cancel if result is undefined

app.js

@@ -1,6 +1,7 @@
 const { app, BrowserWindow, ipcMain, dialog } = require('electron');
 const { setupTitlebar, attachTitlebarToWindow } = require('custom-electron-titlebar/main');
 const windowManager = require('./ui/windowManager');
+const osuUtil = require('./osuUtil');
 
 const run = () => {
     const gotTheLock = app.requestSingleInstanceLock()
@@ -20,11 +21,14 @@ const run = () => {
         app.on('window-all-closed', () => {
             app.quit()
         })
-        ipcMain.handle('open-folder-dialog', async (event) => {
+        ipcMain.handle('set-osu-dir', async (event) => {
             const yes = await dialog.showOpenDialog({
                 properties: ['openDirectory']
             })
-            return yes.filePaths;
+            if (yes.filePaths.length <= 0)
+                return undefined;
+            const folderPath = yes.filePaths[0];
+            return osuUtil.isValidOsuFolder(folderPath);
         })
     })
 }

osuUtil.js

@@ -0,0 +1,42 @@
+const fs = require('fs');
+const path = require('path');
+
+const osuEntities = [
+    'avcodec-51.dll',
+    'avformat-52.dll',
+    'avutil-49.dll',
+    'bass.dll',
+    'bass_fx.dll',
+    'collection.db',
+    'd3dcompiler_47.dll',
+    'Data',
+    'Downloads',
+    'libEGL.dll',
+    'libGLESv2.dll',
+    'Logs',
+    'Microsoft.Ink.dll',
+    'OpenTK.dll',
+    'osu!.cfg',
+    'osu!.db',
+    'osu!.exe',
+    'osu!auth.dll',
+    'osu!gameplay.dll',
+    'osu!seasonal.dll',
+    'osu!ui.dll',
+    'presence.db',
+    'pthreadGC2.dll',
+    'scores.db',
+    'Skins',
+    'Songs'
+]
+
+async function isValidOsuFolder(path) {
+    const allFiles = await fs.promises.readdir(path);
+    let matches = 0;
+    for (const file of allFiles) {
+        if (osuEntities.includes(file)) matches = matches + 1;
+    }
+    return Math.round((matches / osuEntities.length) * 100) >= 60;
+}
+
+module.exports = { isValidOsuFolder }

preload/preload.js

@@ -16,7 +16,9 @@ window.addEventListener('DOMContentLoaded', () => {
     const $ = require('jquery');
 
     $("#folder-btn").on('click', async () => {
-        const folderLoc = await ipcRenderer.invoke('open-folder-dialog');
+        const success = await ipcRenderer.invoke('set-osu-dir');
-        alert(folderLoc);
+        if (success == undefined)
+            return;
+        alert(success);
     });
 })