import {Merge} from './Merge'
import {Exclude} from './Exclude'
import {Match} from '../Any/_Internal'

/** Get an **`object`** that is the difference between **`O`** & **`O1`**
 * (**`O`**'s differences have priority over **`O1`**'s if fields overlap)
 * (If `match = 'default'`, no type checks are done)
 * @param O to check differences with
 * @param O1 to check differences against
 * @param match to change precision (?=`'default'`)
 * @returns **`object`**
 * @example
 * ```ts
 * import {O} from 'ts-toolbelt'
 *
 * type Person0 = {
 *     name: string
 *     age: string
 * }
 *
 * type Person1 = {
 *     name: string
 *     age: number | string
 *     nick: string
 * }
 *
 * type test0 = O.Diff<Person0, Person1, 'default'>   // {nick: string}
 * type test1 = O.Diff<Person0, Person1, 'extends->'> // {nick: string; age: string | number}
 * type test2 = O.Diff<Person0, Person1, '<-extends'> // {nick: string; age: string}
 * type test3 = O.Diff<Person0, Person1, 'equals'>    // {nick: string; age: string}
 * ```
 */
export type Diff<O extends object, O1 extends object, match extends Match = 'default'> =
    Merge<Exclude<O, O1, match>, Exclude<O1, O, match>>