# WhatsApp Business Cloud API Implementation Summary

## Overview

Successfully implemented WhatsApp Business Cloud API integration for sending free template-based notifications to suppliers about purchase orders.

---

## Implementation Details

### 🎯 Objectives Achieved

✅ Direct integration with Meta's WhatsApp Business Cloud API (no Twilio)
✅ Template-based messaging for proactive notifications
✅ Delivery tracking with webhooks
✅ Database persistence for message history
✅ Backward-compatible wrapper for existing code
✅ Complete setup documentation

---

## Files Created

### 1. Database Layer

#### [app/models/whatsapp_messages.py](app/models/whatsapp_messages.py)
- **WhatsAppMessage**: Track sent messages and delivery status
- **WhatsAppTemplate**: Store template metadata
- Enums for message types and statuses

#### [migrations/versions/20251113_add_whatsapp_business_tables.py](migrations/versions/20251113_add_whatsapp_business_tables.py)
- Creates `whatsapp_messages` table
- Creates `whatsapp_templates` table
- Adds indexes for performance

#### [app/repositories/whatsapp_message_repository.py](app/repositories/whatsapp_message_repository.py)
- **WhatsAppMessageRepository**: CRUD operations for messages
- **WhatsAppTemplateRepository**: Template management
- Delivery statistics and analytics

### 2. Service Layer

#### [app/services/whatsapp_business_service.py](app/services/whatsapp_business_service.py)
- Direct WhatsApp Cloud API integration
- Template message sending
- Text message support
- Bulk messaging with rate limiting
- Health checks

#### [app/schemas/whatsapp.py](app/schemas/whatsapp.py)
- Request/response schemas
- Template message schemas
- Webhook payload schemas
- Delivery statistics schemas

### 3. API Layer

#### [app/api/whatsapp_webhooks.py](app/api/whatsapp_webhooks.py)
- Webhook verification endpoint (GET)
- Webhook event handler (POST)
- Status update processing
- Incoming message handling

### 4. Documentation

#### [WHATSAPP_SETUP_GUIDE.md](WHATSAPP_SETUP_GUIDE.md)
Complete step-by-step setup guide covering:
- Meta Business Account creation
- WhatsApp Business registration
- API credential generation
- Template creation and approval
- Webhook configuration
- Environment setup
- Testing procedures
- Troubleshooting

---

## Files Modified

### 1. [app/services/whatsapp_service.py](app/services/whatsapp_service.py)
**Changes**:
- Replaced Twilio integration with WhatsApp Business Cloud API
- Created backward-compatible wrapper around new service
- Maintains existing method signatures
- Added `tenant_id` parameter support

**Before**:
```python
# Twilio-based implementation
async def send_message(self, to_phone, message, template_name=None, template_params=None):
    # Twilio API calls
```

**After**:
```python
# Wrapper around WhatsAppBusinessService
async def send_message(self, to_phone, message, template_name=None, template_params=None, tenant_id=None):
    # Delegates to WhatsAppBusinessService
```

### 2. [app/core/config.py](app/core/config.py)
**Added**:
```python
# WhatsApp Business Cloud API Configuration
WHATSAPP_ACCESS_TOKEN: str
WHATSAPP_PHONE_NUMBER_ID: str
WHATSAPP_BUSINESS_ACCOUNT_ID: str
WHATSAPP_API_VERSION: str
WHATSAPP_WEBHOOK_VERIFY_TOKEN: str
```

**Deprecated** (kept for backward compatibility):
```python
WHATSAPP_API_KEY: str  # Deprecated
WHATSAPP_BASE_URL: str  # Deprecated
WHATSAPP_FROM_NUMBER: str  # Deprecated
```

### 3. [app/main.py](app/main.py)
**Changes**:
- Updated expected migration version to `whatsapp001`
- Added `whatsapp_messages` and `whatsapp_templates` to expected tables
- Imported and registered `whatsapp_webhooks_router`
- Updated PO consumer initialization to include WhatsApp service

