class Animal {
  constructor(name) {
    this.name = name
  }

  speak() {
    console.log(`${this.name} 发出声音`)
  }
}

class Dog extends Animal {
  constructor(name, breed) {
    super(name) // 调用父类构造函数
    this.breed = breed
  }

  speak() {
    console.log(`${this.name} 汪汪叫`)
  }
}

const dog = new Dog('旺财', '柴犬')
dog.speak() // 旺财 汪汪叫

class Parent {}
class Child extends Parent {}

// 原型链关系
Child.prototype.__proto__ === Parent.prototype // true
Child.__proto__ === Parent // true

// instanceof 检查
const child = new Child()
child instanceof Child // true
child instanceof Parent // true

class Animal {
  constructor(name) {
    this.name = name
  }
}

class Dog extends Animal {
  constructor(name, age) {
    // super() 必须在使用 this 之前调用
    super(name)
    this.age = age
  }
}

class Animal {
  speak() {
    return '动物的声音'
  }
}

class Dog extends Animal {
  speak() {
    // super.speak() 调用父类方法
    return super.speak() + '，汪汪汪'
  }
}

new Dog().speak() // '动物的声音，汪汪汪'

class Animal {
  static getType() {
    return '动物'
  }
}

class Dog extends Animal {
  static getType() {
    return super.getType() + ' - 狗'
  }
}

Dog.getType() // '动物 - 狗'

class Shape {
  getArea() {
    return 0
  }
}

class Rectangle extends Shape {
  constructor(width, height) {
    super()
    this.width = width
    this.height = height
  }

  getArea() {
    return this.width * this.height
  }
}

class Logger {
  log(message) {
    console.log(`[LOG] ${message}`)
  }
}

class TimestampLogger extends Logger {
  log(message) {
    const timestamp = new Date().toISOString()
    super.log(`${timestamp} - ${message}`)
  }
}

new TimestampLogger().log('Hello')
// [LOG] 2024-01-01T00:00:00.000Z - Hello

class Cache {
  get(key) {
    return this.data[key]
  }
}

class ExpiringCache extends Cache {
  get(key) {
    const item = super.get(key)
    if (item && item.expiry < Date.now()) {
      delete this.data[key]
      return undefined
    }
    return item?.value
  }
}

class MyArray extends Array {
  // 获取第一个元素
  first() {
    return this[0]
  }

  // 获取最后一个元素
  last() {
    return this[this.length - 1]
  }

  // 求和
  sum() {
    return this.reduce((a, b) => a + b, 0)
  }
}

const arr = new MyArray(1, 2, 3, 4, 5)
arr.first() // 1
arr.last() // 5
arr.sum() // 15

// 继承的方法返回的仍是 MyArray 实例
arr.map((x) => x * 2) instanceof MyArray // true

class ValidationError extends Error {
  constructor(message, field) {
    super(message)
    this.name = 'ValidationError'
    this.field = field

    // 修复原型链（某些环境需要）
    Object.setPrototypeOf(this, ValidationError.prototype)
  }
}

class NetworkError extends Error {
  constructor(message, status) {
    super(message)
    this.name = 'NetworkError'
    this.status = status
    Object.setPrototypeOf(this, NetworkError.prototype)
  }
}

try {
  throw new ValidationError('邮箱格式错误', 'email')
} catch (error) {
  if (error instanceof ValidationError) {
    console.log(`字段 ${error.field}: ${error.message}`)
  }
}

class ObservableMap extends Map {
  #listeners = new Set()

  set(key, value) {
    const oldValue = this.get(key)
    super.set(key, value)
    this.#notify('set', { key, value, oldValue })
    return this
  }

  delete(key) {
    const value = this.get(key)
    const result = super.delete(key)
    if (result) {
      this.#notify('delete', { key, value })
    }
    return result
  }

  subscribe(listener) {
    this.#listeners.add(listener)
    return () => this.#listeners.delete(listener)
  }

