// 类型断言
const getLength = (target: (string | number)): number => {
  /* 
  在这个if里面我们知道target就是string类型而不是number,但是ts编译器不知道
  所以, 需要类型断言告诉编译器这里的target是string类型的
  */
  if ((<string>target).length || (target as string).length === 0) {
    return (<string>target).length
  } else {
    return target.toString().length
  }
}

getLength(123)

// 没有参数的情况
let s1 = Symbol();
let s2 = Symbol();

s1 === s2 // false

// 有参数的情况
let s1 = Symbol('foo');
let s2 = Symbol('foo');

s1 === s2 // false

let sym = Symbol('My symbol');

"your symbol is " + sym
// TypeError: can't convert symbol to string
1 + sym
// TypeError

String(sym) // 'Symbol(My symbol)'
sym.toString() // 'Symbol(My symbol)'

Boolean(sym) // true
!sym  // false

// 使用接口限制属性类型
interface NameInterface {
  firstName: string,
  lastName: string
}

// 限制对象作为参数传递时属性的类型
function getFullname({firstName, lastName}: NameInterface): string {
  return `${firstName}·${lastName}`
}

console.log(getFullname({
  firstName: "Samuel",
  lastName: 'Sue'
}))

// 对于可选参数接口
interface VegetableInterface {
  color?: string, // 可以有color也可以没有
  type: string
}

function VegInfo({color, type}: VegetableInterface): string {
  return `${color || ''}${type}`
}

console.log(VegInfo({type: 'Onion'}))

enum Gender {
  Female,
  Male,
}

// 对于多余属性
interface PersonInfo {
  name: string,
  age: number,
  gender: Gender,

  // 多余属性解决方法1, 定义其他属性
  [props: string]: any
}

function logPerson({name, age, gender}: PersonInfo): void {
  console.log(`Person：${name},${age} years old,${gender}`)
}

logPerson({
  name: 'Samuel',
  age: 25,
  gender: Gender.Male,
  hobby:'Basketball' // 可以传递多余属性
})

// ==========================================
logPerson(({
  name: 'Samuel',
  age: 25,
  gender: Gender.Male,
  hobby:'Basketball' // 可以传递多余属性
}as PersonInfo)) // 多余属性解决方法2,类型断言
// ===========================================
// 多余属性解决方法3 类型兼容性
const person = {
  name: 'Samuel',
  age: 25,
  gender: Gender.Male,
  hobby:'Basketball' // 可以传递多余属性
}
logPerson(person)

interface Role{
    [prop:string]:number,  // 这就规定了Role接口描述的对象的所有属性的值都必须是number
    // name: string,   // 这就报错了，因为name属性的值是string类型的，没法赋值给number类型.
}

// 只读属性
interface ArrInterface {
  0: number, // 0位置只能是number
  readonly 1: string  // 1位置只读，不可改
}

const arr:ArrInterface = [123,'hahah']
// arr[1] = 'good' // Cannot assign to '1' because it is a read-only property.

// 属性名如果是number类型，会自动转换成string
interface RoleDict {
  [id:string]:number
}

const role:RoleDict = {
  12:123,  // 12实际上是转换成了string
  // '12':234  // 报 属性重复 的错误
}
console.log(role['12'])

// 接口继承
interface Tomato extends VegetableInterface{
  radius: number
}

// 计数器函数接口
interface CounterInterface {
  (): void,  // 函数类型属性, 参数为空，无返回值
  counter: number
}

const countFn = ():CounterInterface => {
  const fn = function () {
    fn.counter++
  }
  fn.counter = 0
  return fn
}

const countFunc:CounterInterface = countFn()
countFunc()
console.log(countFunc.counter)
countFunc()
console.log(countFunc.counter)

// 接口来定义函数类型(lint推荐使用类型别名来定义)
interface AddFnInterface {
  (x: number,y: number):number  // 函数类型属性
}
// 类型别名定义函数类型
type Add = (x: number, y: number) => number
const addFunc: Add = (x: number, y: number) => x + y

// 函数可选参数，默认参数
type AddFnType = (x: number, y?: number) => number
const fn2: AddFnType = (x = 3, y) => x + (y || 0)

