DoorAdmin/imaginaerraum_door_admin/webapp.py

from flask import Flask, render_template, request, flash, redirect, session, send_file
from werkzeug.utils import secure_filename
from flask_wtf import FlaskForm
from wtforms.fields.html5 import DateField, EmailField
from wtforms.fields import StringField, BooleanField
from wtforms.validators import DataRequired, ValidationError, EqualTo
from flask_sqlalchemy import SQLAlchemy
from flask_security import Security, SQLAlchemyUserDatastore, auth_required, hash_password, uia_email_mapper, \
    current_user, roles_required
from flask_security.models import fsqla_v2 as fsqla
from flask_security.forms import LoginForm, Required, PasswordField
from flask_security.utils import find_user
from flask_mail import Mail
from email_validator import validate_email

import json
import secrets
import bleach
import ldap3
from ldap3.core.exceptions import LDAPBindError, LDAPSocketOpenError
from pathlib import Path
import logging
import tempfile

from datetime import date
from .door_handle import DoorHandle


def validate_valid_thru_date(form, field):
    if form.limit_validity.data:  # only check date format if limited validity of token is set
        try:
            if not field.data >= date.today():
                raise ValueError
        except ValueError as e:
            flash("Ungültiges Datum")
            raise ValidationError
    return True


class TokenForm(FlaskForm):
    name = StringField('Name', validators=[DataRequired()])
    email = EmailField('E-Mail', validators=[DataRequired()])
    organization = StringField('Organization', validators=[DataRequired()])
    limit_validity = BooleanField('Gültigkeit begrenzen?')
    valid_thru = DateField('Gültig bis', validators=[validate_valid_thru_date])
    active = BooleanField('Aktiv?')
    dsgvo = BooleanField('Einwilligung Nutzungsbedingungen erfragt?', validators=[DataRequired()])


class ConfirmDeleteForm(FlaskForm):
    name = StringField('Name', validators=[DataRequired(), EqualTo('name_confirm', 'Name stimmt nicht überein')])
    name_confirm = StringField('Name confirm')


class AdminCreationForm(FlaskForm):
    name = StringField('Name', validators=[DataRequired()])
    email = EmailField('E-Mail', validators=[DataRequired()])


def uia_username_mapper(identity):
    # we allow pretty much anything - but we bleach it.
    return bleach.clean(identity, strip=True)


def create_application(config):
    # set up logging for the web app
    logger = logging.getLogger('webapp')
    logger.setLevel(logging.INFO)

    if config.log_file is not None:
        ch = logging.FileHandler(config.log_file)
        ch.setLevel(logging.INFO)
    else:
        # create console handler and set level to debug
        ch = logging.StreamHandler()
        ch.setLevel(logging.DEBUG)
    # create formatter
    formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    # add formatter to ch
    ch.setFormatter(formatter)
    # add ch to logger
    logger.addHandler(ch)

    # do some checks for file existence etc.
    try:
        with open(config.key_file) as f:
            data = f.readlines()
            if 'SECRET_KEY' in data[0]:
                secret_key = data[0].split()[-1]
            else:
                raise Exception("Could not read SECURITY_PASSWORD_SALT")
            if 'SECURITY_PASSWORD_SALT' in data[1]:
                security_password_salt = data[1].split()[-1]
            else:
                raise Exception("Could not read SECURITY_PASSWORD_SALT")
    except Exception as e:
        logger.warning(f"Flask keys could not be read from file at {Path(config.key_file).absolute()}. Exception: {e}. Using default values instead.")
        secret_key = 'Q7PJu2fg2jabYwP-Psop6c6f2G4'
        security_password_salt = '10036796768252925167749545152988277953'

