var Class = require('./Class');
var contain = require('./contain');
function retTrue() {
    return true;
}
function retFalse() {
    return false;
}
function trigger(e) {
    var handlers = this.events[e.type];
    var handler;
    var handlerQueue = formatHandlers.call(this, e, handlers);
    e = new exports.Event(e);
    var i = 0,
        j,
        matched,
        ret;
    while ((matched = handlerQueue[i++]) && !e.isPropagationStopped()) {
        e.curTarget = matched.el;
        j = 0;
        while (
            (handler = matched.handlers[j++]) &&
            !e.isImmediatePropagationStopped()
        ) {
            ret = handler.handler.apply(matched.el, [e]);
            if (ret === false) {
                e.preventDefault();
                e.stopPropagation();
            }
        }
    }
}
function formatHandlers(e, handlers) {
    var current = e.target;
    var ret = [];
    var delegateCount = handlers.delegateCount;
    var selector;
    var matches;
    var handler;
    var i;
    if (current.nodeType) {
        for (; current !== this; current = current.parentNode || this) {
            matches = [];
            for (i = 0; i < delegateCount; i++) {
                handler = handlers[i];
                selector = handler.selector + ' ';
                if (matches[selector] === undefined) {
                    matches[selector] = contain(
                        this.querySelectorAll(selector),
                        current
                    );
                }
                if (matches[selector]) matches.push(handler);
            }
            if (matches.length)
                ret.push({
                    el: current,
                    handlers: matches
                });
        }
    }
    if (delegateCount < handlers.length) {
        ret.push({
            el: this,
            handlers: handlers.slice(delegateCount)
        });
    }
    return ret;
}
exports = {
    add: function(el, type, selector, fn) {
        var handler = {
            selector: selector,
            handler: fn
        };
        var handlers;
        if (!el.events) el.events = {};
        if (!(handlers = el.events[type])) {
            handlers = el.events[type] = [];
            handlers.delegateCount = 0;
            el.addEventListener(
                type,
                function() {
                    trigger.apply(el, arguments);
                },
                false
            );
        }
        selector
            ? handlers.splice(handlers.delegateCount++, 0, handler)
            : handlers.push(handler);
    },
    remove: function(el, type, selector, fn) {
        var events = el.events;
        if (!events || !events[type]) return;
        var handlers = events[type];
        var i = handlers.length;
        var handler;
        while (i--) {
            handler = handlers[i];
            if (
                (!selector || handler.selector == selector) &&
                handler.handler == fn
            ) {
                handlers.splice(i, 1);
                if (handler.selector) {
                    handlers.delegateCount--;
                }
            }
        }
    },
    Event: Class({
        className: 'Event',
        initialize: function Event(e) {
            this.origEvent = e;
        },
        isDefaultPrevented: retFalse,
        isPropagationStopped: retFalse,
        isImmediatePropagationStopped: retFalse,
        preventDefault: function() {
            var e = this.origEvent;
            this.isDefaultPrevented = retTrue;
            if (e && e.preventDefault) e.preventDefault();
        },
        stopPropagation: function() {
            var e = this.origEvent;
            this.isPropagationStopped = retTrue;
            if (e && e.stopPropagation) e.stopPropagation();
        },
        stopImmediatePropagation: function() {
            var e = this.origEvent;
            this.isImmediatePropagationStopped = retTrue;
            if (e && e.stopImmediatePropagation) e.stopImmediatePropagation();
            this.stopPropagation();
        }
    })
};

module.exports = exports;