// 剩余参数
type SumFnType = (...args: number[]) => number
const fn3: SumFnType = (...args) => args.reduce((previousValue, currentValue) => previousValue + currentValue, 0)
console.log(fn3(1, 2, 3, 4, 5, 6))

// 函数重载(ts的重载只是用于代码提示,不是真正意义上的重载)
function splitChar(x: number): string[]
function splitChar(x: string): string[]
function splitChar(x: any): any {  // 前两个是方法声明(支持重载类型), 这里才是方法实体(必须这么写)
  if (typeof x === 'string') {
    return x.split('')
  } else {
    return (x as number).toString().split('')
  }
}

console.log(splitChar(123456))
console.log(splitChar('我是爸爸'))

// (函数)变量类型泛型
const genArr = <T>(val: T, times: number): T[] => {
  return new Array(times).fill(val)
}

// 函数类型别名泛型
type GenArr = <T>(val: T, times: number) => T[]
const genFn: GenArr = (val, times) => {
  return new Array(times).fill(val)
}

// genArr(123,3).map(item=>item.length) // Property 'length' does not exist on type 'number'.
genArr(123,3).map(item=>item.toFixed())
console.log(genArr('爸爸',3).map(item=>item.split('')))  // 根据val类型, 可以提示响应类型的方法

// 泛型约束, 假如只允许带length属性的类型传入
interface WithLength {
  length: number
}
const genFn2 = <T extends WithLength>(val: T, times: number): T[] => {
  return new Array(times).fill(val)
}
genFn2([1,2,3],2)
genFn2('爸爸',2)
// genFn2(123,2) //Argument of type '123' is not assignable to parameter of type 'WithLength

interface WithLength {
    length: number
}

// 这里T extends WithLength, 理解上就是泛型类型T=WithLength(type T = WithLength)
const genFn2 = <T extends WithLength>(val: T, times: number): T[] => {
  return new Array(times).fill(val)
}

interface Person{
    name: string;
    age: number;
    gender: string;
}

class Teacher{
    constructor(private info:Person){}
    /*
    keyof Person就是:'name','age','gender',
    T extends 'name':等价与 type T = 'name'
    ...
    T类型就是属性名的联合类型。
    所以这里参数key就是属性名。 Person[T]就是属性值类型
    */
    getInfo<T extends keyof Person>(key: T):Person[T] {
        return this.info[T];
    }
}
// keyof Person 其返回类型是联合类
// type K1 = keyof Person;
// "name" | "age" | "gender"
// type K2 = keyof Person[]; 
// number | "length" | "push" | "concat" | ...
// type K3 = keyof { [x: string]: Person };  
// string | number

// keyof 操作符除了支持接口和类之外，它也支持基本数据类型：  
// let K1: keyof boolean; 
// let K1: "valueOf"
// let K2: keyof number; 
// let K2: "toString" | "toFixed" | "toExponential" | ...
// let K3: keyof symbol; 
// let K1: "valueOf"

const teacher = new Teacher({
  name: 'sssssss',
  age: 18,
  gender: 'male'
})

const test = teacher.getInfo('age');
console.log(test);

const COLORS = {
  red: 'red',
  blue: 'blue'
}

// 首先通过typeof操作符获取color变量的类型，然后通过keyof操作符获取该类型的所有键，
// 即字符串字面量联合类型 'red' | 'blue'

type Colors = typeof COLORS 
let color: Colors;
color = 'red' 	// Ok
color = 'blue' 	// Ok

// Type '"yellow"' is not assignable to type '"red" | "blue"'.
color = 'yellow' // Error

// 泛型约束, 只允许访问对象存在的属性
function showProp<T, K extends keyof T>(obj: T, prop: K) {
  return obj[prop]
}

const person1 = {
  name: 'Samuel',
  age: 26,
  gender: 'Male'
}
console.log(showProp(person1,"age"))
// console.log(showProp(person1,"addr")) //Argument of type '"addr"' is not assignable to parameter of type '"age" | "name" | "gender"'.

class Parent {
  protected x: number

  // 构造方法声明protect, 只能在派生类中被super执行
  protected constructor(x: number) {
    this.x = x
  }

  protected getX() {
    return this.x
  }
}

class Child extends Parent {
  constructor(x: number) {
    super(x);  //
  }

  getX(): number {
    // console.log(super.x) //子类内部只能通过super访问父类的protect方法，不能访问protect属性
    return super.getX();
  }
}

