feat: Improve module import paths and add package initialization files

Web/__init__.py

@@ -0,0 +1 @@
+# Web package initialization

Web/app.py

@@ -28,7 +28,20 @@ Features:
 from flask import Flask, render_template, request, redirect, url_for, session, flash, send_from_directory, get_flashed_messages, jsonify, Response, make_response, send_file, abort
 from werkzeug.utils import secure_filename
 from werkzeug.middleware.proxy_fix import ProxyFix
+from werkzeug.exceptions import HTTPException
+from werkzeug.routing import BuildError
 from jinja2 import TemplateNotFound
+import os
+import sys
+
+# Ensure imports work regardless of whether gunicorn starts in /app or /app/Web.
+_CURRENT_DIR = os.path.dirname(os.path.abspath(__file__))
+_PROJECT_ROOT = os.path.dirname(_CURRENT_DIR)
+if _PROJECT_ROOT not in sys.path:
+    sys.path.insert(0, _PROJECT_ROOT)
+if _CURRENT_DIR not in sys.path:
+    sys.path.insert(0, _CURRENT_DIR)
+
 import Web.modules.database.user as us
 import Web.modules.database.items as it
 import Web.modules.database.ausleihung as au
@@ -42,7 +55,6 @@ from urllib.parse import urlparse, urlunparse
 import requests
 import csv
 import ipaddress
-import os
 import json
 import datetime
 import time
@@ -63,7 +75,6 @@ except Exception:
 # import qrcode
 # from qrcode.constants import ERROR_CORRECT_L
 import threading
-import sys
 import shutil
 import uuid
 from PIL import Image, ImageOps
@@ -373,7 +384,7 @@ def _enforce_module_access():
             if name != 'inventory' and cfg.MODULES.is_enabled('inventory'):
                 return redirect(url_for('home'))
             elif name != 'library' and cfg.MODULES.is_enabled('library'):
-                return redirect(url_for('library_view'))
+                return redirect('/library')
             
             return redirect(url_for('my_borrowed_items'))
 
@@ -433,6 +444,41 @@ def handle_not_found(e):
     return redirect(url_for('login'))
 
 
+@app.errorhandler(BuildError)
+def handle_build_error(e):
+    """Handle url_for endpoint mismatches without crashing the whole request."""
+    app.logger.error(f"BuildError while resolving endpoint: {e}", exc_info=True)
+    if request.is_json or request.path.startswith('/api/'):
+        return jsonify({'error': 'Route resolution failed', 'status': 500}), 500
+
+    # Known fallback for legacy library endpoint naming issues.
+    if 'library_view' in str(e):
+        return redirect('/library')
+
+    if 'username' in session:
+        return redirect(url_for('home'))
+    return redirect(url_for('login'))
+
+
+@app.errorhandler(Exception)
+def handle_unexpected_exception(e):
+    """Last-resort handler to avoid raw 500 pages for unhandled exceptions."""
+    if isinstance(e, HTTPException):
+        return e
+
+    app.logger.error('Unhandled exception', exc_info=True)
+    if request.is_json or request.path.startswith('/api/'):
+        return jsonify({'error': 'Internal server error', 'status': 500}), 500
+
+    if 'username' in session:
+        try:
+            return render_template('error.html', error_code=500, error_message='Interner Serverfehler.'), 500
+        except Exception:
+            return 'Internal Server Error', 500
+
+    return redirect(url_for('login'))
+
+
 def _csrf_error_response(message='CSRF token fehlt oder ist ungültig.'):
     if request.is_json or request.path.startswith('/api/') or request.path in {'/download_book_cover', '/proxy_image', '/log_mobile_issue'}:
         return jsonify({'error': message}), 400
@@ -2640,7 +2686,7 @@ def home():
         
     if not cfg.MODULES.is_enabled('inventory'):
         if cfg.MODULES.is_enabled('library'):
-            return redirect(url_for('library_view'))
+            return redirect('/library')
         else:
             return "Weder Inventar- noch Bibliotheks-Modul sind aktiviert.", 403
 
@@ -2716,8 +2762,9 @@ def tutorial_page():
         student_max_borrow_days=cfg.STUDENT_MAX_BORROW_DAYS
     )
 
+@app.route('/library/export', defaults={'scope': 'all'})
 @app.route('/library/export/<scope>')
-def library_export_excel(scope):
+def library_export_excel(scope='all'):
     if 'username' not in session:
         return redirect(url_for('login'))
         
@@ -2737,7 +2784,7 @@ def library_export_excel(scope):
         filename = f"Bibliothek_Ausgeliehen_{username}.xlsx"
     elif scope == 'all_borrowed':
         if not is_admin_user:
-            return redirect(url_for('library_view'))
+            return redirect('/library')
         query['Verfuegbar'] = False
         filename = "Bibliothek_Alle_Ausleihen.xlsx"
     elif scope == 'schulbuecher':

Web/modules/__init__.py

@@ -0,0 +1 @@
+# Web.modules package initialization

Web/modules/bibliothek/__init__.py

@@ -0,0 +1 @@
+# Web.modules.bibliothek package initialization

Web/modules/database/settings.py

@@ -135,7 +135,7 @@ def _get_int_env(name, default):
         return int(default)
 
 def get_version():
-    with open(os.path.join(BASE_DIR, '..', '.docker-build.env'), 'r') as f:
+    with open(os.path.join(BASE_DIR, '..', '..', '..', '.docker-build.env'), 'r') as f:
         for l in f:
             if l.startswith('INVENTAR_APP_IMAGE='):
                 return l.split(':', 1)[1].strip()

Web/modules/emailservice/__init__.py

@@ -0,0 +1 @@
+# Web.modules.emailservice package initialization

Web/templates/library_item_invoices.html

@@ -124,7 +124,7 @@
     </div>
     <div class="head-actions">
       <a class="btn btn-outline-secondary" href="{{ url_for('library_loans_admin') }}">Zur Bibliotheks-Ausleihenverwaltung</a>
-      <a class="btn btn-secondary" href="{{ url_for('library_view') }}">Bibliothek öffnen</a>
+      <a class="btn btn-secondary" href="{{ url_for('library_admin') }}">Bibliothek öffnen</a>
     </div>
   </div>