/**
 * Throttle execution of a function. Especially useful for rate limiting
 * execution of handlers on events like resize and scroll.
 *
 * @param  {Number}    delay          A zero-or-greater delay in milliseconds. For event callbacks, values around 100 or 250 (or even higher) are most useful.
 * @param  {Boolean}   [noTrailing]   Optional, defaults to false. If noTrailing is true, callback will only execute every `delay` milliseconds while the
 *                                    throttled-function is being called. If noTrailing is false or unspecified, callback will be executed one final time
 *                                    after the last throttled-function call. (After the throttled-function has not been called for `delay` milliseconds,
 *                                    the internal counter is reset)
 * @param  {Function}  callback       A function to be executed after delay milliseconds. The `this` context and all arguments are passed through, as-is,
 *                                    to `callback` when the throttled-function is executed.
 * @param  {Boolean}   [debounceMode] If `debounceMode` is true (at begin), schedule `clear` to execute after `delay` ms. If `debounceMode` is false (at end),
 *                                    schedule `callback` to execute after `delay` ms.
 *
 * @return {Function}  A new, throttled, function.
 */
define([], function () {
	"use strict";
  
	var exports = {};
	Object.defineProperty(exports, "__esModule", {
	  value: true
	});
  
	exports.default = function (delay, noTrailing, callback, debounceMode) {
	  /*
	   * After wrapper has stopped being called, this timeout ensures that
	   * `callback` is executed at the proper times in `throttle` and `end`
	   * debounce modes.
	   */
	  var timeoutID;
	  var cancelled = false; // Keep track of the last time `callback` was executed.
  
	  var lastExec = 0; // Function to clear existing timeout
  
	  function clearExistingTimeout() {
		if (timeoutID) {
		  clearTimeout(timeoutID);
		}
	  } // Function to cancel next exec
  
  
	  function cancel() {
		clearExistingTimeout();
		cancelled = true;
	  } // `noTrailing` defaults to falsy.
  
  
	  if (typeof noTrailing !== 'boolean') {
		debounceMode = callback;
		callback = noTrailing;
		noTrailing = undefined;
	  }
	  /*
	   * The `wrapper` function encapsulates all of the throttling / debouncing
	   * functionality and when executed will limit the rate at which `callback`
	   * is executed.
	   */
  
  
	  function wrapper() {
		var self = this;
		var elapsed = Date.now() - lastExec;
		var args = arguments;
  
		if (cancelled) {
		  return;
		} // Execute `callback` and update the `lastExec` timestamp.
  
  
		function exec() {
		  lastExec = Date.now();
		  callback.apply(self, args);
		}
		/*
		 * If `debounceMode` is true (at begin) this is used to clear the flag
		 * to allow future `callback` executions.
		 */
  
  
		function clear() {
		  timeoutID = undefined;
		}
  
		if (debounceMode && !timeoutID) {
		  /*
		   * Since `wrapper` is being called for the first time and
		   * `debounceMode` is true (at begin), execute `callback`.
		   */
		  exec();
		}
  
		clearExistingTimeout();
  
		if (debounceMode === undefined && elapsed > delay) {
		  /*
		   * In throttle mode, if `delay` time has been exceeded, execute
		   * `callback`.
		   */
		  exec();
		} else if (noTrailing !== true) {
		  /*
		   * In trailing throttle mode, since `delay` time has not been
		   * exceeded, schedule `callback` to execute `delay` ms after most
		   * recent execution.
		   *
		   * If `debounceMode` is true (at begin), schedule `clear` to execute
		   * after `delay` ms.
		   *
		   * If `debounceMode` is false (at end), schedule `callback` to
		   * execute after `delay` ms.
		   */
		  timeoutID = setTimeout(debounceMode ? clear : exec, debounceMode === undefined ? delay - elapsed : delay);
		}
	  }
  
	  wrapper.cancel = cancel; // Return the wrapper function.
  
	  return wrapper;
	};
  
	return exports.default;
  });