**Added**:
```python
from app.api.whatsapp_webhooks import router as whatsapp_webhooks_router

service.add_router(whatsapp_webhooks_router, tags=["whatsapp-webhooks"])
```

### 4. [app/consumers/po_event_consumer.py](app/consumers/po_event_consumer.py)
**Changes**:
- Added WhatsApp service dependency
- Implemented `send_po_approved_whatsapp()` method
- Integrated WhatsApp sending into event processing
- Added template-based notification for PO events

**New Method**:
```python
async def send_po_approved_whatsapp(self, event_data: Dict[str, Any]) -> bool:
    # Sends template message to supplier
    # Template: po_notification
    # Parameters: supplier_name, po_number, total_amount
```

---

## API Endpoints Added

### Webhook Endpoints

#### GET `/api/v1/whatsapp/webhook`
- **Purpose**: Webhook verification by Meta
- **Parameters**: hub.mode, hub.verify_token, hub.challenge
- **Response**: Challenge token if verified

#### POST `/api/v1/whatsapp/webhook`
- **Purpose**: Receive webhook events from WhatsApp
- **Events**: Message status updates, incoming messages
- **Response**: Success acknowledgment

#### GET `/api/v1/whatsapp/health`
- **Purpose**: Health check for webhook endpoint
- **Response**: Service status

---

## Environment Variables

### Required

```bash
# WhatsApp Business Cloud API
WHATSAPP_ACCESS_TOKEN=EAAxxxxxxxxxxxxx
WHATSAPP_PHONE_NUMBER_ID=123456789012345
WHATSAPP_BUSINESS_ACCOUNT_ID=987654321098765
WHATSAPP_WEBHOOK_VERIFY_TOKEN=your-random-token

# Feature Flag
ENABLE_WHATSAPP_NOTIFICATIONS=true
```

### Optional

```bash
WHATSAPP_API_VERSION=v18.0  # Default: v18.0
```

---

## Database Schema

### whatsapp_messages Table

| Column | Type | Description |
|--------|------|-------------|
| id | UUID | Primary key |
| tenant_id | UUID | Tenant identifier |
| notification_id | UUID | Link to notification |
| whatsapp_message_id | String | WhatsApp's message ID |
| recipient_phone | String | E.164 phone number |
| message_type | Enum | TEMPLATE, TEXT, IMAGE, etc. |
| status | Enum | PENDING, SENT, DELIVERED, READ, FAILED |
| template_name | String | Template name used |
| template_parameters | JSON | Template parameter values |
| sent_at | DateTime | When sent |
| delivered_at | DateTime | When delivered |
| read_at | DateTime | When read |
| error_message | Text | Error if failed |
| provider_response | JSON | Full API response |
| metadata | JSON | Additional context |
| created_at | DateTime | Record created |
| updated_at | DateTime | Record updated |

### whatsapp_templates Table

| Column | Type | Description |
|--------|------|-------------|
| id | UUID | Primary key |
| template_name | String | WhatsApp template name |
| template_key | String | Internal identifier |
| category | String | MARKETING, UTILITY, etc. |
| language | String | Language code |
| status | String | PENDING, APPROVED, REJECTED |
| body_text | Text | Template body |
| parameter_count | Integer | Number of parameters |
| sent_count | Integer | Usage counter |
| is_active | Boolean | Active status |

---

## Message Flow

### Outgoing Message (PO Notification)

```
1. Purchase Order Approved
   ↓
2. RabbitMQ Event Published
   ↓
3. PO Event Consumer Receives Event
   ↓
4. Extract supplier phone & data
   ↓
5. Build template parameters
   ↓
6. WhatsAppService.send_message()
   ↓
7. WhatsAppBusinessService.send_message()
   ↓
8. Create DB record (PENDING)
   ↓
9. Send to WhatsApp Cloud API
   ↓
10. Update DB record (SENT)
    ↓
11. Return success
```

