// Page A：Red Button
<button style={{ backgroundColor: 'red', color: 'white' }}>
  Delete
</button>

// Page B：Blue Button
<button style={{ backgroundColor: 'blue', color: 'white' }}>
  Submit
</button>

// Page C：Small gray button
<button style={{ backgroundColor: 'gray', color: 'black', fontSize: '12px' }}>
  Cancel
</button>

function Button({ variant = 'primary', size = 'medium', children }) {
  const styles = {
    primary: { backgroundColor: '#1890ff', color: 'white' },
    danger:  { backgroundColor: '#ff4d4f', color: 'white' },
    default: { backgroundColor: '#f0f0f0', color: '#333' }
  }

  return (
    <button style={{
      ...styles[variant],
      padding: size === 'large' ? '12px 24px' : '8px 16px',
      border: 'none',
      borderRadius: '6px',
      cursor: 'pointer'
    }}>
      {children}
    </button>
  )
}

// Usage：Done in one line of code
<Button variant="danger">Delete</Button>
<Button variant="primary">Submit</Button>
<Button variant="default">Cancel</Button>

// The Simplest Function Component
function Welcome() {
  return <h1>Hello, React!</h1>
}

// How to Write Arrow Functions（More common）
const Welcome = () => {
  return <h1>Hello, React!</h1>
}

// Implicit Return（Only one line JSX "when " can be omitted return）
const Welcome = () => <h1>Hello, React!</h1>

// ---- Define a Component ----
function Greeting(props) {
  // props It is an object，Includes all incoming parameters
  return <h1>Hello，{props.name}！This year, you {props.age} years old。</h1>
}

// ---- Using Components ----
<Greeting name="Alice" age={28} />

// Rendering Results：
// <h1>Hello，Alice！This year, you 28 years old。</h1>

// Deconstructive Writing Style（Recommendations）
function Greeting({ name, age }) {
  return <h1>Hello，{name}！This year, you {age} years old。</h1>
}

// equivalent to：
function Greeting(props) {
  const { name, age } = props
  return <h1>Hello，{name}！This year, you {age} years old。</h1>
}

function UserCard({ name, role }) {
  return (
    <div className="card">
      <h2>{name}</h2>
      <p>Characters：{role}</p>
    </div>
  )
}

// Strings are enclosed in double quotes，For other types {} Package
<UserCard name="Alice" role="Administrator" />

function Product({ name, price, inStock, details }) {
  return (
    <div className="product">
      <h3>{name}</h3>
      <p>Price：${price}</p>
      {/* Boolean values are used for conditional rendering */}
      {inStock ? <span>In stock ✅</span> : <span>Out of stock ❌</span>}
      {/* Object：Accessible properties */}
      <p>Category：{details.category} | Weight：{details.weight}g</p>
    </div>
  )
}

// Using Components
<Product
  name="Wireless Mouse"
  price={89}
  inStock={true}
  details={{ category: 'Peripherals', weight: 120 }}
/>

// ============================================
// Example：use  Props Build a User Information Card
// Features：Display Props Transmission of Various Types
// ============================================

function UserCard({ name, age, isOnline, avatar, tags }) {
  return (
    <div style={{
      border: '1px solid #ddd',
      borderRadius: '8px',
      padding: '20px',
      maxWidth: '300px'
    }}>
      <img
        src={avatar}
        alt={name}
        style={{ width: '80px', height: '80px', borderRadius: '50%' }}
      />
      <h2>{name}</h2>
      <p>Age：{age} years old</p>
      <p>
        Status：
        <span style={{ color: isOnline ? '#52c41a' : '#999' }}>
          {isOnline ? 'Online' : 'Offline'}
        </span>
      </p>
      <div>
        Tags：
        {tags.map(tag => (
          <span key={tag} style={{
            background: '#f0f0f0',
            padding: '2px 8px',
            borderRadius: '4px',
            margin: '0 4px',
            fontSize: '12px'
          }}>
            {tag}
          </span>
        ))}
      </div>
    </div>
  )
}

