anu - event

import { document } from "./browser";
import { isFn, noop, options } from "./util";

var globalEvents = {};
export var eventPropHooks = {}; //用于在事件回调里对事件对象进行
export var eventHooks = {}; //用于在元素上绑定特定的事件
//根据onXXX得到其全小写的事件名, onClick --> click, onClickCapture --> click,
// onMouseMove --> mousemove

export var eventLowerCache = {
    onClick: "click",
    onChange: "change",
    onWheel: "wheel"
};
/**
 * 判定否为与事件相关
 *
 * @param {any} name
 * @returns
 */
export function isEventName(name) {
    return /^on[A-Z]/.test(name);
}

export var isTouch = "ontouchstart" in document;

export function dispatchEvent(e, type, end) {
    //__type__ 在injectTapEventPlugin里用到
    e = new SyntheticEvent(e);
    if (type) {
        e.type = type;
    }
    var bubble = e.type;

    var hook = eventPropHooks[bubble];
    if (hook && false === hook(e)) {
        return;
    }

    var paths = collectPaths(e.target, end || document);
    var captured = bubble + "capture";
    options.async = true;
    triggerEventFlow(paths, captured, e);

    if (!e._stopPropagation) {
        triggerEventFlow(paths.reverse(), bubble, e);
    }
    options.async = false;
    options.flushBatchedUpdates();
}

function collectPaths(from, end) {
    var paths = [];
    do {
        if (from === end) {
            break;
        }
        var events = from.__events;
        if (events) {
            paths.push({ dom: from, events: events });
        }

    } while ((from = from.parentNode) && from.nodeType === 1);
    // target --> parentNode --> body --> html
    return paths;
}

function triggerEventFlow(paths, prop, e) {
    for (var i = paths.length; i--;) {
        var path = paths[i];
        var fn = path.events[prop];
        if (isFn(fn)) {
            e.currentTarget = path.dom;
            fn.call(path.dom, e);
            if (e._stopPropagation) {
                break;
            }
        }
    }
}

export function addGlobalEvent(name) {
    if (!globalEvents[name]) {
        globalEvents[name] = true;
        addEvent(document, name, dispatchEvent);
    }
}

export function addEvent(el, type, fn, bool) {
    if (el.addEventListener) {
        // Unable to preventDefault inside passive event listener due to target being
        // treated as passive
        el.addEventListener(
            type,
            fn,
            bool || false
        );
    } else if (el.attachEvent) {
        el.attachEvent("on" + type, fn);
    }
}


var rcapture = /Capture$/;
export function getBrowserName(onStr) {
    var lower = eventLowerCache[onStr];
    if (lower) {
        return lower;
    }
    var camel = onStr.slice(2).replace(rcapture, "");
    lower = camel.toLowerCase();
    eventLowerCache[onStr] = lower;
    return lower;
}


eventPropHooks.click = function (e) {
    return !e.target.disabled;
};

/* IE6-11 chrome mousewheel wheelDetla 下 -120 上 120
            firefox DOMMouseScroll detail 下3 上-3
            firefox wheel detlaY 下3 上-3
            IE9-11 wheel deltaY 下40 上-40
            chrome wheel deltaY 下100 上-100 */
/* istanbul ignore next  */
const fixWheelType =
    "onmousewheel" in document
        ? "mousewheel"
        : document.onwheel !== void 666 ? "wheel" : "DOMMouseScroll";
const fixWheelDelta =
    fixWheelType === "mousewheel"
        ? "wheelDetla"
        : fixWheelType === "wheel" ? "deltaY" : "detail";
eventHooks.wheel = function (dom) {
    addEvent(dom, fixWheelType, function (e) {
        var delta = e[fixWheelDelta] > 0 ? -120 : 120;
        var deltaY = ~~dom.__wheel + delta;
        dom.__wheel = deltaY;
        e = new SyntheticEvent(e);
        e.type = "wheel";
        e.deltaY = deltaY;
        dispatchEvent(e);
    });
};

