feat: implement token counter (#3)

components/ChatView/index.tsx

@@ -3,13 +3,17 @@ import { useEffect, useRef, useState } from "react";
 import { toast } from "react-hot-toast";
 import { getAssistantById, getPromptGeneratorOfAssistant, useChatStore, useMessageStore, useConnectionStore } from "@/store";
 import { CreatorRole, Message } from "@/types";
-import { generateUUID } from "@/utils";
+import { countTextTokens, generateUUID } from "@/utils";
 import Header from "./Header";
 import EmptyView from "../EmptyView";
 import MessageView from "./MessageView";
 import MessageTextarea from "./MessageTextarea";
 import MessageLoader from "../MessageLoader";
 
+// The maximum number of tokens that can be sent to the OpenAI API.
+// reference: https://platform.openai.com/docs/api-reference/completions/create#completions/create-max_tokens
+const MAX_TOKENS = 4000;
+
 const ChatView = () => {
   const connectionStore = useConnectionStore();
   const chatStore = useChatStore();
@@ -86,24 +90,38 @@ const ChatView = () => {
     setIsRequesting(true);
     const messageList = messageStore.getState().messageList.filter((message) => message.chatId === currentChat.id);
     let prompt = "";
+    let tokens = 0;
     if (connectionStore.currentConnectionCtx?.database) {
       const tables = await connectionStore.getOrFetchDatabaseSchema(connectionStore.currentConnectionCtx?.database);
       const promptGenerator = getPromptGeneratorOfAssistant(getAssistantById(currentChat.assistantId)!);
-      prompt = promptGenerator(tables.map((table) => table.structure).join("/n"));
+      let schema = "";
+      for (const table of tables) {
+        if (tokens < MAX_TOKENS / 2) {
+          tokens += countTextTokens(schema + table.structure);
+          schema += table.structure;
         }
+      }
+      prompt = promptGenerator(schema);
+    }
+    let formatedMessageList = [];
+    for (let i = messageList.length - 1; i >= 0; i--) {
+      const message = messageList[i];
+      if (tokens < MAX_TOKENS) {
+        tokens += countTextTokens(message.content);
+        formatedMessageList.unshift({
+          role: message.creatorRole,
+          content: message.content,
+        });
+      }
+    }
+    formatedMessageList.unshift({
+      role: CreatorRole.System,
+      content: prompt,
+    });
     const rawRes = await fetch("/api/chat", {
       method: "POST",
       body: JSON.stringify({
-        messages: [
-          {
-            role: CreatorRole.System,
-            content: prompt,
-          },
-          ...messageList.map((message) => ({
-            role: message.creatorRole,
-            content: message.content,
-          })),
-        ],
+        messages: formatedMessageList,
       }),
     });
     setIsRequesting(false);

package.json

@@ -35,6 +35,7 @@
     "zustand": "^4.3.6"
   },
   "devDependencies": {
+    "@nem035/gpt-3-encoder": "^1.1.7",
     "@tailwindcss/typography": "^0.5.9",
     "@types/lodash-es": "^4.17.7",
     "@types/node": "^18.11.18",

pages/api/chat.ts

@@ -17,7 +17,6 @@ const handler = async (req: NextRequest) => {
     body: JSON.stringify({
       model: "gpt-3.5-turbo",
       messages: reqBody.messages,
-      max_tokens: 1000,
       temperature: 0,
       frequency_penalty: 0.0,
       presence_penalty: 0.0,

pnpm-lock.yaml

@@ -5,6 +5,7 @@ specifiers:
   '@emotion/styled': ^11.10.6
   '@mui/material': ^5.11.14
   '@mui/styled-engine-sc': ^5.11.11
+  '@nem035/gpt-3-encoder': ^1.1.7
   '@tailwindcss/typography': ^0.5.9
   '@types/lodash-es': ^4.17.7
   '@types/node': ^18.11.18
@@ -74,6 +75,7 @@ dependencies:
   zustand: 4.3.6_react@18.2.0
 
 devDependencies:
+  '@nem035/gpt-3-encoder': 1.1.7
   '@tailwindcss/typography': 0.5.9_tailwindcss@3.2.7
   '@types/lodash-es': 4.17.7
   '@types/node': 18.15.3
@@ -580,6 +582,10 @@ packages:
       react-is: 18.2.0
     dev: false
 
+  /@nem035/gpt-3-encoder/1.1.7:
+    resolution: {integrity: sha512-dtOenP4ZAmsKXkobTDUCcbkQvPJbuJ6Kp/LHqWDYLK//XNgGs3Re8ymcQzyVhtph8JckdI3K8FR5Q+6mX7HnpQ==}
+    dev: true
+
   /@next/env/13.2.4:
     resolution: {integrity: sha512-+Mq3TtpkeeKFZanPturjcXt+KHfKYnLlX6jMLyCrmpq6OOs4i1GqBOAauSkii9QeKCMTYzGppar21JU57b/GEA==}
     dev: false

utils/openai.ts

@@ -1 +1,7 @@
+import { encode } from "@nem035/gpt-3-encoder";
+
 export const openAIApiKey = process.env.OPENAI_API_KEY;
+
+export const countTextTokens = (text: string) => {
+  return encode(text).length;
+};