// Using Components
<UserCard
  name="Alice"
  age={28}
  isOnline={true}
  avatar="https://i.pravatar.cc/80"
  tags={['Front End', 'React', 'TypeScript']}
/>

// Definition：use  children Content between tags
function Card({ children, title }) {
  return (
    <div style={{ border: '1px solid #ddd', padding: '16px', borderRadius: '8px' }}>
      <h3>{title}</h3>
      <div>{children}</div>  {/* The content between the tags is displayed here */}
    </div>
  )
}

// Usage：The content between the tags automatically becomes children
<Card title="Announcement">
  <p>The system will go live tonight 22:00 Perform maintenance，Expected to continue 2 hours。</p>
  <p>Please save your work in advance.，To prevent data loss。</p>
</Card>

// Rendering Results：
// <div class="card">
//   <h3>Announcement</h3>
//   <div>
//     <p>The system will go live tonight 22:00 Perform maintenance...</p>
//     <p>Please save your work in advance....</p>
//   </div>
// </div>

function Button({ text = 'Click', color = 'blue', size = 'medium' }) {
  return (
    <button style={{
      backgroundColor: color,
      padding: size === 'large' ? '12px 24px' : '8px 16px',
      color: 'white',
      border: 'none',
      borderRadius: '4px'
    }}>
      {text}
    </button>
  )
}

// No parameters → Use the default values
<Button />                    // Blue、medium、"Click"

// Pass some parameters → Override the default value
<Button text="Submit" />        // Blue、medium、"Submit"
<Button color="red" size="large" />  // Red、large、"Click"

// ---- Definition Props Type ----
interface ButtonProps {
  text: string           // Required：string
  color?: string         // Optional: add ? suffix
  size?: 'small' | 'medium' | 'large'  // Optional: limited to 3 values
  onClick: () => void    // Required：Function Types
  disabled?: boolean     // Optional: boolean, defaults to false
}

// ---- Using in a component ----
function Button({ text, color = 'blue', size = 'medium', onClick, disabled = false }: ButtonProps) {
  return (
    <button
      onClick={onClick}
      disabled={disabled}
      style={{
        backgroundColor: color,
        padding: size === 'large' ? '12px 24px' : '8px 16px',
        opacity: disabled ? 0.5 : 1,
        color: 'white',
        border: 'none',
        borderRadius: '4px'
      }}
    >
      {text}
    </button>
  )
}

// Usage：The editor provides smart suggestions
<Button
  text="Save"
  color="#1890ff"
  size="medium"
  onClick={() => alert('Saved successfully！')}
/>

// ❌ Error：TypeScript It will throw an error
<Button text="Test" />  // Required field is missing onClick
<Button text="Test" size="xl" onClick={fn} />  // size Outside the permitted range

// ============================================
// Example：Product Card Component（Comprehensive Application Props Various Types）
// ============================================

// Type Definitions
interface Product {
  id: number
  name: string
  price: number
  image: string
  category: string
  tags: string[]
}

interface ProductCardProps {
  product: Product
  onAddToCart: (productId: number) => void
  showDiscount?: boolean
  size?: 'small' | 'large'
}

