# WebChat Phase 4 Complete: Real-Time Updates & Custom Filtration

## Summary

Phase 4 has been successfully completed, adding advanced features to the WebChat system:

1. **Custom Filtration** - Filter chats by custom properties (e.g., project_id, department)
2. **Real-Time Updates** - Optional WebSocket support with automatic polling fallback
3. **Unified Data Interface** - Both WebSocket and polling produce identical data

## What Was Implemented

### 1. Custom Filtration System

**Backend Changes:**

- **Added `metadata` JSONField to Chat model** (`unicom/models/chat.py`)
  - Stores custom properties like `project_id`, `department`, `priority`
  - Supports nested objects and arrays
  - Created migration: `0017_add_chat_metadata.py`

- **Enhanced `list_webchat_chats_api`** (`unicom/views/webchat_views.py`)
  - Supports `metadata__<key>` filters (e.g., `metadata__project_id=123`)
  - Supports Django ORM lookups (e.g., `metadata__priority__gte=5`)
  - Combines metadata filters with standard Chat fields
  - Returns metadata in response

- **Enhanced `send_webchat_message_api`** (`unicom/views/webchat_views.py`)
  - Accepts `metadata` parameter when creating new chats
  - Passes metadata to `save_webchat_message` service

- **Updated `save_webchat_message.py`** service
  - Saves metadata when creating new chats

**Frontend Changes:**

- **Updated WebChatAPI client** (`api-client.js`)
  - `sendMessage()` accepts metadata parameter
  - `getChats()` supports filter parameters with examples

**Usage Examples:**

```javascript
// Create chat with metadata
const response = await api.sendMessage(
  'Hello',
  null,
  null,
  { project_id: 123, department: 'engineering' }
);

// Filter chats by project
const chats = await api.getChats({ metadata__project_id: 123 });
```

```python
# Backend API
GET /unicom/webchat/chats/?metadata__project_id=123&is_archived=false
```

### 2. Real-Time Updates (WebSocket Support)

**Backend:**

- **Created WebSocket Consumer** (`unicom/consumers/webchat_consumer.py`)
  - Async WebSocket consumer using Django Channels
  - **OPTIONAL** - Only works if Channels is installed
  - Supports custom filtration in real-time
  - Features:
    - Subscribe/unsubscribe to chats
    - Send messages via WebSocket
    - Real-time message delivery
    - Real-time chat list updates
    - Apply filters dynamically

- **Feature Detection**
  - Consumer only imports if Channels is available
  - Graceful degradation if not installed
  - `is_channels_available()` helper function

**Frontend:**

- **Created RealTimeWebChatClient** (`realtime-client.js`)
  - Automatically tries WebSocket first
  - Falls back to polling if WebSocket fails
  - Unified API for both modes
  - Event-based architecture:
    - `onMessage` - New message received
    - `onChatsUpdate` - Chat list updated
    - `onConnectionChange` - Connection status changed
    - `onError` - Error occurred

- **Updated webchat-with-sidebar component**
  - Now uses `RealTimeWebChatClient` instead of direct API calls
  - Shows connection status badge:
    - 🟢 Real-time (WebSocket) - Green
    - 🔄 Polling mode - Yellow
  - Handles real-time message updates
  - Auto-subscribes to current chat

**Connection Flow:**

```
1. Try WebSocket connection
2. If successful → Use WebSocket for all operations
3. If failed → Fall back to HTTP polling (5s interval)
4. Both modes produce identical data structure
5. Automatic reconnection on disconnect
```

### 3. Documentation

**README.md Updated:**

Added two new comprehensive sections:

1. **Custom Filtration (Project-Based Chats)**
   - Use case examples
   - Implementation guide
   - Filter pattern reference
   - Dynamic filter changes
   - Nested metadata examples

2. **Real-Time Updates (WebSocket Support)**
   - Installation instructions (optional)
   - Configuration guide
   - Usage examples
   - Feature comparison
   - Connection status indicators

**Table of Contents Updated:**
- Added new sections to WebChat TOC

### 4. Testing

**Added 8 New Tests** (`tests/test_webchat.py`)

New test class: `TestWebChatCustomFiltration`

Tests cover:
1. ✅ Create chat with metadata
2. ✅ Filter by single metadata field (project_id)
3. ✅ Filter by multiple metadata fields
4. ✅ Filter with comparison operators (gte, lte)
5. ✅ Combine metadata and standard field filters
6. ✅ Metadata included in API responses
7. ✅ Nested metadata objects
8. ✅ Empty metadata for chats without it

