src/app.ts

import express, { Request, Response, NextFunction } from "express";
import { ChildProcessWithoutNullStreams, spawn } from "child_process";
import fs from "fs";
import path from "path";
import bodyParser from "body-parser";
import axios from "axios";
import https from "https";
import os from "os";
import { encode } from "gpt-3-encoder";
import { randomUUID } from "crypto";
import { config } from "dotenv";

config();

// Constants for the server and API configuration
const port = process.env.SERVER_PORT || 3040;
const baseUrl = "https://chat.openai.com";
const apiUrl = `${baseUrl}/backend-anon/conversation`;
const refreshInterval = 60000; // Interval to refresh token in ms
const errorWait = 120000; // Wait time in ms after an error
let cloudflared: ChildProcessWithoutNullStreams;

// Initialize global variables to store the session token and device ID
let token: string;
let oaiDeviceId: string;

// Function to wait for a specified duration
const wait = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));

function GenerateCompletionId(prefix: string = "cmpl-") {
	const characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
	const length = 28;

	for (let i = 0; i < length; i++) {
		prefix += characters.charAt(Math.floor(Math.random() * characters.length));
	}

	return prefix;
}

async function* chunksToLines(chunksAsync: any) {
	let previous = "";
	for await (const chunk of chunksAsync) {
		const bufferChunk = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk);
		previous += bufferChunk;
		let eolIndex: number;
		while ((eolIndex = previous.indexOf("\n")) >= 0) {
			// line includes the EOL
			const line = previous.slice(0, eolIndex + 1).trimEnd();
			if (line === "data: [DONE]") break;
			if (line.startsWith("data: ")) yield line;
			previous = previous.slice(eolIndex + 1);
		}
	}
}

async function* linesToMessages(linesAsync: any) {
	for await (const line of linesAsync) {
		const message = line.substring("data :".length);

		yield message;
	}
}

async function* StreamCompletion(data: any) {
	yield* linesToMessages(chunksToLines(data));
}

// Setup axios instance for API requests with predefined configurations
const axiosInstance = axios.create({
	httpsAgent: new https.Agent({ rejectUnauthorized: false }),
	proxy:
		process.env.PROXY === "true"
			? {
					host: process.env.PROXY_HOST,
					port: Number(process.env.PROXY_PORT),
					auth:
						process.env.PROXY_AUTH === "true"
							? {
									username: process.env.PROXY_USERNAME,
									password: process.env.PROXY_PASSWORD,
							  }
							: undefined,
					protocol: process.env.PROXY_PROTOCOL,
			  }
			: false,
	headers: {
		accept: "*/*",
		"accept-language": "en-US,en;q=0.9",
		"cache-control": "no-cache",
		"content-type": "application/json",
		"oai-language": "en-US",
		origin: baseUrl,
		pragma: "no-cache",
		referer: baseUrl,
		"sec-ch-ua": '"Google Chrome";v="123", "Not:A-Brand";v="8", "Chromium";v="123"',
		"sec-ch-ua-mobile": "?0",
		"sec-ch-ua-platform": '"Windows"',
		"sec-fetch-dest": "empty",
		"sec-fetch-mode": "cors",
		"sec-fetch-site": "same-origin",
		"user-agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0.0.0 Safari/537.36",
	},
});

// Function to get a new session ID and token from the OpenAI API
async function getNewSessionId() {
	let newDeviceId = randomUUID();
	const response = await axiosInstance.post(
		`${baseUrl}/backend-anon/sentinel/chat-requirements`,
		{},
		{
			headers: { "oai-device-id": newDeviceId },
		}
	);
	console.log(`System: Successfully refreshed session ID and token. ${!token ? "(Now it's ready to process requests)" : ""}`);
	oaiDeviceId = newDeviceId;
	token = response.data.token;

	// console.log("New Token:", token);
	// console.log("New Device ID:", oaiDeviceId);
}

// Middleware to enable CORS and handle pre-flight requests
function enableCORS(req: Request, res: Response, next: NextFunction) {
	res.header("Access-Control-Allow-Origin", "*");
	res.header("Access-Control-Allow-Headers", "*");
	res.header("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
	if (req.method === "OPTIONS") {
		return res.status(200).end();
	}
	next();
}

