# Notification System

EasyStream now includes a comprehensive notification system with in-app and email delivery.

## Features

- 🔔 **In-app notifications** with real-time updates
- 📧 **Email notifications** with digest support (instant, hourly, daily, weekly)
- 🎯 **Fine-grained preferences** - users control what they receive
- ⚡ **Lightweight polling** - updates every 30 seconds without performance impact
- 📱 **Modern UI** - notification bell with dropdown list
- 🎨 **Multiple notification types** - comments, likes, subscribes, uploads, mentions, system

## Setup

### 1. Database Migration

Run the migration to create notification tables:

```bash
docker-compose exec db mysql -u easystream -peasystream easystream < __install/migrations/002_add_notifications_system.sql
```

This creates:
- `db_notifications` - stores all notifications
- `db_notification_preferences` - user notification settings
- `db_email_queue` - queued emails for batched sending

### 2. Add Notification Bell to Header

Include the JavaScript and add the widget container to your header template:

```html
<!-- In your header template -->
<script src="/f_scripts/fe/js/notifications.js"></script>

<!-- Add the notification bell to your navigation -->
<div id="notification-widget"></div>
```

The widget will auto-initialize and start polling for updates.

### 3. Configure Email Sending

By default, the system uses PHP's `mail()` function. For production, integrate with a proper email service:

Edit `f_core/f_classes/class.notifications.php` → `sendEmail()` method to integrate:
- **SendGrid**
- **Mailgun**
- **Amazon SES**
- **SMTP**

### 4. Set Up Cron Job

Add a cron job to process the email queue:

```bash
# Process email queue every 15 minutes
*/15 * * * * cd /srv/easystream && php app_scripts/cron/process_notification_emails.php >> /var/log/notification-emails.log 2>&1
```

## Usage

### Triggering Notifications

Use the `VNotificationTriggers` helper class for common events:

```php
require_once 'f_core/f_classes/class.notification_triggers.php';
$triggers = new VNotificationTriggers();

// When someone comments on a video
$triggers->notifyVideoComment(
    $video_owner_id,
    $commenter_id,
    $commenter_name,
    $video_id,
    $video_title,
    $comment_text
);

// When someone likes a video
$triggers->notifyVideoLike(
    $video_owner_id,
    $liker_id,
    $liker_name,
    $video_id,
    $video_title
);

// When someone subscribes
$triggers->notifySubscribe(
    $channel_owner_id,
    $subscriber_id,
    $subscriber_name
);

// When uploading a new video (notifies all subscribers)
$triggers->notifySubscribersNewVideo(
    $channel_owner_id,
    $channel_name,
    $video_id,
    $video_title
);

// When mentioning a user in a comment
$triggers->notifyMention(
    $mentioned_user_id,
    $mentioner_id,
    $mentioner_name,
    $video_id,
    $comment_text
);

// System notification
$triggers->notifySystem(
    $user_id,
    'Your video was approved',
    'Your video "Tutorial" is now live!',
    '/watch?v=123'
);
```

### API Endpoints

#### Get Notifications

```http
GET /api/notifications.php?limit=20&offset=0&unread_only=true
```

**Response:**
```json
{
  "success": true,
  "data": {
    "notifications": [
      {
        "notification_id": 123,
        "type": "comment",
        "title": "John commented on your video",
        "message": "Great tutorial!",
        "link": "/watch?v=456#comments",
        "is_read": 0,
        "created_at": "2026-03-30 17:30:00",
        "actor_username": "john",
        "actor_avatar": "/avatars/john.jpg"
      }
    ],
    "unread_count": 5
  }
}
```

#### Get Unread Count (Lightweight)

```http
GET /api/notifications_count.php
```

**Response:**
```json
{
  "success": true,
  "unread_count": 5
}
```

#### Mark as Read

```http
POST /api/notifications.php?action=mark_read
Content-Type: application/json

{"id": 123}
```

Or mark multiple:
```json
{"id": "123,124,125"}
```

#### Mark All as Read

```http
POST /api/notifications.php?action=mark_all_read
```

#### Delete Notification

```http
DELETE /api/notifications.php?id=123
```

### User Preferences

#### Get Preferences

```http
GET /api/notification_preferences.php
```

**Response:**
```json
{
  "success": true,
  "data": {
    "email_comments": 1,
    "email_likes": 1,
    "email_subscribes": 1,
    "email_uploads": 1,
    "email_mentions": 1,
    "email_digest": "instant",
    "push_enabled": 1,
    "push_comments": 1,
    "push_likes": 1,
    "push_subscribes": 1
  }
}
```

#### Update Preferences

```http
POST /api/notification_preferences.php
Content-Type: application/json

{
  "email_digest": "daily",
  "email_likes": 0,
  "push_comments": 1
}
```

## Email Digest Modes

Users can choose how often they receive emails:

