Fixes #7 Binding to channel events cancels calls to onConnectionState…

…Change

Added Stream Handler to allow multiple classes to listen to event channel stream

example/.gitignore

@@ -39,3 +39,4 @@ app.*.symbols
 
 # Obfuscation related
 app.*.map.json
+testdata.txt

lib/src/contracts/stream_handler.dart

@@ -0,0 +1,32 @@
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+
+abstract class StreamHandler {
+  static const EventChannel _eventStream =
+      const EventChannel('com.github.chinloyal/pusher_client_stream');
+  StreamSubscription _eventStreamSubscription;
+
+  static Map<String, dynamic Function(dynamic)> _listeners = {};
+
+  /// Add a listener to the event channel stream for pusher,
+  /// any class that extends [StreamHandler] should use this method.
+  void registerListener(String classId, dynamic Function(dynamic) method) {
+    StreamHandler._listeners[classId] = method;
+
+    _eventStreamSubscription =
+        _eventStream.receiveBroadcastStream().listen(_eventHandler);
+  }
+
+  /// This method will close the entire event channel stream
+  /// which is why it should only be used by [PusherClient]
+  void cancelEventChannelStream() {
+    _eventStreamSubscription.cancel();
+  }
+
+  void _eventHandler(event) {
+    _listeners.values.forEach((method) {
+      method(event);
+    });
+  }
+}

lib/src/pusher/channel.dart

@@ -2,18 +2,17 @@ import 'dart:async';
 import 'dart:convert';
 
 import 'package:flutter/services.dart';
+import 'package:pusher_client/src/contracts/stream_handler.dart';
 import 'package:pusher_client/src/models/event_stream_result.dart';
 import 'package:pusher_client/src/pusher/pusher_event.dart';
 
-class Channel {
+class Channel extends StreamHandler {
   static const MethodChannel _mChannel =
       const MethodChannel('com.github.chinloyal/pusher_client');
-  static const EventChannel _eventStream =
-      const EventChannel('com.github.chinloyal/pusher_client_stream');
+  static const classId = 'Channel';
 
   static Map<String, void Function(PusherEvent)> _eventCallbacks =
       Map<String, void Function(PusherEvent)>();
-  StreamSubscription _eventStreamSubscription;
 
   final String name;
 
@@ -34,8 +33,7 @@ class Channel {
     String eventName,
     void Function(PusherEvent event) onEvent,
   ) async {
-    _eventStreamSubscription =
-        _eventStream.receiveBroadcastStream().listen(_eventHandler);
+    registerListener(classId, _eventHandler);
     _eventCallbacks[this.name + eventName] = onEvent;
 
     await _mChannel.invokeMethod('bind', {
@@ -49,10 +47,6 @@ class Channel {
   Future<void> unbind(String eventName) async {
     _eventCallbacks.remove(this.name + eventName);
 
-    if (_eventCallbacks.isEmpty) {
-      _eventStreamSubscription.cancel();
-    }
-
     await _mChannel.invokeMethod('unbind', {
       'channelName': this.name,
       'eventName': eventName,

lib/src/pusher/pusher_client.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 
 import 'package:flutter/services.dart';
 import 'package:pusher_client/pusher_client.dart';
+import 'package:pusher_client/src/contracts/stream_handler.dart';
 import 'package:pusher_client/src/models/connection_error.dart';
 import 'package:pusher_client/src/models/connection_state_change.dart';
 import 'package:pusher_client/src/models/event_stream_result.dart';
@@ -15,16 +16,14 @@ part 'pusher_client.g.dart';
 /// created automatically unless [autoConnect] is set to false,
 /// if auto connect is disabled this means you can call
 /// `connect()` at a later point.
-class PusherClient {
+class PusherClient extends StreamHandler {
   static const MethodChannel _channel =
       const MethodChannel('com.github.chinloyal/pusher_client');
-  static const EventChannel _eventStream =
-      const EventChannel('com.github.chinloyal/pusher_client_stream');
+  static const classId = 'PusherClient';
 
   static PusherClient _singleton;
   void Function(ConnectionStateChange) _onConnectionStateChange;
   void Function(ConnectionError) _onConnectionError;
-  StreamSubscription _eventStreamSubscription;
   String _socketId;
 
   PusherClient._(
@@ -58,8 +57,7 @@ class PusherClient {
   }
 
   Future _init(String appKey, PusherOptions options, InitArgs initArgs) async {
-    _singleton._eventStreamSubscription =
-        _eventStream.receiveBroadcastStream().listen(_eventHandler);
+    registerListener(classId, _eventHandler);
     await _channel.invokeMethod(
       'init',
       jsonEncode({
@@ -98,7 +96,7 @@ class PusherClient {
   Future disconnect() async {
     await _channel.invokeMethod('disconnect');
 
-    _eventStreamSubscription.cancel();
+    cancelEventChannelStream();
   }
 
   /// The id of the current connection