Add daily cleanup task to delete old files and update README

Author: Ray6602

README.md

@@ -1,10 +1,8 @@
 # Secure Document Share - Backend
 
-## Overview
-This is the backend for our Secure Document Share App.
-
-## Features
-tbd
+## About
+This is the backend for our Secure Document Share App.<br>
+It provides the WebSocket and Http Server.
 
 ### Prerequisites
 Ensure you have the following installed:
@@ -30,3 +28,8 @@ Ensure you have the following installed:
    ```sh
    node server.mjs --port=<port>
    ```
+
+4. **Setup the cron**
+    ```sh
+    0 0 * * * /usr/bin/node /path/to/your/project/cron/daily.mjs
+    ```

cron/daily.mjs

@@ -0,0 +1,4 @@
+import { deleteOldFiles } from './lib.js';
+
+// Run the cleanup task to delete old files
+deleteOldFiles('./data', 3).catch(console.error);

cron/lib.js

@@ -0,0 +1,20 @@
+import * as fs from 'fs/promises';
+import * as path from 'path';
+
+export async function deleteOldFiles(dir, retentionDays) {
+    const now = Date.now();
+    const files = await fs.readdir(dir);
+
+    for (const file of files) {
+        const filePath = path.join(dir, file);
+        const stat = await fs.stat(filePath);
+
+        if (file.endsWith('.bin')) {
+            const ageInDays = (now - stat.mtimeMs) / (1000 * 60 * 60 * 24);
+            if (ageInDays > retentionDays && stat.isFile()) {
+                await fs.unlink(filePath);
+                console.log(`Deleted: ${filePath}`);
+            }
+        }
+    }
+}