# Graph Settings Feature

Complete implementation of Obsidian-compatible graph settings panel for ObsiViewer.

## Overview

This feature adds a comprehensive settings panel for the graph view, matching Obsidian's interface and functionality. Settings are stored in `.obsidian/graph.json` and synchronized in real-time with the graph rendering.

## Features

- ⚙️ **Settings Button**: Gear icon in top-right of graph view
- 🎨 **Settings Panel**: Slide-over panel with four collapsible sections
- 💾 **Persistence**: Auto-save to `.obsidian/graph.json` with 250ms debounce
- 🔄 **Live Sync**: Watch for external file changes and reload
- 📱 **Responsive**: Desktop slide-over, mobile full-screen
- ♿ **Accessible**: Keyboard navigation, ARIA labels, focus management

## Architecture

### Files Created

```
src/app/graph/
├── graph-settings.types.ts          # Type definitions & utilities
├── graph-settings.service.ts        # Config read/write/watch service
├── graph-runtime-adapter.ts         # Apply settings to graph engine
└── ui/
    ├── settings-button.component.ts # Gear icon button
    ├── settings-panel.component.ts  # Main panel with sections
    └── sections/
        ├── filters-section.component.ts
        ├── groups-section.component.ts
        ├── display-section.component.ts
        └── forces-section.component.ts

server/
└── index.mjs                        # API endpoints added
```

## Configuration Structure

### graph.json Format

```json
{
  "collapse-filter": false,
  "search": "",
  "showTags": false,
  "showAttachments": false,
  "hideUnresolved": false,
  "showOrphans": true,
  
  "collapse-color-groups": false,
  "colorGroups": [
    {
      "query": "tag:#markdown",
      "color": { "a": 1, "rgb": 14701138 }
    }
  ],
  
  "collapse-display": false,
  "showArrow": false,
  "textFadeMultiplier": 0,
  "nodeSizeMultiplier": 1,
  "lineSizeMultiplier": 1,
  
  "collapse-forces": false,
  "centerStrength": 0.5,
  "repelStrength": 10,
  "linkStrength": 1,
  "linkDistance": 250,
  
  "scale": 1,
  "close": false
}
```

## Settings Sections

### 1. Filters

Controls which nodes appear in the graph.

| Control | JSON Key | Type | Description |
|---------|----------|------|-------------|
| Search | `search` | string | Filter nodes by text search |
| Tags | `showTags` | boolean | Show/hide tag nodes |
| Attachments | `showAttachments` | boolean | Show/hide attachment files |
| Existing files only | `hideUnresolved` | boolean | Hide unresolved links (inverted) |
| Orphans | `showOrphans` | boolean | Show/hide orphan nodes |

### 2. Groups

Color nodes based on queries.

- **Color Groups**: Array of `{ query, color }` objects
- **Query Types**:
  - `tag:#tagname` - Match notes with tag
  - `file:filename` - Match by filename
  - `path:folder` - Match by folder path
- **Color Format**: `{ a: number, rgb: number }` (RGB as integer 0-16777215)
- **Actions**: New group, Duplicate, Delete, Reorder (drag & drop)

### 3. Display

Visual appearance settings.

| Control | JSON Key | Range | Step | Description |
|---------|----------|-------|------|-------------|
| Arrows | `showArrow` | boolean | - | Show directional arrows on links |
| Text fade threshold | `textFadeMultiplier` | -3 to 3 | 0.1 | When to fade node labels |
| Node size | `nodeSizeMultiplier` | 0.25 to 3 | 0.05 | Size multiplier for nodes |
| Link thickness | `lineSizeMultiplier` | 0.25 to 3 | 0.05 | Thickness multiplier for links |

### 4. Forces

Physics simulation parameters.

| Control | JSON Key | Range | Step | Description |
|---------|----------|-------|------|-------------|
| Center force | `centerStrength` | 0 to 2 | 0.01 | Pull toward center |
| Repel force | `repelStrength` | 0 to 20 | 0.5 | Push nodes apart |
| Link force | `linkStrength` | 0 to 2 | 0.01 | Pull connected nodes together |
| Link distance | `linkDistance` | 20 to 300 | 1 | Target distance between linked nodes |

## API Endpoints

### GET /api/vault/graph

Load graph configuration.

**Response:**
```json
{
  "config": { /* GraphConfig */ },
  "rev": "abc123-456"
}
```

### PUT /api/vault/graph

Save graph configuration.

**Headers:**
- `If-Match`: Optional revision for conflict detection

**Body:** Complete `GraphConfig` object

**Response:**
```json
{
  "rev": "def456-789"
}
```

**Status Codes:**
- `200` - Success
- `409` - Conflict (file modified externally)
- `500` - Server error

## Color Conversion

### RGB Integer Format

Obsidian stores colors as integers (0-16777215):

```typescript
// HEX to Integer
const hex = "#E06C75";
const rgb = hexToInt(hex); // 14707829

// Integer to RGBA
const { r, g, b, a } = intToRgba(14707829, 1);
// r: 224, g: 108, b: 117, a: 1

// To CSS
const css = colorToCss({ a: 1, rgb: 14707829 });
// "rgba(224, 108, 117, 1)"
```

## Runtime Adapter

The `GraphRuntimeAdapter` translates config to runtime options:

### Filters Application

```typescript
const filtered = GraphRuntimeAdapter.applyFilters(
  baseGraphData,
  config,
  allNotes
);
```

Applies:
- Text search on node labels
- Tag/attachment/orphan filtering
- Unresolved link filtering

### Display Options Conversion

```typescript
const displayOptions = GraphRuntimeAdapter.configToDisplayOptions(config);
```

Converts:
- `textFadeMultiplier` (-3 to 3) → `textFadeThreshold` (0 to 100)
- `nodeSizeMultiplier` → absolute `nodeSize` (base: 5px)
- `lineSizeMultiplier` → absolute `linkThickness` (base: 1px)
- `repelStrength` (0 to 20) → `chargeStrength` (0 to -200)

### Color Groups Application

```typescript
const nodeColors = GraphRuntimeAdapter.applyColorGroups(
  nodes,
  config,
  allNotes
);
```

Returns `Map<nodeId, cssColor>` for node coloring.

## State Management

### Service Layer

**GraphSettingsService**:
- `config: Signal<GraphConfig>` - Current configuration
- `load()` - Load from API
- `save(patch)` - Save with debounce (250ms)
- `watch(callback)` - Subscribe to changes
- `resetToDefaults()` - Reset all settings
- `resetSection(section)` - Reset specific section
- `toggleCollapse(section)` - Toggle section expand/collapse

### Reactive Updates

All settings changes trigger:
1. Immediate UI update (signal update)
2. Debounced file write (250ms)
3. Graph re-render (via computed signals)

### External Change Detection

Polls every 2 seconds to detect external file modifications and reload config.

## Usage Examples

### Open Settings Panel

Click the gear icon (⚙️) in top-right of graph view.

### Keyboard Shortcuts

- `Esc` - Close settings panel
- `Enter`/`Space` - Activate buttons/toggles
- `Tab` - Navigate controls

### Programmatic Access

```typescript
import { GraphSettingsService } from './app/graph/graph-settings.service';

// Inject service
constructor(private settings: GraphSettingsService) {}

// Get current config
const config = this.settings.config();

// Update settings
this.settings.save({
  showArrow: true,
  nodeSizeMultiplier: 1.5
});

// Watch for changes
this.settings.watch(config => {
  console.log('Config updated:', config);
});

// Reset
this.settings.resetToDefaults();
this.settings.resetSection('display');
```

## Testing Checklist

### Manual Tests

- [ ] Click gear icon → panel slides in
- [ ] All sections expand/collapse correctly
- [ ] Each control modifies corresponding JSON key
- [ ] Settings persist after page reload
- [ ] External file edit → UI updates
- [ ] Search filter works on node labels
- [ ] Tags toggle hides/shows tag nodes
- [ ] Existing files only hides unresolved links
- [ ] Orphans toggle hides/shows orphan nodes
- [ ] New color group adds with default color
- [ ] Color picker updates group color
- [ ] Query input filters matching nodes
- [ ] Delete group removes from list
- [ ] Duplicate group creates copy
- [ ] Arrows toggle shows/hides link arrows
- [ ] All sliders update in real-time
- [ ] Animate button restarts simulation
- [ ] Force sliders affect node positions
- [ ] Reset all restores defaults
- [ ] Reset section restores section defaults
- [ ] Close button closes panel
- [ ] Esc key closes panel
- [ ] Mobile: full-screen panel
- [ ] Dark mode: correct theming

### Integration Tests

- [ ] graph.json created on first run
- [ ] Atomic writes prevent corruption
- [ ] Backup file created (.bak)
- [ ] Conflict detection works (409 response)
- [ ] Polling detects external changes
- [ ] Debounce prevents excessive writes
- [ ] Invalid JSON handled gracefully
- [ ] Missing file uses defaults

## Performance

- **Debounce**: 250ms write delay
- **Polling**: 2-second interval
- **Atomic Writes**: Temp file + rename
- **Validation**: Clamps values to bounds
- **Signal-based**: Minimal re-renders

## Browser Compatibility

- Chrome/Edge: ✅ Full support
- Firefox: ✅ Full support
- Safari: ✅ Full support
- Mobile browsers: ✅ Responsive design

## Known Limitations

1. **Drag & Drop**: Groups reordering not yet implemented
2. **Scale/Close**: Preserved but not exposed in UI
3. **Advanced Queries**: Only basic query types supported
4. **Undo/Redo**: Not implemented

## Future Enhancements

- [ ] Drag & drop for color group reordering
- [ ] Advanced query builder UI
- [ ] Preset configurations
- [ ] Export/import settings
- [ ] Undo/redo for settings changes
- [ ] Keyboard shortcuts for common actions
- [ ] Animation presets
- [ ] Graph layout algorithms selector

## Troubleshooting

### Settings Not Saving

- Check browser console for errors
- Verify `.obsidian` directory exists
- Check file permissions
- Ensure server is running

### Panel Not Opening

- Check for JavaScript errors
- Verify all components imported correctly
- Clear browser cache

### External Changes Not Detected

- Polling interval is 2 seconds
- Check file watcher is enabled
- Verify file path is correct

### Performance Issues

- Reduce polling frequency
- Increase debounce delay
- Disable external change detection

## Credits

Designed to match [Obsidian](https://obsidian.md/) graph view interface and behavior.