geutebruck/P0_Backend_API_Approach.md

# P0 Implementation - Backend API Approach (RECOMMENDED)

**This is the CORRECT approach for your architecture!**

You already have:
- ✅ FastAPI backend at `http://100.81.138.77:8000/api/v1`
- ✅ Flutter app making REST calls
- ✅ Swagger UI documentation
- ✅ Authentication with Bearer tokens

**DON'T create a native Windows plugin!** Instead, add GeViServer integration to your existing backend.

---

## Current Architecture (What You Have)

```
┌─────────────────────────────────────────┐
│         Flutter App (Dart)              │
│  ┌───────────────────────────────────┐  │
│  │   ActionMappingBloc               │  │
│  │   ServerBloc                      │  │
│  └──────────────┬────────────────────┘  │
│                 │                        │
│  ┌──────────────▼────────────────────┐  │
│  │   DioClient (HTTP)                │  │
│  │   http://100.81.138.77:8000       │  │
│  └──────────────┬────────────────────┘  │
└─────────────────┼────────────────────────┘
                  │ REST API
┌─────────────────▼────────────────────────┐
│      FastAPI Backend (Python)            │
│  ┌───────────────────────────────────┐   │
│  │   /api/v1/configuration/...       │   │
│  │   /api/v1/auth/...                │   │
│  │   /api/v1/excel/...               │   │
│  └───────────────────────────────────┘   │
│                                           │
│  Database: PostgreSQL/SQLite             │
└───────────────────────────────────────────┘
```

---

## Target Architecture (What You Need)

```
┌─────────────────────────────────────────┐
│         Flutter App (Dart)              │
│  ┌───────────────────────────────────┐  │
│  │   GeViServerConnectionBloc        │  │  ← New BLoC
│  │   VideoControlBloc                │  │  ← New BLoC
│  └──────────────┬────────────────────┘  │
│                 │                        │
│  ┌──────────────▼────────────────────┐  │
│  │   DioClient (HTTP)                │  │
│  │   Existing HTTP client            │  │
│  └──────────────┬────────────────────┘  │
└─────────────────┼────────────────────────┘
                  │ REST API (new endpoints)
┌─────────────────▼────────────────────────┐
│      FastAPI Backend (Python)            │
│  ┌───────────────────────────────────┐   │
│  │   NEW: /api/v1/geviserver/...     │   │  ← Add these!
│  │   - POST /connect                 │   │
│  │   - POST /disconnect              │   │
│  │   - POST /send-action             │   │
│  │   - GET  /video-inputs            │   │
│  │   - POST /crossswitch             │   │
│  │   - POST /digital-io/close        │   │
│  │   - GET  /connection-status       │   │
│  └──────────────┬────────────────────┘   │
│                 │                         │
│  ┌──────────────▼────────────────────┐   │
│  │   GeViServer Service (Python)     │   │  ← New service
│  │   - Wrapper around GeViProcAPI    │   │
│  │   - Connection pooling            │   │
│  │   - Message construction          │   │
│  └──────────────┬────────────────────┘   │
│                 │                         │
│  ┌──────────────▼────────────────────┐   │
│  │   Python → GeViProcAPI.dll        │   │  ← Integration
│  │   (ctypes or subprocess)          │   │
│  └──────────────┬────────────────────┘   │
└─────────────────┼─────────────────────────┘
                  │ Native calls
┌─────────────────▼─────────────────────────┐
│      GeViServer (Windows Service)         │
│      C:\GEVISOFT\geviserver.exe           │
└───────────────────────────────────────────┘
```

---

## Implementation Steps

### Step 1: Add GeViServer Integration to Backend

**Location:** `geutebruck-api/src/api/routers/geviserver.py`

#### 1.1 Install Python Dependencies

```bash
cd C:\DEV\COPILOT\geutebruck-api
pip install ctypes  # Already included in Python
```

