import { Parametric } from "./Parametric";
import { Primitive } from "./Primitive";

/**
 * Promisify a function type.
 *
 * Return type of the target function would be promisified and primitified.
 *
 *   - `Ret`: `Promise<Primitive<Ret>>`
 *   - `Promise<Ret>`: `Promise<Primitive<Ret>>`
 *
 * @template Method A function type to be promisified.
 * @template UseParametric Whether to convert type of function parameters to be compatible with their pritimive.
 * @author Jeongho Nam - https://github.com/samchon
 */
export type Functional<
  Method extends Function,
  UseParametric extends boolean = false,
> = (Method extends (...args: infer Params) => infer Ret
  ? Ret extends Promise<infer PromiseRet>
    ? (
        ...args: FunctionalParams<Params, UseParametric>
      ) => Promise<Primitive<PromiseRet>>
    : (
        ...args: FunctionalParams<Params, UseParametric>
      ) => Promise<Primitive<Ret>>
  : (...args: any[]) => Promise<any>) &
  IRemoteFunction;

/**
 * @hidden
 */
type FunctionalParams<
  Params extends any[],
  UseParametric extends boolean,
> = UseParametric extends true ? Parametric<Params> : Params;

/**
 * Restrictions for Remote Function
 */
type IRemoteFunction = {
  /**
   * Remote Function does not allow it.
   */
  [P in keyof Function | "Symbol"]: never;
};