// const p = new Parent(123)
const ch = new Child(234)
console.log(ch.getX())

// 只读属性
class ReadOnlyInfo {
  public readonly info: string

  constructor(info: string) {
    this.info = info
  }
}

const rInfo = new ReadOnlyInfo('只能读，不能改')
// rInfo.info = '改一个试试' // Cannot assign to 'info' because it is a read-only property.
console.log(rInfo)

// 参数修饰符(简写)
class A {
  constructor(private name: string) {
    // 使用参数修饰符可以自动帮你把参数绑定到this上
  }
}

const a = new A('Samuel')
console.log(a)  // {name:'Samuel'}

// 静态成员属性
class B {
  public static readonly pi = 3.1415926
  private static num = 2333
}

console.log(B.pi)
// B.pi = 3.14
// console.log(B.num)

// 可选属性/可选参数  set/get
class Human {
  private _name: string
  public age?: number

  constructor(name: string, age?: number, public gender?: string) {
    this._name = name
    this.age = age
  }

  public set name(newVal: string) {
    this._name = newVal
  }

  public get name() {
    return this._name.replace(/./, substring => substring.toUpperCase())
  }
}

const h = new Human("samuel")
h.name = 'zhangboy'
console.log(h.name)

// 抽象类
abstract class MyFile {
  protected constructor(public size: number) {
  }

  public abstract save(): void // 抽象函数,没有函数体
}


class MediaFile extends MyFile {
  constructor(public size: number, public type: string) {
    super(size) // 必须执行父类(抽象类)构造函数
  }

  save(): void {
    console.log('save media file')
  }

  play(): void {
    console.log('play media File')
  }
}

// 类实现接口
interface player {
  supportType: string[],
  play: () => void
}

class MusicPlayer implements player {
  play(): void {
    console.log('play music')
  }

  supportType: string[];

  constructor(...types: string[]) {
    this.supportType = types
  }
}

const player = new MusicPlayer('mp3', 'wav', 'wma', 'acc')
player.play()

// 接口继承类
class Point {
  protected x: number; // 因为是protect，因此只能在内部或者派生类中初始化
  protected y: number;

  protected constructor(x: number, y: number) {
    this.x = x
    this.y = y
  }
}

interface Point3d extends Point {
  z: number;
}

// 因为要初始化protected x,y 所以要继承类
class AcPoint extends Point implements Point3d {
  z: number;

  constructor(x: number, y: number, z: number) {
    super(x, y)
    this.z = 312
  }
}

/*
假如我们要限制参数是一个具体类的构造函数，此时就需要使用类类型
*/
class TestE {
  public info: string

  constructor() {
    console.log('constructor exec')
    this.info = 'hhh'
  }
}

// c的类型是对象类型且这个对象包含返回类型是T的构造函数。
// 理解c是一个对象(构造函数),执行new之后返回一个类型为T的对象
const testFn1 = <T>(c: new() => T): T => {
  return new c()
}

testFn1(TestE)

const f = 400

enum Code {
  OK,
  Fault = f, // 可以用const或者函数返回值来编号
  Error = 3, // 紧接着的一个枚举值要手动编号
  Success
}

console.log(Code[400]) // 可以通过编号获取枚举值

// 字符串枚举
enum reply {
  Error = 'Sorry, an error has occurred',
  Success = 'No problem',
  Failed = Error,  // 可以引用枚举
}

// 异构枚举, 枚举值类型不同(不推荐)
enum XX {
  a = 1,
  b = 'hehe',
}

// 枚举成员类型
enum ShapeKind {
  Circle,
  Square
}
interface Circle {
  kind: ShapeKind.Circle // 使用 ShapeKind.Circle 作为类型，指定接口须有 kind 字段，且类型为 ShapeKind.Circle
  radius: number
}
let c: Circle = {
  kind: ShapeKind.Square, // Error! 因为接口 Circle 的 kind 被指定为 ShapeKind.Circle类型，所以这里会报错
  radius: 100
}

