Better unread counts for MUC

Use the stored version of messages for computing most recent and unread
counts, especially this means that edits are resolved so removing the
duplicate items will make sure we don't count an edit as a second unread
message.

snikket/Chat.hx

@@ -1009,16 +1009,19 @@ class Channel extends Chat {
 						promises.push(new thenshim.Promise((resolve, reject) -> {
 							client.storeMessage(message, resolve);
 						}));
-						if (message.chatId() == chatId) chatMessages.push(message);
 					case ReactionUpdateStanza(update):
 						promises.push(new thenshim.Promise((resolve, reject) -> {
-							persistence.storeReaction(client.accountId(), update, resolve);
+							persistence.storeReaction(client.accountId(), update, (_) -> resolve(null));
 						}));
 					default:
 						// ignore
 				}
 			}
-			thenshim.PromiseTools.all(promises).then((_) -> {
+			thenshim.PromiseTools.all(promises).then((stored) -> {
+				for (message in stored) {
+					if (message != null && message.chatId() == chatId) chatMessages.push(message);
+					if (chatMessages.length > 1000) chatMessages.shift(); // Save some RAM
+				}
 				if (sync.hasMore()) {
 					sync.fetchNext();
 				} else {
@@ -1029,11 +1032,20 @@ class Channel extends Chat {
 						setLastMessage(lastFromSync);
 						client.sortChats();
 					}
-					final readIndex = chatMessages.findIndex((m) -> m.serverId == readUpTo());
+					final serverIds: Map<String, Bool> = [];
+					final dedupedMessages = [];
+					chatMessages.reverse();
+					for (m in chatMessages) {
+						if (!(serverIds[m.serverId] ?? false)) {
+							dedupedMessages.unshift(m);
+							serverIds[m.serverId] = true;
+						}
+					}
+					final readIndex = dedupedMessages.findIndex((m) -> m.serverId == readUpTo());
 					if (readIndex < 0) {
-						setUnreadCount(unreadCount() + chatMessages.length);
+						setUnreadCount(unreadCount() + dedupedMessages.length);
 					} else {
-						setUnreadCount(chatMessages.length - readIndex - 1);
+						setUnreadCount(dedupedMessages.length - readIndex - 1);
 					}
 					client.trigger("chats/update", [this]);
 				}