feat: add way to select game dir

src/main/index.ts

@@ -1,4 +1,4 @@
-import { app, shell, BrowserWindow, ipcMain } from 'electron'
+import { app, shell, BrowserWindow, ipcMain, dialog } from 'electron'
 import { join } from 'path'
 import { setMainWindow } from './events'
 import { IPC, type UserSettings, type PlayOptions } from '../shared/ipc'
@@ -8,6 +8,12 @@ import { getPackMetaCached } from './modpack'
 import { getSettings, setSettings } from './settings'
 import { paths } from './paths'
 import { initUpdater, quitAndInstallUpdate } from './updater'
+import {
+  isFirstLaunch,
+  writeLauncherConfig,
+  defaultDataDir,
+  readLauncherConfigSync
+} from './launcher-config'
 
 function createWindow(): BrowserWindow {
   const win = new BrowserWindow({
@@ -60,6 +66,34 @@ function registerIpc(): void {
   ipcMain.handle(IPC.openInstanceDir, () => shell.openPath(paths.instanceDir))
   ipcMain.handle(IPC.openLogsDir, () => shell.openPath(paths.logsDir))
   ipcMain.handle(IPC.updateInstall, () => quitAndInstallUpdate())
+
+  ipcMain.handle(IPC.isFirstLaunch, () => isFirstLaunch())
+
+  ipcMain.handle(IPC.dataDirGet, () => {
+    const { dataDir } = readLauncherConfigSync()
+    const defaultSuggestion = defaultDataDir()
+    return { current: dataDir ?? defaultSuggestion, defaultSuggestion }
+  })
+
+  ipcMain.handle(IPC.dataDirBrowse, async () => {
+    const { dataDir } = readLauncherConfigSync()
+    const { canceled, filePaths } = await dialog.showOpenDialog({
+      title: 'Choisir le dossier de données',
+      defaultPath: dataDir ?? defaultDataDir(),
+      properties: ['openDirectory', 'createDirectory']
+    })
+    return canceled ? null : filePaths[0]
+  })
+
+  ipcMain.handle(IPC.dataDirSet, async (_e, dir: string, relaunch: boolean) => {
+    await writeLauncherConfig({ dataDir: dir })
+    paths.invalidate()
+    if (relaunch) {
+      app.relaunch()
+      app.exit(0)
+    }
+    return dir
+  })
 }
 
 app.whenReady().then(() => {

src/main/launcher-config.ts

@@ -0,0 +1,33 @@
+import { app } from 'electron'
+import { join } from 'path'
+import { existsSync, readFileSync } from 'fs'
+import { writeFile } from 'fs/promises'
+
+interface LauncherConfig {
+  dataDir?: string
+}
+
+function configPath(): string {
+  return join(app.getPath('userData'), 'launcher.json')
+}
+
+export function readLauncherConfigSync(): LauncherConfig {
+  try {
+    return JSON.parse(readFileSync(configPath(), 'utf-8')) as LauncherConfig
+  } catch {
+    return {}
+  }
+}
+
+export function isFirstLaunch(): boolean {
+  return !existsSync(configPath())
+}
+
+export async function writeLauncherConfig(cfg: LauncherConfig): Promise<void> {
+  const current = readLauncherConfigSync()
+  await writeFile(configPath(), JSON.stringify({ ...current, ...cfg }, null, 2))
+}
+
+export function defaultDataDir(): string {
+  return join(app.getPath('home'), 'Games', 'OFLauncher')
+}

src/main/paths.ts

@@ -1,19 +1,34 @@
 import { app } from 'electron'
 import { join } from 'path'
 import { mkdirSync } from 'fs'
+import { readLauncherConfigSync } from './launcher-config'
 
 /**
- * Arborescence des données du launcher, rangée sous le userData d'Electron :
- *   Windows : %APPDATA%/OFLauncher
- *   Linux   : ~/.config/OFLauncher
+ * Arborescence des données du launcher.
  *
- * On garde le runtime (MC/NeoForge/assets/libs/java) séparé de l'instance de
- * jeu (mods/config/saves) pour que la sync packwiz ne touche jamais au runtime.
+ * La racine est configurable via launcher.json (userData/launcher.json) :
+ *   { "dataDir": "/chemin/choisi/par/l/utilisateur" }
+ * Par défaut : userData d'Electron (%APPDATA%/OFLauncher sur Windows,
+ * ~/.config/OFLauncher sur Linux).
+ *
+ * La config launcher.json elle-même reste toujours dans userData
+ * (point d'ancrage fixe, indépendant du dataDir choisi).
  */
 class LauncherPaths {
-  /** Racine : userData d'Electron. */
+  private _root: string | null = null
+
+  /** Racine des données du jeu (configurable). */
   get root(): string {
-    return app.getPath('userData')
+    if (!this._root) {
+      const { dataDir } = readLauncherConfigSync()
+      this._root = dataDir ?? app.getPath('userData')
+    }
+    return this._root
+  }
+
+  /** Invalide le cache de root (à appeler après écriture d'un nouveau dataDir). */
+  invalidate(): void {
+    this._root = null
   }
 
   /** Dossier "Minecraft" géré par @xmcl : versions/, libraries/, assets/. */
@@ -53,8 +68,6 @@ class LauncherPaths {
 
   /** jar packwiz-installer-bootstrap embarqué dans les resources. */
   get packwizBootstrapJar(): string {
-    // En prod, electron-builder copie resources/ via extraResources.
-    // En dev, on lit directement le dossier resources/ du repo.
     const base = app.isPackaged
       ? join(process.resourcesPath, 'resources')
       : join(app.getAppPath(), 'resources')