# BMS BattleMap Generator - Technical Architecture

## System Overview

```
┌─────────────────────────────────────────────────────────────┐
│                    Frontend Application                      │
├─────────────────────────────────────────────────────────────┤
│  Editor Interface      Preview Canvas       Tools Panel      │
│  (Monaco Editor)      (Konva.js Canvas)    (Export/Options) │
├─────────────────────────────────────────────────────────────┤
│                    State Management                          │
│                    (React Hooks/Context)                     │
├─────────────────────────────────────────────────────────────┤
│  YAML Parser  │  Schema Validator  │  Renderer Engine       │
│  (js-yaml)    │  (Zod)             │  (Konva.js Layers)     │
└─────────────────────────────────────────────────────────────┘
```

## Component Architecture

### 1. BMS Schema Module (`src/schema/`)
```
schema/
├── types.ts              # TypeScript interfaces
├── validators.ts         # Zod validation schemas
├── parsers.ts            # Coordinate/range parsing
├── transformers.ts       # Data transformation
└── index.ts              # Public API
```

### 2. Parser Module (`src/parser/`)
```
parser/
├── yaml-parser.ts        # BMS YAML parsing
├── coordinate-parser.ts  # Grid coordinate parsing
├── validation.ts         # Schema validation logic
├── errors.ts             # Error types and messages
└── index.ts
```

### 3. Renderer Module (`src/renderer/`)
```
renderer/
├── base-renderer.ts      # Abstract base class
├── paperly-renderer.ts   # Paperly style implementation
├── texture-renderer.ts   # Future: texture pack rendering
├── layers/               # Individual layer renderers
│   ├── grid-layer.ts
│   ├── room-layer.ts
│   ├── door-layer.ts
│   ├── object-layer.ts
│   ├── hazard-layer.ts
│   ├── lighting-layer.ts
│   └── annotation-layer.ts
├── styles/               # Style definitions
│   ├── paperly-style.ts
│   └── texture-styles.ts # Future
└── utils/                # Rendering utilities
    ├── geometry.ts
    ├── colors.ts
    └── textures.ts
```

### 4. UI Components (`src/components/`)
```
components/
├── Editor/
│   ├── YAMLEditor.tsx    # Monaco editor wrapper
│   └── EditorPanel.tsx   # Editor with error display
├── Preview/
│   ├── MapCanvas.tsx     # Konva canvas wrapper
│   └── PreviewPanel.tsx  # Preview with controls
├── Tools/
│   ├── ExportMenu.tsx    # Export options
│   ├── StylePicker.tsx   # Style selection
│   └── ValidationPanel.tsx # Validation status
├── Layout/
│   ├── Header.tsx
│   ├── Sidebar.tsx
│   └── StatusBar.tsx
└── Common/
    ├── ErrorDisplay.tsx
    ├── LoadingSpinner.tsx
    └── Tooltip.tsx
```

### 5. State Management (`src/hooks/`, `src/context/`)
```
hooks/
├── useBMS.ts             # BMS schema state
├── useRenderer.ts        # Renderer instance
├── useExport.ts          # Export functionality
└── useUndoRedo.ts        # Undo/redo history

context/
├── AppContext.tsx        # Global app state
└── ThemeContext.tsx      # Theme/stylesheet
```

## Data Flow

### 1. Parsing Pipeline
```
User Input (YAML)
      ↓
YAML Parser (js-yaml)
      ↓
Schema Validator (Zod)
      ↓
BMSSchema Object
      ↓
Renderer Engine
      ↓
Canvas Output
```

### 2. Rendering Pipeline
```
BMSSchema
      ↓
Setup Canvas (grid size, scale)
      ↓
Render Layers (in order):
  1. Grid Layer
  2. Room Layer (walls, floors)
  3. Door Layer
  4. Object Layer
  5. Hazard Layer
  6. Lighting Layer
  7. Annotation Layer
      ↓
Canvas Output
```

### 3. Export Pipeline
```
Canvas State
      ↓
Export Format Selection
      ↓
Format-Specific Exporter:
  - PNG: canvas.toDataURL()
  - JSON: JSON.stringify(BMSSchema)
  - BMS: serializeBMSToYAML()
      ↓
File Download
```

## Key Technical Decisions

### 1. Canvas Library: Konva.js
**Why Konva.js over alternatives:**
- **React Integration**: react-konva provides React component wrappers
- **Performance**: Hardware acceleration, efficient rendering
- **Features**: Layers, events, transforms, filters
- **Size**: Smaller than PIXI.js, more focused than raw Canvas API
- **Maintenance**: Active development, good documentation

### 2. Validation: Zod
**Why Zod over alternatives:**
- **TypeScript Integration**: Automatic type inference
- **Runtime Safety**: Comprehensive validation at runtime
- **Error Messages**: Customizable error messages
- **Size**: Small bundle size
- **Schema Composition**: Easy to compose and extend schemas

### 3. YAML Parsing: js-yaml
**Why js-yaml:**
- **Browser Support**: Works in browser environments
- **Safety**: Secure parsing options
- **Performance**: Fast and efficient
- **Features**: Full YAML 1.2 support

### 4. State Management: React Hooks
**Why React Hooks over Redux/MobX:**
- **Simplicity**: Less boilerplate for MVP
- **Performance**: Optimized re-renders with useMemo/useCallback
- **Scalability**: Can migrate to Context or Zustand if needed
- **Learning Curve**: Familiar to React developers

## Performance Considerations

### 1. Rendering Optimization
```typescript
// Use Konva.js optimizations
const optimizedRender = () => {
  // Batch updates
  stage.batchDraw();
  
  // Use caching for static elements
  shape.cache();
  
  // Implement viewport culling
  if (isInViewport(element)) {
    renderElement(element);
  }
};
```

