index.ts

export class ChatGptConversationService {
  /* ... */ 
  private newMessage = (
		message: OpenAI.Chat.Completions.ChatCompletionMessageParam
	) => ({ ...message, sent: new Date() });
  sendMessages = async (
      id: string,
      messages: OpenAI.Chat.Completions.ChatCompletionMessageParam[]
    ) => {
      ConversationStorage[id].messages.push(...messages.map(this.newMessage));
      const response = await openai.chat.completions.create({
        model: "gpt-3.5-turbo",
        messages: ConversationStorage[id].messages,
      });
      ConversationStorage[id].messages.push(
        this.newMessage(response.choices[0].message)
      );
      return response.choices[0].message.content;
	};
  /* ... */
}


export class InMemoryConversationService implements ConversationService {
  /* ... */
	updateConversation = async (id: string, message: Message) => {
		const response = await this.chatgpt.sendMessages(id, [
			{ role: "user", content: message.text },
		]);

		if (!response) {
			throw new Error("No response from ChatGPT");
		}
		return this.chatgpt.getConversation(id);
	};
  /* ... */
}