authGuard.ts

import { NotLoggedIn } from '../models/errors'

const AuthGuardMethods = Symbol('AuthGuardMethods')

export function AuthGuard() {
  return function(target: any, propertyKey: string, descriptor: PropertyDescriptor) {
    target[AuthGuardMethods] = target[AuthGuardMethods] || new Map()
    // Here we just add some information that class decorator will use
    target[AuthGuardMethods].set(propertyKey, descriptor)
  }
}

export function InjectAuth<T extends { new (...args: any[]): {} }>(Base: T): T {
  return class extends Base {
    constructor(...args: any[]) {
      super(...args)
      const authGuardMethods = Base.prototype[AuthGuardMethods]
      if (authGuardMethods) {
        authGuardMethods.forEach((descriptor: PropertyDescriptor, propertyKey: string) => {
          // @ts-ignore
          this[propertyKey] = function(...args: any[]) {
            if (!(this as any).models.user) return Promise.reject(new NotLoggedIn('You must be logged in'))

            return descriptor.value.apply(this, args)
          }
        })
      }
    }
  }
}