#### 1.2 Create GeViServer Service

**File:** `geutebruck-api/src/services/geviserver_service.py`

```python
import ctypes
import logging
from typing import Optional, Dict, Any
from ctypes import POINTER, c_char_p, c_int, c_bool, c_void_p, CFUNCTYPE, Structure
from dataclasses import dataclass
from enum import Enum

logger = logging.getLogger(__name__)


class TServerNotification(Enum):
    NFServer_SetupModified = 0
    NFServer_Disconnected = 10
    NFServer_GoingShutdown = 11
    NFServer_NewMessage = 12


class TConnectResult(Enum):
    connectOk = 0
    connectWarningInvalidHeaders = 1
    connectAborted = 100
    connectGenericError = 101
    connectRemoteUnknownUser = 302
    connectRemoteConnectionLimitExceeded = 303


@dataclass
class GeViServerConnectionInfo:
    address: str
    username: str
    is_connected: bool
    connected_at: Optional[str] = None


class GeViServerService:
    """Service to interact with GeViServer via GeViProcAPI.dll"""

    def __init__(self, dll_path: str = "C:/GEVISOFT/GeViProcAPI.dll"):
        self.dll_path = dll_path
        self.dll = None
        self.database_handle = None
        self._load_dll()

    def _load_dll(self):
        """Load GeViProcAPI.dll and define function signatures"""
        try:
            self.dll = ctypes.WinDLL(self.dll_path)

            # Define function signatures
            # GeViAPI_InterfaceVersion
            self.dll.GeViAPI_InterfaceVersion.restype = c_int
            self.dll.GeViAPI_InterfaceVersion.argtypes = []

            # GeViAPI_EncodeString
            self.dll.GeViAPI_EncodeString.restype = c_bool
            self.dll.GeViAPI_EncodeString.argtypes = [c_char_p, c_char_p, c_int]

            # GeViAPI_Database_Create
            self.dll.GeViAPI_Database_Create.restype = c_bool
            self.dll.GeViAPI_Database_Create.argtypes = [
                POINTER(c_void_p),  # Database handle (out)
                c_char_p,           # Aliasname
                c_char_p,           # Address
                c_char_p,           # Username
                c_char_p,           # Password
                c_char_p,           # Username2
                c_char_p,           # Password2
            ]

            # GeViAPI_Database_Connect
            self.dll.GeViAPI_Database_Connect.restype = c_bool
            self.dll.GeViAPI_Database_Connect.argtypes = [
                c_void_p,           # Database handle
                POINTER(c_int),     # ConnectResult (out)
                c_void_p,           # Callback (optional)
                c_void_p,           # Instance (optional)
            ]

            # GeViAPI_Database_Connected
            self.dll.GeViAPI_Database_Connected.restype = c_bool
            self.dll.GeViAPI_Database_Connected.argtypes = [
                c_void_p,           # Database handle
                POINTER(c_bool),    # IsConnected (out)
            ]

            # GeViAPI_Database_Disconnect
            self.dll.GeViAPI_Database_Disconnect.restype = c_bool
            self.dll.GeViAPI_Database_Disconnect.argtypes = [c_void_p]

            # GeViAPI_Database_Destroy
            self.dll.GeViAPI_Database_Destroy.restype = c_bool
            self.dll.GeViAPI_Database_Destroy.argtypes = [c_void_p]

            # GeViAPI_Database_SendPing
            self.dll.GeViAPI_Database_SendPing.restype = c_bool
            self.dll.GeViAPI_Database_SendPing.argtypes = [c_void_p]

            # GeViAPI_Database_SendMessage
            self.dll.GeViAPI_Database_SendMessage.restype = c_bool
            self.dll.GeViAPI_Database_SendMessage.argtypes = [
                c_void_p,           # Database handle
                c_char_p,           # Message buffer
                c_int,              # Buffer size
            ]

            # GeViAPI_GetLastError
            self.dll.GeViAPI_GetLastError.restype = c_bool
            self.dll.GeViAPI_GetLastError.argtypes = [
                POINTER(c_int),     # ExceptionClass (out)
                POINTER(c_int),     # ErrorNo (out)
                POINTER(c_int),     # ErrorClass (out)
                POINTER(c_char_p),  # ErrorMessage (out)
            ]

            logger.info(f"Loaded GeViProcAPI.dll version: {self.dll.GeViAPI_InterfaceVersion()}")

        except Exception as e:
            logger.error(f"Failed to load GeViProcAPI.dll: {e}")
            raise

    def _encode_password(self, password: str) -> bytes:
        """Encode password using GeViAPI_EncodeString"""
        encoded = ctypes.create_string_buffer(33)  # 32 bytes + null

        result = self.dll.GeViAPI_EncodeString(
            encoded,
            password.encode('utf-8'),
            33
        )

        if not result:
            raise Exception("Failed to encode password")

        return encoded.value

    def _get_last_error(self) -> str:
        """Get last error from GeViProcAPI"""
        exception_class = c_int()
        error_no = c_int()
        error_class = c_int()
        error_message = c_char_p()

        result = self.dll.GeViAPI_GetLastError(
            ctypes.byref(exception_class),
            ctypes.byref(error_no),
            ctypes.byref(error_class),
            ctypes.byref(error_message)
        )

        if result and error_message:
            return error_message.value.decode('utf-8', errors='ignore')

        return "Unknown error"

    def connect(
        self,
        address: str,
        username: str,
        password: str,
        username2: Optional[str] = None,
        password2: Optional[str] = None
    ) -> Dict[str, Any]:
        """
        Connect to GeViServer

        Args:
            address: Server address (e.g., "localhost" or "192.168.1.100")
            username: Username for authentication
            password: Password (will be encrypted)
            username2: Optional second username
            password2: Optional second password

        Returns:
            Dict with success status and message
        """
        try:
            # Disconnect if already connected
            if self.database_handle:
                self.disconnect()

            # Encode passwords
            encoded_password = self._encode_password(password)
            encoded_password2 = self._encode_password(password2) if password2 else None

            # Create database handle
            db_handle = c_void_p()

            result = self.dll.GeViAPI_Database_Create(