    if Path(config.template_folder).is_absolute():
        if not Path(config.template_folder).exists():
            logger.error(f'Flask template folder not found at {Path(config.template_folder).absolute()}')
    else:
        if not (Path(__file__).parent / config.template_folder).exists():
            logger.error(f'Flask template folder not found at {(Path(__file__).parent / config.template_folder).absolute()}')
    if Path(config.static_folder).is_absolute():
        if not Path(config.static_folder).exists():
            logger.error(f'Flask static folder not found at {Path(config.static_folder).absolute()}')
    else:
        if not (Path(__file__).parent / config.static_folder).exists():
            logger.error(f'Flask static folder not found at {(Path(__file__).parent / config.static_folder).absolute()}')
    if not Path(config.token_file).exists():
        logger.warning(f"Token file not found at {Path(config.token_file).absolute()}")

    # create door objects which provides access to the token file and current door state via MQTT
    door = DoorHandle(token_file=config.token_file, mqtt_host=config.mqtt_host, nfc_socket=config.nfc_socket,
                      logger=logger)

    app = Flask(__name__, template_folder=config.template_folder, static_folder=config.static_folder)

    # Generate a nice key using secrets.token_urlsafe()
    app.config['SECRET_KEY'] = secret_key
    # Bcrypt is set as default SECURITY_PASSWORD_HASH, which requires a salt
    # Generate a good salt using: secrets.SystemRandom().getrandbits(128)
    app.config['SECURITY_PASSWORD_SALT'] = security_password_salt

    app.config['SECURITY_USER_IDENTITY_ATTRIBUTES'] = [
        {"email": {"mapper": uia_email_mapper, "case_insensitive": True}},
        {"username": {"mapper": uia_username_mapper}}
    ]
    app.config['SECURITY_CHANGEABLE'] = True
    app.config['SECURITY_RECOVERABLE'] = True
    app.config['SECURITY_SEND_PASSWORD_CHANGE_EMAIL'] = False

    # Mail Config
    app.config['MAIL_SERVER'] = config.mail_server
    app.config['MAIL_PORT'] = config.mail_port
    app.config['MAIL_USE_TLS'] = config.mail_use_tls
    app.config['MAIL_USE_SSL'] = config.mail_use_ssl
    app.config['MAIL_USERNAME'] = config.mail_username
    app.config['MAIL_PASSWORD'] = config.mail_password
    app.config['MAIL_DEFAULT_SENDER'] = app.config['MAIL_USERNAME']
    mail = Mail(app)

    app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///admin.db'
    # As of Flask-SQLAlchemy 2.4.0 it is easy to pass in options directly to the
    # underlying engine. This option makes sure that DB connections from the
    # pool are still valid. Important for entire application since
    # many DBaaS options automatically close idle connections.
    app.config["SQLALCHEMY_ENGINE_OPTIONS"] = {
        "pool_pre_ping": True,
    }

    # Create database connection object
    db = SQLAlchemy(app)

    # Define models
    fsqla.FsModels.set_db_info(db)

    class Role(db.Model, fsqla.FsRoleMixin):
        pass

    class User(db.Model, fsqla.FsUserMixin):
        username = db.Column(db.String(255))

    # LDAP
    ldap_server = ldap3.Server(config.ldap_url)

    def validate_ldap(username, password):
        """Validate the user and password through an LDAP server.

        If the connection completes successfully the given user and password is authorized.
        Then the permissions and additional information of the user are obtained through an LDAP search.
        The data is stored in a dict which will be used later to create/update the entry for the user in the local
        database.

