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openai.ts
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openai.ts
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import EventEmitter from "events";
import { Configuration, OpenAIApi } from "openai";
import SSE from "./sse";
import { OpenAIMessage, Parameters } from "./types";
export const defaultSystemPrompt = `
You are ChatGPT, a large language model trained by OpenAI.
Knowledge cutoff: 2021-09
Current date and time: {{ datetime }}
`.trim();
export const defaultModel = 'gpt-3.5-turbo';
export interface OpenAIResponseChunk {
id?: string;
done: boolean;
choices?: {
delta: {
content: string;
};
index: number;
finish_reason: string | null;
}[];
model?: string;
}
function parseResponseChunk(buffer: any): OpenAIResponseChunk {
const chunk = buffer.toString().replace('data: ', '').trim();
if (chunk === '[DONE]') {
return {
done: true,
};
}
const parsed = JSON.parse(chunk);
return {
id: parsed.id,
done: false,
choices: parsed.choices,
model: parsed.model,
};
}
export async function createChatCompletion(messages: OpenAIMessage[], parameters: Parameters): Promise<string> {
if (!parameters.apiKey) {
throw new Error('No API key provided');
}
const configuration = new Configuration({
apiKey: parameters.apiKey,
});
const openai = new OpenAIApi(configuration);
const response = await openai.createChatCompletion({
model: parameters.model,
temperature: parameters.temperature,
messages: messages as any,
});
return response.data.choices[0].message?.content?.trim() || '';
}
export async function createStreamingChatCompletion(messages: OpenAIMessage[], parameters: Parameters) {
if (!parameters.apiKey) {
throw new Error('No API key provided');
}
const emitter = new EventEmitter();
let messagesToSend = [...messages].filter(m => m.role !== 'app');
for (let i = messagesToSend.length - 1; i >= 0; i--) {
const m = messagesToSend[i];
if (m.role === 'user') {
break;
}
if (m.role === 'assistant') {
messagesToSend.splice(i, 1);
}
}
messagesToSend.unshift({
role: 'system',
content: (parameters.initialSystemPrompt || defaultSystemPrompt).replace('{{ datetime }}', new Date().toLocaleString()),
});
messagesToSend = await selectMessagesToSendSafely(messagesToSend, 2048);
const eventSource = new SSE('https://api.openai.com/v1/chat/completions', {
method: "POST",
headers: {
'Accept': 'application/json, text/plain, */*',
'Authorization': `Bearer ${parameters.apiKey}`,
'Content-Type': 'application/json',
},
payload: JSON.stringify({
"model": parameters.model,
"messages": messagesToSend,
"temperature": parameters.temperature,
"stream": true,
}),
}) as SSE;
// TODO: enable (optional) server-side completion
/*
const eventSource = new SSE('/chatapi/completion/streaming', {
method: "POST",
headers: {
'Accept': 'application/json, text/plain, *\/*',
'Authorization': `Bearer ${(backend.current as any).token}`,
'Content-Type': 'application/json',
},
payload: JSON.stringify({
"model": "gpt-3.5-turbo",
"messages": messagesToSend,
"temperature": parameters.temperature,
"stream": true,
}),
}) as SSE;
*/
let contents = '';
eventSource.addEventListener('error', (event: any) => {
if (!contents) {
let error = event.data;
try {
error = JSON.parse(error).error.message;
} catch (e) {}
emitter.emit('error', error);
}
});
eventSource.addEventListener('message', async (event: any) => {
if (event.data === '[DONE]') {
emitter.emit('done');
return;
}
try {
const chunk = parseResponseChunk(event.data);
if (chunk.choices && chunk.choices.length > 0) {
contents += chunk.choices[0]?.delta?.content || '';
emitter.emit('data', contents);
}
} catch (e) {
console.error(e);
}
});
eventSource.stream();
return {
emitter,
cancel: () => eventSource.close(),
};
}
async function selectMessagesToSendSafely(messages: OpenAIMessage[], maxTokens: number) {
const { ChatHistoryTrimmer } = await import(/* webpackPreload: true */ './tokenizer/chat-history-trimmer');
const compressor = new ChatHistoryTrimmer(messages, {
maxTokens,
preserveFirstUserMessage: true,
preserveSystemPrompt: true,
});
return compressor.process();
}
setTimeout(() => selectMessagesToSendSafely([], 2048), 2000);