better message status support

lib/chat/models/message_state.dart

@@ -0,0 +1,34 @@
+import 'package:change_case/change_case.dart';
+import 'package:flutter/foundation.dart';
+import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:veilid_support/veilid_support.dart';
+
+part 'message_state.freezed.dart';
+part 'message_state.g.dart';
+
+// Whether or not a message has been fully sent
+enum MessageSendState {
+  // message is still being sent
+  sending,
+  // message issued has not reached the network
+  sent,
+  // message was sent and has reached the network
+  delivered;
+
+  factory MessageSendState.fromJson(dynamic j) =>
+      MessageSendState.values.byName((j as String).toCamelCase());
+  String toJson() => name.toPascalCase();
+}
+
+@freezed
+class MessageState with _$MessageState {
+  const factory MessageState({
+    required TypedKey author,
+    required Timestamp timestamp,
+    required String text,
+    required MessageSendState? sendState,
+  }) = _MessageState;
+
+  factory MessageState.fromJson(dynamic json) =>
+      _$MessageStateFromJson(json as Map<String, dynamic>);
+}