// Middleware to handle chat completions
async function handleChatCompletion(req: Request, res: Response) {
	console.log("Request:", `${req.method} ${req.originalUrl}`, `${req.body?.messages?.length ?? 0} messages`, req.body.stream ? "(stream-enabled)" : "(stream-disabled)");
	try {
		const body = {
			action: "next",
			messages: req.body.messages.map((message: { role: any; content: any }) => ({
				author: { role: message.role },
				content: { content_type: "text", parts: [message.content] },
			})),
			parent_message_id: randomUUID(),
			model: "text-davinci-002-render-sha",
			timezone_offset_min: -180,
			suggestions: [],
			history_and_training_disabled: true,
			conversation_mode: { kind: "primary_assistant" },
			websocket_request_id: randomUUID(),
		};

		let promptTokens = 0;
		let completionTokens = 0;

		for (let message of req.body.messages) {
			promptTokens += encode(message.content).length;
		}

		const response = await axiosInstance.post(apiUrl, body, {
			responseType: "stream",
			headers: {
				"oai-device-id": oaiDeviceId,
				"openai-sentinel-chat-requirements-token": token,
			},
		});

		// Set the response headers based on the request type
		if (req.body.stream) {
			res.setHeader("Content-Type", "text/event-stream");
			res.setHeader("Cache-Control", "no-cache");
			res.setHeader("Connection", "keep-alive");
		} else {
			res.setHeader("Content-Type", "application/json");
		}

		let fullContent = "";
		let requestId = GenerateCompletionId("chatcmpl-");
		let created = Math.floor(Date.now() / 1000); // Unix timestamp in seconds
		let finish_reason = null;

		for await (const message of StreamCompletion(response.data)) {
			// Skip heartbeat detection
			if (message.match(/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}.\d{6}$/)) continue;

			const parsed = JSON.parse(message);

			let content = parsed?.message?.content?.parts[0] ?? "";
			let status = parsed?.message?.status ?? "";

			for (let message of req.body.messages) {
				if (message.content === content) {
					content = "";
					break;
				}
			}

			switch (status) {
				case "in_progress":
					finish_reason = null;
					break;
				case "finished_successfully":
					let finish_reason_data = parsed?.message?.metadata?.finish_details?.type ?? null;
					switch (finish_reason_data) {
						case "max_tokens":
							finish_reason = "length";
							break;
						case "stop":
						default:
							finish_reason = "stop";
					}
					break;
				default:
					finish_reason = null;
			}

			if (content === "") continue;

			let completionChunk = content.replace(fullContent, "");

			completionTokens += encode(completionChunk).length;

			if (req.body.stream) {
				let response = {
					id: requestId,
					created: created,
					object: "chat.completion.chunk",
					model: "gpt-3.5-turbo",
					choices: [
						{
							delta: {
								content: completionChunk,
							},
							index: 0,
							finish_reason: finish_reason,
						},
					],
				};

				res.write(`data: ${JSON.stringify(response)}\n\n`);
			}

			fullContent = content.length > fullContent.length ? content : fullContent;
		}

		if (req.body.stream) {
			res.write(
				`data: ${JSON.stringify({
					id: requestId,
					created: created,
					object: "chat.completion.chunk",
					model: "gpt-3.5-turbo",
					choices: [
						{
							delta: {
								content: "",
							},
							index: 0,
							finish_reason: finish_reason,
						},
					],
				})}\n\n`
			);
		} else {
			res.write(
				JSON.stringify({
					id: requestId,
					created: created,
					model: "gpt-3.5-turbo",
					object: "chat.completion",
					choices: [
						{
							finish_reason: finish_reason,
							index: 0,
							message: {
								content: fullContent,
								role: "assistant",
							},
						},
					],
					usage: {
						prompt_tokens: promptTokens,
						completion_tokens: completionTokens,
						total_tokens: promptTokens + completionTokens,
					},
				})
			);
		}

		res.end();
	} catch (error: any) {
		// console.log('Error:', error.response?.data ?? error.message);
		if (!res.headersSent) res.setHeader("Content-Type", "application/json");
		// console.error('Error handling chat completion:', error);
		res.write(
			JSON.stringify({
				status: false,
				error: {
					message: "An error occurred. Please check the server console to confirm it is ready and free of errors. Additionally, ensure that your request complies with OpenAI's policy.",
					type: "invalid_request_error",
				},
				support: "https://discord.pawan.krd",
			})
		);
		res.end();
	}
}

// Initialize Express app and use middlewares
const app = express();
app.use(bodyParser.json());
app.use(enableCORS);

// Route to handle POST requests for chat completions
app.post("/v1/chat/completions", handleChatCompletion);