                ctypes.byref(db_handle),
                b"PythonAPI",
                address.encode('utf-8'),
                username.encode('utf-8'),
                encoded_password,
                username2.encode('utf-8') if username2 else None,
                encoded_password2 if encoded_password2 else None
            )

            if not result or not db_handle.value:
                error_msg = self._get_last_error()
                logger.error(f"Failed to create database: {error_msg}")
                return {
                    "success": False,
                    "message": f"Database creation failed: {error_msg}"
                }

            self.database_handle = db_handle

            # Connect
            connect_result = c_int()

            result = self.dll.GeViAPI_Database_Connect(
                self.database_handle,
                ctypes.byref(connect_result),
                None,  # Progress callback
                None   # Instance
            )

            if not result or connect_result.value != TConnectResult.connectOk.value:
                error_msg = self._get_last_error()
                connect_result_name = TConnectResult(connect_result.value).name if connect_result.value in [e.value for e in TConnectResult] else f"Unknown({connect_result.value})"

                logger.error(f"Connection failed: {connect_result_name}, {error_msg}")

                # Clean up
                self.dll.GeViAPI_Database_Destroy(self.database_handle)
                self.database_handle = None

                return {
                    "success": False,
                    "message": f"Connection failed: {connect_result_name}",
                    "error": error_msg
                }

            logger.info(f"Successfully connected to GeViServer at {address}")

            return {
                "success": True,
                "message": "Connected to GeViServer",
                "address": address,
                "username": username
            }

        except Exception as e:
            logger.error(f"Exception during connection: {e}")
            return {
                "success": False,
                "message": f"Exception: {str(e)}"
            }

    def disconnect(self) -> Dict[str, Any]:
        """Disconnect from GeViServer"""
        try:
            if not self.database_handle:
                return {
                    "success": True,
                    "message": "Already disconnected"
                }

            # Disconnect
            self.dll.GeViAPI_Database_Disconnect(self.database_handle)

            # Destroy handle
            self.dll.GeViAPI_Database_Destroy(self.database_handle)
            self.database_handle = None

            logger.info("Disconnected from GeViServer")

            return {
                "success": True,
                "message": "Disconnected successfully"
            }

        except Exception as e:
            logger.error(f"Exception during disconnection: {e}")
            return {
                "success": False,
                "message": f"Disconnection error: {str(e)}"
            }

    def is_connected(self) -> bool:
        """Check if connected to GeViServer"""
        if not self.database_handle:
            return False

        connected = c_bool()
        result = self.dll.GeViAPI_Database_Connected(
            self.database_handle,
            ctypes.byref(connected)
        )

        return result and connected.value

    def send_ping(self) -> Dict[str, Any]:
        """Send ping to GeViServer"""
        try:
            if not self.database_handle:
                return {
                    "success": False,
                    "message": "Not connected"
                }

            result = self.dll.GeViAPI_Database_SendPing(self.database_handle)

            if not result:
                error_msg = self._get_last_error()
                logger.error(f"Ping failed: {error_msg}")
                return {
                    "success": False,
                    "message": f"Ping failed: {error_msg}"
                }

            return {
                "success": True,
                "message": "Ping successful"
            }

        except Exception as e:
            logger.error(f"Exception during ping: {e}")
            return {
                "success": False,
                "message": f"Ping error: {str(e)}"
            }

    def send_message(self, message: str) -> Dict[str, Any]:
        """
        Send action message to GeViServer

        Args:
            message: ASCII message string (e.g., "CrossSwitch(7,3,0)")

        Returns:
            Dict with success status
        """
        try:
            if not self.database_handle:
                return {
                    "success": False,
                    "message": "Not connected"
                }

            message_bytes = message.encode('utf-8')

            result = self.dll.GeViAPI_Database_SendMessage(
                self.database_handle,
                message_bytes,
                len(message_bytes)
            )

            if not result:
                error_msg = self._get_last_error()
                logger.error(f"Send message failed: {error_msg}")
                return {
                    "success": False,
                    "message": f"Send failed: {error_msg}"
                }

            logger.info(f"Sent message: {message}")

            return {
                "success": True,
                "message": "Message sent successfully",
                "sent_message": message
            }

        except Exception as e:
            logger.error(f"Exception sending message: {e}")
            return {
                "success": False,
                "message": f"Send error: {str(e)}"
            }

    def __del__(self):
        """Cleanup on destruction"""
        if self.database_handle:
            try:
                self.disconnect()
            except:
                pass


# Global instance (singleton pattern)
_geviserver_service: Optional[GeViServerService] = None


def get_geviserver_service() -> GeViServerService:
    """Get or create GeViServer service instance"""
    global _geviserver_service

    if _geviserver_service is None:
        _geviserver_service = GeViServerService()

    return _geviserver_service
```

