LEDMatrix/docs/ADVANCED_FEATURES.md

# Advanced Features Guide

This guide covers advanced LEDMatrix features for users and developers, including Vegas scroll mode, on-demand display, cache management, background services, and permission management.

---

## 1. Vegas Scroll Mode

### Overview

Vegas scroll mode displays content from multiple plugins in a continuous horizontal scroll, similar to news tickers seen in Las Vegas casinos. Plugins contribute content segments that flow across the display in a seamless ticker-style presentation.

### Display Modes

**SCROLL (Continuous Scrolling):**
- Content scrolls continuously left
- Smooth, fluid motion
- Best for news-ticker style displays

**FIXED_SEGMENT (Fixed-Width Block):**
- Plugin gets fixed-width block on display
- Content doesn't scroll out of its segment
- Multiple plugins can share the display simultaneously

**STATIC (Scroll Pauses):**
- Scrolling pauses when content is fully visible
- Displays for specified duration, then resumes scrolling
- Best for content that needs to be fully read

### Configuration

Enable Vegas mode in `config/config.json`:

```json
{
  "display": {
    "vegas_scroll": {
      "enabled": true,
      "scroll_speed": 50,
      "separator_width": 32,
      "plugin_order": ["clock", "weather", "sports"],
      "excluded_plugins": ["debug_plugin"],
      "target_fps": 125,
      "buffer_ahead": 2
    }
  }
}
```

**Configuration Options:**

| Setting | Default | Description |
|---------|---------|-------------|
| `enabled` | `false` | Enable Vegas scroll mode |
| `scroll_speed` | `50` | Pixels per second scroll speed |
| `separator_width` | `32` | Width between plugin segments (pixels) |
| `plugin_order` | `[]` | Plugin display order (empty = auto) |
| `excluded_plugins` | `[]` | Plugins to exclude from Vegas mode |
| `target_fps` | `125` | Target frame rate |
| `buffer_ahead` | `2` | Number of panels to render ahead |

### Per-Plugin Configuration

Override Vegas behavior for specific plugins:

```json
{
  "my_plugin": {
    "enabled": true,
    "vegas_mode": "scroll",
    "vegas_panel_count": 2,
    "display_duration": 10
  }
}
```

**Per-Plugin Options:**

| Setting | Values | Description |
|---------|--------|-------------|
| `vegas_mode` | `scroll`, `fixed`, `static` | Display mode for this plugin |
| `vegas_panel_count` | `1-10` | Width in panels (1 panel = display width) |
| `display_duration` | seconds | Pause duration for STATIC mode |

### Plugin Integration (Developer Guide)

**1. Implement Content Method:**

```python
def get_vegas_content(self):
    """
    Return PIL Image or list of Images for Vegas mode.

    Returns:
        PIL.Image or list[PIL.Image]: Content to display
        - Single image: fixed-width content
        - List of images: multiple segments
        - None: skip this cycle
    """
    # Example: Return single wide image
    img = Image.new('RGB', (256, 32))
    # ... render your content ...
    return img

    # Example: Return multiple segments
    return [image1, image2, image3]
```

**2. Specify Content Type:**

```python
def get_vegas_content_type(self):
    """
    Specify how content should be handled.

    Returns:
        str: 'multi' | 'static' | 'none'
    """
    return 'multi'  # Default for most plugins
```

**3. Optionally Specify Display Mode:**

```python
def get_vegas_display_mode(self):
    """
    Preferred display mode for this plugin.

    Returns:
        str: 'scroll' | 'fixed' | 'static'
    """
    return 'scroll'

def get_supported_vegas_modes(self):
    """
    List of supported modes.

    Returns:
        list: ['scroll', 'fixed', 'static']
    """
    return ['scroll', 'static']
```

### Content Rendering Guidelines

**Image Dimensions:**
- **Height:** Must match display height (typically 32 pixels)
- **Width:** Varies by mode:
  - SCROLL: Any width (recommended 64-512 pixels)
  - FIXED_SEGMENT: `panel_count * display_width`
  - STATIC: Any width, optimized for readability