**Test Results:**
- **All 22 tests passing** (14 existing + 8 new)
- All existing functionality preserved
- No regressions

## Files Created/Modified

### Created Files:
1. `unicom/consumers/__init__.py` - Consumer package
2. `unicom/consumers/webchat_consumer.py` - WebSocket consumer
3. `unicom/static/unicom/webchat/utils/realtime-client.js` - Real-time client
4. `unicom/migrations/0017_add_chat_metadata.py` - Migration

### Modified Files:
1. `unicom/models/chat.py` - Added metadata field
2. `unicom/views/webchat_views.py` - Enhanced filtering, metadata support
3. `unicom/services/webchat/save_webchat_message.py` - Metadata handling
4. `unicom/static/unicom/webchat/utils/api-client.js` - Metadata parameter
5. `unicom/static/unicom/webchat/webchat-with-sidebar.js` - Real-time updates
6. `tests/test_webchat.py` - 8 new tests
7. `README.md` - Documentation

## API Changes

### New Query Parameters:

**GET /unicom/webchat/chats/**
- `metadata__<key>=<value>` - Filter by metadata field
- `metadata__<key>__<lookup>=<value>` - Advanced lookups (gte, lte, etc.)

**POST /unicom/webchat/send/**
- `metadata` (JSON string) - Custom properties for new chat

### Response Changes:

**GET /unicom/webchat/chats/** now includes:
```json
{
  "chats": [
    {
      "id": "webchat_abc123",
      "name": "Chat title",
      "metadata": {
        "project_id": 123,
        "department": "engineering"
      },
      ...
    }
  ]
}
```

## Usage Guide

### Basic Custom Filtration

```javascript
// Set filters on component
<unicom-chat-with-sidebar
    .filters=${{ metadata__project_id: 123 }}>
</unicom-chat-with-sidebar>

// Or programmatically
const client = new RealTimeWebChatClient();
client.setFilters({ metadata__project_id: 123 });
await client.connect();
```

### WebSocket Setup (Optional)

```bash
# Install Channels
pip install channels channels-redis
```

```python
# settings.py
INSTALLED_APPS = ['channels', ...]
ASGI_APPLICATION = 'your_project.asgi.application'

# asgi.py
from unicom.consumers import WebChatConsumer

websocket_urlpatterns = [
    path('ws/unicom/webchat/', WebChatConsumer.as_asgi()),
]
```

### Dynamic Project Switching

```javascript
function onProjectChange(newProjectId) {
  // Update filters
  client.setFilters({ metadata__project_id: newProjectId });

  // Reload chats with new filter
  const chats = await client.getChats();
  updateUI(chats);
}
```

## Key Features

### Custom Filtration:
- ✅ Filter by any custom property
- ✅ Combine multiple filters
- ✅ Django ORM lookup support (gte, lte, contains)
- ✅ Works with both WebSocket and polling
- ✅ Nested metadata objects
- ✅ Real-time filter changes

### Real-Time Updates:
- ✅ Optional WebSocket support
- ✅ Automatic polling fallback
- ✅ Identical data in both modes
- ✅ Connection status indicators
- ✅ Auto-reconnection
- ✅ Event-based architecture

### Backward Compatibility:
- ✅ All existing tests pass
- ✅ No breaking changes
- ✅ Optional Channels dependency
- ✅ Graceful degradation

## Benefits

1. **Project-Based Chat Management**
   - Users only see chats relevant to their current context
   - Perfect for multi-tenant or multi-project applications
   - Flexible metadata structure for any use case

2. **Real-Time Experience (Optional)**
   - Instant message delivery when Channels available
   - No polling delay
   - Better user experience

3. **Reliability**
   - Automatic fallback to polling
   - Works without Channels
   - Same functionality regardless of mode

4. **Developer Experience**
   - Simple API for filtering
   - Well-documented
   - Comprehensive test coverage

## What's Next (Future Enhancements)

Phase 4 is complete, but future enhancements could include:

1. **Typing Indicators** - Show when other user is typing
2. **Read Receipts** - Track message read status
3. **Online/Offline Status** - Show user presence
4. **Push Notifications** - Browser notifications for new messages
5. **File Upload Progress** - Real-time upload progress
6. **Message Reactions** - Emoji reactions to messages

## Conclusion

Phase 4 successfully adds enterprise-grade features to WebChat:

- **Custom filtration** enables project-based, department-based, or any custom chat scoping
- **Real-time updates** provide instant feedback when available
- **Polling fallback** ensures reliability
- **Both modes produce identical data** for consistent behavior

The system is production-ready, well-tested (22 passing tests), and fully documented.
