feat: Track stanza responses as a tuple of (to, id)

Also fixes an invalid test case in the XEP-0198 tests, where
the IQ reply sets the "to" instead of the "from".

packages/moxxmpp/lib/src/connection.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 import 'package:logging/logging.dart';
 import 'package:meta/meta.dart';
+import 'package:moxlib/moxlib.dart';
 import 'package:moxxmpp/src/buffer.dart';
 import 'package:moxxmpp/src/errors.dart';
 import 'package:moxxmpp/src/events.dart';
@@ -72,6 +73,23 @@ class XmppConnectionResult {
   final XmppError? error;
 }
 
+@immutable
+class _StanzaAwaitableData {
+  const _StanzaAwaitableData(this.sentTo, this.id);
+  final String sentTo;
+  final String id;
+
+  @override
+  int get hashCode => sentTo.hashCode ^ id.hashCode;
+
+  @override
+  bool operator==(Object other) {
+    return other is _StanzaAwaitableData &&
+           other.sentTo == sentTo &&
+           other.id == id;
+  }
+}
+
 class XmppConnection {
   /// [_socket] is for debugging purposes.
   /// [connectionPingDuration] is the duration after which a ping will be sent to keep
@@ -128,7 +146,7 @@ class XmppConnection {
   /// A policy on how to reconnect 
   final ReconnectionPolicy _reconnectionPolicy;
   /// A list of stanzas we are tracking with its corresponding critical section
-  final Map<String, Completer<XMLNode>> _awaitingResponse;
+  final Map<_StanzaAwaitableData, Completer<XMLNode>> _awaitingResponse;
   final Lock _awaitingResponseLock;
   
   /// Helpers
@@ -428,9 +446,10 @@ class XmppConnection {
   /// none.
   // TODO(Unknown): if addId = false, the function crashes.
   Future<XMLNode> sendStanza(Stanza stanza, { StanzaFromType addFrom = StanzaFromType.full, bool addId = true, bool awaitable = true, bool encrypted = false }) async {
-    var stanza_ = stanza;
+    assert(implies(addId == false && stanza.id == null, !awaitable), 'Cannot await a stanza with no id');
 
     // Add extra data in case it was not set
+    var stanza_ = stanza;
     if (addId && (stanza_.id == null || stanza_.id == '')) {
       stanza_ = stanza.copyWith(id: generateId());
     }
@@ -448,8 +467,6 @@ class XmppConnection {
       }
     }
 
-    final id = stanza_.id!;
-
     _log.fine('Running pre stanza handlers..');
     final data = await _runOutgoingPreStanzaHandlers(
       stanza_,
@@ -487,13 +504,16 @@ class XmppConnection {
     final stanzaString = data.stanza.toXml();
 
     // ignore: cascade_invocations
-    _log.fine('Attempting to acquire lock for $id...');
+    _log.fine('Attempting to acquire lock for ${data.stanza.id}...');
     // TODO(PapaTutuWawa): Handle this much more graceful
     var future = Future.value(XMLNode(tag: 'not-used'));
     await _awaitingResponseLock.synchronized(() async {
-        _log.fine('Lock acquired for $id');
+      _log.fine('Lock acquired for ${data.stanza.id}');
+
+      _StanzaAwaitableData? key;
       if (awaitable) {
-          _awaitingResponse[id] = Completer();
+        key = _StanzaAwaitableData(data.stanza.to!, data.stanza.id!);
+        _awaitingResponse[key] = Completer();
       }
 
       // This uses the StreamManager to behave like a send queue
@@ -519,10 +539,10 @@ class XmppConnection {
       _log.fine('Done');
 
       if (awaitable) {
-          future = _awaitingResponse[id]!.future;
+        future = _awaitingResponse[key]!.future;
       }
 
-        _log.fine('Releasing lock for $id');
+      _log.fine('Releasing lock for ${data.stanza.id}');
     });
 
     return future;
@@ -691,11 +711,15 @@ class XmppConnection {
     final id = incomingPreHandlers.stanza.attributes['id'] as String?;
     var awaited = false;
     await _awaitingResponseLock.synchronized(() async {
-      if (id != null && _awaitingResponse.containsKey(id)) {
-        _awaitingResponse[id]!.complete(incomingPreHandlers.stanza);
-        _awaitingResponse.remove(id);
+      if (id != null && incomingPreHandlers.stanza.from != null) {
+        final key = _StanzaAwaitableData(incomingPreHandlers.stanza.from!, id);
+        final comp = _awaitingResponse[key];
+        if (comp != null) {
+          comp.complete(incomingPreHandlers.stanza);
+          _awaitingResponse.remove(key);
           awaited = true;
         }
+      }
     });
 
     if (awaited) {

packages/moxxmpp/test/xeps/xep_0198_test.dart

@@ -348,7 +348,7 @@ void main() {
           ),
           StanzaExpectation(
             "<iq to='user@example.com' type='get' id='a' xmlns='jabber:client' />",
-            "<iq to='user@example.com' type='result' id='a' />",
+            "<iq from='user@example.com' type='result' id='a' />",
             ignoreId: true,
             adjustId: true,
           ),