Maintaining Code Quality

Why? Duplicate code leads to inconsistencies, bugs, and maintenance burden. StickerNest has many utilities that solve common problems.

File Length Limits

Current Large Files (Need Attention)

Based on codebase analysis, these files exceed limits:

1924 lines - src/runtime/WidgetSandboxHost.ts     ⚠️ CRITICAL
1808 lines - src/components/.../StyleGalleryPanel.tsx  ⚠️ CRITICAL
1586 lines - src/runtime/WidgetAPI.ts             ⚠️ CRITICAL
1548 lines - src/widgets/.../LiveChatWidget.ts    ⚠️ CRITICAL
1471 lines - src/services/enhancedAIGenerator.ts  ⚠️ CRITICAL
1403 lines - src/state/useCanvasStore.ts          ⚠️ CRITICAL

When to Refactor

Immediate Refactoring Triggers

1. File exceeds line limit (see table above)
2. Function > 50 lines - Extract helper functions
3. Component > 200 lines JSX - Split into sub-components
4. > 5 useState hooks - Consider useReducer or custom hook
5. > 3 levels of nesting - Extract to separate functions
6. Duplicate code - Extract to shared utility

Refactoring Signals

// 🚩 Too many imports (> 15)
import { a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p } from '...';
// → Split into focused modules

// 🚩 God component (does too much)
function MyComponent() {
  // 500+ lines of mixed concerns
}
// → Split into container + presentational components

// 🚩 Prop drilling (> 3 levels)
<A data={data}><B data={data}><C data={data}><D data={data} /></C></B></A>
// → Use context or Zustand store

// 🚩 Complex conditionals
if (a && (b || c) && (!d || (e && f))) { ... }
// → Extract to named boolean or function

Refactoring Patterns

Extracting Components

// BEFORE: Monolithic component
function BigComponent() {
  return (
    <div>
      {/* 50 lines of header */}
      {/* 100 lines of content */}
      {/* 50 lines of footer */}
    </div>
  );
}

// AFTER: Composed components
function BigComponent() {
  return (
    <div>
      <Header />
      <Content />
      <Footer />
    </div>
  );
}

// Each in its own file if > 100 lines
// src/components/BigComponent/
//   index.tsx
//   Header.tsx
//   Content.tsx
//   Footer.tsx

Extracting Hooks

// BEFORE: Logic in component
function MyComponent() {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState(null);

  useEffect(() => {
    setLoading(true);
    fetchData()
      .then(setData)
      .catch(setError)
      .finally(() => setLoading(false));
  }, []);

  // ... 200 more lines
}

// AFTER: Custom hook
function useDataFetch() {
  const [data, setData] = useState(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState(null);

  useEffect(() => {
    setLoading(true);
    fetchData()
      .then(setData)
      .catch(setError)
      .finally(() => setLoading(false));
  }, []);

  return { data, loading, error };
}

function MyComponent() {
  const { data, loading, error } = useDataFetch();
  // ... cleaner component
}

Extracting Store Slices

// BEFORE: Massive store
// useCanvasStore.ts - 1400 lines

// AFTER: Sliced stores
// useCanvasStore.ts - Main canvas state
// useSelectionStore.ts - Selection logic
// useViewportStore.ts - Viewport/zoom/pan
// useHistoryStore.ts - Undo/redo
// useGridStore.ts - Grid/snap settings

// Or use Zustand slices pattern:
const createSelectionSlice = (set, get) => ({
  selectedIds: new Set(),
  select: (id) => set({ selectedIds: new Set([id]) }),
  // ...
});

Extracting Utilities

// BEFORE: Inline logic
function Component() {
  const formatted = value
    .replace(/[^a-z]/gi, '')
    .toLowerCase()
    .substring(0, 50);
}

// AFTER: Utility function
// src/utils/formatters.ts
export function sanitizeInput(value: string, maxLength = 50): string {
  return value
    .replace(/[^a-z]/gi, '')
    .toLowerCase()
    .substring(0, maxLength);
}

// Component
import { sanitizeInput } from '@/utils/formatters';
const formatted = sanitizeInput(value);

File Organization

Component Structure

src/components/MyFeature/
├── index.tsx           # Main export
├── MyFeature.tsx       # Main component (< 300 lines)
├── MyFeatureHeader.tsx # Sub-component
├── MyFeatureList.tsx   # Sub-component
├── useMyFeature.ts     # Custom hooks
├── MyFeature.types.ts  # Types (if > 50 lines)
├── MyFeature.utils.ts  # Utilities
└── MyFeature.test.tsx  # Tests

Module Structure

src/features/canvas/
├── index.ts            # Public API
├── components/         # UI components
├── hooks/              # Feature hooks
├── store/              # Zustand store(s)
├── utils/              # Utilities
├── types.ts            # Types
└── constants.ts        # Constants

Code Review Checklist

Before Submitting

• Checked for existing code that does similar things
• File lengths within limits
• No duplicate code - extracted to utilities
• Follows existing patterns in codebase
• Imports are reasonable (< 15 per file)
• No commented-out code (delete it)
• No console.log (except error handling)

For New Files

• Placed in correct directory
• Named consistently with conventions
• Has TypeScript types (no any unless necessary)
• Exports are intentional (don't export everything)

For Refactoring

• Behavior unchanged (same inputs → same outputs)
• Tests still pass
• No new TypeScript errors
• Imports updated across codebase

Naming Conventions

// Components: PascalCase
MyComponent.tsx
WidgetCard.tsx

// Hooks: camelCase with 'use' prefix
useCanvasStore.ts
useWidgetDrag.ts

// Utilities: camelCase
formatDate.ts
validateInput.ts

// Types: PascalCase
types.ts → interface WidgetInstance { }
types.ts → type CanvasMode = 'edit' | 'view';

// Constants: SCREAMING_SNAKE_CASE
const MAX_WIDGETS = 100;
const API_ENDPOINT = '/api/v1';

Anti-Patterns to Avoid

// ❌ God objects
const everythingStore = { /* 1000+ properties */ };

// ❌ Prop drilling
<A><B><C><D><E prop={value} /></D></C></B></A>

// ❌ Inline styles everywhere
<div style={{ color: 'red', padding: 20, margin: 10, ... }}>

// ❌ Magic numbers
if (widgets.length > 47) { /* why 47? */ }

// ❌ Nested ternaries
const result = a ? b ? c : d : e ? f : g;

// ❌ any types
function process(data: any): any { }

// ❌ Mutation
state.items.push(newItem); // ❌
set({ items: [...get().items, newItem] }); // ✅

Quick Commands

# Find large files
find src -name "*.ts" -o -name "*.tsx" | xargs wc -l | sort -n | tail -20

# Find files with too many imports
grep -l "^import" src/**/*.{ts,tsx} | xargs -I{} sh -c 'echo "$(grep "^import" {} | wc -l) {}"' | sort -n | tail -10

# Find potential duplicates (similar function names)
grep -rh "function\|const.*=.*=>" src/ | sort | uniq -c | sort -n | tail -20