var __spreadArrays = (this && this.__spreadArrays) || function () {
    for (var s = 0, i = 0, il = arguments.length; i < il; i++) s += arguments[i].length;
    for (var r = Array(s), k = 0, i = 0; i < il; i++)
        for (var a = arguments[i], j = 0, jl = a.length; j < jl; j++, k++)
            r[k] = a[j];
    return r;
};
// Code copied from Vue/src/shared/util.js
var hyphenateRE = /\B([A-Z])/g;
var hyphenate = function (str) { return str.replace(hyphenateRE, '-$1').toLowerCase(); };
/**
 * decorator of an event-emitter function
 * @param  event The name of the event
 * @return MethodDecorator
 */
export function Emit(event) {
    return function (_target, propertyKey, descriptor) {
        var key = hyphenate(propertyKey);
        var original = descriptor.value;
        descriptor.value = function emitter() {
            var _this = this;
            var args = [];
            for (var _i = 0; _i < arguments.length; _i++) {
                args[_i] = arguments[_i];
            }
            var emit = function (returnValue) {
                var emitName = event || key;
                if (returnValue === undefined) {
                    if (args.length === 0) {
                        _this.$emit(emitName);
                    }
                    else if (args.length === 1) {
                        _this.$emit(emitName, args[0]);
                    }
                    else {
                        _this.$emit.apply(_this, __spreadArrays([emitName], args));
                    }
                }
                else {
                    args.unshift(returnValue);
                    _this.$emit.apply(_this, __spreadArrays([emitName], args));
                }
            };
            var returnValue = original.apply(this, args);
            if (isPromise(returnValue)) {
                returnValue.then(emit);
            }
            else {
                emit(returnValue);
            }
            return returnValue;
        };
    };
}
function isPromise(obj) {
    return obj instanceof Promise || (obj && typeof obj.then === 'function');
}