// ✅ GOOD: Descriptive names
const marketSearchQuery = 'election'
const isUserAuthenticated = true
const totalRevenue = 1000

// ❌ BAD: Unclear names
const q = 'election'
const flag = true
const x = 1000

// ✅ GOOD: Verb-noun pattern
async function fetchMarketData(marketId: string) { }
function calculateSimilarity(a: number[], b: number[]) { }
function isValidEmail(email: string): boolean { }

// ❌ BAD: Unclear or noun-only
async function market(id: string) { }
function similarity(a, b) { }
function email(e) { }

// ✅ ALWAYS use spread operator
const updatedUser = {
  ...user,
  name: 'New Name'
}

const updatedArray = [...items, newItem]

// ❌ NEVER mutate directly
user.name = 'New Name'  // BAD
items.push(newItem)     // BAD

// ✅ GOOD: Comprehensive error handling
async function fetchData(url: string) {
  try {
    const response = await fetch(url)

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`)
    }

    return await response.json()
  } catch (error) {
    console.error('Fetch failed:', error)
    throw new Error('Failed to fetch data')
  }
}

// ❌ BAD: No error handling
async function fetchData(url) {
  const response = await fetch(url)
  return response.json()
}

// ✅ GOOD: Parallel execution when possible
const [users, markets, stats] = await Promise.all([
  fetchUsers(),
  fetchMarkets(),
  fetchStats()
])

// ❌ BAD: Sequential when unnecessary
const users = await fetchUsers()
const markets = await fetchMarkets()
const stats = await fetchStats()

// ✅ GOOD: Proper types
interface Market {
  id: string
  name: string
  status: 'active' | 'resolved' | 'closed'
  created_at: Date
}

function getMarket(id: string): Promise<Market> {
  // Implementation
}

// ❌ BAD: Using 'any'
function getMarket(id: any): Promise<any> {
  // Implementation
}

// ✅ GOOD: Functional component with types
interface ButtonProps {
  children: React.ReactNode
  onClick: () => void
  disabled?: boolean
  variant?: 'primary' | 'secondary'
}

export function Button({
  children,
  onClick,
  disabled = false,
  variant = 'primary'
}: ButtonProps) {
  return (
    <button
      onClick={onClick}
      disabled={disabled}
      className={`btn btn-${variant}`}
    >
      {children}
    </button>
  )
}

// ❌ BAD: No types, unclear structure
export function Button(props) {
  return <button onClick={props.onClick}>{props.children}</button>
}

// ✅ GOOD: Reusable custom hook
export function useDebounce<T>(value: T, delay: number): T {
  const [debouncedValue, setDebouncedValue] = useState<T>(value)

  useEffect(() => {
    const handler = setTimeout(() => {
      setDebouncedValue(value)
    }, delay)

    return () => clearTimeout(handler)
  }, [value, delay])

  return debouncedValue
}

// Usage
const debouncedQuery = useDebounce(searchQuery, 500)

// ✅ GOOD: Proper state updates
const [count, setCount] = useState(0)

// Functional update for state based on previous state
setCount(prev => prev + 1)

// ❌ BAD: Direct state reference
setCount(count + 1)  // Can be stale in async scenarios

// ✅ GOOD: Clear conditional rendering
{isLoading && <Spinner />}
{error && <ErrorMessage error={error} />}
{data && <DataDisplay data={data} />}

// ❌ BAD: Ternary hell
{isLoading ? <Spinner /> : error ? <ErrorMessage error={error} /> : data ? <DataDisplay data={data} /> : null}

GET    /api/markets              # List all markets
GET    /api/markets/:id          # Get specific market
POST   /api/markets              # Create new market
PUT    /api/markets/:id          # Update market (full)
PATCH  /api/markets/:id          # Update market (partial)
DELETE /api/markets/:id