**Color Mode:**
- Use RGB color mode
- 24-bit color (8 bits per channel)

**Performance Tips:**
1. **Cache rendered images** - Render in `update()`, not in `get_vegas_content()`
2. **Keep images small** - Larger images use more memory
3. **Pre-render on update** - Don't create images on-demand
4. **Reuse images** - Return same image if content unchanged

### Example Integration

Complete example for a weather plugin:

```python
class WeatherPlugin(BasePlugin):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.vegas_image = None

    def update(self):
        """Update data and pre-render Vegas image"""
        # Fetch weather data
        weather_data = self.fetch_weather()

        # Pre-render Vegas image
        self.vegas_image = self._render_vegas_content(weather_data)

    def _render_vegas_content(self, data):
        """Render weather content for Vegas mode"""
        img = Image.new('RGB', (384, 32))
        draw = ImageDraw.Draw(img)

        # Draw temperature
        draw.text((10, 0), f"{data['temp']}°F", fill=(255, 255, 255))

        # Draw condition
        draw.text((100, 0), data['condition'], fill=(200, 200, 200))

        # Draw icon
        icon = Image.open(f"assets/{data['icon']}.png")
        img.paste(icon, (250, 0))

        return img

    def get_vegas_content(self):
        """Return cached Vegas image"""
        return self.vegas_image

    def get_vegas_content_type(self):
        return 'multi'

    def get_vegas_display_mode(self):
        return 'scroll'

    def get_supported_vegas_modes(self):
        return ['scroll', 'static']
```

### System Architecture

Vegas mode consists of four core components working together to provide smooth 125 FPS continuous scrolling:

#### Component Overview

```
┌─────────────────────────────────────────────────────────────┐
│                   VegasModeCoordinator                      │
│  Main orchestrator - manages lifecycle and coordination     │
└───────┬──────────────────┬──────────────────┬──────────────┘
        │                  │                  │
        ▼                  ▼                  ▼
┌───────────────┐  ┌──────────────┐  ┌─────────────────┐
│ PluginAdapter │  │StreamManager │  │ RenderPipeline  │
│               │  │              │  │                 │
│ Converts      │─▶│ Manages      │─▶│ 125 FPS render  │
│ plugin content│  │ content      │  │ Double-buffered │
│ to images     │  │ stream with  │  │ Smooth scroll   │
│               │  │ 1-2 ahead    │  │                 │
└───────────────┘  │ buffering    │  └─────────────────┘
                   └──────────────┘
```

#### 1. VegasModeCoordinator

**Responsibilities:**
- Initialize and coordinate all Vegas mode components
- Manage the high-FPS render loop (target: 125 FPS)
- Handle live priority interruptions
- Process config updates during runtime
- Provide status and control interface

**Key Features:**
- Thread-safe state management
- Config hot-reload support
- Live priority integration
- Interrupt checking for yielding control back to display controller
- Static pause handling (pauses scroll when content fully visible)

**Main Loop:**
1. Check for interrupts (live priority, on-demand, config updates)
2. If static pause active, wait for duration
3. Otherwise, delegate to render pipeline for frame rendering
4. Sleep to maintain target FPS

#### 2. StreamManager

**Responsibilities:**
- Manage plugin content streaming with look-ahead buffering
- Coordinate with PluginAdapter to fetch plugin content
- Handle plugin ordering and exclusions
- Optimize content generation timing

**Buffering Strategy:**
- **Buffer Ahead:** 1-2 panels (configurable)
- **Just-in-Time Generation:** Fetch content only when needed
- **Memory Efficient:** Only keep necessary content in memory

**Content Flow:**
1. Determine which plugins should appear in stream
2. Respect `plugin_order` configuration (or use default order)
3. Exclude plugins in `excluded_plugins` list
4. Request content from each plugin via PluginAdapter
5. Compose into continuous stream with separators

**Key Methods:**
- `get_stream_content()` - Returns current stream content as PIL Image
- `advance_stream(pixels)` - Advances stream by N pixels
- `refresh_stream()` - Regenerates stream from current plugins

#### 3. PluginAdapter

**Responsibilities:**
- Convert plugin content to scrollable images
- Handle different Vegas display modes (SCROLL, FIXED, STATIC)
- Manage fallback for plugins without Vegas support
- Cache plugin content for performance

