiOptions, clientOptions, previousConnect)) as T,
+  );
   return connect();
 }
 
 /// A helper function to nest and execute calls to plugin close methods.
 Future<void> _doClose(Nyxx client, Future<void> Function() close, List<NyxxPlugin> plugins) {
-  close = plugins.fold(close, (previousClose, plugin) => () => plugin.close(client, previousClose));
+  close = plugins.fold(
+    close,
+    (previousClose, plugin) => () => plugin.doClose(client, previousClose),
+  );
   return close();
 }
 

lib/src/plugin/cli_integration.dart

@@ -1,9 +1,7 @@
 import 'dart:async';
 import 'dart:io';
 
-import 'package:nyxx/src/api_options.dart';
 import 'package:nyxx/src/client.dart';
-import 'package:nyxx/src/client_options.dart';
 import 'package:nyxx/src/plugin/plugin.dart';
 
 /// A global instance of the [CliIntegration] plugin.
@@ -44,26 +42,20 @@ class CliIntegration extends NyxxPlugin {
     for (final subscription in _subscriptions!) {
       subscription.cancel();
     }
+    _subscriptions = null;
   }
 
   @override
-  Future<ClientType> connect<ClientType extends Nyxx>(ApiOptions apiOptions, ClientOptions clientOptions, Future<ClientType> Function() connect) async {
+  void afterConnect(Nyxx client) {
     _ensureListening();
 
-    try {
-      final client = await connect();
-      _watchedClients.add(client);
-      client.logger.info('Listening for SIGINT or SIGTERM to safely close');
-      return client;
-    } finally {
-      _removeListenersIfNeeded();
-    }
+    _watchedClients.add(client);
+    client.logger.info('Listening for SIGINT or SIGTERM to safely close');
   }
 
   @override
-  Future<void> close(Nyxx client, Future<void> Function() close) async {
+  void beforeClose(Nyxx client) {
     _watchedClients.remove(client);
     _removeListenersIfNeeded();
-    await close();
   }
 }

lib/src/plugin/ignore_exceptions.dart

@@ -1,9 +1,7 @@
 import 'dart:isolate';
 
 import 'package:logging/logging.dart';
-import 'package:nyxx/src/api_options.dart';
 import 'package:nyxx/src/client.dart';
-import 'package:nyxx/src/client_options.dart';
 import 'package:nyxx/src/plugin/plugin.dart';
 
 /// A global instance of the [IgnoreExceptions] plugin.
@@ -53,18 +51,13 @@ class IgnoreExceptions extends NyxxPlugin {
   }
 
   @override
-  Future<ClientType> connect<ClientType extends Nyxx>(ApiOptions apiOptions, ClientOptions clientOptions, Future<ClientType> Function() connect) async {
-    final client = await connect();
-
+  void afterConnect(Nyxx client) {
     _clients++;
     _listenIfNeeded();
-
-    return client;
   }
 
   @override
-  Future<void> close(Nyxx client, Future<void> Function() close) async {
-    await close();
+  void afterClose() {
     _clients--;
     _stopListeningIfNeeded();
   }

lib/src/plugin/logging.dart

@@ -111,19 +111,19 @@ class Logging extends NyxxPlugin {
   }
 
   @override
-  Future<ClientType> connect<ClientType extends Nyxx>(ApiOptions apiOptions, ClientOptions clientOptions, Future<ClientType> Function() connect) async {
+  void beforeConnect(ApiOptions apiOptions, ClientOptions clientOptions) {
     if (apiOptions is RestApiOptions) {
       _tokens.add(apiOptions.token);
     }
 
