I know it's bad form to submit a large PR like this but this fixes almost everything in https://github.com/firefly-iii/firefly-iii/issues/9183 and I was too lazy to create a branch for it.

app/Notifications/Security/DisabledMFANotification.php

@@ -0,0 +1,117 @@
+<?php
+/*
+ * EnabledMFANotification.php
+ * Copyright (c) 2024 james@firefly-iii.org.
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Notifications\Security;
+
+use FireflyIII\Support\Notifications\UrlValidator;
+use FireflyIII\User;
+use Illuminate\Bus\Queueable;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Messages\SlackMessage;
+use Illuminate\Notifications\Notification;
+
+class DisabledMFANotification extends Notification
+{
+    use Queueable;
+
+    private User   $user;
+
+    /**
+     * Create a new notification instance.
+     */
+    public function __construct(User $user)
+    {
+        $this->user = $user;
+    }
+
+    /**
+     * Get the array representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toArray($notifiable)
+    {
+        return [
+        ];
+    }
+
+    /**
+     * Get the mail representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return MailMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toMail($notifiable)
+    {
+        $subject = (string)trans('email.disabled_mfa_subject');
+
+        return (new MailMessage())->markdown('emails.security.disabled-mfa', ['user' => $this->user])->subject($subject);
+    }
+
+    /**
+     * Get the Slack representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return SlackMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toSlack($notifiable)
+    {
+        $message = (string)trans('email.disabled_mfa_slack', ['email' => $this->user->email]);
+
+        return (new SlackMessage())->content($message);
+    }
+
+    /**
+     * Get the notification's delivery channels.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function via($notifiable)
+    {
+        /** @var null|User $user */
+        $user     = auth()->user();
+        $slackUrl = null === $user ? '' : app('preferences')->getForUser(auth()->user(), 'slack_webhook_url', '')->data;
+        if (is_array($slackUrl)) {
+            $slackUrl = '';
+        }
+        if (UrlValidator::isValidWebhookURL((string)$slackUrl)) {
+            return ['mail', 'slack'];
+        }
+
+        return ['mail'];
+    }
+}

app/Notifications/Security/EnabledMFANotification.php

@@ -0,0 +1,118 @@
+<?php
+/*
+ * EnabledMFANotification.php
+ * Copyright (c) 2024 james@firefly-iii.org.
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Notifications\Security;
+
+use FireflyIII\Models\Bill;
+use FireflyIII\Support\Notifications\UrlValidator;
+use FireflyIII\User;
+use Illuminate\Bus\Queueable;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Messages\SlackMessage;
+use Illuminate\Notifications\Notification;
+
+class EnabledMFANotification extends Notification
+{
+    use Queueable;
+
+    private User   $user;
+
+    /**
+     * Create a new notification instance.
+     */
+    public function __construct(User $user)
+    {
+        $this->user = $user;
+    }
+
+    /**
+     * Get the array representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toArray($notifiable)
+    {
+        return [
+        ];
+    }
+
+    /**
+     * Get the mail representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return MailMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toMail($notifiable)
+    {
+        $subject = (string)trans('email.enabled_mfa_subject');
+
+        return (new MailMessage())->markdown('emails.security.enabled-mfa', ['user' => $this->user])->subject($subject);
+    }
+
+    /**
+     * Get the Slack representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return SlackMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toSlack($notifiable)
+    {
+        $message = (string)trans('email.enabled_mfa_slack', ['email' => $this->user->email]);
+
+        return (new SlackMessage())->content($message);
+    }
+
+    /**
+     * Get the notification's delivery channels.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function via($notifiable)
+    {
+        /** @var null|User $user */
+        $user     = auth()->user();
+        $slackUrl = null === $user ? '' : app('preferences')->getForUser(auth()->user(), 'slack_webhook_url', '')->data;
+        if (is_array($slackUrl)) {
+            $slackUrl = '';
+        }
+        if (UrlValidator::isValidWebhookURL((string)$slackUrl)) {
+            return ['mail', 'slack'];
+        }
+
+        return ['mail'];
+    }
+}

