# In-App Notification System - Setup Guide

## 🎯 Overview

Complete real-time in-app notification system for Royal Enfield Workflow Management System.

## ✅ Features Implemented

### Backend:
1. **Notification Model** (`models/Notification.ts`)
   - Stores all in-app notifications
   - Tracks read/unread status
   - Supports priority levels (LOW, MEDIUM, HIGH, URGENT)
   - Metadata for request context

2. **Notification Controller** (`controllers/notification.controller.ts`)
   - GET `/api/v1/notifications` - List user's notifications with pagination
   - GET `/api/v1/notifications/unread-count` - Get unread count
   - PATCH `/api/v1/notifications/:notificationId/read` - Mark as read
   - POST `/api/v1/notifications/mark-all-read` - Mark all as read
   - DELETE `/api/v1/notifications/:notificationId` - Delete notification

3. **Enhanced Notification Service** (`services/notification.service.ts`)
   - Saves notifications to database (for in-app display)
   - Emits real-time socket.io events
   - Sends push notifications (if subscribed)
   - All in one call: `notificationService.sendToUsers()`

4. **Socket.io Enhancement** (`realtime/socket.ts`)
   - Added `join:user` event for personal notification room
   - Added `emitToUser()` function for targeted notifications
   - Real-time delivery without page refresh

### Frontend:
1. **Notification API Service** (`services/notificationApi.ts`)
   - Complete API client for all notification endpoints

2. **PageLayout Integration** (`components/layout/PageLayout/PageLayout.tsx`)
   - Real-time notification bell with unread count badge
   - Dropdown showing latest 10 notifications
   - Click to mark as read and navigate to request
   - "Mark all as read" functionality
   - Auto-refreshes when new notifications arrive
   - Works even if browser push notifications disabled

3. **Data Freshness** (MyRequests, OpenRequests, ClosedRequests)
   - Fixed stale data after DB deletion
   - Always shows fresh data from API

## 📦 Database Setup

### Step 1: Run Migration

Execute this SQL in your PostgreSQL database:

```bash
psql -U postgres -d re_workflow_db -f migrations/create_notifications_table.sql
```

OR run manually in pgAdmin/SQL tool:

```sql
-- See: migrations/create_notifications_table.sql
```

### Step 2: Verify Table Created

```sql
SELECT table_name FROM information_schema.tables 
WHERE table_schema = 'public' AND table_name = 'notifications';
```

## 🚀 How It Works

### 1. When an Event Occurs (e.g., Request Assigned):

**Backend:**
```typescript
await notificationService.sendToUsers(
  [approverId],
  {
    title: 'New request assigned',
    body: 'Marketing Campaign Approval - REQ-2025-12345',
    requestId: workflowId,
    requestNumber: 'REQ-2025-12345',
    url: `/request/REQ-2025-12345`,
    type: 'assignment',
    priority: 'HIGH',
    actionRequired: true
  }
);
```

This automatically:
- ✅ Saves notification to `notifications` table
- ✅ Emits `notification:new` socket event to user
- ✅ Sends browser push notification (if enabled)

### 2. Frontend Receives Notification:

**PageLayout** automatically:
- ✅ Receives socket event in real-time
- ✅ Updates notification count badge
- ✅ Adds to notification dropdown
- ✅ Shows blue dot for unread
- ✅ User clicks → marks as read → navigates to request

## 📌 Notification Events (Major)

Based on your requirement, here are the key events that trigger notifications:

| Event | Type | Sent To | Priority |
|-------|------|---------|----------|
| Request Created | `created` | Initiator | MEDIUM |
| Request Assigned | `assignment` | Approver | HIGH |
| Approval Given | `approved` | Initiator | HIGH |
| Request Rejected | `rejected` | Initiator | URGENT |
| TAT Alert (50%) | `tat_alert` | Approver | MEDIUM |
| TAT Alert (75%) | `tat_alert` | Approver | HIGH |
| TAT Breached | `tat_breach` | Approver + Initiator | URGENT |
| Work Note Mention | `mention` | Tagged Users | MEDIUM |
| New Comment | `comment` | Participants | LOW |

## 🔧 Configuration

### Backend (.env):
```env
# Already configured - no changes needed
VAPID_PUBLIC_KEY=your_vapid_public_key
VAPID_PRIVATE_KEY=your_vapid_private_key
```

### Frontend (.env):
```env
# Already configured
VITE_API_BASE_URL=http://localhost:5000/api/v1
```

## ✅ Testing

### 1. Test Basic Notification:
```bash
# Create a workflow and assign to an approver
# Check approver's notification bell - should show count
```

### 2. Test Real-Time Delivery:
```bash
# Have 2 users logged in (different browsers)
# User A creates request, assigns to User B
# User B should see notification appear immediately (no refresh needed)
```

### 3. Test TAT Notifications:
```bash
# Create request with 1-hour TAT
# Wait for threshold notifications (50%, 75%, 100%)
# Approver should receive in-app notifications
```

### 4. Test Work Note Mentions:
```bash
# Add work note with @mention
# Tagged user should receive notification
```

## 🎨 UI Features

- **Unread Badge**: Shows count (1-9, or "9+" for 10+)
- **Blue Dot**: Indicates unread notifications
- **Blue Background**: Highlights unread items
- **Time Ago**: "5 minutes ago", "2 hours ago", etc.
- **Click to Navigate**: Automatically opens the related request
- **Mark All Read**: Single click to clear all unread
- **Scrollable**: Shows latest 10, with "View all" link

## 📱 Fallback for Disabled Push Notifications

Even if user denies browser push notifications:
- ✅ In-app notifications ALWAYS work
- ✅ Notifications saved to database
- ✅ Real-time delivery via socket.io
- ✅ No permission required
- ✅ Works on all browsers

## 🔍 Debug Endpoints

```bash
# Get notifications for current user
GET /api/v1/notifications?page=1&limit=10

# Get only unread
GET /api/v1/notifications?unreadOnly=true

# Get unread count
GET /api/v1/notifications/unread-count
```

## 🎉 Benefits

1. **No Browser Permission Needed** - Always works, unlike push notifications
2. **Real-Time Updates** - Instant delivery via socket.io
3. **Persistent** - Saved in database, available after login
4. **Actionable** - Click to navigate to related request
5. **User-Friendly** - Clean UI integrated into header
6. **Complete Tracking** - Know what was sent via which channel

## 🔥 Next Steps (Optional)

1. **Email Integration**: Send email for URGENT priority notifications
2. **SMS Integration**: Critical alerts via SMS
3. **Notification Preferences**: Let users choose which events to receive
4. **Notification History Page**: Full-page view with filters
5. **Sound Alerts**: Play sound when new notification arrives
6. **Desktop Notifications**: Browser native notifications (if permitted)

---

**✅ In-App Notifications are now fully operational!**

Users will receive instant notifications for all major workflow events, even without browser push permissions enabled.