**Plugin Integration:**
1. **Check for Vegas support:**
   - Calls `get_vegas_content()` if available
   - Falls back to `display()` method if not

2. **Handle display mode:**
   - SCROLL: Returns image as-is for continuous scrolling
   - FIXED_SEGMENT: Creates fixed-width block (panel_count * display_width)
   - STATIC: Marks content for pause-when-visible behavior

3. **Content type handling:**
   - `multi`: Multiple segments (list of images)
   - `static`: Single static image
   - `none`: Skip this plugin in current cycle

**Fallback Behavior:**
- If plugin doesn't implement Vegas methods:
  - Calls plugin's `display()` method
  - Captures rendered display as static image
  - Treats as fixed segment
- Ensures all plugins work in Vegas mode without explicit support

#### 4. RenderPipeline

**Responsibilities:**
- High-performance 125 FPS rendering
- Double-buffered composition for smooth scrolling
- Scroll position management
- Frame rate control

**Rendering Process:**
1. **Fetch Stream Content:** Get current stream from StreamManager
2. **Extract Viewport:** Calculate which portion of stream is visible
3. **Compose Frame:** Create frame with visible content
4. **Double Buffer:** Render to off-screen buffer
5. **Display:** Swap buffer to display
6. **Advance:** Update scroll position based on speed and elapsed time

**Performance Optimizations:**
- **Double Buffering:** Eliminates flicker
- **Viewport Extraction:** Only processes visible region
- **Frame Rate Control:** Precise timing to maintain 125 FPS
- **Pre-rendered Content:** Plugins pre-render during update()

**Scroll Speed Calculation:**
```python
pixels_per_frame = (scroll_speed / target_fps)
scroll_position += pixels_per_frame * elapsed_time
```

#### Component Interactions

**Initialization Flow:**
```
1. VegasModeCoordinator created
2. Coordinator creates PluginAdapter
3. Coordinator creates StreamManager (with PluginAdapter)
4. Coordinator creates RenderPipeline (with StreamManager)
5. All components initialized and ready
```

**Render Loop Flow:**
```
1. Coordinator starts render loop
2. Check for interrupts (live priority, on-demand)
3. RenderPipeline.render_frame():
   a. Request current stream from StreamManager
   b. StreamManager uses PluginAdapter to get plugin content
   c. PluginAdapter calls plugin Vegas methods or fallback
   d. Stream content returned to RenderPipeline
   e. RenderPipeline extracts viewport and renders
4. Update scroll position
5. Sleep to maintain target FPS
6. Repeat from step 2
```

**Config Update Flow:**
```
1. Config change detected by Coordinator
2. Set _pending_config_update flag
3. On next render loop iteration:
   a. Pause rendering
   b. Update VegasModeConfig
   c. Notify StreamManager of config change
   d. StreamManager refreshes stream
   e. Resume rendering
```

#### Thread Safety

All components use thread-safe patterns:
- **Coordinator:** Uses `threading.Lock` for state management
- **StreamManager:** Thread-safe content access
- **RenderPipeline:** Atomic frame composition
- **PluginAdapter:** Stateless operations (except caching)

#### Performance Characteristics

**Frame Rate:**
- Target: 125 FPS
- Actual: 100-125 FPS (depends on content complexity)
- Render time budget: ~8ms per frame

**Memory Usage:**
- Stream buffer: ~2-3 panels ahead
- Plugin content: Cached in plugin's `update()` method
- Double buffer: 2x display size

**CPU Usage:**
- Light load: 5-10% (simple content)
- Heavy load: 15-25% (complex content, many plugins)
- Optimized with numpy for pixel operations

### Fallback Behavior

If a plugin doesn't implement Vegas methods:
- System calls the plugin's `display()` method
- Captures the rendered display as a static image
- Treats it as a fixed segment

This ensures all plugins work in Vegas mode, even without explicit support.

