use prev_content to calculate displayname and avatar_url, if content unavailable

lib/src/event.dart

@@ -89,7 +89,13 @@ class Event extends MatrixEvent {
     this.roomId = roomId ?? room?.id;
     this.senderId = senderId;
     this.unsigned = unsigned;
-    this.prevContent = prevContent;
+    // synapse unfortunatley isn't following the spec and tosses the prev_content
+    // into the unsigned block
+    this.prevContent = prevContent != null && prevContent.isNotEmpty
+        ? prevContent
+        : (unsigned != null && unsigned['prev_content'] is Map
+            ? unsigned['prev_content']
+            : null);
     this.stateKey = stateKey;
     this.originServerTs = originServerTs;
   }

lib/src/user.dart

@@ -71,7 +71,10 @@ class User extends Event {
   String get id => stateKey;
 
   /// The displayname of the user if the user has set one.
-  String get displayName => content != null ? content['displayname'] : null;
+  String get displayName =>
+      content != null && content.containsKey('displayname')
+          ? content['displayname']
+          : (prevContent != null ? prevContent['displayname'] : null);
 
   /// Returns the power level of this user.
   int get powerLevel => room?.getPowerLevelByUserId(id);
@@ -89,9 +92,13 @@ class User extends Event {
       }, orElse: () => Membership.join);
 
   /// The avatar if the user has one.
-  Uri get avatarUrl => content != null && content['avatar_url'] is String
-      ? Uri.parse(content['avatar_url'])
-      : null;
+  Uri get avatarUrl => content != null && content.containsKey('avatar_url')
+      ? (content['avatar_url'] is String
+          ? Uri.parse(content['avatar_url'])
+          : null)
+      : (prevContent != null && prevContent['avatar_url'] is String
+          ? Uri.parse(prevContent['avatar_url'])
+          : null);
 
   /// Returns the displayname or the local part of the Matrix ID if the user
   /// has no displayname. If [formatLocalpart] is true, then the localpart will

pubspec.lock

@@ -22,13 +22,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.2.2"
-  archive:
-    dependency: transitive
-    description:
-      name: archive
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.0.13"
   args:
     dependency: transitive
     description:
@@ -323,6 +316,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.12.6"
+  matrix_file_e2ee:
+    dependency: "direct main"
+    description:
+      name: matrix_file_e2ee
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.4"
   meta:
     dependency: transitive
     description:
@@ -331,7 +331,7 @@ packages:
     source: hosted
     version: "1.1.8"
   mime:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: mime
       url: "https://pub.dartlang.org"
@@ -386,6 +386,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.4.8"
+  olm:
+    dependency: "direct main"
+    description:
+      name: olm
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.1"
   package_config:
     dependency: transitive
     description:
@@ -414,13 +421,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.9.0"
-  petitparser:
-    dependency: transitive
-    description:
-      name: petitparser
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "3.0.2"
   pointycastle:
     dependency: transitive
     description:
@@ -652,13 +652,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.5.4"
-  xml:
-    dependency: transitive
-    description:
-      name: xml
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "3.7.0"
   yaml:
     dependency: transitive
     description: