var baseFlatten = require('../internal/baseFlatten'),
    bindCallback = require('../internal/bindCallback'),
    pickByArray = require('../internal/pickByArray'),
    pickByCallback = require('../internal/pickByCallback'),
    restParam = require('../function/restParam');

/**
 * Creates an object composed of the picked `object` properties. Property
 * names may be specified as individual arguments or as arrays of property
 * names. If `predicate` is provided it is invoked for each property of `object`
 * picking the properties `predicate` returns truthy for. The predicate is
 * bound to `thisArg` and invoked with three arguments: (value, key, object).
 *
 * @static
 * @memberOf _
 * @category Object
 * @param {Object} object The source object.
 * @param {Function|...(string|string[])} [predicate] The function invoked per
 *  iteration or property names to pick, specified as individual property
 *  names or arrays of property names.
 * @param {*} [thisArg] The `this` binding of `predicate`.
 * @returns {Object} Returns the new object.
 * @example
 *
 * var object = { 'user': 'fred', 'age': 40 };
 *
 * _.pick(object, 'user');
 * // => { 'user': 'fred' }
 *
 * _.pick(object, _.isString);
 * // => { 'user': 'fred' }
 */
var pick = restParam(function(object, props) {
  if (object == null) {
    return {};
  }
  return typeof props[0] == 'function'
    ? pickByCallback(object, bindCallback(props[0], props[1], 3))
    : pickByArray(object, baseFlatten(props));
});

module.exports = pick;