        Parameters
        ----------
        username :  username for the LDAP server
        password :  password for the LDAP server

        Returns
        -------
            bool : result of the authorization process (True = success, False = failure)
            dict : dictionary with information about an authorized user (contains username, email, hashed password,
                    roles)
        """

        try:
            con = ldap3.Connection(ldap_server, user=f"uid={username},ou=Users,dc=imaginaerraum,dc=de",
                                   password=password, auto_bind=True)
        except ldap3.core.exceptions.LDAPBindError:
            # server reachable but user unauthorized -> fail
            return False, None
        except LDAPSocketOpenError:
            # server not reachable -> fail (but will try authorization from local database later)
            return False, None
        except Exception as e:
            # for other Exceptions we just fail
            return False, None

        # get user data and permissions from LDAP server
        new_user_data = {}
        new_user_data['username'] = username
        new_user_data['password'] = hash_password(password)
        new_user_data['roles'] = []
        lock_permission = con.search('ou=Users,dc=imaginaerraum,dc=de',
                                     f'(&(uid={username})(memberof=cn=Members,ou=Groups,dc=imaginaerraum,dc=de))',
                                     attributes=ldap3.ALL_ATTRIBUTES)
        if lock_permission:
            new_user_data['email'] = con.entries[0].mail.value
        else:
            new_user_data['email'] = None
        token_granting_permission = con.search('ou=Users,dc=imaginaerraum,dc=de',
                                               f'(&(uid={username})(memberof=cn=Vorstand,ou=Groups,dc=imaginaerraum,dc=de))')
        if token_granting_permission:
            new_user_data['roles'].append('admin')

        return True, new_user_data

    class ExtendedLoginForm(LoginForm):
        email = StringField('Benutzername oder E-Mail', [Required()])
        password = PasswordField('Passwort', [Required()])
        remember = BooleanField('Login merken?')

        def validate(self):
            # search for user in the current database
            user = find_user(self.email.data)
            if user is not None:
                # if a user is found we use that username for LDAP authentication
                username = user.username
            else:
                # this means there is no user with that email in the database
                # we assume that the username was entered instead of an email and use that for authentication with LDAP
                username = self.email.data

            # run LDAP authorization
            # if the authorization succeeds we also get the new_user_data dict which contains information about the
            # user's permissions etc.
            authorized, new_user_data = validate_ldap(username, self.password.data)

            if authorized:
                if user is None:
                    # if there was no user in the database before we create a new user
                    user_datastore.create_user(username=new_user_data['username'], email=new_user_data['email'],
                                               password=new_user_data['password'], roles=new_user_data['roles'])
                    logger.info(f"New admin user '{new_user_data['username']} <{new_user_data['email']}>' created after"
                                " successful LDAP authorization")
                else:  # for existing users we update permissions and password/email to stay up to date
                    user.email = new_user_data['email']
                    user.password = new_user_data['password']
                    for role in new_user_data['roles']:
                        user_datastore.add_role_to_user(user, role)
                user_datastore.commit()

                self.user = find_user(self.email.data)
                logger.info(f"User with credentials '{self.email.data}' authorized through LDAP")

            if not authorized:
                # try authorizing locally using Flask security user datastore
                authorized = super(ExtendedLoginForm, self).validate()

                if authorized:
                    logger.info(f"User with credentials '{self.email.data}' authorized through local database")

            # if any of the authorization methods is successful we authorize the user
            return authorized

    # Setup Flask-Security
    user_datastore = SQLAlchemyUserDatastore(db, User, Role)
    security = Security(app, user_datastore, login_form=ExtendedLoginForm)

    # admin user management
    @app.route('/manage_admins', methods=['GET', 'POST'])
    @roles_required('super_admin')
    def manage_admins():
        form = AdminCreationForm()
        if request.method == 'GET':
            users = user_datastore.user_model.query.all()
            admin_data = [{'username': u.username, 'email': u.email, 'active': u.is_active,
                           'admin': u.has_role('admin'), 'super_admin': u.has_role('super_admin'),
                           } for u in users]
            return render_template('admins.html', admin_data=admin_data, form=form)
        elif form.validate():
            if user_datastore.find_user(username=form.name.data) is not None or \
                    user_datastore.find_user(email=form.email.data) is not None:
                flash("Ein Benutzer mit diesem Nutzernamen oder dieser E-Mail-Adresse existiert bereits!")
                return redirect('/manage_admins')
            else:
                pw = secrets.token_urlsafe(16)
                new_user = user_datastore.create_user(username=form.name.data, email=form.email.data,
                                                      password=hash_password(pw))
                logger.info(
                    f"Super admin {current_user.username} created new user account for {new_user.username} <{new_user.email}>")
                flash(f"Ein Account für den Nutzer {new_user.username} wurde erstellt. Verwende das Passwort {pw} um den Nutzer einzuloggen.")
                db.session.commit()
                return redirect('/manage_admins')