// Component Implementation
function ProductCard({
  product,
  onAddToCart,
  showDiscount = false,
  size = 'large'
}: ProductCardProps) {
  return (
    <div style={{
      border: '1px solid #eee',
      borderRadius: '8px',
      padding: size === 'large' ? '16px' : '10px',
      width: size === 'large' ? '280px' : '200px'
    }}>
      <img
        src={product.image}
        alt={product.name}
        style={{ width: '100%', height: '150px', objectFit: 'cover' }}
      />
      <h3>{product.name}</h3>
      <p style={{ color: '#ff4d4f', fontSize: '20px', fontWeight: 'bold' }}>
        ${product.price}
        {showDiscount && <span style={{ fontSize: '12px', color: '#999', textDecoration: 'line-through', marginLeft: '8px' }}>${(product.price * 1.2).toFixed(0)}</span>}
      </p>
      <p style={{ color: '#666', fontSize: '14px' }}>{product.category}</p>
      <div>
        {product.tags.map(tag => (
          <span key={tag} style={{ background: '#f0f5ff', color: '#1890ff', padding: '2px 6px', borderRadius: '4px', margin: '0 2px', fontSize: '12px' }}>
            {tag}
          </span>
        ))}
      </div>
      <button
        onClick={() => onAddToCart(product.id)}
        style={{
          width: '100%',
          padding: '8px',
          marginTop: '10px',
          backgroundColor: '#1890ff',
          color: 'white',
          border: 'none',
          borderRadius: '4px',
          cursor: 'pointer'
        }}
      >
        Add to Cart
      </button>
    </div>
  )
}

// Using Components
const myProduct = {
  id: 101,
  name: 'Mechanical Keyboard',
  price: 299,
  image: 'https://via.placeholder.com/280x150',
  category: 'Computer Peripherals',
  tags: ['Hot Seller', 'New Products']
}

<ProductCard
  product={myProduct}
  onAddToCart={(id) => console.log('Add to Cart：', id)}
  showDiscount={true}
/>

// ============================================
// Example：Profile Card——Props Combined Use of Types and Default Values
// Features：Display string、number、boolean、object、function etc. Props Type Passing
// ============================================

function ProfileCard({
  name = 'Anonymous User',
  age = 0,
  isActive = false,
  avatar = 'https://via.placeholder.com/60',
  skills = [],
  onGreet
}) {
  return (
    <div style={{
      border: '1px solid #e8e8e8',
      borderRadius: '12px',
      padding: '20px',
      maxWidth: '320px',
      boxShadow: '0 2px 8px rgba(0,0,0,0.06)'
    }}>
      <div style={{ display: 'flex', alignItems: 'center', gap: '16px', marginBottom: '16px' }}>
        <img
          src={avatar}
          alt={name}
          style={{ width: '60px', height: '60px', borderRadius: '50%', objectFit: 'cover' }}
        />
        <div>
          <h3 style={{ margin: 0 }}>{name}</h3>
          <p style={{ margin: '4px 0 0 0', color: '#666', fontSize: '14px' }}>
            {age} years old · {isActive ? '🟢 Online' : '🔴 Offline'}
          </p>
        </div>
      </div>

      {skills.length > 0 && (
        <div style={{ marginBottom: '12px' }}>
          <p style={{ margin: '0 0 8px 0', fontWeight: 'bold', fontSize: '14px' }}>Skills：</p>
          <div style={{ display: 'flex', flexWrap: 'wrap', gap: '6px' }}>
            {skills.map((skill, index) => (
              <span key={index} style={{
                backgroundColor: '#f0f5ff',
                color: '#1890ff',
                padding: '4px 10px',
                borderRadius: '12px',
                fontSize: '12px'
              }}>
                {skill}
              </span>
            ))}
          </div>
        </div>
      )}

      {onGreet && (
        <button
          onClick={() => onGreet(name)}
          style={{
            width: '100%',
            padding: '8px',
            backgroundColor: '#1890ff',
            color: 'white',
            border: 'none',
            borderRadius: '6px',
            cursor: 'pointer',
            fontSize: '14px'
          }}
        >
          Say hello to {name}
        </button>
      )}
    </div>
  )
}

// Usage：Pass all parameters
<ProfileCard
  name="Alice"
  age={28}
  isActive={true}
  avatar="https://i.pravatar.cc/60"
  skills={['React', 'TypeScript', 'Node.js']}
  onGreet={(name) => alert(`Hello，${name}！`)}
/>

// Usage：Pass only some parameters（Use the default values for the rest）
<ProfileCard
  name="Bob"
  skills={['Vue', 'Python']}
/>

