import UIKit
import RxSwift
import RxCocoa
import RxSwiftExt

struct Todo: CustomStringConvertible {
   let title: String
   var isCompleted: Bool
   var isFavorited: Bool

   var description: String {
      return "\(title) com: \(isCompleted) fav: \(isFavorited)"
   }
}

class Service {

   func getTodos() -> Observable<[Todo]> {
      return Observable
         .just([
            Todo(title: "todo1", isCompleted: false, isFavorited: false),
            Todo(title: "todo2", isCompleted: true, isFavorited: false)
            ])
         .delaySubscription(0.1, scheduler: MainScheduler.instance)
   }
}

class ViewController: UIViewController {

   private let disposeBag = DisposeBag()
   private let service = Service.init()

   // output
   let todos = PublishSubject<[Todo]>()

   // from api/service
   var todosFromService: Observable<[Todo]>!

   // inputs
   let toggleCompleted = PublishSubject<String>()
   let toggleFavorited = PublishSubject<String>()

   // load data from service
   let loadData = PublishSubject<Void>()

   init() {
      super.init(nibName: nil, bundle: nil)

      todosFromService = loadData.flatMap { [unowned self] in return self.service.getTodos() }
      let completedToggled = toggleCompleted.withLatestFrom(todos) { withTodoCompleted(title: $0, in: $1) }
      let favoritedToggled = toggleFavorited.withLatestFrom(todos) { withTodoFavorited(title: $0, in: $1) }

      todosFromService.bind(to: todos)
      completedToggled.bind(to: todos)
      favoritedToggled.bind(to: todos)

      todos
         .debug("new todos", trimOutput: false)
         .subscribe(onNext: { t in

         })
         .disposed(by: disposeBag)
   }

   required init?(coder aDecoder: NSCoder) {
      fatalError("init(coder:) has not been implemented")
   }

   override func viewDidLoad() {
      super.viewDidLoad()

      view.backgroundColor = .orange

      // add test buttons
      let b1 = UIButton()
      b1.setTitle("toggle completed", for: .normal)
      b1.addTarget(self, action: #selector(toggleButton), for: .touchUpInside)
      let b2 = UIButton()
      b2.setTitle("toggle favorited", for: .normal)
      b2.addTarget(self, action: #selector(favButton), for: .touchUpInside)
      let sv = UIStackView(arrangedSubviews: [b1,b2])
      sv.axis = .vertical
      sv.translatesAutoresizingMaskIntoConstraints = false
      view.addSubview(sv)
      sv.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
      sv.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
   }

   @objc func toggleButton() {
      toggleCompleted.onNext("todo1")
   }
   @objc func favButton() {
      toggleFavorited.onNext("todo1")
   }



   override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
      loadData.onNext(())
   }
}


func withTodoCompleted(title: String, in todos: [Todo]) -> [Todo] {

   func toggle(todo: Todo) -> Todo {
      var todo = todo
      todo.isCompleted = !todo.isCompleted
      return todo
   }

   return todos.map { $0.title == title ? toggle(todo: $0) : $0 }
}

func withTodoFavorited(title: String, in todos: [Todo]) -> [Todo] {

   func toggle(todo: Todo) -> Todo {
      var todo = todo
      todo.isFavorited = !todo.isFavorited
      return todo
   }

   return todos.map { $0.title == title ? toggle(todo: $0) : $0 }
}