    @app.route('/delete_admins/<username>', methods=['GET', 'POST'])
    @roles_required('super_admin')
    def delete_admins(username):
        user = user_datastore.find_user(username=username)
        if user is None:
            flash(f"Ungültiger Nutzer {username}")
            return redirect('/manage_admins')
        if user.has_role('super_admin'):
            flash('Super-Admins können nicht gelöscht werden!')
            return redirect('/manage_admins')
        if user.is_active:
            flash('Aktive Nutzer können nicht gelöscht werden! Bitte den Benutzer zuerst deaktivieren.')
            return redirect('/manage_admins')

        # set up form for confirming deletion
        form = ConfirmDeleteForm()
        form.name_confirm.data = username

        if request.method == 'GET':
            # return page asking the user to confirm delete
            return render_template('delete_user.html', username=username, form=form)
        elif form.validate():
            user_datastore.delete_user(user)
            flash(f"Benutzer {username} wurde gelöscht.")
            logger.info(f"Super admin {current_user.username} deleted admin user {username}")
            db.session.commit()
            return redirect('/manage_admins')
        else:
            flash("Der eingegebene Nutzername stimmt nicht überein. Der Benutzer wurde nicht gelöscht!")
            return redirect('/manage_admins')

    @app.route('/admin_toggle_active/<username>')
    @roles_required('super_admin')
    def admin_toggle_active(username):
        user = user_datastore.find_user(username=username)
        if user is None:
            flash(f"Ungültiger Nutzer {username}")
            return redirect('/manage_admins')
        if user.has_role('super_admin'):
            flash('Super-Admins können nicht deaktiviert werden!')
            return redirect('/manage_admins')
        user_datastore.toggle_active(user)
        if user.is_active:
            logger.info(f"Super admin {current_user.username} activated access for admin user {username}")
        else:
            logger.info(f"Super admin {current_user.username} deactivated access for admin user {username}")
        db.session.commit()
        return redirect('/manage_admins')

    @app.route('/promote_admin/<username>')
    @roles_required('super_admin')
    def promote_admin(username):
        user = user_datastore.find_user(username=username)
        if user is None:
            flash(f"Ungültiger Nutzer {username}")
            return redirect('/manage_admins')
        if user.has_role('admin'):
            flash(f'Benutzer {username} hat bereits Admin-Rechte!')
            return redirect('/manage_admins')
        user_datastore.add_role_to_user(user, 'admin')
        logger.info(f"Super admin {current_user.username} granted admin privileges to user {username}")
        db.session.commit()
        return redirect('/manage_admins')

    @app.route('/demote_admin/<username>')
    @roles_required('super_admin')
    def demote_admin(username):
        user = user_datastore.find_user(username=username)
        if user is None:
            flash(f"Ungültiger Nutzer {username}")
            return redirect('/manage_admins')
        if user.has_role('super_admin'):
            flash(f'Benutzer {username} hat Super-Admin-Rechte und kann nicht verändert werden!')
            return redirect('/manage_admins')
        if user.has_role('admin'):
            user_datastore.remove_role_from_user(user, 'admin')
            logger.info(f"Super admin {current_user.username} revoked admin privileges of user {username}")
            db.session.commit()
        else:
            flash(f'Benutzer {username} ist bereits kein Admin!')
        return redirect('/manage_admins')