  #notify(type, data) {
    this.#listeners.forEach((listener) => listener(type, data))
  }
}

const map = new ObservableMap()
map.subscribe((type, data) => {
  console.log(`${type}:`, data)
})

map.set('name', '张三') // set: { key: 'name', value: '张三', oldValue: undefined }

class Shape {
  getArea() {
    throw new Error('子类必须实现 getArea 方法')
  }

  getInfo() {
    return `面积: ${this.getArea()}`
  }
}

class Circle extends Shape {
  constructor(radius) {
    super()
    this.radius = radius
  }

  getArea() {
    return Math.PI * this.radius ** 2
  }
}

class Rectangle extends Shape {
  constructor(width, height) {
    super()
    this.width = width
    this.height = height
  }

  getArea() {
    return this.width * this.height
  }
}

// 多态使用
function printArea(shape) {
  console.log(shape.getInfo())
}

printArea(new Circle(5)) // 面积: 78.54...
printArea(new Rectangle(4, 6)) // 面积: 24

class DataProcessor {
  // 模板方法
  process(data) {
    const validated = this.validate(data)
    const transformed = this.transform(validated)
    return this.output(transformed)
  }

  // 子类可重写的钩子方法
  validate(data) {
    return data
  }

  transform(data) {
    throw new Error('子类必须实现 transform 方法')
  }

  output(data) {
    return data
  }
}

class JSONProcessor extends DataProcessor {
  transform(data) {
    return JSON.parse(data)
  }

  output(data) {
    return { success: true, data }
  }
}

class CSVProcessor extends DataProcessor {
  transform(data) {
    return data.split('\n').map((line) => line.split(','))
  }
}

class AbstractAnimal {
  constructor() {
    if (new.target === AbstractAnimal) {
      throw new Error('AbstractAnimal 不能被直接实例化')
    }
  }

  // 抽象方法
  speak() {
    throw new Error('子类必须实现 speak 方法')
  }

  // 具体方法
  sleep() {
    console.log('睡觉...')
  }
}

class Dog extends AbstractAnimal {
  speak() {
    console.log('汪汪汪')
  }
}

// new AbstractAnimal(); // Error: AbstractAnimal 不能被直接实例化
new Dog().speak() // 汪汪汪

class Parent {
  #secret = '私密信息'

  getSecret() {
    return this.#secret
  }
}

class Child extends Parent {
  revealSecret() {
    // return this.#secret; // SyntaxError: 私有字段在子类中不可访问
    return this.getSecret() // 可以通过父类方法访问
  }
}

new Child().revealSecret() // '私密信息'

const _protected = Symbol('protected')

class Parent {
  constructor() {
    this[_protected] = '受保护的值'
  }

  getProtected() {
    return this[_protected]
  }
}

class Child extends Parent {
  useProtected() {
    // 子类可以访问 Symbol 属性
    return this[_protected]
  }
}

new Child().useProtected() // '受保护的值'

// 继承导致紧耦合
class Bird {
  fly() {
    console.log('飞行中')
  }
}

class Penguin extends Bird {
  // 企鹅不会飞，但继承了 fly 方法
  fly() {
    throw new Error('企鹅不会飞')
  }
}

// 使用组合
const canFly = {
  fly() {
    console.log(`${this.name} 飞行中`)
  },
}

const canSwim = {
  swim() {
    console.log(`${this.name} 游泳中`)
  },
}

const canWalk = {
  walk() {
    console.log(`${this.name} 行走中`)
  },
}

class Animal {
  constructor(name) {
    this.name = name
  }
}

// 鸟类：会飞会走
class Bird extends Animal {}
Object.assign(Bird.prototype, canFly, canWalk)

// 企鹅：会游泳会走
class Penguin extends Animal {}
Object.assign(Penguin.prototype, canSwim, canWalk)

// 鸭子：会飞会游泳会走
class Duck extends Animal {}
Object.assign(Duck.prototype, canFly, canSwim, canWalk)

class PaymentProcessor {
  constructor(strategy) {
    this.strategy = strategy
  }

  process(amount) {
    return this.strategy.process(amount)
  }
}

const creditCardStrategy = {
  process(amount) {
    console.log(`信用卡支付 ${amount} 元`)
    return { success: true, method: 'creditCard' }
  },
}

const wechatStrategy = {
  process(amount) {
    console.log(`微信支付 ${amount} 元`)
    return { success: true, method: 'wechat' }
  },
}

const alipayStrategy = {
  process(amount) {
    console.log(`支付宝支付 ${amount} 元`)
    return { success: true, method: 'alipay' }
  },
}

// 使用
const processor = new PaymentProcessor(wechatStrategy)
processor.process(100)

class Parent {}
class Child extends Parent {}

Object.getPrototypeOf(Child.prototype) === Parent.prototype // true
Object.getPrototypeOf(Child) === Parent // true