---

## 2. On-Demand Display

### Overview

On-demand display allows users to manually trigger specific plugins to show immediately on the LED matrix, overriding the normal rotation. This is useful for:
- Quick checks (weather, scores, time)
- Pinning important information
- Testing plugins during development
- Showing specific content to visitors

### Priority Hierarchy

On-demand display has the highest priority:

```
Priority Order (highest to lowest):
1. On-Demand Display (manual trigger)
2. Live Priority (games in progress)
3. Normal Rotation
```

When on-demand expires or is cleared, the display returns to the next highest priority (live priority or normal rotation).

### Web Interface Controls

**Access:** Navigate to Settings → Plugin Management

**Controls:**
- **Show Now Button** - Triggers plugin immediately
- **Duration Slider** - Set display time (0 = indefinite)
- **Pin Checkbox** - Keep showing until manually cleared
- **Stop Button** - Clear on-demand and return to rotation
- **Shift+Click Stop** - Stop the entire display service

**Status Card:**
- Real-time status updates
- Shows active plugin and remaining time
- Pin status indicator

### REST API Reference

#### Start On-Demand Display

```bash
POST /api/display/on-demand/start

# Body:
{
  "plugin_id": "weather",
  "duration": 30,        # Optional: seconds (0 = indefinite, null = default)
  "pinned": false        # Optional: keep until manually cleared
}

# Examples:
# 30-second preview
curl -X POST http://localhost:5050/api/display/on-demand/start \
  -H "Content-Type: application/json" \
  -d '{"plugin_id": "weather", "duration": 30}'

# Pin indefinitely
curl -X POST http://localhost:5050/api/display/on-demand/start \
  -H "Content-Type: application/json" \
  -d '{"plugin_id": "hockey-scores", "pinned": true}'
```

#### Stop On-Demand Display

```bash
POST /api/display/on-demand/stop

# Body:
{
  "stop_service": false  # Optional: also stop display service
}

# Examples:
# Clear on-demand
curl -X POST http://localhost:5050/api/display/on-demand/stop

# Stop service too
curl -X POST http://localhost:5050/api/display/on-demand/stop \
  -H "Content-Type: application/json" \
  -d '{"stop_service": true}'
```

#### Get On-Demand Status

```bash
GET /api/display/on-demand/status

# Example:
curl http://localhost:5050/api/display/on-demand/status

# Response:
{
  "active": true,
  "plugin_id": "weather",
  "mode": "weather",
  "remaining": 25.5,
  "pinned": false,
  "status": "active"
}
```

### Python API Methods

```python
from src.display_controller import DisplayController

controller = DisplayController()

# Show plugin for 30 seconds
controller.show_on_demand('weather', duration=30)

# Pin plugin until manually cleared
controller.show_on_demand('hockey-scores', pinned=True)

# Show indefinitely (not pinned, clears on expiry if duration set later)
controller.show_on_demand('weather', duration=0)

# Use plugin's default duration
controller.show_on_demand('weather')

# Clear on-demand
controller.clear_on_demand()

# Check status
is_active = controller.is_on_demand_active()

# Get detailed info
info = controller.get_on_demand_info()
# Returns: {'active': bool, 'mode': str, 'duration': float, 'remaining': float, 'pinned': bool}
```

### Duration Modes

| Duration | Pinned | Behavior |
|----------|--------|----------|
| `None` | `false` | Use plugin's default duration, auto-clear when expires |
| `0` | `false` | Indefinite, clears manually or on error |
| `> 0` | `false` | Timed display, auto-clear after N seconds |
| Any | `true` | Pin until manually cleared (ignores duration) |

### Use Case Examples

**Quick Check (30-second preview):**
```python
controller.show_on_demand('weather', duration=30)
```

**Pin Important Information:**
```python
controller.show_on_demand('game-score', pinned=True)
# ... later ...
controller.clear_on_demand()
```

**Indefinite Display:**
```python
controller.show_on_demand('welcome-message', duration=0)
```

**Testing Plugin:**
```python
controller.show_on_demand('my-new-plugin', duration=60)
```

### Best Practices

**For Users:**
1. Use timed display as default (prevents forgetting to clear)
2. Pin only when necessary
3. Clear when done to return to normal rotation

