// JavaScript

// f1 이라는 함수의 body 에서는 a 를 사용할 것 입니다.
// a 가 할 수 있는 일은 a 의 타입이 결정합니다.

function f1(a) {
  return a;
}

// JavaScript

// (f2 실행의 결과가 NaN 을 의도한 것이 아니라면)
// 이 함수의 작성자는 매개변수 a 가 number 타입이라는 가정으로 함수를 작성했습니다.

function f2(a) {
  return a * 38;
}

// 사용자는 사용법을 숙지하지 않은 채, 문자열을 사용하여 함수를 실행했습니다.

console.log(f2(10)); // 380
console.log(f2('Mark')); // NaN

// 타입스크립트 코드지만,
// a 의 타입을 명시적으로 지정하지 않은 경우이가 때문에 a 는 any 로 추론됩니다.
// 함수의 리턴 타입은 number 로 추론됩니다. (NaN 도 number 의 하나입니다.)

function f3(a) {
  return a * 38;
}

// 사용자는 a 가 any 이기 때문에, 사용법에 맞게 문자열을 사용하여 함수를 실행했습니다.

console.log(f3(10)); // 380
console.log(f3('Mark') + 5); // NaN

// error TS7006: Parameter 'a' implicitly has an 'any' type.

function f3(a) {
  return a * 38;
}

// 사용자의 코드를 실행할 수 없습니다. 컴파일이 정상적으로 마무리 될 수 있도록 수정해야 합니다.

console.log(f3(10));
console.log(f3('Mark') + 5);

// 매개변수의 타입은 명시적으로 지정했습니다.
// 명시적으로 지정하지 않은 함수의 리턴 타입은 number 로 추론됩니다.

function f4(a: number) {
  if (a > 0) {
    return a * 38;
  }
}

// 사용자는 사용법에 맞게 숫자형을 사용하여 함수를 실행했습니다.
// 해당 함수의 리턴 타입은 number 이기 때문에, 타입에 따르면 이어진 연산을 바로 할 수 있습니다.
// 하지만 실제 undefined + 5 가 실행되어 NaN 이 출력됩니다.

console.log(f4(5)); // 190
console.log(f4(-5) + 5); // NaN

// 매개변수의 타입은 명시적으로 지정했습니다.
// 명시적으로 지정하지 않은 함수의 리턴 타입은 number | undefined 로 추론됩니다.

function f4(a: number) {
  if (a > 0) {
    return a * 38;
  }
}

// 사용자는 사용법에 맞게 숫자형을 사용하여 함수를 실행했습니다.
// 해당 함수의 리턴 타입은 number | undefined 이기 때문에,
// 타입에 따르면 이어진 연산을 바로 할 수 없습니다.
// 컴파일 에러를 고쳐야하기 하기 때문에 사용자와 작성자가 의논을 해야합니다.

console.log(f4(5));
console.log(f4(-5) + 5); // error TS2532: Object is possibly 'undefined'.

// 매개변수의 타입과 함수의 리턴 타입을 명시적으로 지정했습니다.
// 실제 함수 구현부의 리턴 타입과 명시적으로 지정한 타입이 일치하지 않아 컴파일 에러가 발생합니다.

// error TS2366: Function lacks ending return statement and return type does not include 'undefined'.
function f5(a: number): number {
  if (a > 0) {
    return a * 38;
  }
}

// if 가 아닌 경우 return 을 직접 하지 않고 코드가 종료된다.

// error TS7030: Not all code paths return a value.
function f5(a: number) {
  if (a > 0) {
    return a * 38;
  }
}

// JavaScript

function f6(a) {
  return `이름은 ${a.name} 이고, 연령대는 ${
    Math.floor(a.age / 10) * 10
  }대 입니다.`;
}

console.log(f6({ name: 'Mark', age: 38 })); // 이름은 Mark 이고, 연령대는 30대 입니다.
console.log(f6('Mark')); // 이름은 undefined 이고, 연령대는 NaN대 입니다.

function f7(a: { name: string; age: number }): string {
  return `이름은 ${a.name} 이고, 연령대는 ${
    Math.floor(a.age / 10) * 10
  }대 입니다.`;
}

console.log(f7({ name: 'Mark', age: 38 })); // 이름은 Mark 이고, 연령대는 30대 입니다.
console.log(f7('Mark')); // error TS2345: Argument of type 'string' is not assignable to parameter of type '{ name: string; age: number; }'.

