galerie/srv/src/sync.ts

import { createHash } from "crypto";
import { Request, Response } from "express";
import { readdirSync, existsSync, mkdirSync, statSync, readFileSync } from "fs";
import path from "path";

class Sync {
  constructor() {
    this.root = path.join(process.cwd(), "public");

    if (!existsSync(this.root)) {
      mkdirSync(this.root);
    }

    this.update();
  }

  async update() {
    return new Promise<void>((res, rej) => {
      this.files = readdirSync(this.root).filter(async (v) => {
        let f = path.join(this.root, v);
        if (existsSync(f)) {
          let s = statSync(f);
          return s.isFile() && s.size > 1;
        } else {
          await this.update();
          res();
        }
      })

      let c = createHash("sha1");

      this.files.forEach(async (v) => {
        let f = path.join(this.root, v);

        if (existsSync(f))
          c.update(readFileSync(f))
        else {
          await this.update();
          res();
        }
      });

      this.checksum = c.digest("hex");
      res();
    });
  }

  root: string;
  files: string[];
  checksum: string;
}

const state: Sync = new Sync();

let sync = async (req: Request, res: Response) => {
  switch (req.method) {
    case "GET": { // "Update me"
      await state.update();
      res.write(JSON.stringify({
        checksum: state.checksum,
        files: state.files
      }));
      break;
    }

    case "POST": { // "Am I up to date?"
      await state.update();
      let checksum = req.body;

      if (checksum == state.checksum)
        res.write('{"valid": true}');
      else
        res.write('{"valid": false}');

      break;
    }
  }
  res.end();
}

export default sync;