#### 1.3 Create API Router

**File:** `geutebruck-api/src/api/routers/geviserver.py`

```python
from fastapi import APIRouter, HTTPException, Depends
from pydantic import BaseModel
from typing import Optional, Dict, Any
import logging

from src.services.geviserver_service import get_geviserver_service, GeViServerService

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/geviserver", tags=["GeViServer"])


# Request/Response Models
class ConnectRequest(BaseModel):
    address: str
    username: str
    password: str
    username2: Optional[str] = None
    password2: Optional[str] = None


class SendMessageRequest(BaseModel):
    message: str


class ConnectionStatusResponse(BaseModel):
    is_connected: bool
    address: Optional[str] = None
    username: Optional[str] = None


# Endpoints

@router.post("/connect")
async def connect_to_server(
    request: ConnectRequest,
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """
    Connect to GeViServer

    Example:
    ```json
    {
        "address": "localhost",
        "username": "admin",
        "password": "admin"
    }
    ```
    """
    logger.info(f"Connecting to GeViServer at {request.address}")

    result = service.connect(
        address=request.address,
        username=request.username,
        password=request.password,
        username2=request.username2,
        password2=request.password2
    )

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "Connection failed"))

    return result


@router.post("/disconnect")
async def disconnect_from_server(
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """Disconnect from GeViServer"""
    logger.info("Disconnecting from GeViServer")

    result = service.disconnect()

    return result


@router.get("/status")
async def get_connection_status(
    service: GeViServerService = Depends(get_geviserver_service)
) -> ConnectionStatusResponse:
    """Get current connection status"""
    is_connected = service.is_connected()

    return ConnectionStatusResponse(
        is_connected=is_connected,
        address=None,  # Could store this in service
        username=None
    )


@router.post("/ping")
async def send_ping(
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """Send ping to GeViServer"""
    result = service.send_ping()

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "Ping failed"))

    return result


@router.post("/send-message")
async def send_message(
    request: SendMessageRequest,
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """
    Send action message to GeViServer

    Example:
    ```json
    {
        "message": "CrossSwitch(7,3,0)"
    }
    ```
    """
    logger.info(f"Sending message: {request.message}")

    result = service.send_message(request.message)

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "Send failed"))

    return result


# Video Control Endpoints

@router.post("/video/crossswitch")
async def crossswitch_video(
    video_input: int,
    video_output: int,
    switch_mode: int = 0,
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """
    Cross-switch video input to output

    Args:
        video_input: Video input channel number
        video_output: Video output channel number
        switch_mode: Switch mode (0=normal, 1=...)
    """
    message = f"CrossSwitch({video_input},{video_output},{switch_mode})"

    logger.info(f"Cross-switching: {message}")

    result = service.send_message(message)

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "CrossSwitch failed"))

    return {
        "success": True,
        "message": f"Routed video input {video_input} to output {video_output}",
        "video_input": video_input,
        "video_output": video_output
    }


@router.post("/video/clear-output")
async def clear_video_output(
    video_output: int,
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """Clear video output"""
    message = f"ClearOutput({video_output})"

    logger.info(f"Clearing output: {message}")

    result = service.send_message(message)

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "ClearOutput failed"))

    return {
        "success": True,
        "message": f"Cleared video output {video_output}",
        "video_output": video_output
    }


# Digital I/O Endpoints

@router.post("/digital-io/close-contact")
async def close_digital_contact(
    contact_id: int,
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """Close digital output contact"""
    message = f"CloseContact({contact_id})"

    logger.info(f"Closing contact: {message}")

    result = service.send_message(message)

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "CloseContact failed"))

    return {
        "success": True,
        "message": f"Closed digital contact {contact_id}",
        "contact_id": contact_id
    }


@router.post("/digital-io/open-contact")
async def open_digital_contact(
    contact_id: int,
    service: GeViServerService = Depends(get_geviserver_service)
) -> Dict[str, Any]:
    """Open digital output contact"""
    message = f"OpenContact({contact_id})"

    logger.info(f"Opening contact: {message}")

    result = service.send_message(message)

    if not result.get("success"):
        raise HTTPException(status_code=400, detail=result.get("message", "OpenContact failed"))

    return {
        "success": True,
        "message": f"Opened digital contact {contact_id}",
        "contact_id": contact_id
    }
```