### Status Updates (Webhook)

```
1. WhatsApp delivers message
   ↓
2. Meta sends webhook event
   ↓
3. POST /api/v1/whatsapp/webhook
   ↓
4. Parse status update
   ↓
5. Find message in DB
   ↓
6. Update status & timestamps
   ↓
7. Record metrics
   ↓
8. Return 200 OK
```

---

## Testing Checklist

### ✅ Before Going Live

- [ ] Meta Business Account created and verified
- [ ] WhatsApp Business phone number registered
- [ ] Permanent access token generated (not temporary)
- [ ] Template `po_notification` created and **APPROVED**
- [ ] Webhook URL configured and verified
- [ ] Environment variables set in production
- [ ] Database migration applied
- [ ] Test message sent successfully
- [ ] Webhook events received and processed
- [ ] Supplier phone numbers in correct format (+34...)
- [ ] Monitoring and alerting configured

### 🧪 Test Commands

```bash
# 1. Verify webhook
curl "https://your-domain.com/api/v1/whatsapp/webhook?hub.mode=subscribe&hub.verify_token=YOUR_TOKEN&hub.challenge=test"

# 2. Check health
curl https://your-domain.com/api/v1/whatsapp/health

# 3. Check migration
kubectl exec -it deployment/notification-service -- alembic current

# 4. View logs
kubectl logs -f deployment/notification-service | grep WhatsApp

# 5. Check database
psql -U notification_user -d notification_db -c "SELECT * FROM whatsapp_messages LIMIT 5;"
```

---

## Pricing Summary

### Free Tier
- **1,000 business-initiated conversations/month** (FREE)
- **1,000 user-initiated conversations/month** (FREE)

### Paid Tier
- After free tier: **€0.01-0.10 per conversation** (varies by country)
- Conversation = 24-hour window
- Multiple messages in 24h = 1 conversation charge

### Cost Example
- **50 PO notifications/month**: FREE
- **1,500 PO notifications/month**: €5-50/month

---

## Backward Compatibility

The implementation maintains full backward compatibility with existing code:

```python
# Existing code still works
whatsapp_service = WhatsAppService()
await whatsapp_service.send_message(
    to_phone="+34612345678",
    message="Test",
    template_name="po_notification",
    template_params=["Supplier", "PO-001", "€100"]
)
```

New code can use additional features:

```python
# New functionality
from app.services.whatsapp_business_service import WhatsAppBusinessService
from app.schemas.whatsapp import SendWhatsAppMessageRequest

service = WhatsAppBusinessService(session)
request = SendWhatsAppMessageRequest(...)
response = await service.send_message(request)
```

---

## Next Steps

1. **Follow Setup Guide**: Complete all steps in [WHATSAPP_SETUP_GUIDE.md](WHATSAPP_SETUP_GUIDE.md)
2. **Add Supplier Phones**: Ensure supplier records include phone numbers
3. **Create More Templates**: Design templates for other notification types
4. **Monitor Usage**: Track conversation usage in Meta Business Suite
5. **Set Up Alerts**: Configure alerts for failed messages

---

## Support & Resources

- **Setup Guide**: [WHATSAPP_SETUP_GUIDE.md](WHATSAPP_SETUP_GUIDE.md)
- **Meta Docs**: https://developers.facebook.com/docs/whatsapp/cloud-api
- **Pricing**: https://developers.facebook.com/docs/whatsapp/pricing
- **Status Page**: https://developers.facebook.com/status

---

## Summary

✅ **Complete WhatsApp Business Cloud API integration**
✅ **Free tier: 1,000 messages/month**
✅ **Template-based notifications ready**
✅ **PO notifications automated**
✅ **Delivery tracking enabled**
✅ **Production-ready documentation**

**Status**: Ready for deployment after Meta account setup