interface PersonInterface {
  name: string;
  age: number;
}

type PersonTypeAlias = {
  name: string;
  age: number;
};

function f8(a: PersonInterface): string {
  return `이름은 ${a.name} 이고, 연령대는 ${
    Math.floor(a.age / 10) * 10
  }대 입니다.`;
}

console.log(f8({ name: 'Mark', age: 38 })); // 이름은 Mark 이고, 연령대는 30대 입니다.
console.log(f8('Mark')); // error TS2345: Argument of type 'string' is not assignable to parameter of type 'PersonInterface'.

interface IPerson {
  name: string;
  age: number;
  speak(): string;
}

type PersonType = {
  name: string;
  age: number;
  speak(): string;
};

let personInterface: IPerson = {} as any;
let personType: PersonType = {} as any;

personInterface = personType;
personType = personInterface;

type PersonID = string & { readonly brand: unique symbol };

function PersonID(id: string): PersonID {
  return id as PersonID;
}

function getPersonById(id: PersonID) {}

getPersonById(PersonID('id-aaaaaa'));
getPersonById('id-aaaaaa'); // error TS2345: Argument of type 'string' is not assignable to parameter of type 'PersonID'. Type 'string' is not assignable to type '{ readonly brand: unique symbol; }'.

// type alias
type EatType = (food: string) => void;

// interface
interface IEat {
  (food: string): void;
}

// type alias
type PersonList = string[];

// interface
interface IPersonList {
  [index: number]: string;
}

interface ErrorHandling {
  success: boolean;
  error?: { message: string };
}

interface ArtistsData {
  artists: { name: string }[];
}

// type alias
type ArtistsResponseType = ArtistsData & ErrorHandling;

// interface
interface IArtistsResponse extends ArtistsData, ErrorHandling {}

let art: ArtistsResponseType;
let iar: IArtistsResponse;

interface Bird {
  fly(): void;
  layEggs(): void;
}

interface Fish {
  swim(): void;
  layEggs(): void;
}

type PetType = Bird | Fish;

interface IPet extends PetType {} // error TS2312: An interface can only extend an object type or intersection of object types with statically known members.

class Pet implements PetType {} // error TS2422: A class can only implement an object type or intersection of object types with statically known members.

interface MergingInterface {
  a: string;
}

interface MergingInterface {
  b: string;
}

let mi: MergingInterface;
mi.

type MergingType = {
  a: string;
};

type MergingType = {
  b: string;
};

// sub1 타입은 sup1 타입의 서브 타입이다.
let sub1: 1 = 1;
let sup1: number = sub1;
sub1 = sup1; // error! Type 'number' is not assignable to type '1'.

// sub2 타입은 sup2 타입의 서브 타입이다.
let sub2: number[] = [1];
let sup2: object = sub2;
sub2 = sup2; // error! Type '{}' is missing the following properties from type 'number[]': length, pop, push, concat, and 16 more.

// sub3 타입은 sup3 타입의 서브 타입이다.
let sub3: [number, number] = [1, 2];
let sup3: number[] = sub3;
sub3 = sup3; // error! Type 'number[]' is not assignable to type '[number, number]'. Target requires 2 element(s) but source may have fewer.

// sub1 타입은 sup1 타입의 서브 타입이다.
// sup1 타입은 sub1 타입의 슈퍼 타입이다.
let sub1: 1 = 1;
let sup1: number = sub1;
sub1 = sup1; // error! Type 'number' is not assignable to type '1'.

// sub2 타입은 sup2 타입의 서브 타입이다.
// sup2 타입은 sub2 타입의 슈퍼 타입이다.
let sub2: number[] = [1];
let sup2: object = sub2;
sub2 = sup2; // error! Type '{}' is missing the following properties from type 'number[]': length, pop, push, concat, and 16 more.

// sub3 타입은 sup3 타입의 서브 타입이다.
// sup3 타입은 sub3 타입의 슈퍼 타입이다.
let sub3: [number, number] = [1, 2];
let sup3: number[] = sub3;
sub3 = sup3; // error! Type 'number[]' is not assignable to type '[number, number]'. Target requires 2 element(s) but source may have fewer.

