/* eslint-disable @typescript-eslint/ban-types */ type LastArrayElement = T extends [...any, infer L] ? L : never; type DropLastArrayElement = T extends [...(infer U), unknown] ? U : []; type StringEndsWith = S extends `${infer _}${X}` ? true : false; type Options = { multiArgs?: MultiArgs; include?: Includes; exclude?: Excludes; errorFirst?: ErrorFirst; promiseModule?: PromiseConstructor; excludeMain?: ExcludeMain; }; type InternalOptions = { multiArgs: MultiArgs; include: Includes; exclude: Excludes; errorFirst: ErrorFirst; }; type Promisify> = ( ...args: DropLastArrayElement ) => LastArrayElement extends (...arguments_: any) => any // For single-argument functions when errorFirst: true we just return Promise as it will always reject. ? Parameters> extends [infer SingleCallbackArg] ? GenericOptions extends {errorFirst: true} ? Promise : Promise : Promise< GenericOptions extends {multiArgs: false} ? LastArrayElement>> : Parameters> > // Functions without a callback will return a promise that never settles. We model this as Promise : Promise; type PromisifyModule< Module extends Record, MultiArgs extends boolean, ErrorFirst extends boolean, Includes extends ReadonlyArray, Excludes extends ReadonlyArray, > = { [K in keyof Module]: Module[K] extends (...arguments_: infer Arguments) => any ? K extends Includes[number] ? Promisify> : K extends Excludes[number] ? Module[K] : StringEndsWith extends true ? Module[K] : Promisify> : Module[K]; }; export default function pify< FirstArgument, Arguments extends readonly unknown[], MultiArgs extends boolean = false, ErrorFirst extends boolean = true, >( input: (argument: FirstArgument, ...arguments_: Arguments) => any, options?: Options<[], [], MultiArgs, ErrorFirst> ): Promisify<[FirstArgument, ...Arguments], InternalOptions<[], [], MultiArgs, ErrorFirst>>; export default function pify< Module extends Record, Includes extends ReadonlyArray = [], Excludes extends ReadonlyArray = [], MultiArgs extends boolean = false, ErrorFirst extends boolean = true, >( // eslint-disable-next-line unicorn/prefer-module module: Module, options?: Options ): PromisifyModule;