RoutingModule

final class RoutingModule {

    weak var rootViewController: UIViewController?

    var navigationController: UINavigationController? {
      if let navigation = self.rootViewController as? UINavigationController {
        return navigation
      } else {
        return self.rootViewController?.navigationController
      }
    }

    var presentDisposeBag: DisposeBag = DisposeBag()
    var presents: [PresentContainer] = []

    init(rootViewController: UIViewController?) {
      self.rootViewController = rootViewController
    }

    func push(viewController: UIViewController) {
      self.navigationController?.pushViewController(viewController, animated: true)
    }

    func present(viewController: UIViewController,
                 wrapWithNavigation: Bool = false,
                 overContext: Bool = false) {
      let presentedViewController = wrapWithNavigation ? NavigationController(rootViewController: viewController) : viewController
      let presentedContainer = PresentContainer(viewController: presentedViewController) { (presenting, presented) in
        if overContext {
          presenting.providesPresentationContextTransitionStyle = true
          presenting.definesPresentationContext = true
          presented.modalPresentationStyle = .overCurrentContext
        }
      }
      self.presents.append(presentedContainer)
      self.present()
    }

    func alert(title: String?, message: String, actions: [UIAlertAction]) {
      let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
      for action in actions {
        alert.addAction(action)
      }
      self.present(viewController: alert)
    }

    func actionSheet(title: String?, message: String, actions: [UIAlertAction]) {

    }

    private func popFirstPresent() -> PresentContainer? {
      guard self.presents.isEmpty == false else { return nil }
      if let first = self.presents.first {
        self.presents.removeFirst()
        return first
      }
      return nil
    }

    private func present() {
      guard let root = self.rootViewController, root.presentedViewController == nil else { return }
      if let presented = self.popFirstPresent() {
        presented.configuration(root, presented.viewController)
        root.present(presented.viewController, animated: true, completion: nil)
        presented.viewController.rx
          .deallocated
          .subscribe(onCompleted: { [weak self] in
            self?.present()
          })
          .disposed(by: self.presentDisposeBag)
      }
    }
  }