switch\case angular di

caseClass.ts

export class CaseOne implements CaseLogicHandler{
  key: any = 1;
  doLogic() {
    // case logic
  }
}

export class CaseTwo implements CaseLogicHandler{
  key: any = 2;
  doLogic() {
    // case logic
  }
}

interface.ts

export interface LogicHandler {
  doLogic();
}

module.ts

@NgModule({
  providers: [
    {provide: CASE_LOGIC_HANDLER, useClass: CaseOne, multi: true},
    {provide: CASE_LOGIC_HANDLER, useClass: CaseOne, multi: true},
    // ...
  ]
})
export class AppModule {
}

nasty.ts

@Injectable()
export class NastyService {
  constructor() {
  }

  doNastyOperation(key: number) {
    switch (key) {
      case 1:
      // logic
      case 2:
      // logic
      case 3:
      // logic
      case 4:
      // logic
      default:
      // logic
    }
  }
}

serviceFinal.ts

@Injectable()
export class NastyService {
  constructor(@Inject(CASE_LOGIC_HANDLER) private caseHandlers: CaseLogicHandler[]) {
  }

  doNastyOperation(key: any) {
    const handler = this.caseHandlers.find(h => h.key === key);
    if (!handler) throw new Error(`No case handler provided for key: ${key}`);
    handler.doLogic();
  }
}

serviceWithToken.ts

@Injectable()
export class NastyService {
  constructor(@Inject(CASE_LOGIC_HANDLER) private caseHandlers: CaseLogicHandler[]) {
  }

  doNastyOperation(key: any) {
    switch (key) {
      case 1:
      // logic
      case 2:
      // logic
      case 3:
      // logic
      case 4:
      // logic
      default:
      // logic
    }
  }
}

token.ts

export const LOGIC_HANDLER = new InjectionToken<LogicHandler>('logic.handlers');