struct Levels {
    let left: Int
    let right: Int
}

enum Event {
    case increaseLeft
    case decreaseLeft 
    case increaseRight
    case decreaseRight
}

func leftEffect(inputLevels: Levels) -> Observable<Event> {
    // this is the stop condition to our Spin
    guard inputLevels.left != inputLevels.right else { return .empty() }

    // this is the regulation for the left level
    if inputLevels.left < inputLevels.right {
        return .just(.increaseLeft)
    }  else {
        return .just(.decreaseLeft)
    }
}

func rightEffect(inputLevels: Levels) -> Observable<Event> {
    // this is the stop condition to our Spin
    guard inputLevels.left != inputLevels.right else { return .empty() }

    // this is the regulation for the right level
    if inputLevels.right < inputLevels.left {
        return .just(.increaseRight)
    }  else {
        return .just(.decreaseRight)
    }
}

func levelsReducer(currentLevels: Levels, event: Event) -> Levels {

	guard currentLevels.left != currentLevels.right else { return currentLevels }

	switch event {
	    case .decreaseLeft:
	        return Levels(left: currentLevels.left-1, right: currentLevels.right)
	    case .increaseLeft:
	        return Levels(left: currentLevels.left+1, right: currentLevels.right)
	    case .decreaseRight:
	        return Levels(left: currentLevels.left, right: currentLevels.right-1)
	    case .increaseRight:
	        return Levels(left: currentLevels.left, right: currentLevels.right+1)
	}
}

let levelsSpin = Spinner
    .initialState(Levels(left: 10, right: 20))
    .feedback(Feedback(effect: leftEffect))
    .feedback(Feedback(effect: rightEffect))
    .reducer(Reducer(levelsReducer))

Observable
    .stream(from: levelsSpin)
    .subscribe()
    .disposed(by: self.disposeBag)

Observable
    .start(spin: levelsSpin)
    .disposed(by: self.disposeBag)

let levelsSpin = Spinner
    .initialState(Levels(left: 10, right: 20))
    .feedback(Feedback(effect: leftEffect))
    .feedback(Feedback(effect: rightEffect))
    .reducer(Reducer(levelsReducer))
	
AnyPublisher
    .stream(from: levelsSpin)
    .sink(receiveCompletion: { _ in }, receiveValue: { _ in })
    .store(in: &cancellables)
	
or

AnyPublisher
    .start(spin: levelsSpin)
    .store(in: &cancellables)

let levelsSpin = Spin(initialState: Levels(left: 10, right: 20)) {
    Feedback(effect: leftEffect)
    Feedback(effect: rightEffect)
    Reducer(levelsReducer)
}

let levelsSpin = Spin(initialState: Levels(left: 10, right: 20)) {
    Feedback(effect: leftEffect)
    Feedback(effect: rightEffect)
    Reducer(levelsReducer)
}

Spinner
    .initialState(Levels(left: 10, right: 20), executeOn: MainScheduler.instance)
    .feedback(Feedback(effect: leftEffect, on: SerialDispatchQueueScheduler(qos: .userInitiated)))
    .feedback(Feedback(effect: rightEffect, on: SerialDispatchQueueScheduler(qos: .userInitiated)))
    .reducer(Reducer(levelsReducer))

Spin(initialState: Levels(left: 10, right: 20), executeOn: MainScheduler.instance) {
    Feedback(effect: leftEffect)
        .execute(on: SerialDispatchQueueScheduler(qos: .userInitiated))
    Feedback(effect: rightEffect)
        .execute(on: SerialDispatchQueueScheduler(qos: .userInitiated))
    Reducer(levelsReducer)
}

class MyUseCase {
    private let networkService: NetworkService
    private let cryptographicTool: CryptographicTool
    
    init(networkService: NetworkService, cryptographicTool: CryptographicTool) {
        self.networkService = networkService
        self.cryptographicTool = cryptographicTool
    }
    
    func load(state: MyState) -> AnyPublisher<MyEvent, Never> {
        guard state == .loading else return { Empty().eraseToAnyPublisher() }
        