var fixFocus = {};
"blur,focus".replace(/\w+/g, function (type) {
    eventHooks[type] = function () {
        if (!fixFocus[type]) {
            fixFocus[type] = true;
            addEvent(
                document,
                type,
                dispatchEvent,
                true
            );
        }
    };
});
/**
 * 
DOM通过event对象的relatedTarget属性提供了相关元素的信息。这个属性只对于mouseover和mouseout事件才包含值；
对于其他事件，这个属性的值是null。IE不支持realtedTarget属性，但提供了保存着同样信息的不同属性。
在mouseover事件触发时，IE的fromElement属性中保存了相关元素；
在mouseout事件出发时，IE的toElement属性中保存着相关元素。
但fromElement与toElement可能同时都有值
 */
function getRelatedTarget(e) {
    if (!e.timeStamp) {
        e.relatedTarget = e.type === "mouseover" ? e.fromElement : e.toElement;
    }
    return e.relatedTarget;
}

function contains(a, b) {
    if (b) {
        while ((b = b.parentNode)) {
            if (b === a) {
                return true;
            }
        }
    }
    return false;
}

String("mouseenter,mouseleave").replace(/\w+/g, function (type) {
    eventHooks[type] = function (dom, name) {
        var mark = "__" + name;
        if (!dom[mark]) {
            dom[mark] = true;
            var mask = name === "mouseenter" ? "mouseover" : "mouseout";
            addEvent(dom, mask, function (e) {
                let t = getRelatedTarget(e);
                if (!t || (t !== dom && !contains(dom, t))) {
                    var common = getLowestCommonAncestor(dom, t);
                    //由于不冒泡，因此paths长度为1 
                    dispatchEvent(e, name, common);
                }
            });
        }
    };
});

function getLowestCommonAncestor(instA, instB) {
    var depthA = 0;
    for (var tempA = instA; tempA; tempA = tempA.parentNode) {
        depthA++;
    }
    var depthB = 0;
    for (var tempB = instB; tempB; tempB = tempB.parentNode) {
        depthB++;
    }

    // If A is deeper, crawl up.
    while (depthA - depthB > 0) {
        instA = instA.parentNode;
        depthA--;
    }

    // If B is deeper, crawl up.
    while (depthB - depthA > 0) {
        instB = instB.parentNode;
        depthB--;
    }

    // Walk in lockstep until we find a match.
    var depth = depthA;
    while (depth--) {
        if (instA === instB) {
            return instA;
        }
        instA = instA.parentNode;
        instB = instB.parentNode;
    }
    return null;
}


if (isTouch) {
    eventHooks.click = noop;
    eventHooks.clickcapture = noop;
}

export function createHandle(name, fn) {
    return function (e) {
        if (fn && fn(e) === false) {
            return;
        }
        dispatchEvent(e, name);
    };
}

var changeHandle = createHandle("change");
var doubleClickHandle = createHandle("doubleclick");

//react将text,textarea,password元素中的onChange事件当成onInput事件
eventHooks.changecapture = eventHooks.change = function (dom) {
    var mask = /text|password/.test(dom.type) ? "input" : "change";
    addEvent(document, mask, changeHandle);
};

eventHooks.doubleclick = eventHooks.doubleclickcapture = function () {
    addEvent(document, "dblclick", doubleClickHandle);
};

export function SyntheticEvent(event) {
    if (event.nativeEvent) {
        return event;
    }
    for (var i in event) {
        if (!eventProto[i]) {
            this[i] = event[i];
        }
    }
    if (!this.target) {
        this.target = event.srcElement;
    }
    this.fixEvent();
    this.timeStamp = new Date() - 0;
    this.nativeEvent = event;
}

var eventProto = (SyntheticEvent.prototype = {
    fixEvent: function () { }, //留给以后扩展用
    preventDefault: function () {
        var e = this.nativeEvent || {};
        e.returnValue = this.returnValue = false;
        if (e.preventDefault) {
            e.preventDefault();
        }
    },
    fixHooks: function () { },
    stopPropagation: function () {
        var e = this.nativeEvent || {};
        e.cancelBubble = this._stopPropagation = true;
        if (e.stopPropagation) {
            e.stopPropagation();
        }
    },
    persist: noop,
    stopImmediatePropagation: function () {
        this.stopPropagation();
        this.stopImmediate = true;
    },
    toString: function () {
        return "[object Event]";
    }
});
/* istanbul ignore next  */
//freeze_start
Object.freeze ||
    (Object.freeze = function (a) {
        return a;
    });
//freeze_end