- **instant** - Send immediately when notification is created
- **hourly** - Batch and send once per hour
- **daily** - Send once per day (at midnight)
- **weekly** - Send once per week (Monday)
- **never** - No email notifications

## Notification Types

| Type | Description | Example |
|------|-------------|---------|
| `comment` | New comment on video or reply to comment | "John commented on your video" |
| `like` | Someone liked a video | "Sarah liked your video" |
| `subscribe` | New channel subscriber | "Mike subscribed to your channel" |
| `video_upload` | Subscribed channel uploaded new video | "TechChannel uploaded a new video" |
| `mention` | User mentioned in a comment | "@username mentioned you" |
| `system` | Admin/system messages | "Your video was approved" |

## Frontend Integration

The notification widget provides:
- Real-time bell icon with unread count badge
- Dropdown with last 20 notifications
- Mark individual or all as read
- Auto-polling every 30 seconds
- Click notification to navigate and mark as read

### JavaScript API

```javascript
// Access the widget instance
const widget = window.notificationWidget;

// Manually fetch notifications
widget.fetchNotifications();

// Manually fetch unread count
widget.fetchUnreadCount();

// Change poll interval (milliseconds)
widget.pollInterval = 60000; // 1 minute
widget.stopPolling();
widget.startPolling();

// Programmatically mark as read
widget.markAsRead(notification_id);

// Mark all as read
widget.markAllAsRead();
```

## Database Schema

### db_notifications

| Column | Type | Description |
|--------|------|-------------|
| notification_id | INT | Primary key |
| usr_id | INT | User receiving notification |
| type | ENUM | Notification type |
| title | VARCHAR(255) | Short title |
| message | TEXT | Optional detailed message |
| link | VARCHAR(512) | URL to navigate to |
| actor_id | INT | User who triggered notification |
| related_video_id | INT | Associated video |
| related_comment_id | INT | Associated comment |
| is_read | TINYINT | Read status |
| is_seen | TINYINT | Seen status (viewed in UI) |
| email_sent | TINYINT | Email delivery status |
| created_at | DATETIME | Creation timestamp |
| read_at | DATETIME | When marked as read |

### db_notification_preferences

| Column | Type | Description |
|--------|------|-------------|
| usr_id | INT | User ID (unique) |
| email_comments | TINYINT | Email for comments |
| email_likes | TINYINT | Email for likes |
| email_subscribes | TINYINT | Email for subscribes |
| email_uploads | TINYINT | Email for new uploads |
| email_mentions | TINYINT | Email for mentions |
| email_digest | ENUM | Digest frequency |
| push_enabled | TINYINT | Push notifications enabled |
| push_comments | TINYINT | Push for comments |
| push_likes | TINYINT | Push for likes |
| push_subscribes | TINYINT | Push for subscribes |

### db_email_queue

| Column | Type | Description |
|--------|------|-------------|
| queue_id | INT | Primary key |
| usr_id | INT | Recipient user |
| email | VARCHAR(255) | Email address |
| subject | VARCHAR(255) | Email subject |
| body | TEXT | Email HTML body |
| scheduled_for | DATETIME | When to send |
| sent_at | DATETIME | Actual send time |
| attempts | INT | Send attempts |
| last_error | TEXT | Last error message |

## Performance

- **Polling:** Lightweight count query every 30s (~1-2ms)
- **Dropdown:** Full notification list only when opened
- **Email queue:** Batched processing reduces database load
- **Auto-cleanup:** Old read notifications purged after 90 days

## Cleanup

The cron script automatically cleans up:
- Read notifications older than 90 days
- Sent emails from queue

Adjust retention in `app_scripts/cron/process_notification_emails.php`:

```php
$notifications->cleanup(90); // Days to keep
```

## Troubleshooting

### Notifications not appearing

1. Check database tables exist
2. Verify JavaScript is loaded: `window.notificationWidget`
3. Check browser console for errors
4. Verify user is authenticated (session active)

### Emails not sending

1. Check cron job is running
2. View email queue: `SELECT * FROM db_email_queue WHERE sent_at IS NULL`
3. Check email configuration in `class.notifications.php`
4. View logs: `docker-compose logs php | grep email`

### High polling load

Increase poll interval in the frontend:

```javascript
// In notifications.js
this.pollInterval = 60000; // 60 seconds instead of 30
```

## Future Enhancements

- [ ] WebSocket/SSE for true real-time updates (eliminate polling)
- [ ] Push notifications (web push API)
- [ ] Mobile app push notifications (FCM/APNS)
- [ ] Notification grouping (e.g., "5 people liked your video")
- [ ] Rich notification preview with thumbnails
- [ ] Notification filtering/search
- [ ] Mark as unread
- [ ] Snooze notifications

## Learn More

- [Web Push API](https://developer.mozilla.org/en-US/docs/Web/API/Push_API)
- [Server-Sent Events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events)
- [Email Best Practices](https://developers.google.com/gmail/design/reference/supported_css)