import {_Omit} from './Omit'
import {_Pick} from './Pick'
import {Key} from '../Any/Key'
import {Strict} from '../Union/Strict'
import {Boolean} from '../Boolean/Boolean'
import {ComputeRaw} from '../Any/Compute'

/**
@hidden
*/
type __Either<O extends object, K extends Key> =
    _Omit<O, K> & ({           // Merge all but K
        [P in K]: _Pick<O, P> // With K possibilities
    }[K])

/**
@hidden
*/
type EitherStrict<O extends object, K extends Key> =
    Strict<__Either<O, K>>

/**
@hidden
*/
type EitherLoose<O extends object, K extends Key> =
    ComputeRaw<__Either<O, K>>

/**
@hidden
*/
export type _Either<O extends object, K extends Key, strict extends Boolean> = {
    1: EitherStrict<O, K>
    0: EitherLoose<O, K>
}[strict]

/**
Split `O` into a [[Union]] with `K` keys in such a way that none of
the keys are ever present with one another within the different unions.
@param O to split
@param K to split with
@param strict (?=`1`) to force excess property checks https://github.com/microsoft/TypeScript/issues/20863
@returns [[Object]] [[Union]]
@example
```ts
```
*/
export type Either<O extends object, K extends Key, strict extends Boolean = 1> =
    O extends unknown
    ? _Either<O, K, strict>
    : never