import { curryN } from "@unboxing/function";
import { isNil } from "@unboxing/is";
import { ReduceFun } from "./reduce";
import { CurriedFunction2, CurriedFunction3 } from '@unboxing/core'

type ReducePred<T, R> = (acc: R, elem: T, index: number, arr: ArrayLike<T>) => boolean;

interface ReduceWhile {
    <T, R>(predicate: ReducePred<T, R>, fn: ReduceFun<T, R>, acc: R, list: ArrayLike<T>): R;
    <T, R>(predicate: ReducePred<T, R>, fn: ReduceFun<T, R>, acc: R): (list: ArrayLike<T>) => R;
    <T, R>(predicate: ReducePred<T, R>, fn: ReduceFun<T, R>): CurriedFunction2<R, ArrayLike<T>, R>;
    <T, R>(predicate: ReducePred<T, R>): CurriedFunction3<ReduceFun<T, R>, R, ArrayLike<T>, R>;
}

/**
 * Returns a single item by iterating through the list, successively calling
 * the iterator function and passing it an accumulator value and the current
 * value from the array, and then passing the result to the next call.
 */
export const reduceWhile = curryN(4, <T, R>(pred: ReducePred<T, R>, fn: ReduceFun<T, R>, acc: R, arr: ArrayLike<T> = []) => {
  // eslint-disable-line max-params
  if (isNil(arr)) {
      return acc;
  }

  const length = arr.length;

  for (
      let index = 0, curr = arr[0];
      index < length && pred(acc, curr, index, arr);
      curr = arr[++index] // eslint-disable-line no-plusplus
  ) {
      acc = fn(acc, curr, index, arr); // eslint-disable-line no-param-reassign
  }

  return acc;
}) as ReduceWhile