app/Notifications/Security/MFABackupFewLeftNotification.php

@@ -0,0 +1,119 @@
+<?php
+/*
+ * EnabledMFANotification.php
+ * Copyright (c) 2024 james@firefly-iii.org.
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Notifications\Security;
+
+use FireflyIII\Support\Notifications\UrlValidator;
+use FireflyIII\User;
+use Illuminate\Bus\Queueable;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Messages\SlackMessage;
+use Illuminate\Notifications\Notification;
+
+class MFABackupFewLeftNotification extends Notification
+{
+    use Queueable;
+
+    private User   $user;
+    private int $count;
+
+    /**
+     * Create a new notification instance.
+     */
+    public function __construct(User $user, int $count)
+    {
+        $this->user = $user;
+        $this->count = $count;
+    }
+
+    /**
+     * Get the array representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toArray($notifiable)
+    {
+        return [
+        ];
+    }
+
+    /**
+     * Get the mail representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return MailMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toMail($notifiable)
+    {
+        $subject = (string)trans('email.mfa_few_backups_left_subject', ['count' => $this->count]);
+
+        return (new MailMessage())->markdown('emails.security.few-backup-codes', ['user' => $this->user, 'count' => $this->count])->subject($subject);
+    }
+
+    /**
+     * Get the Slack representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return SlackMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toSlack($notifiable)
+    {
+        $message = (string)trans('email.mfa_few_backups_left_slack', ['email' => $this->user->email, 'count' => $this->count]);
+
+        return (new SlackMessage())->content($message);
+    }
+
+    /**
+     * Get the notification's delivery channels.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function via($notifiable)
+    {
+        /** @var null|User $user */
+        $user     = auth()->user();
+        $slackUrl = null === $user ? '' : app('preferences')->getForUser(auth()->user(), 'slack_webhook_url', '')->data;
+        if (is_array($slackUrl)) {
+            $slackUrl = '';
+        }
+        if (UrlValidator::isValidWebhookURL((string)$slackUrl)) {
+            return ['mail', 'slack'];
+        }
+
+        return ['mail'];
+    }
+}

app/Notifications/Security/MFABackupNoLeftNotification.php

@@ -0,0 +1,117 @@
+<?php
+/*
+ * EnabledMFANotification.php
+ * Copyright (c) 2024 james@firefly-iii.org.
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Notifications\Security;
+
+use FireflyIII\Support\Notifications\UrlValidator;
+use FireflyIII\User;
+use Illuminate\Bus\Queueable;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Messages\SlackMessage;
+use Illuminate\Notifications\Notification;
+
+class MFABackupNoLeftNotification extends Notification
+{
+    use Queueable;
+
+    private User   $user;
+
+    /**
+     * Create a new notification instance.
+     */
+    public function __construct(User $user)
+    {
+        $this->user = $user;
+    }
+
+    /**
+     * Get the array representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toArray($notifiable)
+    {
+        return [
+        ];
+    }
+
+    /**
+     * Get the mail representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return MailMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toMail($notifiable)
+    {
+        $subject = (string)trans('email.mfa_no_backups_left_subject');
+
+        return (new MailMessage())->markdown('emails.security.no-backup-codes', ['user' => $this->user])->subject($subject);
+    }
+
+    /**
+     * Get the Slack representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return SlackMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toSlack($notifiable)
+    {
+        $message = (string)trans('email.mfa_no_backups_left_slack', ['email' => $this->user->email]);
+
+        return (new SlackMessage())->content($message);
+    }
+
+    /**
+     * Get the notification's delivery channels.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function via($notifiable)
+    {
+        /** @var null|User $user */
+        $user     = auth()->user();
+        $slackUrl = null === $user ? '' : app('preferences')->getForUser(auth()->user(), 'slack_webhook_url', '')->data;
+        if (is_array($slackUrl)) {
+            $slackUrl = '';
+        }
+        if (UrlValidator::isValidWebhookURL((string)$slackUrl)) {
+            return ['mail', 'slack'];
+        }
+
+        return ['mail'];
+    }
+}

