Limit sent chat to 2048 tokens.

This also solves the issue where we would request more tokens,
than the model is capable of (over 4096)

src/toOpenAIMessages.ts

@@ -3,6 +3,7 @@ import { Collection, Message as DiscordMessage } from "discord.js";
 import FoldToAscii from "fold-to-ascii";
 
 import config from "./config.json";
+import countTokens from "./tokenCounter";
 
 /**
  * Formats the message to use as a message content in OpenAI api
@@ -74,24 +75,29 @@ function getAuthorUsername(message: DiscordMessage): string {
 }
 
 /**
- * Converts the Collection of Discord Messages to array of OpenAI Messages
+ * Converts the Collection of Discord Messages to array of OpenAI Messages to send
  * @param messages the collection to convert
  * @returns the converted messages
  */
 export default function toOpenAIMessages(messages: Collection<string, DiscordMessage>): OpenAIMessage[] {
   const rvalue: OpenAIMessage[] = [];
+  let tokenCount = 0;
+
+  messages.sort((a, b) => b.createdTimestamp - a.createdTimestamp);
+
+  for (const message of messages.values()) {
+    const content = formatMessage(message);
+    // FIXME: tokens are not being counted properly (it's lower than it is) but it's enough for me for now.
+    tokenCount += countTokens(content);
+    if (tokenCount > 2048) break;
+    rvalue.push({
+      role: message.author.id == message.client.user.id ? "assistant" : "user",
+      content: content,
+      name: getAuthorUsername(message),
+    });
+  }
 
   rvalue.push({ role: "system", content: config.systemPrompt});
 
-  messages
-  .sort((a, b) => a.createdTimestamp - b.createdTimestamp)
-  .each(message => {
-    rvalue.push({
-      role: message.author.id == message.client.user.id ? "assistant" : "user",
-      content: formatMessage(message),
-      name: getAuthorUsername(message),
-    });
-  });
-
-  return rvalue;
+  return rvalue.reverse();
 }

src/tokenCounter.ts

@@ -0,0 +1,5 @@
+import { encode } from "gpt-3-encoder";
+
+export default function countTokens(text: string): number {
+    return encode(text).length;
+}