set.ts

// Copyright (c) 2020 Jozty. All rights reserved. MIT license.

import type { Lens } from './lens.ts';
import type { PH } from './utils/types.ts';
import { over } from './over.ts';
import { always } from './always.ts';
import curryN from './utils/curry_n.ts';

// @types
type Set_1<T, F> = (lens: Lens<T, F>) => T;

type Set_2<T, F> = (value: F) => T;

type Set_3<T, F> = (target: T) => T;

type Set_2_3<T, F> =
  & ((value: F) => Set_3<T, F>)
  & ((value: PH, target: T) => Set_2<T, F>)
  & ((value: F, target: T) => T);

type Set_1_3<F> =
  & (<T>(lens: Lens<T, F>) => Set_3<T, F>)
  & (<T>(lens: PH, target: T) => Set_1<T, F>)
  & (<T>(lens: Lens<T, F>, target: T) => T);

type Set_1_2<T> =
  & (<F>(lens: Lens<T, F>) => Set_2<T, F>)
  & (<F>(lens: PH, value: F) => Set_1<T, F>)
  & (<F>(lens: Lens<T, F>, value: F) => T);

type Set =
  & (<T, F>(lens: Lens<T, F>) => Set_2_3<T, F>)
  & (<F>(lens: PH, value: F) => Set_1_3<F>)
  & (<T>(lens: PH, value: PH, target: T) => Set_1_2<T>)
  & (<T, F>(lens: Lens<T, F>, value: F) => Set_3<T, F>)
  & (<T, F>(lens: Lens<T, F>, value: PH, target: T) => Set_2<T, F>)
  & (<T, F>(lens: PH, value: F, target: T) => Set_1<T, F>)
  & (<T, F>(lens: Lens<T, F>, value: F, target: T) => T);

function _set<T, F>(lens: Lens<T, F>, value: F, target: T) {
  return over(lens, always(value), target);
}

/**
 * Returns the result of "setting" the portion of the given data structure `target`
 * focused by the given `len`s to the given `value`.
 *
 *      const xLens = Fae.lensProp('x')
 *      Fae.set(xLens, 4, {x: 1, y: 2})  // {x: 4, y: 2}
 *      Fae.set(xLens, 8, {x: 1, y: 2})  // {x: 8, y: 2}
 */
export const set = curryN(3, _set) as Set;