HORIZON PROJECT

var arrayMap = require('./_arrayMap'),

    baseIntersection = require('./_baseIntersection'),

    baseIteratee = require('./_baseIteratee'),

    baseRest = require('./_baseRest'),

    castArrayLikeObject = require('./_castArrayLikeObject'),

    last = require('./last');

/**

 * This method is like `_.intersection` except that it accepts `iteratee`

 * which is invoked for each element of each `arrays` to generate the criterion

 * by which they're compared. The order and references of result values are

 * determined by the first array. The iteratee is invoked with one argument:

 * (value).

 *

 * @static

 * @memberOf _

 * @since 4.0.0

 * @category Array

 * @param {...Array} [arrays] The arrays to inspect.

 * @param {Function} [iteratee=_.identity] The iteratee invoked per element.

 * @returns {Array} Returns the new array of intersecting values.

 * @example

 *

 * _.intersectionBy([2.1, 1.2], [2.3, 3.4], Math.floor);

 * // => [2.1]

 *

 * // The `_.property` iteratee shorthand.

 * _.intersectionBy([{ 'x': 1 }], [{ 'x': 2 }, { 'x': 1 }], 'x');

 * // => [{ 'x': 1 }]

 */

var intersectionBy = baseRest(function(arrays) {

  var iteratee = last(arrays),

      mapped = arrayMap(arrays, castArrayLikeObject);

  if (iteratee === last(mapped)) {

    iteratee = undefined;

  } else {

    mapped.pop();

  }

  return (mapped.length && mapped[0] === arrays[0])

    ? baseIntersection(mapped, baseIteratee(iteratee, 2))

    : [];

});

module.exports = intersectionBy;