custom deepkit http decorator

http.ts

import {http as _http, HttpAction, httpAction, HttpActionDecorator, httpClass} from "@deepkit/http";
import {
    createPropertyDecoratorContext,
    DualDecorator,
    mergeDecorator,
    PropertyDecoratorFn,
    ReceiveType
} from "@deepkit/type";
import {ClassType,UnionToIntersection} from "@deepkit/core";

export enum Role {
    ADMIN = 'admin',
    USER = 'user',
}

class HttpAuthActionDecorator extends HttpActionDecorator {
    t = new HttpAction();

    roles(...roles: Role[]) {
        this.t.data.set('roles', roles);
    }
}


export const httpAuthAction = createPropertyDecoratorContext(HttpAuthActionDecorator);

//this workaround is necessary since generic functions are lost during a mapped type and changed ReturnType
type HttpMerge<U> = { [K in keyof U]: K extends 'response' ? <T2>(statusCode: number, description?: string, type?: ReceiveType<T2>) => PropertyDecoratorFn & U : U[K] extends ((...a: infer A) => infer R) ? R extends DualDecorator ? (...a: A) => PropertyDecoratorFn & R & U : (...a: A) => R : never };
type MergedHttp<T extends any[]> = HttpMerge<Omit<UnionToIntersection<T[number]>, '_fetch' | 't'>>

export const http = mergeDecorator(httpClass, httpAuthAction) as any as MergedHttp<[typeof httpClass, typeof httpAuthAction]>;

@http.controller('/test')
class TestController {
    @(http.POST('test')).roles(Role.ADMIN)
    test() {

    }
}

console.log(httpClass._fetch(TestController));

It logs

HttpController {
  baseUrl: "/test",
  actions: Set(1) {
    HttpAuthAction {
      name: "",
      description: "",
      category: "",
      path: "test",
      httpMethods: [ "POST" ],
      methodName: "test",
      groups: [],
      middlewares: [],
      resolverForToken: Map {},
      resolverForParameterName: Map {},
      data: Map(1) {
        "roles": [ "admin" ],
      },
      responses: [],
    },
  },
  groups: [],
  middlewares: [],
  resolverForToken: Map {},
  resolverForParameterName: Map {},
  actionsProcessed: Set {},
  getUrl: [Function: getUrl],
  addAction: [Function: addAction],
  getActions: [Function: getActions],
  removeAction: [Function: removeAction],
  getAction: [Function: getAction],
}