**For Developers:**
1. Validate plugin ID exists before calling
2. Provide visual feedback in UI (loading state, status updates)
3. Handle concurrent requests gracefully
4. Log on-demand activations for debugging

### Security Considerations

**Authentication:**
- Add authentication to API endpoints
- Restrict on-demand to authorized users

**Rate Limiting:**
- Prevent abuse from rapid requests
- Implement cooldown between activations

**Input Validation:**
- Sanitize plugin IDs
- Validate duration values
- Check plugin exists before activation

---

## 3. On-Demand Cache Management

### Overview

On-demand display uses Redis cache keys to manage state across service restarts and coordinate between web interface and display controller. Understanding these keys helps troubleshoot stuck states.

### Cache Keys

**1. display_on_demand_request** (TTL: 1 hour)
```json
{
  "request_id": "uuid-string",
  "action": "start|stop",
  "plugin_id": "plugin-name",
  "mode": "mode-name",
  "duration": 30.0,
  "pinned": true,
  "timestamp": 1234567890.123
}
```
**Purpose:** Communication from web interface to display controller
**When Set:** API endpoint receives request
**Auto-Cleared:** After processing or 1 hour TTL

**2. display_on_demand_config** (No TTL)
```json
{
  "mode": "mode-name",
  "duration": 30.0,
  "pinned": true
}
```
**Purpose:** Persistent configuration for display controller
**When Set:** Controller processes start request
**Auto-Cleared:** When on-demand stops

**3. display_on_demand_state** (Continuously updated)
```json
{
  "active": true,
  "mode": "mode-name",
  "remaining": 25.5,
  "pinned": true,
  "status": "active|idle|restarting|error"
}
```
**Purpose:** Real-time state for web interface status card
**When Set:** Every display loop iteration
**Auto-Cleared:** Never (continuously updated)

**4. display_on_demand_processed_id** (TTL: 5 minutes)
```
"uuid-string-of-last-processed-request"
```
**Purpose:** Prevents duplicate request processing
**When Set:** After processing request
**Auto-Cleared:** After 5 minutes TTL

### When Manual Clearing is Needed

**Scenario 1: Stuck in On-Demand State**
- Symptom: Display stays on one plugin, won't return to rotation
- Clear: `config`, `state`, `request`

**Scenario 2: Mode Switching Issues**
- Symptom: Can't change to different plugin
- Clear: `request`, `processed_id`, `state`

**Scenario 3: On-Demand Not Activating**
- Symptom: Button click does nothing
- Clear: `processed_id`, `request`

**Scenario 4: After Service Crash**
- Symptom: Strange behavior after crash/restart
- Clear: All four keys

### Manual Recovery Procedures

**Via Web Interface (Recommended):**
1. Navigate to Settings → Cache Management
2. Search for "on_demand" keys
3. Select keys to delete
4. Click "Delete Selected"
5. Restart display: `sudo systemctl restart ledmatrix`

**Via Command Line:**
```bash
# Clear specific key
redis-cli DEL display_on_demand_config

# Clear all on-demand keys
redis-cli KEYS "display_on_demand_*" | xargs redis-cli DEL

# Restart service
sudo systemctl restart ledmatrix
```

**Via Python:**
```python
from src.cache_manager import CacheManager

cache = CacheManager()
cache.delete('display_on_demand_config')
cache.delete('display_on_demand_state')
cache.delete('display_on_demand_request')
cache.delete('display_on_demand_processed_id')
```

### Cache Impact on Running Service

**IMPORTANT:** Clearing cache keys does NOT immediately affect the running controller in memory.

**To fully reset:**
1. Stop the service: `sudo systemctl stop ledmatrix`
2. Clear cache keys (web UI or redis-cli)
3. Clear systemd environment: `sudo systemctl daemon-reload`
4. Start the service: `sudo systemctl start ledmatrix`

### Automatic Cleanup

The display controller automatically handles cleanup:
- **Config key**: Cleared when on-demand stops
- **State key**: Updated every display loop iteration
- **Request key**: Expires after 1 hour TTL (or after processing)
- **Processed ID**: Expires after 5 minutes TTL

---

## 4. Background Data Service

### Overview

The Background Data Service enables non-blocking data fetching through background threading. This prevents the main display loop from freezing during slow API requests, maintaining smooth display rotation.