// sub4 타입은 sup4 타입의 서브 타입이다.
let sub4: number = 1;
let sup4: any = sub4;
sub4 = sup4;

// sub5 타입은 sup5 타입의 서브 타입이다.
let sub5: never = 0 as never;
let sup5: number = sub5;
sub5 = sup5; // error! Type 'number' is not assignable to type 'never'.

class SubAnimal {}
class SubDog extends SubAnimal {
  eat() {}
}

// sub6 타입은 sup6 타입의 서브 타입이다.
let sub6: SubDog = new SubDog();
let sup6: SubAnimal = sub6;
sub6 = sup6;

// sub4 타입은 sup4 타입의 서브 타입이다.
// sup4 타입은 sub4 타입의 슈퍼 타입이다.
let sub4: number = 1;
let sup4: any = sub4;
sub4 = sup4;

// sub5 타입은 sup5 타입의 서브 타입이다.
// sup5 타입은 sub5 타입의 슈퍼 타입이다.
let sub5: never = 0 as never;
let sup5: number = sub5;
sub5 = sup5; // error! Type 'number' is not assignable to type 'never'.

class SubAnimal {}
class SubDog extends SubAnimal {
  eat() {}
}

// sub6 타입은 sup6 타입의 서브 타입이다.
// sup6 타입은 sub6 타입의 슈퍼 타입이다.
let sub6: SubDog = new SubDog();
let sup6: SubAnimal = sub6;
sub6 = sup6; // error! Property 'eat' is missing in type 'SubAnimal' but required in type 'SubDog'.

// primitive type
let sub7: string = '';
let sup7: string | number = sub7;

// object - 각각의 프로퍼티가 대응하는 프로퍼티와 같거나 서브타입이어야 한다.
let sub8: { a: string; b: number } = { a: '', b: 1 };
let sup8: { a: string | number; b: number } = sub8;

// array - object 와 마찬가지
let sub9: Array<{ a: string; b: number }> = [{ a: '', b: 1 }];
let sup9: Array<{ a: string | number; b: number }> = sub8;

class Person {}
class Developer extends Person {
  coding() {}
}
class StartupDeveloper extends Developer {
  burning() {}
}

function tellme(f: (d: Developer) => Developer) {}

// Developer => Developer 에다가 Developer => Developer 를 할당하는 경우
tellme(function dToD(d: Developer): Developer {
  return new Developer();
});

// Developer => Developer 에다가 Person => Developer 를 할당하는 경우
tellme(function pToD(d: Person): Developer {
  return new Developer();
});

// Developer => Developer 에다가 StartipDeveloper => Developer 를 할당하는 경우
tellme(function sToD(d: StartupDeveloper): Developer {
  return new Developer();
});

// 입력은 마음대로,
// 함수 구현이 자유롭게 => 자유가 항상 좋은건 아니다.
function fany(a: any): number | string | void {
  a.toString();

  if (typeof a === 'number') {
    return a * 38;
  } else if (typeof a === 'string') {
    return `Hello ${a}`;
  }
}

console.log(fany(10)); // 380
console.log(fany('Mark')); // Hello Mark
console.log(fany(true)); // undefined

// 입력은 마음대로,
// 함수 구현은 문제 없도록
function funknown(a: unknown): number | string | void {
  a.toString(); // error! Object is of type 'unknown'.

  if (typeof a === 'number') {
    return a * 38;
  } else if (typeof a === 'string') {
    return `Hello ${a}`;
  }
}

console.log(funknown(10)); // 380
console.log(funknown('Mark')); // Hello Mark
console.log(funknown(true)); // undefined

let a = 'Mark'; // string
const b = 'Mark'; // 'Mark' => literal type

let c = 38; // number
const d = 38; // 38 => literal type

let e = false; // boolean
const f = false; // false => literal type

let g = ['Mark', 'Haeun']; // string[]
const h = ['Mark', 'Haeun']; // string[]

const i = ['Mark', 'Haeun', 'Bokdang'] as const; // readonly ["Mark", "Haeun", "Bokdang"]

let j = [0, 1, null]; // (number | null)[]
const k = [0, 1, null]; // (number | null)[]

class Animal {}
class Rhino extends Animal {}
class Elephant extends Animal {}
class Snake extends Animal {}

let l = [new Rhino(), new Elephant(), new Snake()]; // (Rhino | Elephant | Snake)[]
const m = [new Rhino(), new Elephant(), new Snake()]; // (Rhino | Elephant | Snake)[]
const n = [new Animal(), new Rhino(), new Elephant(), new Snake()]; // Animal[]
const o: Animal[] = [new Rhino(), new Elephant(), new Snake()]; // Animal[]