    @app.route('/backup_user_datastore')
    @roles_required('super_admin')
    def backup_user_datastore():
        # get list of defined admin users for backup
        users = user_datastore.user_model.query.all()
        user_data = [{'username': u.username, 'email': u.email, 'active': u.is_active, 'password_hash': u.password,
                      'roles': [r.name for r in u.roles]}
                     for u in users if not u.has_role('super_admin')]
        try:
            with tempfile.TemporaryDirectory() as tmpdir:
                file = Path(tmpdir, 'user_data.txt')
                file.write_text(json.dumps(user_data))
                return send_file(file, as_attachment=True, cache_timeout=-1)
        except Exception as e:
            return str(e)

    @app.route('/restore_user_datastore', methods=['POST'])
    @roles_required('super_admin')
    def restore_user_datastore():
        # check if the post request has the file part
        if 'file' not in request.files:
            flash('Keine Datei ausgewählt!')
            return redirect(request.url)
        file = request.files['file']
        # if user does not select file, browser also
        # submit an empty part without filename
        if file.filename == '':
            flash('Keine Datei ausgewählt!')
            return redirect('/manage_admins')
        filename = secure_filename(file.filename)
        if file and filename.endswith('.txt'):
            data = file.stream.read()
            try:
                # check validity of user data
                user_data = json.loads(data)
                valid = type(user_data) == list
                valid &= all(type(d) == dict for d in user_data)
                if valid:
                    for d in user_data:
                        entry_valid = set(d.keys()) == { 'active', 'email', 'password_hash', 'username', 'roles'}
                        entry_valid &= all(len(d[key]) > 0 for key in ['email', 'password_hash', 'username'])
                        entry_valid &= type(d['active']) == bool
                        entry_valid &= type(d['roles']) == list
                        validate_email(d['email'])
                        if entry_valid:
                            existing_user = user_datastore.find_user(username=d['username'], email=d['email'])
                            if existing_user is None:
                                user_datastore.create_user(username=d['username'], email=d['email'],
                                                           password=d['password_hash'], active=d['active'],
                                                           roles=d['roles'])
                                flash(f"Account für Benutzer '{d['username']} wurde wiederhergestellt.")
                            else:
                                flash(f"Benutzer '{d['username']} existiert bereits. Eintrag wird übersprungen.")
                        else:
                            raise ValueError(f"Ungültige Daten für User Entry {d}")
                else:
                    raise ValueError("Admin User Datei hat ungültiges Format.")
            except Exception as e:
                flash(f"Die Datei konnte nicht gelesen werden. Exception: {e}")
                return redirect('/manage_admins')
            flash("Benutzer aus Datei gelesen.")
            db.session.commit()
        else:
            flash("Ungültige Dateiendung")
        return redirect('/manage_admins')
    # main page
    @app.route('/')
    def door_lock():
        return render_template('index.html', door_state=door.state, encoder_position=door.encoder_position)

    # token overview
    @app.route('/tokens')
    @roles_required('admin')
    def list_tokens():
        tokens = door.get_tokens()
        assigned_tokens = {t: data for t, data in tokens.items() if not data['inactive']}
        inactive_tokens = {t: data for t, data in tokens.items() if data['inactive']}
        return render_template('tokens.html', assigned_tokens=assigned_tokens, inactive_tokens=inactive_tokens)

    # routes for registering, editing and deleting tokens
    @app.route('/register-token', methods=['GET', 'POST'])
    @roles_required('admin')
    def register():
        """Register new token for locking and unlocking the door.

        This route displays the most recently scanned invalid token as reported in the logfile and provides a form for
        entering user info (name, email, valid thru date (optional)) for the new token.

