import { Request, Response } from 'express';
import { http } from '@scode/consts';
import Transaction from './Transaction';

export default abstract class Handler {
  private _handlers: Array<Function> = [];
  private _method_handlers: Record<string, Function> = {};

  protected register_handler (f: Function, method?: string): void {
    if (typeof method === 'undefined') {
      this._handlers.push (f);
    }
    else {
      const m = method.toUpperCase ();
      if (typeof this._method_handlers[m] !== 'undefined')
        throw new Error (`Handler for ${m} already registered`);
      this._method_handlers[m] = f;
    }
  }

  private async run_method_handler (
    method: string,
    t: Transaction
  ): Promise<void> {
    const m = method.toUpperCase ();
    if (typeof this._method_handlers[m] !== 'undefined')
      await this._method_handlers[m] (t);
  }

  public async run_http_handler (req: Request, res: Response): Promise<void> {
    const t = new Transaction (req, res);
    for (const handler of this._handlers) {
      // eslint-disable-next-line no-await-in-loop
      if (await handler (t) === false) {
        if (!t.has_status)
          t.status = http.status_internal_server_error;
        t.finalize ();
        return;
      }
    }
    await this.run_method_handler ('ALL', t);
    await this.run_method_handler (t.req.method, t);
  }

  public abstract get path(): string;
}