        // use the deps here
        self.networkService
            .fetch()
            .map { [cryptographicTool] in cryptographicTool.decrypt($0) }
            ...
    }
}

// then we can build a Feedback with this UseCase
let myUseCase = MyUseCase(networkService: MyNetworkService(), cryptographicTool: MyCryptographicTool())
let feedback = Feedback(effect: myUseCase.load)

typealias LoadEffect: (MyState) -> AnyPublisher<MyEvent, Never>
func makeLoadEffect(networkService: NetworkService, cryptographicTool: CryptographicTool) -> LoadEffect {
   return { state in
       guard state == .loading else return { Empty().eraseToAnyPublisher() }
       
       networkService
            .fetch()
            .map { cryptographicTool.decrypt($0) }
            ...
   }
} 

// then we can build a Feedback using this factory function
let effect = makeLoadEffect(networkService: MyNetworkService(), cryptographicTool: MyCryptographicTool())
let feedback = Feedback(effect: effect)

func loadEffect(networkService: NetworkService,
                cryptographicTool: CryptographicTool,
                state: MyState) -> AnyPublisher<MyEvent, Never> {
    guard state == .loading else return { Empty().eraseToAnyPublisher() }
    
    networkService
            .fetch()
            .map 
}

// then we can build a Feedback directly using the appropriate initializer
let feedback = Feedback(effect: effect, dep1: MyNetworkService(), dep2: MyCryptographicTool())

func render(state: State) {
    switch state {
    case .increasing(let value):
        self.counterLabel.text = "\(value)"
        self.counterLabel.textColor = .green
    case .decreasing(let value):
        self.counterLabel.text = "\(value)"
        self.counterLabel.textColor = .red
    }
}

// previously defined or injected: counterSpin is the Spin that handles our counter business
self.uiSpin = UISpin(spin: counterSpin)

// self.uiSpin is now able to handle UI side effects

// we now want to attach the UI Spin to the rendering function of the ViewController:
self.uiSpin.render(on: self, using: { $0.render(state:) })

Observable
    .start(spin: self.uiSpin)
    .disposed(by: self.disposeBag)

self.uiSpin.start()
// the underlying reactive stream will be disposed once the uiSpin will be deinit

self.uiSpin.emit(Event.startCounter)

@ObservedObject
private var uiSpin: SwiftUISpin<State, Event> = {
    // previously defined or injected: counterSpin is the Spin that handles our counter business
    let spin = SwiftUISpin(spin: counterSpin)
    spin.start()
    return spin
}()

Button(action: {
    self.uiSpin.emit(Event.startCounter)
}) {
    Text("\(self.uiSpin.state.isCounterPaused ? "Start": "Stop")")
}

Toggle(isOn: self.uiSpin.binding(for: \.isPaused, event: .toggle) {
    Text("toggle")
}

// A Gear has its own event type:
enum GearEvent {
    case authorizationIssueHappened
}

let gear = Gear<GearEvent>()

let feedback = Feedback<State, Event>(attachedTo: gear, propagating: { (event: GearEvent) in
	if event == .authorizationIssueHappened {
		// the feedback will emit an event only in case of .authorizationIssueHappened
		return .checkAuthorization
	}
	return nil
})

// or with the short syntax

let feedback = Feedback<State, Event>(attachedTo: gear, catching: .authorizationIssueHappened, emitting: .checkAuthorization)

...
// then, create the Check Authorization Spin with this feedback
...

let feedback = Feedback<State, Event>(attachedTo: gear, propagating: { (state: State) in
	if state == .unauthorized {
		// only the .unauthorized state should trigger en event in the Gear
		return .authorizationIssueHappened
	}
	return nil
})

// or with the short syntax

let feedback = Feedback<State, Event>(attachedTo: gear, catching: .unauthorized, propagating: .authorizationIssueHappened)

...
// then, create the Feature Spin with this feedback
...