(function(global, factory) {
  //https://github.com/jquery/jquery/blob/master/src/wrapper.js
  if (typeof define === "function" && define.amd) {
    define(["react"], function(React) {
      global.injectTapEventPlugin = factory(global, React);
    });
  } else if (typeof exports !== "undefined") {
    var React = require("react");
    factory(global, React);
  } else {
    global.injectTapEventPlugin = factory(
      global,
      global.React || global.ReactDOM
    );
  }
})(typeof window !== "undefined" ? window : this, function(window, React) {
  var alreadyInjected = false;
  var eventSystem = React.eventSystem;
  if (!eventSystem) {
    throw new Error("请确保你加载的是anujs");
  }
  var isTouch = eventSystem.isTouch;
  var eventPropHooks = eventSystem.eventPropHooks;
  var addEvent = eventSystem.addEvent;
  var eventLowerCache = eventSystem.eventLowerCache;
  var dispatchEvent = eventSystem.dispatchEvent;
  //==============isXXX系列

  function isEndish(eventType) {
    return (
      eventType === "mouseup" ||
      eventType === "touchend" ||
      eventType === "touchcancel"
    );
  }

  function isStartish(eventType) {
    return eventType === "mousedown" || eventType === "touchstart";
  }

  //=============
  var tapMoveThreshold = 10;
  var startCoords = { x: null, y: null };
  var lastTouchTime = null;

  var Axis = {
    x: { page: "pageX" },
    y: { page: "pageY" }
  };

  // fbjs/lib/TouchEventUtils
  var TouchEventUtils = {
    extractSingleTouch: function extractSingleTouch(nativeEvent) {
      var touches = nativeEvent.touches || [];
      var changedTouches = nativeEvent.changedTouches || [];

      return changedTouches[0] || touches[0] || nativeEvent;
    }
  };
  function getAxisCoordOfEvent(axis, nativeEvent) {
    var singleTouch = TouchEventUtils.extractSingleTouch(nativeEvent);
    return singleTouch[axis.page];
  }

  function getDistance(coords, nativeEvent) {
    var pageX = getAxisCoordOfEvent(Axis.x, nativeEvent);
    var pageY = getAxisCoordOfEvent(Axis.y, nativeEvent);
    return Math.pow(
      Math.pow(pageX - coords.x, 2) + Math.pow(pageY - coords.y, 2),
      0.5
    );
  }

  function now() {
    return new Date() - 0;
  }
  function shouldRejectClick() {}

  eventLowerCache["touchtap"] = "touchTap";
  eventPropHooks.touchtap = function(event) {
    var type = event.type;
    if (!isStartish(type) && !isEndish(type)) {
      return false;
    }

    if (isTouch) {
      lastTouchTime = now();
    } else {
      if (shouldRejectClick(lastTouchTime, now())) {
        return false;
      }
    }

    var distance = getDistance(startCoords, event);
    var returnFalse = true;
    if (isEndish(type) && distance < tapMoveThreshold) {
      event.type = "touchTap";
    } else {
      returnFalse = false;
    }
    if (isStartish(type)) {
      startCoords.x = getAxisCoordOfEvent(Axis.x, event);
      startCoords.y = getAxisCoordOfEvent(Axis.y, event);
    } else if (isEndish(type)) {
      startCoords.x = 0;
      startCoords.y = 0;
    }
    return returnFalse && event;
  };
  var events = isTouch
    ? ["touchstart", "touchmove", "touchend", "touchcancel"]
    : ["mousedown", "mousemove", "mouseup"];

  function injectTapEventPlugin() {
    if (alreadyInjected) return;
    alreadyInjected = true;
    events.forEach(function(type) {
      addEvent(window.document, type, function(e) {
       // e.__type__ = "touchtap";
        dispatchEvent(e, "touchtap");
      });
    });
  }
  injectTapEventPlugin();

  return injectTapEventPlugin;
});