// 联合枚举
enum Status {
  on,
  off
}
interface Light {
  status: Status // 只能是Status中的枚举值
}
const light:Light = {
  status: Status.off,
}

// const enum
const enum Animal{
  Dog,
  Cat,
  GoldFish
}

const kitty = Animal.Cat  // 编译后是kitty=1, 不会产生Animal对象

// 断言为number
let a = 1;
// 断言为number[]
let b = [1,2]

// 类型兼容
let fn1 = (x: string, y: string): void => {
  console.log(11)
}
let fn12 = (x: string): void => {
  console.log(22)
}

// fn12 = fn1  // 函数，只能参数多的兼容少的
fn1 = fn12

interface Aitf {
  name:string
}
interface Bitf {
  name:string,
  age:number
}
let aObj : Aitf = {name:'Samuel'}
let bObj : Bitf = {name:'Samuel',age:25}
// bObj = aObj  // 结构数据，只能成员少的兼容多的
aObj = bObj

// 重载类型兼容
function shk(x: number, y: number): number
function shk(x: string, y: string): string
function shk(x: any, y: any): any {
  return x + y
}

function shl(x: number, y: number): number
function shl(x: any, y: any): any {
  return x + y
}

let fna = shl
fna = shk  // 重载类型少的兼容多的

// 类兼容性
class AC{
  // public static num = 3.14  // 静态成员不参与兼容性检测
  protected num:number
  private age:number
  constructor(public name:string,age:number) {
    this.num = 13
    this.age = age
  }
}

class ACsub extends AC{
  constructor(public name:string,age:number) {
    super(name,age);
    this.num = 15
  }
}

class BC{
  constructor(public name:string) {
  }
}

let ax:BC = new BC('name')  // 结构成员
ax = new AC('hh',17)   // 少的兼容多的
ax = new ACsub('hh',25)  // protected以及private成员必须保证来自同一个类

console.log(ax)

const mergeObj = <T, U>(a: T, b: U): T & U => {
  let res = {} as T & U  // 类型断言
  res = Object.assign(a, b)
  return res
}

const showRes = (): string | number => {
  const arr = ['Samuel', 123]
  return Math.random() > .5 ? arr[0] : arr[1]
}

interface Bird {
  fly():void
  layEggs():void
}
interface Turtle {
  swim():void
  layEggs():void
}

function getSmallPet ():Bird|Turtle {
  return {} as Bird|Turtle
}

getSmallPet().layEggs() // 返回的联合类型只能访问其类型的共有属性
// getSmallPet().swim()  // 各自的非共有属性无法访问

function isString(x: string | number): x is string {
  return typeof x === 'string'
}

const res1 = showRes() // 联合类型 string | number
if (isString(res1)) {
  console.log('string length:', res1.length)
} else {
  console.log('number:', res1.toFixed())
}

// 对于简单的类型保护，可以直接使用typeof(只能做===或!==判断)
if (typeof res1 === 'string') {
  console.log('string length:', res1.length)
} else {
  console.log('number:', res1.toFixed())
}

class Axx {
  public age = 13
}

class Bxx {
  public name = 'Sam'
}

function getRandomAB() {
  return Math.random() > .5 ? new Axx() : new Bxx()
}

const rsAB = getRandomAB()
if (rsAB instanceof Axx) {
  console.log(rsAB.age)
} else {
  console.log(rsAB.name)
}

function getPrefixStr(x:number|null) {
  function addPrefix(prefix:string):string {
    // 因为下面已经对null情况进行排除,这里使用'!'类型断言x不为null/undefined
    return prefix + x!.toFixed().toString()
  }
  x = x || 0.1
  return addPrefix('pr')
}

type Container<T> = { value: T };

type Tree<T> = {
    value: T;
    left: Tree<T>;
    right: Tree<T>;
}

type LinkedList<T> = T & { next: LinkedList<T> };

interface Person {
    name: string;
}

var people: LinkedList<Person>;
var s = people.name;
var s = people.next.name;
var s = people.next.next.name;
var s = people.next.next.next.name;

abstract class AbsC{
  protected name:string
  protected constructor() {
    this.name = 'Samuel'
  }
}

type absc = AbsC // 不能Extends
class CCC extends AbsC{
  constructor() {
    super();
  }
}

// 字符串字面量类型
type Direction = 'east'|'west'|'south'|'north'
const DirFn = (direc:Direction) => {
  console.log(direc)
}
DirFn('west')
// DirFn('hollyshit') // Argument of type '"hollyshit"' is not assignable to parameter of type 'Direction'.

