import Mediator from './Mediator';
import Colleague from './Colleague';
import 'reflect-metadata';

function mediatorFactory() {
	const mediator = new Mediator();
	// 创建闭包
	return {
		// 类装饰器
		colleague: function(colleagueName: string) {
			return function<T extends {new (...args: any[]): {}}>(target: T) {
				// 劫持构造函数只为获得this
				return class extends target {
					static displayName = (target as any).displayName + '$Colleague';
					constructor(...arg: any[]) {
						super(...arg);
						const colleague = new Colleague(colleagueName, this);
						// 从元数据中获取保存的公开的方法
						Reflect.ownKeys(target.prototype).forEach(key => {
							if (typeof key === 'number') {
								key = key.toString();
							}
							const actionMethod = Reflect.getMetadata('action', target.prototype, key);
							if (actionMethod) {
								colleague.setAction(actionMethod.name, actionMethod.value);
							}
						});
						mediator.registColleague(colleague);
					}
				};
			};
		},
		// 方法装饰器，开放的方法
		colleagueAction: function(actionName: string) {
			return function(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
				// 将开放的方法放入中介,此时还未执行类装饰器，需要先保存起来
				Reflect.defineMetadata('action', {name: actionName, value: descriptor.value}, target, propertyKey);
			};
		},
		// 方法装饰器
		notifyMediator: function(colleagueName: string, actionName: string, ...payload: any[]) {
			return function(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
				// 劫持方法，通知中介
				return {
					writable: true,
					enumerable: true,
					configurable: true,
					value: function(...args: any[]) {
						// tslint:disable-next-line:no-invalid-this
						let result = descriptor.value.apply(this, args);
						if (result instanceof Promise) {
							result.then(function() {
								mediator.notify(colleagueName, actionName, payload);
							});
						} else {
							mediator.notify(colleagueName, actionName, payload);
						}
						return result;
					}
				};
			};
		}
	};
}

export const {colleague, colleagueAction, notifyMediator} = mediatorFactory();