// Parameter 'e' implicitly has an 'any' type.
const click = (e) => {
  e; // any
};

document.addEventListener('click', click);
document.addEventListener('click', (e) => {
  e; // MouseEvent
});

function getNumber(value: number | string): number {
  value; // number | string
  if (typeof value === 'number') {
    value; // number
	return value;
  }
  value; // string
  return -1;
}

interface IMachine {
  name: string;
}

class Car implements IMachine {
  name: string;
  wheel: number;
}

class Boat implements IMachine {
  name: string;
  motor: number;
}

function getWhellOrMotor(machine: Car | Boat): number {
  if (machine instanceof Car) {
    return machine.wheel; // Car
  } else {
    return machine.motor; // Boat
  }
}

class NegativeNumberError extends Error {}

function getNumber(value: number): number | NegativeNumberError {
  if (value < 0) return new NegativeNumberError();

  return value;
}

function main() {
  const num = getNumber(-10);

  if (num instanceof NegativeNumberError) {
    return;
  }

  num; // number
}

interface Admin {
  id: string;
  role: string:
}

interface User {
  id: string;
  email: string;
}

function redirect(user: Admin | User) {
  if(/*user is admin*/) {
    routeToAdminPage(usr.role);
  } else {
    routeToHomePage(usr.email);
  }
}

interface Admin {
  id: string;
  role: string:
}

interface User {
  id: string;
  email: string;
}

function redirect(user: Admin | User) {
  if("role" in user) {
    routeToAdminPage(user.role);
  } else {
    routeToHomePage(user.email);
  }
}

interface IMachine {
  type: string;
}

class Car implements IMachine {
  type: 'CAR';
  wheel: number;
}

class Boat implements IMachine {
  type: 'BOAT';
  motor: number;
}

function getWhellOrMotor(machine: Car | Boat): number {
  if (machine.type === 'CAR') {
    return machine.wheel;
  } else {
    return machine.motor;
  }
}

function getWhellOrMotor(machine: any): number {
  if (isCar(machine)) {
    return machine.wheel;
  } else if (isBoat(machine)) {
    return machine.motor;
  } else {
    return -1;
  }
}

function isCar(arg: any): arg is Car {
    return arg.type === 'CAR';
}

function isBoat(arg: any): arg is Boat {
    return arg.type === 'BOAT';
}

// v3.9.7

class Square1 {
  area; // error! implicit any
  sideLength; // error! implicit any
}

// v3.9.7

class Square2 {
  area: number;
  sideLength: number;
}

const square2 = new Square2();
console.log(square2.area); // compile time - number, runtime - undefined
console.log(square2.sideLength); // compile time - number, runtime - undefined

// v3.9.7

class Square2 {
  area: number; // error TS2564: Property 'area' has no initializer and is not definitely assigned in the constructor.
  sideLength: number; // error TS2564: Property 'sideLength' has no initializer and is not definitely assigned in the constructor.
}

// 사용자는 시도조차 할 수 없도록 만듭니다.

const square2 = new Square2();
console.log(square2.area);
console.log(square2.sideLength);

// v3.9.7

class Square3 {
  area: number = 0;
  sideLength: number = 0;
}

// v3.9.7

class Square4 {
  area: number;
  sideLength: number;

  constructor(sideLength: number) {
    this.sideLength = sideLength;
    this.area = sideLength ** 2;
  }
}

// v4.0.2

class Square5 {
  area; // 4 부터는 any 가 아니라, 생성자에 의해 추론된다.
  sideLength; // 4 부터는 any 가 아니라, 생성자에 의해 추론된다.

  constructor(sideLength: number) {
    this.sideLength = sideLength;
    this.area = sideLength ** 2;
  }
}

// v4.0.2

class Square6 {
  sideLength;

  constructor(sideLength: number) {
    if (Math.random()) {
      this.sideLength = sideLength;
    }
  }

  get area() {
    return this.sideLength ** 2; // error! Object is possibly 'undefined'.
  }
}

// v4.0.2

class Square7 {
  sideLength!: number; // ! 로 의도를 표현해야 한다.