// 404 handler for unmatched routes
app.use((req, res) =>
	res.status(404).send({
		status: false,
		error: {
			message: `The requested endpoint (${req.method.toLocaleUpperCase()} ${req.path}) was not found. please make sure to use "http://localhost:3040/v1" as the base URL.`,
			type: "invalid_request_error",
		},
		support: "https://discord.pawan.krd",
	})
);

async function DownloadCloudflared(): Promise<string> {
	const platform = os.platform();
	let url: string;

	if (platform === "win32") {
		const arch = os.arch() === "x64" ? "amd64" : "386";
		url = `https://github.com/cloudflare/cloudflared/releases/latest/download/cloudflared-windows-${arch}.exe`;
	} else {
		let arch = os.arch();
		switch (arch) {
			case "x64":
				arch = "amd64";
				break;
			case "arm":
			case "arm64":
				break;
			default:
				arch = "amd64"; // Default to amd64 if unknown architecture
		}
		const platformLower = platform.toLowerCase();
		url = `https://github.com/cloudflare/cloudflared/releases/latest/download/cloudflared-${platformLower}-${arch}`;
	}

	const fileName = platform === "win32" ? "cloudflared.exe" : "cloudflared";
	const filePath = path.resolve(fileName);

	if (fs.existsSync(filePath)) {
		return filePath;
	}

	try {
		const response = await axiosInstance({
			method: "get",
			url: url,
			responseType: "stream",
		});

		const writer = fs.createWriteStream(filePath);

		response.data.pipe(writer);

		return new Promise<string>((resolve, reject) => {
			writer.on("finish", () => {
				if (platform !== "win32") {
					fs.chmodSync(filePath, 0o755);
				}
				resolve(filePath);
			});

			writer.on("error", reject);
		});
	} catch (error: any) {
		// console.error("Failed to download file:", error.message);
		return null;
	}
}

async function StartCloudflaredTunnel(cloudflaredPath: string): Promise<string> {
	const localUrl = `http://localhost:${port}`;
	return new Promise<string>((resolve, reject) => {
		cloudflared = spawn(cloudflaredPath, ["tunnel", "--url", localUrl]);

		cloudflared.stdout.on("data", (data: any) => {
			const output = data.toString();
			// console.log("Cloudflared Output:", output);

			// Adjusted regex to specifically match URLs that end with .trycloudflare.com
			const urlMatch = output.match(/https:\/\/[^\s]+\.trycloudflare\.com/);
			if (urlMatch) {
				let url = urlMatch[0];
				resolve(url);
			}
		});

		cloudflared.stderr.on("data", (data: any) => {
			const output = data.toString();
			// console.error("Error from cloudflared:", output);

			const urlMatch = output.match(/https:\/\/[^\s]+\.trycloudflare\.com/);
			if (urlMatch) {
				let url = urlMatch[0];
				resolve(url);
			}
		});

		cloudflared.on("close", (code: any) => {
			resolve(null);
			// console.log(`Cloudflared tunnel process exited with code ${code}`);
		});
	});
}

// Start the server and the session ID refresh loop
app.listen(port, async () => {
	if (process.env.CLOUDFLARED === undefined) process.env.CLOUDFLARED = "true";
	let cloudflared = process.env.CLOUDFLARED === "true";
	let filePath: string;
	let publicURL: string;
	if (cloudflared) {
		filePath = await DownloadCloudflared();
		publicURL = await StartCloudflaredTunnel(filePath);
	}

	console.log(`💡 Server is running at http://localhost:${port}`);
	console.log();
	console.log(`🔗 Local Base URL: http://localhost:${port}/v1`);
	console.log(`🔗 Local Endpoint: http://localhost:${port}/v1/chat/completions`);
	console.log();
	if (cloudflared && publicURL) console.log(`🔗 Public Base URL: ${publicURL}/v1`);
	if (cloudflared && publicURL) console.log(`🔗 Public Endpoint: ${publicURL}/v1/chat/completions`);
	else if (cloudflared && !publicURL) {
		console.log("🔗 Public Endpoint: (Failed to start cloudflared tunnel, please restart the server.)");
		if (filePath) fs.unlinkSync(filePath);
	}
	if (cloudflared && publicURL) console.log();
	console.log("📝 Author: Pawan.Krd");
	console.log(`🌐 Discord server: https://discord.gg/pawan`);
	console.log("🌍 GitHub Repository: https://github.com/PawanOsman/ChatGPT");
	console.log(`💖 Don't forget to star the repository if you like this project!`);
	console.log();

	setTimeout(async () => {
		while (true) {
			try {
				await getNewSessionId();
				await wait(refreshInterval);
			} catch (error) {
				console.error("Error refreshing session ID, retrying in 2 minute...");
				console.error("If this error persists, your country may not be supported yet.");
				console.error("If your country was the issue, please consider using a U.S. VPN.");
				await wait(errorWait);
			}
		}
	}, 0);
});