import ObservableKit

let observable: OKObservable<OKState<Data, Error>> = OKObservable(OKState.loading)

func fetchImage() {
  let url = URL(string: model.image)!
  observable.value = .loading
  URLSession.shared.dataTask(with: url, completionHandler: { data, _, error in
    if let error = error {
      self.observable.value = .errored(error: error)
      return
    }
    self.observable.value = data != nil ? .load(data: data!) : .empty
  }).resume()
}

@IBOutlet weak var imageView: UIImageView!

private let viewModel = ViewModel()

override func viewDidLoad() {
  super.viewDidLoad()
  addObservers()
}

private func addObservers() {
  viewModel.observable.didChange = { [weak self] status in
    DispatchQueue.main.async {
      switch status {
      case .load(data: let data):
        print("✅ fetch image with succss")
        let image = UIImage(data: data)
        self?.imageView.image = image
      case .loading:
        print("🚀 loading data...")
      case .errored(error: let error):
        print("❌ get an error: \(error)")
      case .empty:
        print("❌ data not found")
      }
    }
  }
}

private func loadImage() {
  viewModel.fetchImage()
}