  constructor(sideLength: number) {
    this.initialize(sideLength);
  }

  initialize(sideLength: number) {
    this.sideLength = sideLength;
  }

  get area() {
    return this.sideLength ** 2;
  }
}

interface StringContainer {
  value: string;
  format(): string;
  split(): string[];
}

interface NumberContainer {
  value: number;
  nearestPrime: number;
  round(): number;
}

type Item1<T> = {
  id: T,
  container: any;
};

const item1: Item1<string> = {
  id: "aaaaaa",
  container: null
};

type Item2<T> = {
  id: T;
  container: T extends string ? StringContainer : NumberContainer;
};

const item2: Item2<string> = {
  id: 'aaaaaa',
  container: null, // Type 'null' is not assignable to type 'StringContainer'.
};

type Item3<T> = {
  id: T extends string | number ? T : never;
  container: T extends string
    ? StringContainer
    : T extends number
    ? NumberContainer
    : never;
};

const item3: Item3<boolean> = {
  id: true, // Type 'boolean' is not assignable to type 'never'.
  container: null, // Type 'null' is not assignable to type 'never'.
};

type ArrayFilter<T> = T extends any[] ? T : never;

type StringsOrNumbers = ArrayFilter<string | number | string[] | number[]>;

// 1. string | number | string[] | number[]
// 2. never | never | string[] | number[]
// 3. string[] | number[]

interface Table {
  id: string;
  chairs: string[];
}

interface Dino {
  id: number;
  legs: number;
}

interface World {
  getItem<T extends string | number>(id: T): T extends string ? Table : Dino;
}

let world: World = null as any;

const dino = world.getItem(10);
const what = world.getItem(true); // Error! Argument of type 'boolean' is not assignable to parameter of type 'string | number'.ts(2345)

type Flatten<T> = T extends any[]
  ? T[number]
  : T extends object
  ? T[keyof T]
  : T;


const numbers = [1, 2, 3];
type NumbersArrayFlattened = Flatten<typeof numbers>;
// 1. number[]
// 2. number

const person = {
  name: 'Mark',
  age: 38
};
                             
type SomeObjectFlattened = Flatten<typeof person>;
// 1. keyof T --> "id" | "name"
// 2. T["id" | "name"] --> T["id"] | T["name"] --> number | string

const isMale = true;
type SomeBooleanFlattened = Flatten<typeof isMale>;
// true

type UnpackPromise<T> = T extends Promise<infer K>[] ? K : any;
const promises = [Promise.resolve('Mark'), Promise.resolve(38)];

type Expected = UnpackPromise<typeof promises>; // string | number

function plus1(seed: number): number {
  return seed + 1;
}

type MyReturnType<T extends (...args: any) => any> = T extends (
  ...args: any
) => infer R
  ? R
  : any;

type Id = MyReturnType<typeof plus1>;

lookupEntity(plus1(10));

function lookupEntity(id: Id) {
  // query DB for entity by ID
}

// type Exclude<T, U> = T extends U ? never : T;
type Excluded = Exclude<string | number, string>; // number - diff

// type Extract<T, U> = T extends U ? T : never;
type Extracted = Extract<string | number, string>; // string - filter

// Pick<T, Exclude<keyof T, K>>; (Mapped Type)
type Picked = Pick<{name: string, age: number}, 'name'>;

// type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;
type Omited = Omit<{name: string, age: number}, 'name'>;

// type NonNullable<T> = T extends null | undefined ? never : T;
type NonNullabled = NonNullable<string | number | null | undefined>;

/*
type ReturnType<T extends (...args: any) => any> = T extends (
  ...args: any
) => infer R
  ? R
  : any;
*/

/*
type Parameters<T extends (...args: any) => any> = T extends (
  ...args: infer P
) => any
  ? P
  : never;
*/
type MyParameters = Parameters<(name: string, age: number) => void>; // [name: string, age: number]

interface Constructor {
  new (name: string, age: number): string;
}

/*
type ConstructorParameters<
  T extends new (...args: any) => any
> = T extends new (...args: infer P) => any ? P : never;
*/

type MyConstructorParameters = ConstructorParameters<Constructor>; // [name: string, age: number]