     _clients++;
     _listenIfNeeded();
-    return await connect();
   }
 
   @override
-  Future<void> close(Nyxx client, Future<void> Function() close) async {
-    await close();
+  Future<void> doClose(Nyxx client, Future<void> Function() close) async {
+    await super.doClose(client, close);
+
     _clients--;
     _stopListeningIfNeeded();
 

lib/src/plugin/plugin.dart

@@ -1,19 +1,85 @@
+import 'dart:async';
+
+import 'package:meta/meta.dart';
 import 'package:nyxx/src/api_options.dart';
 import 'package:nyxx/src/client.dart';
 import 'package:nyxx/src/client_options.dart';
 
 /// Provides access to the connection and closing process for implementing plugins.
-abstract class NyxxPlugin {
+abstract class NyxxPlugin<ClientType extends Nyxx> {
   /// The name of this plugin.
   String get name;
 
+  late final Expando<NyxxPluginState<ClientType, NyxxPlugin<ClientType>>> _states = Expando('$name plugin states');
+
   /// Perform the connection operation.
   ///
-  /// The function passed as an argument should be called to obtain the underlying client.
-  Future<ClientType> connect<ClientType extends Nyxx>(ApiOptions apiOptions, ClientOptions clientOptions, Future<ClientType> Function() connect) => connect();
+  /// People overriding this method should call it to obtain the client instance.
+  @mustCallSuper
+  Future<ClientType> doConnect(ApiOptions apiOptions, ClientOptions clientOptions, Future<ClientType> Function() connect) async {
+    final state = await createState();
+    await state.beforeConnect(apiOptions, clientOptions);
+
+    final client = await connect();
+    _states[client] = state;
+
+    await state.afterConnect(client);
+    return client;
+  }
 
   /// Perform the close operation.
   ///
-  /// The function passed as an argument should be called to close the underlying client.
-  Future<void> close(Nyxx client, Future<void> Function() close) => close();
+  /// People overriding this method should call it to obtain the client instance.
+  Future<void> doClose(ClientType client, Future<void> Function() close) async {
+    final state = _states[client];
+    await state?.beforeClose(client);
+
+    await close();
+    _states[client] = null;
+
+    await state?.afterClose();
+  }
+
+  /// Called to create the state for this plugin.
+  ///
+  /// Each plugin creates a state for each client is attached to. States can contain mutable fields that can be updated at any time without affecting other
+  /// instances of the plugin attached to other clients.
+  FutureOr<NyxxPluginState<ClientType, NyxxPlugin<ClientType>>> createState() => NyxxPluginState(this);
+
+  /// Called before each client this plugin is added to connects.
+  FutureOr<void> beforeConnect(ApiOptions apiOptions, ClientOptions clientOptions) {}
+
+  /// Called after each client this plugin is added to connects.
+  FutureOr<void> afterConnect(ClientType client) {}
+
+  /// Called before each client this plugin is added to closes.
+  FutureOr<void> beforeClose(ClientType client) {}
+
+  /// Called after each client this plugin is added to closes.
+  FutureOr<void> afterClose() {}
+}
+
+/// Holds the state of a plugin added to a client.
+class NyxxPluginState<ClientType extends Nyxx, PluginType extends NyxxPlugin<ClientType>> {
+  /// The plugin this state belongs to.
+  final PluginType plugin;
+
+  /// Create a new plugin state.
+  NyxxPluginState(this.plugin);
+
+  /// Called before each client this plugin is added to connects.
+  @mustCallSuper
+  FutureOr<void> beforeConnect(ApiOptions apiOptions, ClientOptions clientOptions) => plugin.beforeConnect(apiOptions, clientOptions);
+
+  /// Called after each client this plugin is added to connects.
+  @mustCallSuper
+  FutureOr<void> afterConnect(ClientType client) => plugin.afterConnect(client);
+
+  /// Called before each client this plugin is added to closes.
+  @mustCallSuper
+  FutureOr<void> beforeClose(ClientType client) => plugin.beforeClose(client);
+
+  /// Called after each client this plugin is added to closes.
+  @mustCallSuper
+  FutureOr<void> afterClose() => plugin.afterClose();
 }