import _ from "lodash";
import { Router, RequestHandler, Request, Response, NextFunction } from "express";

export type HandlerFn<T> = (
  req: Request,
  res: Response,
  next: NextFunction
) => Promise<T | number | undefined>;

export class BaseController {
  router: Router;

  constructor() {
    this.router = Router();
  }

  get<T>(path: string, handler: HandlerFn<T>) {
    this.router.get(path, this.prepareHandler(handler));
  }

  post<T>(path: string, handler: HandlerFn<T>) {
    this.router.post(path, this.prepareHandler(handler));
  }

  use<T>(path: string, handler: HandlerFn<T>) {
    this.router.use(path, this.prepareHandler(handler));
  }

  prepareHandler<T>(handler: HandlerFn<T>): RequestHandler {
    handler = handler.bind(this);

    return async (req: Request, res: Response, next: NextFunction) => {
      try {
        const result = await handler(req, res, next);

        if (_.isObject(result)) {
          return res.json(result);
        } else if (result !== undefined) {
          return res.end(result);
        }

        return null;
      } catch (err: any) {
        next(err);
      }
    };
  }
}