/*
type InstanceType<T extends new (...args: any) => any> = T extends new (
  ...args: any
) => infer R
  ? R
  : any;
*/

type MyInstanceType = InstanceType<Constructor>; // string

type FunctionPropertyNames<T> = {
  [K in keyof T]: T[K] extends Function ? K : never;
}[keyof T];
type FunctionProperties<T> = Pick<T, FunctionPropertyNames<T>>;

type NonFunctionPropertyNames<T> = {
  [K in keyof T]: T[K] extends Function ? never : K;
}[keyof T];
type NonFunctionProperties<T> = Pick<T, NonFunctionPropertyNames<T>>;

interface Person {
  id: number;
  name: string;
  hello(message: string): void;
}

type T1 = FunctionPropertyNames<Person>;
type T2 = NonFunctionPropertyNames<Person>;
type T3 = FunctionProperties<Person>;
type T4 = NonFunctionProperties<Person>;

function shuffle(value: string | any[]): string | any[] {
  if (typeof value === 'string')
    return value
      .split('')
      .sort(() => Math.random() - 0.5)
      .join('');
  return value.sort(() => Math.random() - 0.5);
}

console.log(shuffle('Hello, Mark!')); // string | any[]
console.log(shuffle(['Hello', 'Mark', 'long', 'time', 'no', 'see'])); // string | any[]
console.log(shuffle([1, 2, 3, 4, 5])); // string | any[]

function shuffle2<T extends string | any[]>(
  value: T,
): T extends string ? string : T;
function shuffle2(value: any) {
  if (typeof value === 'string')
    return value
      .split('')
      .sort(() => Math.random() - 0.5)
      .join('');
  return value.sort(() => Math.random() - 0.5);
}

// function shuffle2<"Hello, Mark!">(value: "Hello, Mark!"): string
shuffle2('Hello, Mark!');

// function shuffle2<string[]>(value: string[]): string[]
shuffle2(['Hello', 'Mark', 'long', 'time', 'no', 'see']);

// function shuffle2<number[]>(value: number[]): number[]
shuffle2([1, 2, 3, 4, 5]);

// error! Argument of type 'number' is not assignable to parameter of type 'string | any[]'.
shuffle2(1);

function shuffle3(value: string): string;
function shuffle3<T>(value: T[]): T[];
function shuffle3(value: string | any[]): string | any[] {
  if (typeof value === 'string')
    return value
      .split('')
      .sort(() => Math.random() - 0.5)
      .join('');
  return value.sort(() => Math.random() - 0.5);
}

shuffle3('Hello, Mark!');
shuffle3(['Hello', 'Mark', 'long', 'time', 'no', 'see']);
shuffle3([1, 2, 3, 4, 5]);

class ExportLibraryModal {
  public openComponentsToLibrary(
    libraryId: string,
    componentIds: string[],
  ): void;
  public openComponentsToLibrary(componentIds: string[]): void;
  public openComponentsToLibrary(
    libraryIdOrComponentIds: string | string[],
    componentIds?: string[],
  ): void {
    if (typeof libraryIdOrComponentIds === 'string') {
      if (componentIds !== undefined) { // 이건 좀 별루지만,
        // 첫번째 시그니처
        libraryIdOrComponentIds;
        componentIds;
      }
    }

    if (componentIds === undefined) { // 이건 좀 별루지만,
      // 두번째 시그니처
      libraryIdOrComponentIds;
    }
  }
}

const modal = new ExportLibraryModal();

modal.openComponentsToLibrary(
  'library-id',
  ['component-id-1', 'component-id-1'],
);

modal.openComponentsToLibrary(['component-id-1', 'component-id-1']);

class Layer {
  id!: string;
  name!: string;
  x: number = 0;
  y: number = 0;
  width: number = 0;
  height: number = 0;
}

const LAYER_DATA_INITIALIZE_INCLUDE_KEYS: ReadonlyArray<keyof Layer> = [
  'x',
  'y',
  'width',
  'height',
];
const x = LAYER_DATA_INITIALIZE_INCLUDE_KEYS[0]; // "id" | "name" | "x" | "y" | "width" | "height"

const LAYER_DATA_INITIALIZE_EXCLUDE_KEYS = ['id', 'name'] as const;
const id = LAYER_DATA_INITIALIZE_EXCLUDE_KEYS[0]; // "id"

const weekdays: ReadonlyArray<string> = [
  'Sunday',
  'Monday',
  'Tuesday',
  'Wednesday',
  'Thursday',
  'Friday',
  'Saturday',
];

weekdays[0]; // readonly string[]
weekdays[0] = 'Fancyday'; // error! Index signature in type 'readonly string[]' only permits reading.