#### 1.4 Register Router

**File:** `geutebruck-api/src/api/main.py`

Add this to your main.py:

```python
from src.api.routers import geviserver

# ... existing imports and app setup ...

# Register GeViServer router
app.include_router(geviserver.router, prefix="/api/v1")
```

---

### Step 2: Update Flutter App to Use API

Your Flutter app **already has everything it needs** - just add new endpoints!

#### 2.1 Update API Constants

**File:** `geutebruck_app/lib/core/constants/api_constants.dart`

```dart
class ApiConstants {
  // ... existing constants ...

  // GeViServer endpoints
  static const String geviServerConnect = '/geviserver/connect';
  static const String geviServerDisconnect = '/geviserver/disconnect';
  static const String geviServerStatus = '/geviserver/status';
  static const String geviServerPing = '/geviserver/ping';
  static const String geviServerSendMessage = '/geviserver/send-message';

  // Video control
  static const String videoCrossSwitch = '/geviserver/video/crossswitch';
  static const String videoClearOutput = '/geviserver/video/clear-output';

  // Digital I/O
  static const String digitalIoCloseContact = '/geviserver/digital-io/close-contact';
  static const String digitalIoOpenContact = '/geviserver/digital-io/open-contact';
}
```

#### 2.2 Create Remote Data Source

**File:** `geutebruck_app/lib/data/data_sources/remote/geviserver_remote_data_source.dart`

```dart
import 'package:dio/dio.dart';
import '../../../core/network/dio_client.dart';
import '../../../core/constants/api_constants.dart';

class GeViServerRemoteDataSource {
  final DioClient _dioClient;

  GeViServerRemoteDataSource({required DioClient dioClient})
      : _dioClient = dioClient;

  /// Connect to GeViServer
  Future<Map<String, dynamic>> connect({
    required String address,
    required String username,
    required String password,
  }) async {
    try {
      final response = await _dioClient.post(
        ApiConstants.geviServerConnect,
        data: {
          'address': address,
          'username': username,
          'password': password,
        },
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('Connection failed: ${e.message}');
    }
  }

  /// Disconnect from GeViServer
  Future<Map<String, dynamic>> disconnect() async {
    try {
      final response = await _dioClient.post(
        ApiConstants.geviServerDisconnect,
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('Disconnection failed: ${e.message}');
    }
  }

  /// Get connection status
  Future<Map<String, dynamic>> getStatus() async {
    try {
      final response = await _dioClient.get(
        ApiConstants.geviServerStatus,
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('Status check failed: ${e.message}');
    }
  }

  /// Send ping
  Future<Map<String, dynamic>> sendPing() async {
    try {
      final response = await _dioClient.post(
        ApiConstants.geviServerPing,
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('Ping failed: ${e.message}');
    }
  }

  /// Cross-switch video
  Future<Map<String, dynamic>> crossSwitch({
    required int videoInput,
    required int videoOutput,
    int switchMode = 0,
  }) async {
    try {
      final response = await _dioClient.post(
        ApiConstants.videoCrossSwitch,
        queryParameters: {
          'video_input': videoInput,
          'video_output': videoOutput,
          'switch_mode': switchMode,
        },
