GOG Login: Nahtloser Auth-Flow wie Steam (kein Code-Paste noetig)

- Electron: Fängt GOG Redirect automatisch ab (will-redirect Interceptor)
- Code-Exchange passiert im Hintergrund, User sieht nur Erfolgs-Popup
- GOG Auth-URLs (auth.gog.com, login.gog.com, embed.gog.com) in Popup erlaubt
- Server: GET /gog/login Redirect + POST /gog/exchange Endpoint
- Browser-Fallback: Code-Paste Dialog falls nicht in Electron
- gog.ts: Feste redirect_uri (embed.gog.com/on_login_success)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/plugins/game-library/gog.ts

@@ -10,6 +10,7 @@ const GOG_CLIENT_SECRET =
 const GOG_AUTH_URL = 'https://auth.gog.com/auth';
 const GOG_TOKEN_URL = 'https://auth.gog.com/token';
 const GOG_EMBED_URL = 'https://embed.gog.com';
+const GOG_REDIRECT_URI = 'https://embed.gog.com/on_login_success?origin=client';
 
 // ── Types ────────────────────────────────────────────────────────────────────
 
@@ -37,13 +38,13 @@ export interface GogGame {
 
 /**
  * Build the GOG OAuth authorization URL that the user should visit to grant
- * access.  After approval, GOG will redirect to `redirectUri` with a `code`
- * query parameter.
+ * access.  After approval, GOG redirects to `embed.gog.com/on_login_success`
+ * with a `code` query parameter that the user copies back into the app.
  */
-export function getGogAuthUrl(redirectUri: string): string {
+export function getGogAuthUrl(): string {
   const params = new URLSearchParams({
     client_id: GOG_CLIENT_ID,
-    redirect_uri: redirectUri,
+    redirect_uri: GOG_REDIRECT_URI,
     response_type: 'code',
     layout: 'client2',
   });
@@ -53,10 +54,10 @@ export function getGogAuthUrl(redirectUri: string): string {
 
 /**
  * Exchange an authorization code for GOG access + refresh tokens.
+ * Uses the fixed GOG_REDIRECT_URI that matches the OAuth registration.
  */
 export async function exchangeGogCode(
   code: string,
-  redirectUri: string,
 ): Promise<GogTokens> {
   console.log('[GOG] Exchanging authorization code for tokens...');
 
@@ -65,7 +66,7 @@ export async function exchangeGogCode(
     client_secret: GOG_CLIENT_SECRET,
     grant_type: 'authorization_code',
     code,
-    redirect_uri: redirectUri,
+    redirect_uri: GOG_REDIRECT_URI,
   });
 
   const res = await fetch(`${GOG_TOKEN_URL}?${params.toString()}`);

server/src/plugins/game-library/index.ts

@@ -613,32 +613,29 @@ const gameLibraryPlugin: Plugin = {
       res.json({ profiles });
     });
 
-    // ── GOG Login ──
+    // ── GOG Login (redirect to GOG auth page) ──
     app.get('/api/game-library/gog/login', (req, res) => {
-      const proto = req.headers['x-forwarded-proto'] || req.protocol || 'http';
-      const host = req.headers['x-forwarded-host'] || req.headers.host || 'localhost';
-      const realm = `${proto}://${host}`;
-      const redirectUri = `${realm}/api/game-library/gog/callback`;
-      const linkTo = req.query.linkTo ? `&state=${req.query.linkTo}` : '';
-      res.redirect(getGogAuthUrl(redirectUri) + linkTo);
+      const linkTo = req.query.linkTo ? String(req.query.linkTo) : '';
+      // Pass linkTo as OAuth state param — GOG passes it back to redirect_uri
+      let authUrl = getGogAuthUrl();
+      if (linkTo) authUrl += `&state=${encodeURIComponent(linkTo)}`;
+      res.redirect(authUrl);
     });
 
-    // ── GOG Callback ──
-    app.get('/api/game-library/gog/callback', async (req, res) => {
+    // ── GOG Code Exchange ──
+    // User pastes the code from the GOG redirect URL.  We exchange it for
+    // tokens and fetch the game library.
+    app.post('/api/game-library/gog/exchange', async (req, res) => {
       try {
-        const code = String(req.query.code || '');
-        const linkToProfileId = String(req.query.state || '');
+        const code = String(req.body?.code || '');
+        const linkToProfileId = String(req.body?.linkTo || '');
         if (!code) {
-          res.status(400).send(errorPage('GOG-Authentifizierung fehlgeschlagen', 'Kein Authorization-Code erhalten.'));
+          res.status(400).json({ error: 'Kein Authorization-Code angegeben.' });
           return;
         }
 
-        const proto = req.headers['x-forwarded-proto'] || req.protocol || 'http';
-        const host = req.headers['x-forwarded-host'] || req.headers.host || 'localhost';
-        const redirectUri = `${proto}://${host}/api/game-library/gog/callback`;
-
         // Exchange code for tokens
-        const tokens = await exchangeGogCode(code, redirectUri);
+        const tokens = await exchangeGogCode(code);
 
         // Fetch user info + games
         const [userInfo, games] = await Promise.all([
@@ -689,10 +686,10 @@ const gameLibraryPlugin: Plugin = {
 
         console.log(`[GameLibrary] GOG verknuepft: ${profileName} (${userInfo.userId}) - ${games.length} Spiele`);
 
-        res.send(`<!DOCTYPE html><html><head><title>GOG verbunden</title><style>body{background:#1a1a2e;color:#fff;font-family:sans-serif;display:flex;align-items:center;justify-content:center;height:100vh;margin:0}div{text-align:center}h2{color:#a855f7}</style></head><body><div><h2>GOG verbunden!</h2><p>${profileName}: ${games.length} Spiele geladen.</p><p>Du kannst dieses Fenster schliessen.</p><script>setTimeout(()=>window.close(),3000)</script></div></body></html>`);
+        res.json({ ok: true, username: userInfo.username, gameCount: games.length, profileName });
       } catch (err) {
-        console.error('[GameLibrary] GOG Callback error:', err);
-        res.status(500).send(errorPage('GOG-Fehler', 'Ein unerwarteter Fehler ist aufgetreten.'));
+        console.error('[GameLibrary] GOG exchange error:', err);
+        res.status(500).json({ error: 'GOG-Authentifizierung fehlgeschlagen.' });
       }
     });