app/Notifications/Security/MFAUsedBackupCodeNotification.php

@@ -0,0 +1,117 @@
+<?php
+/*
+ * EnabledMFANotification.php
+ * Copyright (c) 2024 james@firefly-iii.org.
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Notifications\Security;
+
+use FireflyIII\Support\Notifications\UrlValidator;
+use FireflyIII\User;
+use Illuminate\Bus\Queueable;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Messages\SlackMessage;
+use Illuminate\Notifications\Notification;
+
+class MFAUsedBackupCodeNotification extends Notification
+{
+    use Queueable;
+
+    private User   $user;
+
+    /**
+     * Create a new notification instance.
+     */
+    public function __construct(User $user)
+    {
+        $this->user = $user;
+    }
+
+    /**
+     * Get the array representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toArray($notifiable)
+    {
+        return [
+        ];
+    }
+
+    /**
+     * Get the mail representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return MailMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toMail($notifiable)
+    {
+        $subject = (string)trans('email.used_backup_code_subject');
+
+        return (new MailMessage())->markdown('emails.security.used-backup-code', ['user' => $this->user])->subject($subject);
+    }
+
+    /**
+     * Get the Slack representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return SlackMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toSlack($notifiable)
+    {
+        $message = (string)trans('email.used_backup_code_slack', ['email' => $this->user->email]);
+
+        return (new SlackMessage())->content($message);
+    }
+
+    /**
+     * Get the notification's delivery channels.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function via($notifiable)
+    {
+        /** @var null|User $user */
+        $user     = auth()->user();
+        $slackUrl = null === $user ? '' : app('preferences')->getForUser(auth()->user(), 'slack_webhook_url', '')->data;
+        if (is_array($slackUrl)) {
+            $slackUrl = '';
+        }
+        if (UrlValidator::isValidWebhookURL((string)$slackUrl)) {
+            return ['mail', 'slack'];
+        }
+
+        return ['mail'];
+    }
+}

app/Notifications/Security/NewBackupCodesNotification.php

@@ -0,0 +1,117 @@
+<?php
+/*
+ * EnabledMFANotification.php
+ * Copyright (c) 2024 james@firefly-iii.org.
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see https://www.gnu.org/licenses/.
+ */
+
+declare(strict_types=1);
+
+namespace FireflyIII\Notifications\Security;
+
+use FireflyIII\Support\Notifications\UrlValidator;
+use FireflyIII\User;
+use Illuminate\Bus\Queueable;
+use Illuminate\Notifications\Messages\MailMessage;
+use Illuminate\Notifications\Messages\SlackMessage;
+use Illuminate\Notifications\Notification;
+
+class NewBackupCodesNotification extends Notification
+{
+    use Queueable;
+
+    private User   $user;
+
+    /**
+     * Create a new notification instance.
+     */
+    public function __construct(User $user)
+    {
+        $this->user = $user;
+    }
+
+    /**
+     * Get the array representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toArray($notifiable)
+    {
+        return [
+        ];
+    }
+
+    /**
+     * Get the mail representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return MailMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toMail($notifiable)
+    {
+        $subject = (string)trans('email.new_backup_codes_subject');
+
+        return (new MailMessage())->markdown('emails.security.new-backup-codes', ['user' => $this->user])->subject($subject);
+    }
+
+    /**
+     * Get the Slack representation of the notification.
+     *
+     * @param mixed $notifiable
+     *
+     * @return SlackMessage
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function toSlack($notifiable)
+    {
+        $message = (string)trans('email.new_backup_codes_slack', ['email' => $this->user->email]);
+
+        return (new SlackMessage())->content($message);
+    }
+
+    /**
+     * Get the notification's delivery channels.
+     *
+     * @param mixed $notifiable
+     *
+     * @return array
+     *
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    public function via($notifiable)
+    {
+        /** @var null|User $user */
+        $user     = auth()->user();
+        $slackUrl = null === $user ? '' : app('preferences')->getForUser(auth()->user(), 'slack_webhook_url', '')->data;
+        if (is_array($slackUrl)) {
+            $slackUrl = '';
+        }
+        if (UrlValidator::isValidWebhookURL((string)$slackUrl)) {
+            return ['mail', 'slack'];
+        }
+
+        return ['mail'];
+    }
+}