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('CrossSwitch failed: ${e.message}');
    }
  }

  /// Clear video output
  Future<Map<String, dynamic>> clearOutput({
    required int videoOutput,
  }) async {
    try {
      final response = await _dioClient.post(
        ApiConstants.videoClearOutput,
        queryParameters: {
          'video_output': videoOutput,
        },
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('ClearOutput failed: ${e.message}');
    }
  }

  /// Close digital contact
  Future<Map<String, dynamic>> closeContact({
    required int contactId,
  }) async {
    try {
      final response = await _dioClient.post(
        ApiConstants.digitalIoCloseContact,
        queryParameters: {
          'contact_id': contactId,
        },
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('CloseContact failed: ${e.message}');
    }
  }

  /// Open digital contact
  Future<Map<String, dynamic>> openContact({
    required int contactId,
  }) async {
    try {
      final response = await _dioClient.post(
        ApiConstants.digitalIoOpenContact,
        queryParameters: {
          'contact_id': contactId,
        },
      );
      return response.data;
    } on DioException catch (e) {
      throw Exception('OpenContact failed: ${e.message}');
    }
  }
}
```

---

### Step 3: Test the Integration

#### 3.1 Start GeViServer

```bash
cd C:\GEVISOFT
geviserver.exe console
```

#### 3.2 Start Backend API

```bash
cd C:\DEV\COPILOT\geutebruck-api
python -m uvicorn src.api.main:app --reload --host 0.0.0.0 --port 8000
```

#### 3.3 Test with Swagger UI

Open: `http://localhost:8000/docs`

**Test Sequence:**
1. POST `/api/v1/geviserver/connect` with:
   ```json
   {
     "address": "localhost",
     "username": "admin",
     "password": "admin"
   }
   ```
2. GET `/api/v1/geviserver/status` - should show `is_connected: true`
3. POST `/api/v1/geviserver/ping` - should return success
4. POST `/api/v1/geviserver/video/crossswitch?video_input=7&video_output=3`
5. POST `/api/v1/geviserver/disconnect`

#### 3.4 Test from Flutter App

Your existing Flutter app can now call these endpoints using `DioClient`!

---

## Architecture Benefits

### ✅ Why This is Better

1. **No Native Code in Flutter**
   - Flutter stays platform-independent
   - Easier to test and maintain
   - Can run on mobile later (just API calls)

2. **Backend Handles Complexity**
   - Connection pooling
   - Error handling
   - Password encryption
   - Message construction

3. **Swagger Documentation**
   - All endpoints documented automatically
   - Easy for other clients to integrate
   - Built-in testing UI

4. **Centralized Logic**
   - Multiple Flutter clients can connect
   - Web dashboard can use same API
   - Mobile app can use same API

5. **Existing Architecture**
   - Uses your existing DioClient
   - Uses your existing authentication
   - Uses your existing error handling

---

## Next Steps

1. ✅ **Implement backend endpoints** (Step 1)
2. ✅ **Add Flutter data source** (Step 2)
3. ✅ **Test with Swagger** (Step 3)
4. **Add BLoC for connection state**
5. **Add UI screens for video control**
6. **Execute action mappings**

---

## Summary

**DON'T create a native Windows plugin!**

**DO extend your existing FastAPI backend** with GeViServer integration.

Your architecture becomes:
```
Flutter (Dart) → HTTP → FastAPI (Python) → ctypes → GeViProcAPI.dll → GeViServer
```

This is the **CORRECT and RECOMMENDED** approach! 🎯