[Mongo] count messages (aggregate) only when needed (#863)

* [Mongo] count messages (aggregate) only when needed

* more restrictive

* even more stricter

* Update src/routes/+layout.server.ts

Co-authored-by: Eliott C. <[email protected]>

* format

---------

Co-authored-by: Eliott C. <[email protected]>

src/routes/+layout.server.ts

@@ -46,26 +46,6 @@ export const load: LayoutServerLoad = async ({ locals, depends }) => {
 		});
 	}
 
-	// get the number of messages where `from === "assistant"` across all conversations.
-	const totalMessages =
-		(
-			await collections.conversations
-				.aggregate([
-					{ $match: authCondition(locals) },
-					{ $project: { messages: 1 } },
-					{ $unwind: "$messages" },
-					{ $match: { "messages.from": "assistant" } },
-					{ $count: "messages" },
-				])
-				.toArray()
-		)[0]?.messages ?? 0;
-
-	const messagesBeforeLogin = MESSAGES_BEFORE_LOGIN ? parseInt(MESSAGES_BEFORE_LOGIN) : 0;
-
-	const userHasExceededMessages = messagesBeforeLogin > 0 && totalMessages > messagesBeforeLogin;
-
-	const loginRequired = requiresUser && !locals.user && userHasExceededMessages;
-
 	const enableAssistants = ENABLE_ASSISTANTS === "true";
 
 	const assistantActive = !models.map(({ id }) => id).includes(settings?.activeModel ?? "");
@@ -101,6 +81,29 @@ export const load: LayoutServerLoad = async ({ locals, depends }) => {
 
 	const assistants = await collections.assistants.find({ _id: { $in: assistantIds } }).toArray();
 
+	const messagesBeforeLogin = MESSAGES_BEFORE_LOGIN ? parseInt(MESSAGES_BEFORE_LOGIN) : 0;
+
+	let loginRequired = conversations.length > messagesBeforeLogin;
+
+	if (!loginRequired && messagesBeforeLogin && requiresUser && !locals.user) {
+		// get the number of messages where `from === "assistant"` across all conversations.
+		const totalMessages =
+			(
+				await collections.conversations
+					.aggregate([
+						{ $match: authCondition(locals), "messages.from": "assistant" },
+						{ $project: { messages: 1 } },
+						{ $limit: messagesBeforeLogin + 1 },
+						{ $unwind: "$messages" },
+						{ $match: { "messages.from": "assistant" } },
+						{ $count: "messages" },
+					])
+					.toArray()
+			)[0]?.messages ?? 0;
+
+		loginRequired = totalMessages > messagesBeforeLogin;
+	}
+
 	return {
 		conversations: conversations.map((conv) => {
 			if (settings?.hideEmojiOnSidebar) {