import { isFunction, isObjTag } from '../../is'
import curry from '../../fp/curry'
import keys from '../../util/keys'
import preAllocate from '../../array/preAllocate'
import reduce from './_reduce'

interface Functor<Value> {}
interface MapFunction<FunctorWithValue, ReturnValue> {
  (fn: FunctorWithValue): ReturnValue
}

function _map<FunctorWithValue, ReturnValue>(
  fn: FunctorWithValue,
  functorList: MapFunction<FunctorWithValue, ReturnValue>
): ReturnValue[] {
  let idx = 0
  const len = functorList.length
  const result = preAllocate(len)

  while (idx < len) {
    result[idx] = fn(functorList[idx])
    idx += 1
  }

  return result
}

/**
 * @desc `while (index < list.length) push fn(list[index++])`
 * @name _map
 * @alias baseMaps
 * @since 5.0.0-beta.1
 * @memberOf loop
 *
 * {@link https://github.com/ramda/ramda/blob/master/src/internal/_map.js ramda-_map}
 * @see {@link ramda-_map}
 *
 * @param fn function to apply
 * @param functorList function/list
 */
function map<FunctorWithValue, ReturnValue>(
  fn: FunctorWithValue,
  functor:
    | MapFunction<FunctorWithValue, ReturnValue>
    | MapFunction<FunctorWithValue, ReturnValue>[]
): ReturnValue[] {
  if (isFunction(functor)) {
    return curry(functor.length, function(this: any) {
      return fn.call(this, functor.apply(this, arguments))
    })
  } else if (isObjTag(functor)) {
    return reduce(
      (acc: any, key: string | symbol | number) => {
        acc[key] = fn(functor[key])
        return acc
      },
      {},
      keys(functor)
    )
  } else {
    return _map(fn, functor)
  }
}

export default map