// 同理还有数字字面量类型

interface Square {
    kind: "square";
    size: number;
}
interface Rectangle {
    kind: "rectangle";
    width: number;
    height: number;
}
interface Circle {
    kind: "circle";
    radius: number;
}

type Shape = Square | Rectangle | Circle; // 声明为联合类型

function area(s: Shape) {
    // 类型保护
    switch (s.kind) {
        case "square": return s.size * s.size;
        case "rectangle": return s.height * s.width;
        case "circle": return Math.PI * s.radius ** 2;
    }
}

interface ACtp2 {
  name: string,
  age: number
}

let k: keyof ACtp2  // 返回索引属性名构成的联合类型  "name" | "age"

// --------------------------------------------------- T[K]是索引访问操作符
function pluck<T, K extends keyof T>(o: T, names: K[]): T[K][] {
  return names.map(n => o[n]);
}

interface Person {
    name: string;
    age: number;
}
let person: Person = {
    name: 'Jarid',
    age: 35
};
let strings: string[] = pluck(person, ['name']); // ok, string[]

// [] 取出接口类型
interface Types {
  a: number,
  b: string,
  c: boolean,
}

type AllTypes = Types[keyof Types]  // number | string | boolean

type ReadOnlyTypes<T> = {
  readonly [P in keyof T]: T[P]  // in 表示遍历
}

// 显示添加/删除修饰符
type RemoveReadonly<K> = {
  -readonly [P in keyof K]: K[P] // - 表示删除修饰符,可以是readonly,?(可选修饰符）
}

type noReadOnlyTypes = RemoveReadonly<readTypess>

type Typs<T> = T extends string ? string : number
let vals2: Typs<'2'>  // let vals2: string
let vals3: Typs<false>  // let vals3: number  走后面的逻辑

type onlyString<T> = (T extends string ? T : never)
type someTypes = 'a' | 'b' | 123 | false
type resultTypes = onlyString<someTypes>  // Initial type: "a" | "b"

type reserveFunction<T> = {
  [P in keyof T]: T[P] extends () => void ? P : never  // 取出所有是函数类型的属性P, 其他为never
}[keyof T] // 索引属性来去掉never类型属性
/*
不加这个索引属性，下面的Res2会变成:
type Res2 = {
user: never;
code: never;     
subparts: never;     
updateTime: "updateTime";     
thankU: "thankU"; }
*/

interface Part {
  user: 'Sam',
  code: 132,
  subparts: Part[]
  updateTime:()=>void,
  thankU(): void
}

type Res2 = reserveFunction<Part>
const obj2: Res2 = 'updateTime'

// 推断元素类型
type Type2<T> = T extends any[] ? T[number] : T // 如果T是一个数组, 那就取T元素的类型(当元素类型不一样时是联合类型)
type typesX = Type2<string[]>  // Initial type:string
type typesX2 = Type2<boolean[]>  // Initial type:boolean

// infer 推断元素类型
type Type3<T> = T extends Array<infer U> ? U : T
type typesY = Type3<string[]>  // Initial type:string
type typesY2 = Type3<boolean[]>  // Initial type:boolean
type typesY3 = Type3<[false,123,'sam']>  // Initial type:false | 123 | "sam"

// T是一个函数类型(参数:any)返回值any, infer P推断参数类型
type Parameters<T extends (...args: any) => any> = T extends (...args: infer P) => any ? P : never;

// T是一个构造函数类型
type ConstructorParameters<T extends new(...arg: any) => any> = T extends new(...arg: infer P) => any ? P : never

// components.ts
namespace Components{
    // 导出需要暴露的内容
    export class Header {
        constructor() {
            const elem = document.createElment('div');
            elem.innerText = 'this is header';
            document.body.appendChild(elem);
        }
    }
    export class Content{}
    export class Footer{}
    // 可以暴露接口
    export interface User{
        name:string
    }
    // 可以暴露命名空间
    export namespace Sub{
        export class Test{}
    }
}