import * as Router from 'koa-router';
import { GatewayApiBase } from 'sasdn';

const API_PATHS = [
  '../router/demo/DemoApiService/postGetDemoOrderApi',
];

export default class RouteLoader {
  private static _instance: RouteLoader;

  private _initialized: boolean;
  private _router: Router;

  private constructor() {
    this._initialized = false;
    this._router = new Router();
  }

  public static instance(): RouteLoader {
    if (RouteLoader._instance === undefined) {
      RouteLoader._instance = new RouteLoader();
    }
    return RouteLoader._instance;
  }

  public init(): Promise<boolean> {
    return new Promise((resolve, reject) => {
      // create koa-router
      let queue = [] as Array<Promise<void>>;
      for (let path of API_PATHS) {
        queue.push(this._createRouter(path));
      }

      // promise queue
      Promise.all(queue).then(() => {
        this._initialized = true;
        resolve(true);
      }).catch((err: Error) => {
        reject(err);
      });
    });
  }

  public getRouter(): Router {
    return this._router;
  }

  private async _createRouter(path: string): Promise<void> {
    try {
      let api = require(path).api as GatewayApiBase;
      this._router[api.method].apply(this._router, api.register());
    } catch (err) {
      console.error(err.toString());
    }
  }
}