Turbo-iOS Native Authentication View, not modally presented

SignInViewModel.swift

//
//  SignInViewModel.swift
//
//  Created by @SylarRuby on 11/11/2022.
//
// This a continuation of https://masilotti.com/turbo-ios/native-authentication/.
// Instead of showing a modal for the form to sign in, we replace the all views
// with the sign in screen/view.

import Foundation
import UIKit
import Turbo
import KeychainAccess
import WebKit

class SignInViewModel: ObservableObject {
    let session: Session!
    let navigationController: UINavigationController!
    
    @Published var email: String = ""
    @Published var password: String = ""
    
    init(
        session: Session!,
        email: String = "",
        password: String = "",
        navigationController: UINavigationController!
    ) {
        self.session = session
        self.email = email
        self.password = password
        self.navigationController = navigationController
        
    }
    
    private var request: URLRequest {
        let url = URL(string: "...")!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"

        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.setValue("My App (Turbo Native)", forHTTPHeaderField: "User-Agent")

        let credentials = Credentials(email: email, password: password)
        request.httpBody = try? JSONEncoder().encode(credentials)

        return request
    }

    private struct Credentials: Encodable {
        let email: String
        let password: String
    }
    
    private struct AccessToken: Decodable {
        let token: String
    }

    public func signIn() {
        URLSession.shared.dataTask(with: request) { data, response, error in
            guard
                error == nil,
                let response = response as? HTTPURLResponse,
                // Ensure the response was successful
                (200 ..< 300).contains(response.statusCode),
                let headers = response.allHeaderFields as? [String: String],
                let data = data,
                let token = try? JSONDecoder().decode(AccessToken.self, from: data)
            else { return /* TODO: Handle errors */ }
            
            let keychain = Keychain(service: "Turbo-Credentials")
            keychain["access-token"] = token.token
            
            let url = URL(string: "...")!
            // Copy the "Set-Cookie" headers to the shared web view storage
            let cookies = HTTPCookie.cookies(withResponseHeaderFields: headers, for: url)
            HTTPCookieStorage.shared.setCookies(cookies, for: url, mainDocumentURL: nil)
            
            DispatchQueue.main.async {
                let cookieStore = WKWebsiteDataStore.default().httpCookieStore
                cookies.forEach { cookie in
                    cookieStore.setCookie(cookie, completionHandler: nil)
                }
                
                self.successAuth()
            }
        
        }.resume()
        
    }
    
    // Show the aunthenticated view...
    private func successAuth() -> Void {
        let url = URL(string: "...")!
        let viewController = VisitableViewController(url: url)
        
        guard let sceneDelegate = UIApplication.shared.connectedScenes.first?.delegate as? SceneDelegate else {
            fatalError("could not get scene delegate ")
        }

        sceneDelegate.window?.rootViewController = navigationController
        navigationController.viewControllers = [viewController]
        session.visit(viewController, reload: true)
    }
}
  
// SceneDelegate
func session(_ session: Session, didFailRequestForVisitable visitable: Visitable, error: Error) {      
  if error.isUnauthorized {
    // Render native sign-in flow
    let viewModel = SignInViewModel(session: session, navigationController: navigationController)
    let view = NewSessionView(viewModel: viewModel)
    let controller = UIHostingController(rootView: view)
    // We do not want to present a modal, replace the view with the NewSessionView
    navigationController.viewControllers = [controller]
    
    // navigationController.present(controller, animated: true)
  } else {
      // Handle actual errors
  }
}