import {Keys} from './Keys'
import {Intersect} from '../Union/Intersect'
import {Match} from '../Any/_Internal'
import {Is} from '../Any/Is'
import {At} from './At'

type IntersectMatch<O extends object, O1 extends object, match extends Match> = {
    [K in Keys<O>]: {
        1: K
        0: never
    }[Is<O[K], At<O1, K>, match>]
}[Keys<O>]

/** Get the intersecting keys of **`O`** & **`O1`**
 * (If `match = 'default'`, no type checks are done)
 * @param O to check similarities with
 * @param O1 to check similarities against
 * @returns **`keyof`**
 * @example
 * ```ts
 * ```
 */
export type IntersectKeys<O extends object, O1 extends object, match extends Match = 'default'> = {
    'default'     : Intersect<keyof O, keyof O1>
    'implements->': IntersectMatch<O,  O1, 'implements->'>
    'extends->'   : IntersectMatch<O,  O1, 'extends->'>
    '<-implements': IntersectMatch<O,  O1, '<-implements'>
    '<-extends'   : IntersectMatch<O,  O1, '<-extends'>
    'equals'      : IntersectMatch<O,  O1, 'equals'>
}[match]