### Benefits

**Performance:**
- Display loop never freezes during API calls
- Immediate response with cached/partial data
- Complete data loads in background

**User Experience:**
- No "frozen" display during data updates
- Smooth transitions between plugins
- Faster perceived load times

**Architecture:**
```
Cache Check → Background Fetch → Partial Data → Completion → Cache
    (0.1s)         (async)            (<1s)         (10-30s)    (cache)
```

### Configuration

Enable background service per plugin in `config/config.json`:

```json
{
  "nfl_scoreboard": {
    "enabled": true,
    "background_service": {
      "enabled": true,
      "max_workers": 3,
      "request_timeout": 30,
      "max_retries": 3,
      "priority": 2
    }
  }
}
```

**Configuration Options:**

| Setting | Default | Description |
|---------|---------|-------------|
| `enabled` | `false` | Enable background service for this plugin |
| `max_workers` | `3` | Max concurrent background tasks |
| `request_timeout` | `30` | Timeout per API request (seconds) |
| `max_retries` | `3` | Retry attempts on failure |
| `priority` | `1` | Task priority (1=highest, 10=lowest) |

### Performance Impact

**First Request (Cache Empty):**
- Returns partial data: < 1 second
- Background completes: 10-30 seconds
- Subsequent requests use cache: < 0.1 seconds

**Subsequent Requests (Cache Hit):**
- Returns immediately: < 0.1 seconds
- Background refresh (if stale): async, no blocking

### Implementation Status

**Phase 1 (Complete):**
- ✅ NFL scoreboard implemented
- ✅ Background threading architecture
- ✅ Cache integration
- ✅ Error handling and retry logic

**Phase 2 (Planned):**
- ⏳ NCAAFB (college football)
- ⏳ NBA (basketball)
- ⏳ NHL (hockey)
- ⏳ MLB (baseball)

### Error Handling & Fallback

**Automatic Retry:**
- Exponential backoff (1s, 2s, 4s, 8s, ...)
- Maximum retry attempts configurable
- Logs all retry attempts

**Fallback Behavior:**
- If background service disabled: reverts to synchronous fetching
- If background fetch fails: returns cached data
- If no cache: returns empty/error state

### Testing

```bash
# Run background service test
python test_background_service.py

# Check logs for background operations
sudo journalctl -u ledmatrix -f | grep "background"
```

### Monitoring

**View Statistics:**
```python
from src.background_data_service import BackgroundDataService

service = BackgroundDataService()
stats = service.get_statistics()
print(f"Active tasks: {stats['active_tasks']}")
print(f"Completed: {stats['completed']}")
print(f"Failed: {stats['failed']}")
```

**Enable Debug Logging:**
```python
import logging
logging.getLogger('src.background_data_service').setLevel(logging.DEBUG)
```

---

## 5. Permission Management

### Overview

LEDMatrix uses a dual-user architecture: the display service runs as root (hardware access), while the web interface runs as a non-privileged user. Centralized permission management ensures both can access necessary files.

### Why It Matters

**Problem:**
- Root service creates files with root ownership
- Web user cannot read/write those files
- Results in `PermissionError` exceptions

**Solution:**
- Set group ownership to shared group
- Grant group write permissions
- Use setgid bit for automatic inheritance

### Permission Utilities

```python
from src.common.permission_utils import (
    ensure_directory_permissions,
    ensure_file_permissions,
    get_config_file_mode,
    get_assets_file_mode,
    get_plugin_file_mode,
    get_cache_dir_mode
)

# Create directory with correct permissions
ensure_directory_permissions(Path("assets/sports"), get_assets_dir_mode())

# Set file permissions after writing
ensure_file_permissions(Path("config/config.json"), get_config_file_mode())
```

### When to Use Utilities

**Use permission utilities when:**
1. Creating new directories
2. Writing configuration files
3. Downloading/creating asset files (logos, fonts)
4. Creating plugin files
5. Writing cache files

**Don't use for:**
1. Reading files (permissions don't change)
2. Temporary files in `/tmp`
3. Files in already-managed directories (if parent has setgid)