const weekdays = [
  'Sunday',
  'Monday',
  'Tuesday',
  'Wednesday',
  'Thursday',
  'Friday',
  'Saturday',
] as const;

weekdays[0]; // "Sunday"
weekdays[0] = 'Fancyday'; // error! Cannot assign to '0' because it is a read-only property.

interface IPerson {
  name: string;
  age: number;
}

type ReadonlyPerson = Readonly<IPerson>;

const person: ReadonlyPerson = Object.freeze<IPerson>({
  name: "Mark",
  age: 38,
});

person.name = "Hanna"; // error!
person.age = 27; // error!

interface IPerson {
  name: string;
  age: number;
}

type Nullable<T> = {
  [P in keyof T]: T[P] | null;
};

type Stringify<T> = {
  [P in keyof T]: string;
};

type PartialNullablePerson = Partial<Nullable<Stringify<IPerson>>>;
/*
type PartialNullablePerson = {
    name?: string | null | undefined;
    age?: string | null | undefined;
    speak?: string | null | undefined;
}
*/

let pnp: PartialNullablePerson;
pnp = { name: 'Mark', age: '38' };
pnp = { name: 'Mark' };
pnp = { name: undefined, age: null };

// Make all properties in T optional
type Partial<T> = {
    [P in keyof T]?: T[P];
};

// Make all properties in T required
type Required<T> = {
    [P in keyof T]-?: T[P];
};

// Make all properties in T readonly
type Readonly<T> = {
    readonly [P in keyof T]: T[P];
};

// From T, pick a set of properties whose keys are in the union K
type Pick<T, K extends keyof T> = {
    [P in K]: T[P];
};

// Construct a type with a set of properties K of type T
type Record<K extends keyof any, T> = {
    [P in K]: T;
};

interface Book {
  title: string;
  author: string;
}

interface IRootState {
  book: {
    books: Book[];
    loading: boolean;
    error: Error | null;
  };
}

type IReadonlyRootState = Readonly<IRootState>;
let state1: IReadonlyRootState = {} as IReadonlyRootState;
const book1 = state1.book.books[0];
book1.title = 'new';

type DeepReadonly<T> = T extends (infer E)[]
  ? ReadonlyArray<DeepReadonlyObject<E>>
  : T extends object
  ? DeepReadonlyObject<T>
  : T;

type DeepReadonlyObject<T> = { readonly [K in keyof T]: DeepReadonly<T[K]> };

type IDeepReadonlyRootState = DeepReadonly<IRootState>;
let state2: IDeepReadonlyRootState = {} as IDeepReadonlyRootState;
const book2 = state2.book.books[0];
book2.title = 'new'; // error! Cannot assign to 'title' because it is a read-only property.

// array and tuple literal types.

function freturn1(): string[] {
  return ['readonly'];
}

const fr1 = freturn1();
fr1[0] = 'hello';

function freturn2(): readonly string[] {
  return ['readonly'];
}

const fr2 = freturn2();
fr2[0] = 'hello'; // error! Index signature in type 'readonly string[]' only permits reading.

type Result1<T> = {
  data?: T;
  error?: Error;
  loading: boolean;
};

declare function getResult1(): Result1<string>;

const r1 = getResult1();
r1.data; // string | undefined
r1.error; // Error | undefined
r1.loading; // boolean

if (r1.data) {
  r1.error; // Error | undefined
  r1.loading; // boolean
}

type Result2<T> =
  | { loading: true }
  | { data: T; loading: false }
  | { error: Error; loading: false };

declare function getResult2(): Result2<string>;

const r2 = getResult2();

r2.data; // error! Property 'data' does not exist on type 'Result2<string>'. Property 'data' does not exist on type '{ loading: true; }'.
r2.error; // error! Property 'error' does not exist on type 'Result2<string>'. Property 'error' does not exist on type '{ loading: true; }'.
r2.loading; // boolean

if ('data' in r2) {
  r2.error; // error! Property 'error' does not exist on type '{ data: string; loading: false; }'.
  r2.loading; // false
}

