base.js

const Koa    = require('koa');
const Router = require('@koa/router');

class Controller {
  constructor(app, ctx) {
    this.app = app;
    this.ctx = ctx;
  }

  get req () { return this.ctx.request }
  get res () { return this.ctx.response }
}

class App {
  constructor (config = {}) {
    this.config = config;
    this.koa    = new Koa();
    this.router = new Router();
    this.startup();
    this.koa
      .use(this.router.routes())
      .use(this.router.allowedMethods());
  }

  to (action, cls=Controller) {
    return (ctx, next) => {
      const c = new cls(this, ctx);
      if (action in c) {
        action = c[action];
      }
      return action.call(c,next);
    }
  }

  startup() {}
}

module.exports = {
  App,
  Controller,
}