import { isArray } from '../../is'
import objOrArrayKeys from '../../util/keysObjOrArray'
import curry from '../../fp/curry'
import emptyTarget from '../../dopemerge/emptyTarget'
import { AnyArrayOrObj } from '../../_typings'

/**
 * filters an object or array
 * `iteratee`. The iteratee is invoked with three arguments: (value, key, object).
 * @memberOf loop
 *
 * @param {Object} obj The object to iterate over.
 * @param {Function} predicate The function invoked per iteration.
 * @param {Object} [init={}] output result object initial value
 * @return {Array} Returns the new mapped array.
 *
 * @name filterWhere
 * @alias pluckWhere
 * @alias filter
 *
 * @since 5.0.0
 * @category Object
 *
 * {@link https://github.com/ramda/ramda/tree/v0.24.1/src/filter.js ramda-filter}
 * {@link https://github.com/lodash/lodash/blob/master/mapObject.js lodash-map-obj}
 * {@link https://github.com/jashkenas/underscore/blob/master/underscore.js#L1021 underscore-map-obj}
 * {@link https://github.com/lodash/lodash/blob/master/map.js lodash-map}
 * @see {@link lodash-map}
 * @see {@link underscore-map}
 * @see {@link ramda-filter}
 *
 * @TODO add `key first` sig option
 *
 * @example
 *
 *   map([1, 2, 3, 'nope'], isNumber)
 *   //=> [1, 2, 3]
 *
 * @example
 *
 *   /// because `value` is first
 *   map({'1': 1, 'nope': 'nope'}, isNumber)
 *   //=> [1, 2, 3]
 *
 */
function filterMap(
  obj: AnyArrayOrObj,
  predicate: (value: any, key: string, obj: AnyArrayOrObj) => any,
  init?: any
) {
  // @@todo @@perf
  const result = emptyTarget(obj) ? emptyTarget(obj) : init
  const isArrayObj = isArray(obj)
  const keys = objOrArrayKeys(obj)

  for (let index = 0; index < keys.length; index++) {
    const key = isArrayObj ? index : keys[index]
    const value = obj[key]

    if (predicate(value, key, obj)) {
      result[key] = value
    }
  }

  return result
}

export default curry(2, filterMap)