// Usage：Do not pass any parameters（Use all default values）
<ProfileCard />

function AddToCartButton({ productName, onAdd }) {
  const [adding, setAdding] = useState(false)

  async function handleClick() {
    setAdding(true)
    await onAdd(productName)
    setAdding(false)
  }

  return (
    <button onClick={handleClick} disabled={adding}
      style={{ padding: '8px 16px', cursor: adding ? 'wait' : 'pointer' }}>
      {adding ? 'Adding...' : `Add ${productName}`}
    </button>
  )
}

function ProductPage() {
  const [cart, setCart] = useState([])

  function handleAdd(name) {
    setCart(prev => [...prev, name])
  }

  return (
    <div>
      <h2>Products</h2>
      <AddToCartButton productName="Keyboard" onAdd={handleAdd} />
      <AddToCartButton productName="Mouse" onAdd={handleAdd} />
      <p>Cart: {cart.join(', ') || 'empty'}</p>
    </div>
  )
}

function StatusMessage({ status }) {
  const config = {
    loading: { icon: '⏳', color: '#1890ff', text: 'Loading...' },
    success: { icon: '✅', color: '#52c41a', text: 'Success!' },
    error:   { icon: '❌', color: '#ff4d4f', text: 'Error occurred' },
    empty:   { icon: '📭', color: '#999', text: 'No data' },
  }
  const { icon, color, text } = config[status] || config.empty

  return (
    <div style={{ padding: 16, textAlign: 'center', color }}>
      <span style={{ fontSize: 32 }}>{icon}</span>
      <p>{text}</p>
    </div>
  )
}

function DataViewer() {
  const [status, setStatus] = useState('loading')
  return (
    <div style={{ maxWidth: 300, margin: '0 auto' }}>
      <StatusMessage status={status} />
      <div style={{ display: 'flex', gap: 4 }}>
        {['loading', 'success', 'error', 'empty'].map(s => (
          <button key={s} onClick={() => setStatus(s)}
            style={{ padding: '4px 8px', cursor: 'pointer', fontSize: 12 }}>
            {s}
          </button>
        ))}
      </div>
    </div>
  )
}

function DataList({ items, renderItem, keyExtractor, emptyMessage = 'No items' }) {
  if (!items || items.length === 0) {
    return <p style={{ color: '#999', textAlign: 'center', padding: 20 }}>{emptyMessage}</p>
  }

  return (
    <ul style={{ listStyle: 'none', padding: 0 }}>
      {items.map(item => (
        <li key={keyExtractor(item)} style={{ borderBottom: '1px solid #f0f0f0', padding: 8 }}>
          {renderItem(item)}
        </li>
      ))}
    </ul>
  )
}

function App() {
  const users = [
    { id: 1, name: 'Alice', email: 'alice@example.com', active: true },
    { id: 2, name: 'Bob', email: 'bob@example.com', active: false },
    { id: 3, name: 'Charlie', email: 'charlie@example.com', active: true },
  ]

  const products = [
    { id: 'a', name: 'Keyboard', price: 79 },
    { id: 'b', name: 'Monitor', price: 399 },
  ]

  return (
    <div style={{ maxWidth: 400, margin: '0 auto' }}>
      <h3>Users</h3>
      <DataList
        items={users}
        keyExtractor={u => u.id}
        renderItem={u => (
          <div style={{ display: 'flex', justifyContent: 'space-between' }}>
            <span>{u.name} ({u.email})</span>
            <span style={{ color: u.active ? '#52c41a' : '#999' }}>
              {u.active ? 'Active' : 'Inactive'}
            </span>
          </div>
        )}
      />
      <h3>Products</h3>
      <DataList
        items={products}
        keyExtractor={p => p.id}
        emptyMessage="No products available"
        renderItem={p => (
          <span>{p.name} - ${p.price}</span>
        )}
      />
    </div>
  )
}