        If the route is called via POST the provided form data is checked and if the check succeeds the /store-token route
        will be called which adds the new token to the database.
        """
        form = TokenForm()
        if request.method == 'GET':
            # set default valid thru date to today to make sure form validity check passes
            # (will not be used if limited validity is disabled)
            form.valid_thru.data = date.today()
            return render_template('register.html', token=door.get_most_recent_token(), form=form)
        elif request.method == 'POST' and form.validate():
            # store data in session cookie
            session['token'] = door.get_most_recent_token()['token']
            session['name'] = form.name.data
            session['email'] = form.email.data
            session['organization'] = form.organization.data
            if form.limit_validity.data:
                session['valid_thru'] = form.valid_thru.data.isoformat()
            else:
                session['valid_thru'] = ''
            session['inactive'] = not form.active.data
            return redirect('/store-token')
        else:
            return render_template('register.html', token=door.get_most_recent_token(), form=form)

    @app.route('/edit-token/<token>', methods=['GET', 'POST'])
    @roles_required('admin')
    def edit_token(token):
        """Edit data in the token file (name, email, valid_thru date, active/inactive).

        If the route is accessed via GET it will provide a form for editing the currently stored data for the user.
        If the route is accessed via POST it will check if the form data is good and then store the modified user data in
        the database (by redirecting to the /store-token route)

        Parameters
        ----------
        token : str
            The token for which data should be edited.
        """
        form = TokenForm(request.form)
        form.dsgvo.validators = []  # we skip the validation of the DSGVO checkbox here because we assume the user agreed
        # to it before
        if request.method == 'GET':
            tokens = door.get_tokens()
            if token in tokens:
                # set default for form according to values from the token file
                et = tokens[token]
                form.active.data = not et['inactive']
                form.name.data = et['name'] if et['name'] else ''
                form.email.data = et['email'] if et['email'] else ''
                form.organization.data = et['organization'] if et['organization'] else ''

                # for the valid thru date we use today's date in case there is not valid date in the database
                try:
                    form.valid_thru.data = date.fromisoformat(et['valid_thru'])
                    form.limit_validity.data = True
                except Exception:
                    form.valid_thru.data = date.today()

                return render_template('edit.html', token=token, form=form)
            else:
                # flash an error message if the route is accessed with an invalid token
                flash(f'Ausgewaehlter Token {token} in Tokenfile nicht gefunden.')
                return redirect('/tokens')
        elif request.method == 'POST':
            if form.validate():
                # store data in session cookie
                session['token'] = token
                session['name'] = form.name.data
                session['organization'] = form.organization.data
                session['email'] = form.email.data
                if form.limit_validity.data:
                    session['valid_thru'] = form.valid_thru.data.isoformat()
                else:
                    session['valid_thru'] = ''
                session['inactive'] = not form.active.data
                return redirect(f'/store-token')
            else:
                return render_template('edit.html', token=token, form=form)

    @app.route('/store-token')
    @roles_required('admin')
    def store_token():
        """Store token to the token file on disk.

        This will use the token id and the associated data stored in the session cookie (filled by register_token() or
         edit_token()) and create/modify a token and store the new token file to disk.
        """
        token = session['token']
        tokens = door.get_tokens()
        tokens[token] = {'name': session['name'],
                         'email': session['email'],
                         'valid_thru': session['valid_thru'],
                         'inactive': session['inactive'],
                         'organization': session['organization']}
        try:
            door.store_tokens(tokens)
            logger.info(f"Token {token} stored in database by admin user {current_user.username}")
        except Exception as e:
            flash(f"Error during store_tokens. Exception: {e}")
        return redirect('/tokens')

    @app.route('/delete-token/<token>', methods=['GET', 'POST'])
    @roles_required('admin')
    def delete_token(token):
        """Delete the given token from the token file and store the new token file to disk

        Parameters
        ----------
        token : str
            The token to delete from the database.
        """
        tokens = door.get_tokens()

        if token in tokens:
            token_to_delete = tokens[token]

