feat: Trigger an event when the roster changes

packages/moxxmpp/lib/src/events.dart

@@ -61,6 +61,21 @@ class RosterPushEvent extends XmppEvent {
   final String? ver;
 }
 
+/// Triggered when the roster has been modified
+class RosterUpdatedEvent extends XmppEvent {
+  RosterUpdatedEvent(this.removed, this.modified, this.added);
+
+  /// A list of bare JIDs that are removed from the roster
+  final List<String> removed;
+
+  /// A list of XmppRosterItems that are modified. Can be correlated with one's cache
+  /// using the jid attribute.
+  final List<XmppRosterItem> modified;
+
+  /// A list of XmppRosterItems that are added to the roster.
+  final List<XmppRosterItem> added;
+}
+
 /// Triggered when a message is received
 class MessageEvent extends XmppEvent {
   MessageEvent({

packages/moxxmpp/lib/src/roster/roster.dart

@@ -61,7 +61,9 @@ class RosterFeatureNegotiator extends XmppFeatureNegotiatorBase {
 
 /// This manager requires a RosterFeatureNegotiator to be registered.
 class RosterManager extends XmppManagerBase {
-  RosterManager(this._stateManager) : super();
+  RosterManager(this._stateManager) : super() {
+    _stateManager.register(getAttributes().sendEvent);
+  }
   final BaseRosterStateManager _stateManager;
   
   @override

packages/moxxmpp/lib/src/roster/state.dart

@@ -27,6 +27,9 @@ abstract class BaseRosterStateManager {
 
   /// A critical section locking both _currentRoster and _currentVersion.
   final Lock _lock = Lock();
+
+  /// A function to send an XmppEvent to moxxmpp's main event bus
+  late void Function(XmppEvent) _sendEvent;
   
   /// Overrideable function
   /// Loads the old cached version of the roster and optionally that roster version
@@ -49,6 +52,12 @@ abstract class BaseRosterStateManager {
   /// roster push or roster fetch request.
   Future<void> commitRoster(String? version, List<String> removed, List<XmppRosterItem> modified, List<XmppRosterItem> added);
 
+  /// Internal function. Registers functions from the RosterManger against this
+  /// instance.
+  void register(void Function(XmppEvent) sendEvent) {
+    _sendEvent = sendEvent;
+  }
+  
   /// Load and cache or return the cached roster version.
   Future<String?> getRosterVersion() async {
     return _lock.synchronized(() async {
@@ -58,6 +67,20 @@ abstract class BaseRosterStateManager {
     });
   }
 
+  /// A wrapper around _commitRoster that also sends an event to moxxmpp's event
+  /// bus.
+  Future<void> _commitRoster(String? version, List<String> removed, List<XmppRosterItem> modified, List<XmppRosterItem> added) async {
+    _sendEvent(
+      RosterUpdatedEvent(
+        removed,
+        modified,
+        added,
+      ),
+    );
+    
+    await commitRoster(version, removed, modified, added);
+  }
+  
   /// Loads the cached roster data into memory, if that has not already happened.
   /// NOTE: Must be called from within the _lock critical section.
   Future<void> _loadRosterCache() async {
@@ -111,21 +134,21 @@ abstract class BaseRosterStateManager {
       final result = _handleRosterItem(event.item);
 
       if (result.removed != null) {
-        return commitRoster(
+        return _commitRoster(
           _currentVersion,
           [result.removed!],
           [],
           [],
         );
       } else if (result.modified != null) {
-        return commitRoster(
+        return _commitRoster(
           _currentVersion,
           [],
           [result.modified!],
           [],
         );
       } else if (result.added != null) {
-        return commitRoster(
+        return _commitRoster(
           _currentVersion,
           [],
           [],
@@ -153,7 +176,7 @@ abstract class BaseRosterStateManager {
         if (result.added != null) added.add(result.added!);
       }
 
-      await commitRoster(
+      await _commitRoster(
         _currentVersion,
         removed,
         modified,
@@ -187,5 +210,4 @@ class TestingRosterStateManager extends BaseRosterStateManager {
 
   @override
   Future<void> commitRoster(String? version, List<String> removed, List<XmppRosterItem> modified, List<XmppRosterItem> added) async {}
-
 }