# Payment API Updates Summary

## 🚀 Payment API Updates - Status Query Integration

### Status Response - Removed Timestamps

The payment status response no longer includes `created_at` and `updated_at` fields:

**Old Response:**
```json
{
  "transaction_id": "uuid",
  "checkout_id": "string",
  "status": "completed",
  "amount": 1500,
  "reference": "string",
  "phone_number": "+254...",
  "created_at": "2026-01-28T15:36:05Z",
  "updated_at": "2026-01-28T15:36:10Z"
}
```

**New Response:**
```json
{
  "transaction_id": "uuid",
  "checkout_id": "string",
  "status": "completed",
  "amount": 1500,
  "reference": "string",
  "phone_number": "+254..."
}
```

### Real-time Status from Safaricom

The `/api/v1/payments/status` endpoint now queries **Safaricom directly** instead of the local database:

1. **Request arrives** → System queries local DB for transaction details
2. **Safaricom API call** → Real-time status query using CheckoutRequestID
3. **Response mapping** → Safaricom result codes mapped to payment status:
   - `0` → `completed` (Success)
   - `1032` → `cancelled` (User cancelled)
   - Others → `failed` (Various failures)
4. **Local update** → Transaction record updated with Safaricom's result

### Safaricom Query Details

**Endpoint Used:** `/mpesa/stkpushquery/v1/query`

**Request Parameters:**
- `BusinessShortCode` - Organization's shortcode
- `Password` - Base64(ShortCode + PassKey + Timestamp)
- `Timestamp` - Current time (YYYYMMDDHHmmss)
- `CheckoutRequestID` - The checkout ID from payment initiation

**Benefits:**
✅ Always get actual payment status from Safaricom
✅ No dependency on callback timing
✅ Immediate status confirmation
✅ System records stay in sync with Safaricom

Two public endpoints now accept minimal, simplified payloads:

#### Endpoint 1: Initiate Payment
```
POST /api/v1/payments/initiate
```

**Required fields (only 3):**
- `client_id` (UUID) - The client identifier
- `package_id` (UUID) - The internet package to purchase
- `description` (String) - Payment description/notes

**Response:**
```json
{
  "transaction_id": "uuid",
  "checkout_id": "string",
  "message": "Payment initiated successfully",
  "status": "pending"
}
```

#### Endpoint 2: Query Payment Status
```
POST /api/v1/payments/status
```

**Required fields:**
- `client_id` (UUID) - The client identifier
- `checkout_id` (String) - The checkout ID from initiate response

**Response:**
```json
{
  "transaction_id": "uuid",
  "checkout_id": "string",
  "status": "completed|pending|failed|cancelled",
  "amount": 1500,
  "reference": "string",
  "phone_number": "+254...",
  "created_at": "timestamp",
  "updated_at": "timestamp"
}
```

### 2. **Key Implementation Details**

#### Phone Number Handling
- Phone number is **automatically retrieved** from the client's profile
- No need to pass phone number in the API request
- Ensures consistency and reduces data entry errors

#### Automatic Package Lookup
- Package details are fetched from the database using `package_id`
- Amount, speed, duration are all pulled from package configuration

#### Request Validation
- All requests validate client exists and is active
- Returns descriptive error messages for validation failures
- Proper HTTP status codes (400, 403, 404, 500)

### 3. **Files Modified**

#### [internal/handlers/payment_handler.go](internal/handlers/payment_handler.go)
- Updated `InitiatePayment()` handler to accept simplified payload
- Updated `CheckPaymentStatus()` handler with string UUID parsing
- Added input validation with helpful error messages

#### [internal/services/payment_service.go](internal/services/payment_service.go)
- Added new `InitiatePaymentPublic()` method for public API
- Retrieves phone number from client profile automatically
- Simplified payment initiation flow

### 4. **New Documentation**

#### [docs/PUBLIC_PAYMENT_API.md](docs/PUBLIC_PAYMENT_API.md)
Complete API documentation including:
- Endpoint details with request/response schemas
- Status codes and error responses
- Usage examples in cURL, JavaScript, and Python
- Testing instructions with Postman
- Best practices and error handling

---

## API Usage Examples

### cURL - Initiate Payment
```bash
curl -X POST http://localhost:8080/api/v1/payments/initiate \
  -H "Content-Type: application/json" \
  -d '{
    "client_id": "550e8400-e29b-41d4-a716-446655440000",
    "package_id": "660e8400-e29b-41d4-a716-446655440001",
    "description": "Internet package - Professional Plan"
  }'
```

### cURL - Check Status
```bash
curl -X POST http://localhost:8080/api/v1/payments/status \
  -H "Content-Type: application/json" \
  -d '{
    "client_id": "550e8400-e29b-41d4-a716-446655440000",
    "checkout_id": "abc123xyz456"
  }'
```

---

## Benefits

✅ **Simplified API** - Only 3 required fields instead of many
✅ **Less Error-Prone** - Phone number auto-retrieved from profile
✅ **Better UX** - Clear, descriptive error messages
✅ **Secure** - Client validation on every request
✅ **Well Documented** - Comprehensive API documentation provided
✅ **Public Access** - No authentication required for payment operations
✅ **Backward Compatible** - Old payment methods still available for authenticated requests

---

## Routes Status

| Endpoint | Access | Status |
|----------|--------|--------|
| `POST /api/v1/payments/initiate` | Public | ✅ Updated |
| `POST /api/v1/payments/status` | Public | ✅ Updated |
| `GET /api/v1/payments/transactions` | Protected | ℹ️ Unchanged |
| `GET /api/v1/payments/transactions/:id` | Protected | ℹ️ Unchanged |
| `POST /api/v1/callbacks/mpesa` | Public | ℹ️ Unchanged |

---

## Testing the APIs

1. **Start the server:**
   ```bash
   go run main.go
   ```

2. **Use the seed data:**
   ```bash
   go run cmd/seed/main.go
   ```

3. **Test with cURL or Postman** using the examples above

4. **Check documentation** at [docs/PUBLIC_PAYMENT_API.md](docs/PUBLIC_PAYMENT_API.md)

---

## Next Steps

- Test the endpoints with actual M-Pesa credentials
- Monitor callback processing for transaction status updates
- Implement additional security measures if needed (IP whitelisting, API keys, etc.)
- Consider adding rate limiting per client