/**
 * lodash 4.1.1 (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 createWrapper = require('lodash._createwrapper'),
    rest = require('lodash.rest');

/** Used to compose bitmasks for wrapper metadata. */
var BIND_FLAG = 1,
    BIND_KEY_FLAG = 2,
    PARTIAL_FLAG = 32;

/** Used as the internal argument placeholder. */
var PLACEHOLDER = '__lodash_placeholder__';

/**
 * Replaces all `placeholder` elements in `array` with an internal placeholder
 * and returns an array of their indexes.
 *
 * @private
 * @param {Array} array The array to modify.
 * @param {*} placeholder The placeholder to replace.
 * @returns {Array} Returns the new array of placeholder indexes.
 */
function replaceHolders(array, placeholder) {
  var index = -1,
      length = array.length,
      resIndex = -1,
      result = [];

  while (++index < length) {
    var value = array[index];
    if (value === placeholder || value === PLACEHOLDER) {
      array[index] = PLACEHOLDER;
      result[++resIndex] = index;
    }
  }
  return result;
}

/**
 * Gets the argument placeholder value for `func`.
 *
 * @private
 * @param {Function} func The function to inspect.
 * @returns {*} Returns the placeholder value.
 */
function getPlaceholder(func) {
  var object = func;
  return object.placeholder;
}

/**
 * Creates a function that invokes the method at `object[key]` and prepends
 * any additional `_.bindKey` arguments to those provided to the bound function.
 *
 * This method differs from `_.bind` by allowing bound functions to reference
 * methods that may be redefined or don't yet exist.
 * See [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern)
 * for more details.
 *
 * The `_.bindKey.placeholder` value, which defaults to `_` in monolithic
 * builds, may be used as a placeholder for partially applied arguments.
 *
 * @static
 * @memberOf _
 * @category Function
 * @param {Object} object The object to invoke the method on.
 * @param {string} key The key of the method.
 * @param {...*} [partials] The arguments to be partially applied.
 * @returns {Function} Returns the new bound function.
 * @example
 *
 * var object = {
 *   'user': 'fred',
 *   'greet': function(greeting, punctuation) {
 *     return greeting + ' ' + this.user + punctuation;
 *   }
 * };
 *
 * var bound = _.bindKey(object, 'greet', 'hi');
 * bound('!');
 * // => 'hi fred!'
 *
 * object.greet = function(greeting, punctuation) {
 *   return greeting + 'ya ' + this.user + punctuation;
 * };
 *
 * bound('!');
 * // => 'hiya fred!'
 *
 * // Bound with placeholders.
 * var bound = _.bindKey(object, 'greet', _, '!');
 * bound('hi');
 * // => 'hiya fred!'
 */
var bindKey = rest(function(object, key, partials) {
  var bitmask = BIND_FLAG | BIND_KEY_FLAG;
  if (partials.length) {
    var holders = replaceHolders(partials, getPlaceholder(bindKey));
    bitmask |= PARTIAL_FLAG;
  }
  return createWrapper(key, bitmask, object, partials, holders);
});

// Assign default placeholders.
bindKey.placeholder = {};

module.exports = bindKey;