feat: Allow clients to read Message Processing Hints

packages/moxxmpp/lib/src/events.dart

@@ -6,6 +6,7 @@ import 'package:moxxmpp/src/xeps/xep_0030/types.dart';
 import 'package:moxxmpp/src/xeps/xep_0060/xep_0060.dart';
 import 'package:moxxmpp/src/xeps/xep_0066.dart';
 import 'package:moxxmpp/src/xeps/xep_0085.dart';
+import 'package:moxxmpp/src/xeps/xep_0334.dart';
 import 'package:moxxmpp/src/xeps/xep_0359.dart';
 import 'package:moxxmpp/src/xeps/xep_0385.dart';
 import 'package:moxxmpp/src/xeps/xep_0424.dart';
@@ -77,6 +78,7 @@ class MessageEvent extends XmppEvent {
     this.messageRetraction,
     this.messageCorrectionId,
     this.messageReactions,
+    this.messageProcessingHints,
   });
   final StanzaError? error;
   final String body;
@@ -100,6 +102,7 @@ class MessageEvent extends XmppEvent {
   final MessageRetractionData? messageRetraction;
   final String? messageCorrectionId;
   final MessageReactions? messageReactions;
+  final List<MessageProcessingHint>? messageProcessingHints;
   final Map<String, dynamic> other;
 }
 

packages/moxxmpp/lib/src/message.dart

@@ -13,6 +13,7 @@ import 'package:moxxmpp/src/xeps/xep_0085.dart';
 import 'package:moxxmpp/src/xeps/xep_0184.dart';
 import 'package:moxxmpp/src/xeps/xep_0308.dart';
 import 'package:moxxmpp/src/xeps/xep_0333.dart';
+import 'package:moxxmpp/src/xeps/xep_0334.dart';
 import 'package:moxxmpp/src/xeps/xep_0359.dart';
 import 'package:moxxmpp/src/xeps/xep_0424.dart';
 import 'package:moxxmpp/src/xeps/xep_0444.dart';
@@ -40,6 +41,7 @@ class MessageDetails {
     this.messageRetraction,
     this.lastMessageCorrectionId,
     this.messageReactions,
+    this.messageProcessingHints,
   });
   final String to;
   final String? body;
@@ -59,6 +61,7 @@ class MessageDetails {
   final MessageRetractionData? messageRetraction;
   final String? lastMessageCorrectionId;
   final MessageReactions? messageReactions;
+  final List<MessageProcessingHint>? messageProcessingHints;
 }
 
 class MessageManager extends XmppManagerBase {
@@ -84,6 +87,11 @@ class MessageManager extends XmppManagerBase {
     final message = state.stanza;
     final body = message.firstTag('body');
 
+    final hints = List<MessageProcessingHint>.empty(growable: true);
+    for (final element in message.findTagsByXmlns(messageProcessingHintsXmlns)) {
+      hints.add(messageProcessingHintFromXml(element)); 
+    }
+    
     getAttributes().sendEvent(MessageEvent(
       body: body != null ? body.innerText() : '',
       fromJid: JID.fromString(message.attributes['from']! as String),
@@ -106,6 +114,9 @@ class MessageManager extends XmppManagerBase {
       messageRetraction: state.messageRetraction,
       messageCorrectionId: state.lastMessageCorrectionSid,
       messageReactions: state.messageReactions,
+      messageProcessingHints: hints.isEmpty ?
+        null :
+        hints,
       other: state.other,
       error: StanzaError.fromStanza(message),
     ),);
@@ -270,6 +281,12 @@ class MessageManager extends XmppManagerBase {
       stanza.addChild(details.messageReactions!.toXml());
     }
     
+    if (details.messageProcessingHints != null) {
+      for (final hint in details.messageProcessingHints!) {
+        stanza.addChild(hint.toXml());
+      }
+    }
+    
     getAttributes().sendStanza(stanza, awaitable: false);
   }
 }

packages/moxxmpp/lib/src/stringxml.dart

@@ -129,6 +129,12 @@ class XMLNode {
     }).toList();
   }
   
+  List<XMLNode> findTagsByXmlns(String xmlns) {
+    return children
+      .where((element) => element.attributes['xmlns'] == xmlns)
+      .toList();
+  }
+  
   /// Returns the inner text of the node. If none is set, returns the "".
   String innerText() {
     return text ?? '';

packages/moxxmpp/lib/src/xeps/xep_0334.dart

@@ -8,8 +8,18 @@ enum MessageProcessingHint {
   store,
 }
 
-/// NOTE: We do not define a function for turning a Message Processing Hint element into
+MessageProcessingHint messageProcessingHintFromXml(XMLNode element) {
-///       an enum value since the elements do not concern us as a client.
+  switch (element.tag) {
+    case 'no-permanent-store': return MessageProcessingHint.noPermanentStore;
+    case 'no-store': return MessageProcessingHint.noStore;
+    case 'no-copy': return MessageProcessingHint.noCopies;
+    case 'store': return MessageProcessingHint.store;
+  }
+    
+  assert(false, 'Invalid Message Processing Hint: ${element.tag}');
+  return MessageProcessingHint.noStore;
+}
+
 extension XmlExtension on MessageProcessingHint {
   XMLNode toXml() {
     String tag;