### 2. Memory Management
```typescript
// Clean up resources
useEffect(() => {
  const renderer = new PaperlyRenderer();
  return () => {
    renderer.destroy(); // Clean up Konva objects
  };
}, []);
```

### 3. Large Map Handling
```typescript
// Implement level of detail
const getDetailLevel = (zoom: number): DetailLevel => {
  if (zoom < 0.5) return 'low';
  if (zoom < 1.0) return 'medium';
  return 'high';
};

// Progressive rendering
const renderProgressive = async (schema: BMSSchema) => {
  // Render grid first
  renderGrid();
  
  // Render rooms
  await renderRooms(schema.rooms);
  
  // Render details progressively
  requestIdleCallback(() => {
    renderDoors(schema.doors);
    renderObjects(schema.objects);
  });
};
```

## Security Considerations

### 1. YAML Parsing Security
```typescript
import { load } from 'js-yaml';

// Safe YAML parsing
const parseBMSYAML = (yaml: string): BMSSchema => {
  try {
    // Use safeLoad to prevent code execution
    const parsed = load(yaml, {
      schema: yaml.DEFAULT_SAFE_SCHEMA,
      onWarning: (warning) => console.warn(warning)
    });
    
    // Validate structure
    return bmsSchema.parse(parsed);
  } catch (error) {
    throw new BMSValidationError('Invalid BMS YAML', error);
  }
};
```

### 2. File Export Security
```typescript
// Safe file naming
const sanitizeFilename = (name: string): string => {
  return name.replace(/[^a-z0-9-_.]/gi, '_');
};

// Content security for downloads
const downloadFile = (content: string, filename: string) => {
  const blob = new Blob([content], { type: 'application/octet-stream' });
  const url = URL.createObjectURL(blob);
  // Use safe download pattern
  const a = document.createElement('a');
  a.href = url;
  a.download = sanitizeFilename(filename);
  a.click();
  URL.revokeObjectURL(url);
};
```

## Testing Strategy

### 1. Unit Tests
```typescript
// Test coordinate parsing
describe('parseCoordinate', () => {
  it('should parse valid coordinates', () => {
    expect(parseCoordinate('(5,10)')).toEqual([5, 10]);
  });
  
  it('should throw error for invalid format', () => {
    expect(() => parseCoordinate('5,10')).toThrow();
  });
});
```

### 2. Integration Tests
```typescript
// Test full parsing pipeline
describe('BMS Parser Integration', () => {
  it('should parse and validate complete BMS', () => {
    const yaml = sampleBMSYAML;
    const schema = parseBMSYAML(yaml);
    expect(schema.mapName).toBe('Guard Room');
    expect(schema.rooms).toHaveLength(1);
  });
});
```

### 3. Visual Regression Tests
```typescript
// Compare rendered output
describe('Renderer Visual Tests', () => {
  it('should render rooms correctly', async () => {
    const schema = createTestSchema();
    const renderer = new PaperlyRenderer();
    const image = await renderer.renderToImage(schema);
    
    // Compare with baseline
    expect(image).toMatchImageSnapshot();
  });
});
```

## Deployment Architecture

### 1. Development Environment
```
Local Machine → Vite Dev Server → Browser
```

### 2. Alpha Deployment
```
Git Repository → Build (Vite) → Static Files → maps.bouncypixel.com
```

### 3. Future Production Deployment
```
GitHub Actions → Build & Test → CDN (Vercel/Netlify) → Custom Domain
              ↘ Texture Packs → Cloud Storage (S3/Cloudflare)
```

## Scalability Considerations

### 1. Frontend Scaling
- **Code Splitting**: Lazy load components
- **Bundle Optimization**: Tree shaking, compression
- **CDN**: Static assets via CDN

### 2. Rendering Scaling
- **Virtualization**: Only render visible area
- **Web Workers**: Offload heavy computation
- **Caching**: Cache rendered elements

### 3. Data Scaling
- **IndexedDB**: Local storage for large maps
- **Compression**: Compress BMS data
- **Streaming**: Progressive loading

## Monitoring & Analytics

### 1. Performance Monitoring
```typescript
// Track rendering performance
const measureRender = (schema: BMSSchema) => {
  performance.mark('render-start');
  renderer.render(schema);
  performance.mark('render-end');
  
  const measure = performance.measure('render', 'render-start', 'render-end');
  console.log(`Render time: ${measure.duration}ms`);
};
```

### 2. Error Tracking
```typescript
// Centralized error handling
class ErrorTracker {
  static track(error: Error, context?: any) {
    console.error('BMS Error:', error, context);
    // Send to error tracking service (future)
  }
}
```

### 3. Usage Analytics (Optional)
```typescript
// Basic usage tracking
const trackEvent = (event: string, data?: any) => {
  if (process.env.NODE_ENV === 'production') {
    // Send to analytics service
  }
};
```

## Future Technical Considerations

### 1. Plugin System
```typescript
interface BMSPlugin {
  name: string;
  version: string;
  init: (app: BMSApp) => void;
  render?: (context: RenderContext) => void;
  export?: (schema: BMSSchema) => any;
}
```

### 2. Collaborative Features
- **WebSocket**: Real-time collaboration
- **Conflict Resolution**: Operational transforms
- **Presence**: User cursor/selection

### 3. Offline Support
- **Service Workers**: Offline functionality
- **Local Storage**: Save work locally
- **Sync**: Background synchronization

---
*Last Updated: March 19, 2026*