### Permission Standards

**File Permissions:**

| File Type | Mode | Octal | Description |
|-----------|------|-------|-------------|
| Config (main) | `rw-r--r--` | `0o644` | Owner write, all read |
| Config (secrets) | `rw-r-----` | `0o640` | Owner write, group read |
| Assets | `rw-rw-r--` | `0o664` | Owner/group write, all read |
| Plugins | `rw-rw-r--` | `0o664` | Owner/group write, all read |
| Cache files | `rw-rw-r--` | `0o664` | Owner/group write, all read |

**Directory Permissions:**

| Directory Type | Mode | Octal | Description |
|----------------|------|-------|-------------|
| All directories | `rwxrwsr-x` | `0o2775` | With setgid bit for inheritance |

**Note:** The `s` in `rwxrwsr-x` is the setgid bit (2000), which makes new files inherit the directory's group ownership.

### Common Patterns

**Pattern 1: Creating Config Directory**
```python
from pathlib import Path
from src.common.permission_utils import ensure_directory_permissions, get_config_dir_mode

config_dir = Path("config/plugins")
ensure_directory_permissions(config_dir, get_config_dir_mode())
```

**Pattern 2: Saving Config File**
```python
from src.common.permission_utils import ensure_file_permissions, get_config_file_mode

config_path = Path("config/config.json")
with open(config_path, 'w') as f:
    json.dump(data, f)
ensure_file_permissions(config_path, get_config_file_mode())
```

**Pattern 3: Downloading Logo**
```python
from src.common.permission_utils import ensure_directory_permissions, ensure_file_permissions
from src.common.permission_utils import get_assets_dir_mode, get_assets_file_mode

logo_path = Path("assets/sports/nhl/logo.png")
ensure_directory_permissions(logo_path.parent, get_assets_dir_mode())
# ... download and save logo ...
ensure_file_permissions(logo_path, get_assets_file_mode())
```

**Pattern 4: Creating Plugin File**
```python
from src.common.permission_utils import ensure_file_permissions, get_plugin_file_mode

plugin_file = Path("plugins/my-plugin/data.json")
with open(plugin_file, 'w') as f:
    json.dump(data, f)
ensure_file_permissions(plugin_file, get_plugin_file_mode())
```

**Pattern 5: Cache Directory Setup**
```python
from src.common.permission_utils import ensure_directory_permissions, get_cache_dir_mode

cache_dir = Path("cache/plugin-name")
ensure_directory_permissions(cache_dir, get_cache_dir_mode())
```

### Integration with Core Utilities

These core utilities **already handle permissions** - you don't need to call permission utilities when using them:

- **ConfigManager** - Handles config file permissions
- **CacheManager** - Handles cache file permissions
- **LogoHelper** - Handles logo file permissions
- **PluginManager** - Handles plugin file permissions

### Manual Fixes

If you encounter permission issues:

```bash
# Fix all permissions at once
sudo ./scripts/fix_permissions.sh

# Fix specific directory
sudo chown -R ledpi:ledpi /home/ledpi/LEDMatrix/config
sudo chmod -R 2775 /home/ledpi/LEDMatrix/config
sudo find /home/ledpi/LEDMatrix/config -type f -exec chmod 664 {} \;

# Verify permissions
ls -la config/
ls -la assets/
```

### Verification

```bash
# Check directory has setgid bit
ls -ld assets/
# Should show: drwxrwsr-x (note the 's')

# Check file has correct group
ls -l assets/logo.png
# Should show group 'ledpi'

# Check file permissions
stat -c "%a %n" config/config.json
# Should show: 644 config/config.json
```

---

## Related Documentation

- [PLUGIN_DEVELOPMENT.md](PLUGIN_DEVELOPMENT.md) - Creating plugins with Vegas/on-demand support
- [WEB_INTERFACE_GUIDE.md](WEB_INTERFACE_GUIDE.md) - Using on-demand controls in web UI
- [PLUGIN_API_REFERENCE.md](PLUGIN_API_REFERENCE.md) - Complete API documentation
- [DEVELOPMENT.md](DEVELOPMENT.md) - Development environment and testing