type Result3<T> =
  | { type: 'pending'; loading: true }
  | { type: 'success'; data: T; loading: false }
  | { type: 'fail'; error: Error; loading: false };

declare function getResult3(): Result3<string>;

const r3 = getResult3();

if (r3.type === 'success') {
  r3; // { type: 'success'; data: string; loading: false; }
}
if (r3.type === 'pending') {
  r3; // { type: 'pending'; loading: true; }
}
if (r3.type === 'fail') {
  r3; // { type: 'fail'; error: Error; loading: false; }
}

interface Dog {
  kind: 'dog';
  eat: () => string;
}

interface Cat {
  kind: 'cat';
  jump: () => string;
}

interface Cow {
  kind: 'cow';
  milk: () => string;
}

type Pet = Dog | Cat | Cow;

function stringifyPaymentMethod(pet: Pet): string {
  switch (pet.kind) {
    case 'dog':
      return pet.eat();
    case 'cat':
      return pet.jump();
    case 'cow':
      return pet.milk();
  }
}

enum ToastType {
    AFTER_SAVED,
    AFTER_PUBLISHED,
    AFTER_RESTORE,
}

interface Toast {
    type: ToastType,
    createdAt: string,
}

const toasts: Toast[] = [...];

// toastNodes1 -> (JSX.Element | undefined)[]
const toastNodes1 = toasts.map((toast) => {
  if (toast.type === ToastType.AFTER_SAVED)
    return (
      <div key={toast.createdAt}>
        <AfterSavedToast />
      </div>
    );
  else if (toast.type === ToastType.AFTER_PUBLISHED)
    return (
      <div key={toast.createdAt}>
        <AfterPublishedToast />
      </div>
    );
  else if (toast.type === ToastType.AFTER_RESTORE)
    return (
      <div key={toast.createdAt}>
        <AfterRestoredToast />
      </div>
    );
});

// toastNodes2 -> JSX.Element[]
const toastNodes2 = toasts.map((toast) => {
  if (toast.type === ToastType.AFTER_SAVED)
    return (
      <div key={toast.createdAt}>
        <AfterSavedToast />
      </div>
    );
  else if (toast.type === ToastType.AFTER_PUBLISHED)
    return (
      <div key={toast.createdAt}>
        <AfterPublishedToast />
      </div>
    );
  else
    return (
      <div key={toast.createdAt}>
        <AfterRestoredToast />
      </div>
    );
});

// toastNodes3 -> JSX.Element[]
const toastNodes3 = toasts.map((toast) => {
  if (toast.type === ToastType.AFTER_SAVED)
    return (
      <div key={toast.createdAt}>
        <AfterSavedToast />
      </div>
    );
  else if (toast.type === ToastType.AFTER_PUBLISHED)
    return (
      <div key={toast.createdAt}>
        <AfterPublishedToast />
      </div>
    );
  else if (toast.type === ToastType.AFTER_RESTORE)
    return (
      <div key={toast.createdAt}>
        <AfterRestoredToast />
      </div>
    );
  else return neverExpected(toast.typs);
});

function neverExpected(value: never): never {
  throw new Error(`Unexpected value : ${value}`);
}

// toastNodes4 -> JSX.Element[]
const toastNodes4 = toasts.map((toast) => {
  if (toast.type === ToastType.AFTER_SAVED)
    return (
      <div key={toast.createdAt}>
        <AfterSavedToast />
      </div>
    );
  if (toast.type === ToastType.AFTER_PUBLISHED)
    return (
      <div key={toast.createdAt}>
        <AfterPublishedToast />
      </div>
    );
  if (toast.type === ToastType.AFTER_RESTORE)
    return (
      <div key={toast.createdAt}>
        <AfterRestoredToast />
      </div>
    );

  return neverExpected(toast.typs);
});

const toastNodes5 = toasts.map((toast) => {
  switch (toast.type) {
    case ToastType.AFTER_SAVED:
      return (
        <div key={toast.createdAt}>
          <AfterSavedToast />
        </div>
      );
    case ToastType.AFTER_PUBLISHED:
      return (
        <div key={toast.createdAt}>
          <AfterPublishedToast />
        </div>
      );
    case ToastType.AFTER_RESTORE:
      return (
        <div key={toast.createdAt}>
          <AfterRestoredToast />
        </div>
      );
    default:
      return neverExpected(toast.type);
  }
});