            # set up form for confirming deletion
            form = ConfirmDeleteForm()
            form.name_confirm.data = token_to_delete['name']

            if request.method == 'GET':
                # return page asking the user to confirm delete
                return render_template('delete.html', token=token_to_delete, form=form)
            elif form.validate():
                # form validation successful -> can delete the token
                tokens.pop(token)
                try:
                    door.store_tokens(tokens)
                    logger.info(f"Token {token} was deleted from database by admin user {current_user.username}")
                except Exception as e:
                    flash(f"Error during store_tokens. Exception: {e}")
                flash(f"Token {token} wurde gelöscht!")
                return redirect('/tokens')
            else:
                # form validation failed -> return to token overview and flash message
                flash(
                    f"Der eingegebene Name stimmt nicht überein. Der Token {token} von {token_to_delete['name']} wurde nicht gelöscht.")
                return redirect('/tokens')
        else:
            flash(f'Ungültiger Token {token} für Löschung.')
            return redirect('/tokens')

    @app.route('/deactivate-token/<token>')
    @roles_required('admin')
    def deactivate_token(token):
        """Deactivate access for the given token. This updates the token file on disk.

        Parameters
        ----------
        token : str
            The token to deactivate.
        """
        tokens = door.get_tokens()
        if token in tokens:
            tokens[token]['inactive'] = True
            try:
                door.store_tokens(tokens)
                logger.info(f"Token {token} deactivated by admin user {current_user.username}")
            except Exception as e:
                flash(f"Error during store_tokens. Exception: {e}")
        return redirect('/tokens')

    @app.route('/backup_tokens')
    @roles_required('admin')
    def backup_tokens():
        # get list of defined admin users for backup
        tokens = door.get_tokens()
        try:
            with tempfile.TemporaryDirectory() as tmpdir:
                file = Path(tmpdir, 'token_data.txt')
                file.write_text(json.dumps(tokens))
                return send_file(file, as_attachment=True, cache_timeout=-1)
        except Exception as e:
            return str(e)

    @app.route('/open')
    @auth_required()
    def open_door():
        try:
            door.open_door()
            logger.info(f"Door opened by admin user {current_user.username}")
        except Exception as e:
            flash(f'Could not open door. Exception: {e}')
        return redirect('/')

    # routes for opening and closing the door via the web interface
    @app.route('/close')
    @auth_required()
    def close_door():
        try:
            door.close_door()
            logger.info(f"Door closed by admin user {current_user.username}")
        except Exception as e:
            flash(f'Could not close door. Exception: {e}')
        return redirect('/')

    # setup user database when starting the app
    with app.app_context():
        new_admin_data = []
        if config.admin_file is not None:
            if not Path(config.admin_file).exists():
                logger.warning(f"Admin user creation file not found at {config.admin_file}")
            else:
                # store data for new admins in memory s.t. the file can be deleted afterwards
                with open(config.admin_file) as f:
                    for i, d in enumerate(f.readlines()):
                        try:
                            user, email, pw = d.split()
                            validate_email(email)
                            new_admin_data.append({'username': user, 'email': email, 'password': pw})
                        except Exception as e:
                            print(
                                f"Error while parsing line {i} in admin config file. Config file should contain lines of "
                                f"'<username> <email> <password>\\n'\n Exception: {e}\nAdmin account could not be created.")

        # create admin users (only if they don't exists already)
        def create_super_admins(new_admin_data):
            db.create_all()
            super_admin_role = user_datastore.find_or_create_role('super_admin')  # root admin = can create other admins
            admin_role = user_datastore.find_or_create_role('admin')  # 'normal' admin

            for d in new_admin_data:
                if user_datastore.find_user(email=d['email'], username=d['username']) is None:
                    logger.info(f"New super admin user created with username '{d['username']}' and email '{d['email']}'")
                    # create new admin (only if admin does not already exist)
                    new_admin = user_datastore.create_user(email=d['email'], username=d['username'],
                                                           password=hash_password(d['password']),
                                                           roles=[super_admin_role, admin_role])
            db.session.commit()

        create_super_admins(new_admin_data)

    return app