/**
 * lodash (Custom Build) <https://lodash.com/>
 * Build: `lodash modularize exports="npm" -o ./`
 * Copyright 2012-2016 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2016 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseFor = require('lodash._basefor'),
    keys = require('lodash.keys');

/**
 * The base implementation of `_.forOwn` without support for iteratee shorthands.
 *
 * @private
 * @param {Object} object The object to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @returns {Object} Returns `object`.
 */
function baseForOwn(object, iteratee) {
  return object && baseFor(object, iteratee, keys);
}

/**
 * The base implementation of `_.invert` and `_.invertBy` which inverts
 * `object` with values transformed by `iteratee` and set by `setter`.
 *
 * @private
 * @param {Object} object The object to iterate over.
 * @param {Function} setter The function to set `accumulator` values.
 * @param {Function} iteratee The iteratee to transform values.
 * @param {Object} accumulator The initial inverted object.
 * @returns {Function} Returns `accumulator`.
 */
function baseInverter(object, setter, iteratee, accumulator) {
  baseForOwn(object, function(value, key, object) {
    setter(accumulator, iteratee(value), key, object);
  });
  return accumulator;
}

/**
 * Creates a function like `_.invertBy`.
 *
 * @private
 * @param {Function} setter The function to set accumulator values.
 * @param {Function} toIteratee The function to resolve iteratees.
 * @returns {Function} Returns the new inverter function.
 */
function createInverter(setter, toIteratee) {
  return function(object, iteratee) {
    return baseInverter(object, setter, toIteratee(iteratee), {});
  };
}

/**
 * Creates an object composed of the inverted keys and values of `object`.
 * If `object` contains duplicate values, subsequent values overwrite
 * property assignments of previous values.
 *
 * @static
 * @memberOf _
 * @since 0.7.0
 * @category Object
 * @param {Object} object The object to invert.
 * @returns {Object} Returns the new inverted object.
 * @example
 *
 * var object = { 'a': 1, 'b': 2, 'c': 1 };
 *
 * _.invert(object);
 * // => { '1': 'c', '2': 'b' }
 */
var invert = createInverter(function(result, value, key) {
  result[value] = key;
}, constant(identity));

/**
 * Creates a function that returns `value`.
 *
 * @static
 * @memberOf _
 * @since 2.4.0
 * @category Util
 * @param {*} value The value to return from the new function.
 * @returns {Function} Returns the new constant function.
 * @example
 *
 * var object = { 'user': 'fred' };
 * var getter = _.constant(object);
 *
 * getter() === object;
 * // => true
 */
function constant(value) {
  return function() {
    return value;
  };
}

/**
 * This method returns the first argument given to it.
 *
 * @static
 * @since 0.1.0
 * @memberOf _
 * @category Util
 * @param {*} value Any value.
 * @returns {*} Returns `value`.
 * @example
 *
 * var object = { 'user': 'fred' };
 *
 * _.identity(object) === object;
 * // => true
 */
function identity(value) {
  return value;
}

module.exports = invert;