❌ AVOID: getUserData(), UtilityClass, helperMethod(), DataProcessor
✅ PREFER: getUserProfile(), OrderCalculator, calculateTotal(), InvoiceGenerator

🟡 Generic naming at src/utils/DataHelper.ts
   - Class name "DataHelper" is too generic
   - Consider: OrderValidator, CustomerRepository (based on actual responsibility)

🔴 Indentation violation at User.ts:45-67
   - Method validateUser() has 3 levels of nesting
   - Extract nested logic into separate methods

🟡 ELSE keyword at Order.ts:23
   - Can restructure with early return

❌ Feature Envy:
class UserProfile {
  displaySubscriptionInfo(): string {
    // Accessing multiple properties of Subscription - too much interest in its data
    return `Plan: ${this.subscription.planName}, ` +
           `Price: $${this.subscription.monthlyPrice}/mo, ` +
           `Screens: ${this.subscription.maxScreens}, ` +
           `Quality: ${this.subscription.videoQuality}`;
  }
}

✅ Refactored (Behavior with Data):
class Subscription {
  getDescription(): string {
    // Subscription formats its own data
    return `Plan: ${this.planName}, ` +
           `Price: $${this.monthlyPrice}/mo, ` +
           `Screens: ${this.maxScreens}, ` +
           `Quality: ${this.videoQuality}`;
  }
}

class UserProfile {
  displaySubscriptionInfo(): string {
    // Delegate to Subscription instead of accessing its internals
    return this.subscription.getDescription();
  }
}

🔴 Feature envy at OrderService.ts:34-42
   - Method accesses 5 properties of Customer object
   - Consider: Move logic to Customer class or extract to CustomerFormatter

❌ AVOID:
   let total = 0;
   items.forEach(item => total += item.price);

✅ PREFER:
   const total = items.reduce((sum, item) => sum + item.price, 0);

🟡 Mutable state at Cart.ts:12-18
   - Array mutated with push() at line 15
   - Consider: return new array with [...items, newItem]

❌ Poor encapsulation / Anemic domain:
class PlaceOrderUseCase {
  placeOrder(orderId) {
    const order = repository.load(orderId)
    if (order.getStatus() === 'DRAFT'){
      order.place()
    }
    repository.save(order)
  }
}

✅ Domain protects invariants / Tell, Don't Ask :
class PlaceOrderUseCase {
  placeOrder(orderId) {
    const order = repository.load(orderId)
    order.place()
    repository.save(order)
  }
}

class Order {
  ...

  place() {
    if (this.status !== 'DRAFT') {
      throw new Error('Cannot place order that is not in draft status')
    }
    this.status === 'PLACED'
  }
}

🔴 Anemic domain model at Order.ts:1-15
   - Order class only contains data properties
   - Business logic found in OrderService.ts:45-89
   - Consider: Move calculateTotal(), validateItems() into Order class

❌ AVOID:
   status: string;  // Can be any string

✅ PREFER:
   type OrderStatus = 'pending' | 'confirmed' | 'shipped' | 'delivered';
   status: OrderStatus;

🔴 Type safety violation at Payment.ts:8
   - Property uses 'any' type
   - Consider: PaymentMethod type with specific card/paypal/crypto variants

🟡 Primitive obsession at Order.ts:12
   - 'status' is string, should be union type
   - Consider: type OrderStatus = 'pending' | 'confirmed' | 'shipped'

❌ AVOID:
   function calculatePrice(item, discount, tax, shipping, insurance, gift) {
     // 8 parameters handling every possible scenario
   }

✅ PREFER:
   function calculatePrice(item, options) {
     // Simple, extensible
   }

🟡 Code duplication at Cart.ts:23-28 and Cart.ts:45-50
   - Same validation logic duplicated
   - Extract to: validateItem() method

❌ AVOID:
   items.forEach(item => {
     const category = categories.find(c => c.id === item.categoryId); // O(n²)
   });

✅ PREFER:
   const categoryMap = new Map(categories.map(c => [c.id, c])); // O(n)
   items.forEach(item => {
     const category = categoryMap.get(item.categoryId); // O(1)
   });

🔴 Performance issue at ProductList.ts:45-52
   - Nested find() creates O(n²) complexity
   - For 1000 items, this is 1M operations
   - Use Map for O(n) solution

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Understanding UserService.ts...
- UserService.createUser() [line 23]
  ↓ validates user data
  ↓ calls database.insert() [line 45]
  ↓ sends email via emailService.send() [line 52]

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