jan/server/middleware/s3.ts

import { join } from "path";

// Middleware to intercept requests and proxy if certain conditions are met
const config = {
  endpoint: process.env.AWS_ENDPOINT,
  region: process.env.AWS_REGION,
  credentials: {
    accessKeyId: process.env.AWS_ACCESS_KEY_ID,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  },
};

const S3_BUCKET_NAME = process.env.S3_BUCKET_NAME;

const fs = require("@cyclic.sh/s3fs")(S3_BUCKET_NAME, config);
const PROXY_PREFIX = "/v1/fs";
const PROXY_ROUTES = ["/threads", "/messages"];

export const s3 = (req: any, reply: any, done: any) => {
  // Proxy FS requests to S3 using S3FS
  if (req.url.startsWith(PROXY_PREFIX)) {
    const route = req.url.split("/").pop();
    const args = parseRequestArgs(req);

    // Proxy matched requests to the s3fs module
    if (args.length && PROXY_ROUTES.some((route) => args[0].includes(route))) {
      try {
        // Handle customized route
        // S3FS does not handle appendFileSync
        if (route === "appendFileSync") {
          let result = handAppendFileSync(args);

          reply.status(200).send(result);
          return;
        }
        // Reroute the other requests to the s3fs module
        const result = fs[route](...args);
        reply.status(200).send(result);
        return;
      } catch (ex) {
        console.log(ex);
      }
    }
  }
  // Let other requests go through
  done();
};

const parseRequestArgs = (req: Request) => {
  const {
    getJanDataFolderPath,
    normalizeFilePath,
  } = require("@janhq/core/node");

  return JSON.parse(req.body as any).map((arg: any) =>
    typeof arg === "string" &&
    (arg.startsWith(`file:/`) || arg.startsWith(`file:\\`))
      ? join(getJanDataFolderPath(), normalizeFilePath(arg))
      : arg
  );
};

const handAppendFileSync = (args: any[]) => {
  if (fs.existsSync(args[0])) {
    const data = fs.readFileSync(args[0], "utf-8");
    return fs.writeFileSync(args[0], data + args[1]);
  } else {
    return fs.writeFileSync(args[0], args[1]);
  }
};