# Feature Summary: Device Settings Verification

## What Was Added

A new API endpoint that retrieves all current device settings in a single request, allowing users to quickly verify the NL43/NL53 configuration before starting measurements.

## New Endpoint

**`GET /api/nl43/{unit_id}/settings`**

Returns comprehensive device configuration including:
- Measurement state and weighting settings
- Timing and interval configuration
- Battery level and device clock
- Sleep mode and FTP status

## Files Modified

### 1. [app/routers.py](app/routers.py)
**Lines:** 728-761

Added new route handler `get_all_settings()` that:
- Validates device configuration exists
- Checks TCP communication is enabled
- Calls `NL43Client.get_all_settings()`
- Returns formatted JSON response with all settings
- Handles connection errors, timeouts, and exceptions

### 2. [README.md](README.md)
**Updated sections:**
- Line 134: Added new endpoint to Measurement Settings table
- Lines 259-283: Added usage example showing how to verify device settings

## Files Created

### 1. [test_settings_endpoint.py](test_settings_endpoint.py)
Test/demonstration script showing:
- How to use the `get_all_settings()` method
- Example API endpoint usage with curl
- Expected response format

### 2. [SETTINGS_ENDPOINT.md](SETTINGS_ENDPOINT.md)
Comprehensive documentation including:
- Detailed endpoint description
- Complete list of settings retrieved
- Usage examples in bash, Python, and JavaScript
- Performance considerations
- Best practices and troubleshooting

### 3. [FEATURE_SUMMARY.md](FEATURE_SUMMARY.md)
This file - summary of changes for reference

## Existing Functionality Used

The implementation leverages the existing `get_all_settings()` method in [app/services.py](app/services.py#L538) which was already implemented but not exposed via the API. This method queries multiple device settings and handles errors gracefully.

## How It Works

1. **User makes GET request** to `/api/nl43/{unit_id}/settings`
2. **Router validates** device configuration exists and TCP is enabled
3. **NL43Client queries device** for each setting sequentially (with 1-second delays)
4. **Individual errors** are caught and returned as error strings
5. **Response returned** with all settings in JSON format

## Usage Example

```bash
# Quick verification before measurement
curl http://localhost:8100/api/nl43/NL43-001/settings

# Response:
{
  "status": "ok",
  "unit_id": "NL43-001",
  "settings": {
    "measurement_state": "Stop",
    "frequency_weighting": "A",
    "time_weighting": "F",
    "measurement_time": "00:01:00",
    "leq_interval": "1s",
    "lp_interval": "125ms",
    "index_number": "0",
    "battery_level": "100%",
    "clock": "2025/12/24,20:45:30",
    "sleep_mode": "Off",
    "ftp_status": "On"
  }
}
```

## Benefits

1. **Single request** - Get all settings at once instead of multiple API calls
2. **Pre-flight checks** - Verify configuration before starting measurements
3. **Documentation** - Easy to save configuration snapshots for audit trails
4. **Troubleshooting** - Quickly identify misconfigured settings
5. **Multi-device** - Compare settings across multiple devices

## Performance Notes

- **Query time:** ~10-15 seconds (due to required 1-second delays between commands)
- **Rate limiting:** Automatically enforced by NL43Client
- **Error handling:** Partial failures don't prevent other settings from being retrieved
- **Caching recommended:** Settings don't change frequently, cache for 5-10 minutes

## Testing

To test the new endpoint:

1. **Start the server:**
   ```bash
   uvicorn app.main:app --reload --port 8100
   ```

2. **Configure a device** (if not already configured):
   ```bash
   curl -X PUT http://localhost:8100/api/nl43/test-meter/config \
     -H "Content-Type: application/json" \
     -d '{"host": "192.168.1.100", "tcp_port": 80, "tcp_enabled": true}'
   ```

3. **Query settings:**
   ```bash
   curl http://localhost:8100/api/nl43/test-meter/settings
   ```

4. **Check Swagger UI:**
   - Navigate to http://localhost:8100/docs
   - Find "GET /api/nl43/{unit_id}/settings" endpoint
   - Click "Try it out" and test interactively

## Integration Tips

### Frontend Integration
```javascript
// React/Vue/Angular example
async function verifyDeviceBeforeMeasurement(unitId) {
  const response = await fetch(`/api/nl43/${unitId}/settings`);
  const { settings } = await response.json();

  // Verify critical settings
  if (settings.frequency_weighting !== 'A') {
    alert('Warning: Frequency weighting not set to A');
  }

  // Check battery
  const batteryPercent = parseInt(settings.battery_level);
  if (batteryPercent < 20) {
    alert('Low battery! Please charge device.');
  }

  return settings;
}
```

### Python Automation
```python
def ensure_correct_config(unit_id: str, required_config: dict):
    """Verify device matches required configuration."""
    settings = get_device_settings(unit_id)

    mismatches = []
    for key, expected in required_config.items():
        actual = settings.get(key)
        if actual != expected:
            mismatches.append(f"{key}: expected {expected}, got {actual}")

    if mismatches:
        raise ValueError(f"Configuration mismatch: {', '.join(mismatches)}")

    return True
```

## Future Enhancements

Potential improvements for future versions:

1. **Filtered queries** - Query parameter to select specific settings
2. **Diff mode** - Compare current settings to expected values
3. **Batch queries** - Get settings from multiple devices in one request
4. **Settings profiles** - Save/load common configuration profiles
5. **Change detection** - Track when settings were last modified

## Support

For questions or issues with this feature:
- See [SETTINGS_ENDPOINT.md](SETTINGS_ENDPOINT.md) for detailed documentation
- Check [README.md](README.md) for general API usage
- Review [COMMUNICATION_GUIDE.md](COMMUNICATION_GUIDE.md) for protocol details

## Version Info

- **Added:** December 24, 2025
- **API Version:** Compatible with existing v1 API
- **Breaking Changes:** None - purely additive feature