# Migration to aiohttp for WebSocket and HTTP

## Summary

The control server has been refactored to use **aiohttp** for both WebSocket and HTTP endpoints, replacing the previous `websockets` library for the WebSocket server.

## What Changed

### 1. Server Architecture

**Before:**
- Separate `websockets` server on port 8765
- Separate `aiohttp` HTTP API server on port 8766

**After:**
- Single `aiohttp` application serving both:
  - WebSocket endpoint: `ws://host:8765/ws`
  - HTTP API endpoints: `http://host:8765/api/*`
  - HTTP API also available on port 8766 for backward compatibility

### 2. Code Changes

#### `/home/pi/lighting-controller/src/control_server.py`

**Removed:**
- `import websockets`
- `handle_ui_client()` method (used websockets library)
- `start_websocket_server()` method
- `_websocket_server_task()` method

**Added:**
- `handle_websocket()` method using aiohttp's WebSocket support
- Updated `start_http_server()` to include WebSocket endpoint
- Combined server startup (HTTP and WebSocket on same port)

**Key Differences:**

```python
# OLD (websockets library)
async def handle_ui_client(self, websocket):
    async for message in websocket:
        data = json.loads(message)
        await websocket.send(json.dumps(response))

# NEW (aiohttp)
async def handle_websocket(self, request):
    ws = web.WebSocketResponse()
    await ws.prepare(request)
    async for msg in ws:
        if msg.type == web.WSMsgType.TEXT:
            data = json.loads(msg.data)
            await ws.send_json(response)
    return ws
```

#### `/home/pi/lighting-controller/Pipfile`

Both `aiohttp` and `websockets` are now in the dependencies:
- `aiohttp` - for server WebSocket and HTTP
- `websockets` - for client connections to LED bars (in `networking.py`)

### 3. Client Changes Required

**WebSocket URL Update:**

Clients must update their connection URL to include the `/ws` path:

```javascript
// OLD
const ws = new WebSocket('ws://10.42.0.1:8765');

// NEW
const ws = new WebSocket('ws://10.42.0.1:8765/ws');
```

**Python Client:**
```python
# OLD
uri = "ws://10.42.0.1:8765"

# NEW
uri = "ws://10.42.0.1:8765/ws"
```

### 4. HTTP API

The HTTP API endpoints remain the same, but are now available on both ports:

- **Primary:** `http://10.42.0.1:8765/api/color-palette`
- **Backward Compatibility:** `http://10.42.0.1:8766/api/color-palette`

### 5. Configuration

Environment variables remain the same:

```bash
CONTROL_SERVER_HOST=0.0.0.0
CONTROL_SERVER_PORT=8765
HTTP_API_PORT=8766
```

## Benefits

1. **Unified Server:** Single aiohttp application handles all HTTP and WebSocket traffic
2. **Easier CORS:** Can add CORS middleware once for both REST and WebSocket
3. **Simpler Deployment:** One port for UI clients (WebSocket + API)
4. **Standard REST Patterns:** aiohttp's routing and middleware ecosystem
5. **Less Dependencies:** One web framework instead of two

## Testing

### Test WebSocket Connection

```bash
# Python test client
pipenv run python test/test_control_server.py --pattern rainbow
```

### Test HTTP API

```bash
# Get color palette
curl http://localhost:8765/api/color-palette

# Update selected colors
curl -X POST http://localhost:8765/api/color-palette \
  -H "Content-Type: application/json" \
  -d '{"selected_indices": [3, 6]}'
```

## Backward Compatibility

- HTTP API still available on port 8766
- WebSocket protocol unchanged (JSON message format)
- Only the WebSocket URL path changed (added `/ws`)

## Files Modified

1. `/home/pi/lighting-controller/src/control_server.py` - Main refactor
2. `/home/pi/lighting-controller/Pipfile` - Dependencies (kept both aiohttp and websockets)
3. `/home/pi/lighting-controller/COLOR_PALETTE_API.md` - Updated documentation

## Files NOT Modified

- `/home/pi/lighting-controller/src/networking.py` - Still uses `websockets` for client connections
- `/home/pi/lighting-controller/src/ui_client.py` - UI being worked on elsewhere (needs URL update)
- `/home/pi/led-bar/*` - No changes needed