import type { Equal, Expect } from './test-utils'

type A1 = If<true, 'a', 'b'>;
type B1 = 'a';
type C1 = Expect<Equal<A1, B1>>;

type A2 = If<false, 'a', 2>;
type B2 = 2;
type C2 = Expect<Equal<A2, B2>>;

// @ts-expect-error(2344)
type E1 = If<null, 'a', 'b'>

// ============= Your Code Here =============
type If<C extends boolean, T, F> =
  C extends true
  ? T
  : F
;

// ============== Alternatives ==============
// you can flip the expression if you want
type If<C extends boolean, T, F> =
  C extends false
  ? F
  : T
;

// nested condition not necessary
type If<C extends boolean, T, F> =
  C extends true
  ? T
  : C extends false
    ? F
    : C
;

// equality check not necessary
type If<C extends boolean, T, F> =
  Equal<C, true> extends true
  ? T
  : F
;

// ================== NOPE ==================
// doesn't constrain `C`,
//so doesn't error for `null`
type Nope0<C, T, F> =
  C extends false | null
  ? F
  : T
;