Refactor

lib/llm.ts

@@ -3,6 +3,7 @@ import { fileURLToPath } from "node:url";
 
 import {
   type ChatHistoryItem,
+  type ChatSessionModelFunctions,
   type LLamaChatPromptOptions,
   LlamaChatSession,
   type LlamaModel,
@@ -13,66 +14,88 @@ import {
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
+const llama = await getLlama({
+  maxThreads: 2,
+});
+
 export async function getModel(model: string) {
   const downloader = await createModelDownloader({
     modelUri: `hf:${model}`,
     dirPath: path.join(__dirname, "..", "models"),
   });
   const modelPath = await downloader.download();
-  const llama = await getLlama({
-    maxThreads: 2,
-  });
   return await llama.loadModel({ modelPath });
 }
 
-export type Message = {
-  type: "system" | "model" | "user";
-  text: string;
-};
+export const grammar = await llama.createGrammarForJsonSchema({
+  type: "object",
+  properties: {
+    text: { type: "string" },
+  },
+  required: ["text"],
+  additionalProperties: false,
+});
 
-export async function complete(
-  model: LlamaModel,
-  messages: Message[],
-  options: LLamaChatPromptOptions = {},
-) {
-  if (messages.length < 1) throw new Error("messages are empty");
-  const init = messages.slice(0, -1);
-  const last = messages.at(-1) as Message;
-  const context = await model.createContext();
-  const session = new LlamaChatSession({
-    contextSequence: context.getSequence(),
-    chatWrapper: resolveChatWrapper(model),
-  });
-  session.setChatHistory(
-    init.map((m): ChatHistoryItem => {
-      switch (m.type) {
-        case "system":
-          return {
-            type: "system",
-            text: m.text,
-          };
-        case "model":
-          return {
-            type: "model",
-            response: [m.text],
-          };
-        case "user":
-          return {
-            type: "user",
-            text: m.text,
-          };
-      }
-    }),
-  );
-
-  const res = await session.prompt(last.text, {
-    trimWhitespaceSuffix: true,
-    onResponseChunk(chunk) {
-      process.stderr.write(chunk.text);
-    },
-    ...options,
-  });
-  session.dispose();
-  await context.dispose();
-  return res;
+export function parseResponse(text: string) {
+  try {
+    const res = grammar.parse(text.trim());
+    return res.text;
+  } catch (e) {
+    console.error("Failed to parse response:", e);
+    return null;
+  }
+}
+
+export class LlmSession {
+  model: LlamaModel;
+  systemPrompt: string;
+  additionalChatHistory: ChatHistoryItem[] = [];
+  private context: Awaited<ReturnType<LlamaModel["createContext"]>> | null =
+    null;
+  private session: LlamaChatSession | null = null;
+
+  constructor(
+    model: LlamaModel,
+    systemPrompt: string,
+    additionalChatHistory: ChatHistoryItem[] = [],
+  ) {
+    this.model = model;
+    this.systemPrompt = systemPrompt;
+    this.additionalChatHistory = additionalChatHistory;
+  }
+
+  async init() {
+    this.context = await this.model.createContext();
+    this.session = new LlamaChatSession({
+      contextSequence: this.context.getSequence(),
+      chatWrapper: resolveChatWrapper(this.model),
+    });
+    this.session.setChatHistory([
+      {
+        type: "system",
+        text: this.systemPrompt,
+      },
+      ...this.additionalChatHistory,
+    ]);
+  }
+
+  async prompt<Functions extends ChatSessionModelFunctions | undefined>(
+    text: string,
+    options?: LLamaChatPromptOptions<Functions>,
+  ) {
+    if (!this.session) await this.init();
+    if (!this.session) throw new Error("session is not initialized");
+    return await this.session.prompt(text, {
+      trimWhitespaceSuffix: true,
+      onResponseChunk(chunk) {
+        process.stderr.write(chunk.text);
+      },
+      ...options,
+    });
+  }
+
+  async [Symbol.asyncDispose]() {
+    await this.session?.dispose();
+    await this.context?.dispose();
+  }
 }