import ViperServices

protocol Service1: AnyObject {
    func foo()
}

class Service1Impl: Service1, ViperService {
    
    func setupDependencies(_ container: ViperServicesContainer) -> [AnyObject]? {
        return [ // depends on
            container.resolve() as Service2
        ]
    }
    
    func boot(launchOptions: [UIApplication.LaunchOptionsKey : Any]?, completion: @escaping ViperServiceBootCompletion) {
        print("boot 1 called")
        completion(.succeeded) // sync completion
    }
    
    func foo() {
        print("foo 1 called")
    }
    
}

protocol Service2: AnyObject {
    func foo()
}

enum Service2Error: Error {
    case SomeError
}

class Service2Impl: Service2, ViperService {
    
    private weak var container: ViperServicesContainer!
    
    func setupDependencies(_ container: ViperServicesContainer) -> [AnyObject]? {
        self.container = container
        return nil
    }
    
    func boot(launchOptions: [UIApplication.LaunchOptionsKey : Any]?, completion: @escaping ViperServiceBootCompletion) {
        print("boot 2 called")
        DispatchQueue.main.asyncAfter(deadline: .now() + 3) { // async completion
            switch arc4random() % 2 { // emulate random result
            case 0:
                completion(.failed(error: Service2Error.SomeError))
            default:
                completion(.succeeded)
            }
            
        }
    }
    
    func foo() {
        print("foo 2 called")
    }
    
}

var window: UIWindow?

// use DefaultViperServicesContainer or implement your own container
let services = DefaultViperServicesContainer() 

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    
    try! services.register(Service1Impl() as Service1)
    try! services.register(Service2Impl() as Service2)
    
    services.boot(launchOptions: launchOptions) { (result) in
        switch result {
        case .succeeded:
            // All ok, now it is safe to use any service!
            (self.services.resolve() as Service1).foo()
            (self.services.resolve() as Service2).foo()
            
        case let .failed(failedServices):
            // Boot failed, show error to user
            let alert = UIAlertController(title: "Error",
                                      message: failedServices.first!.error.localizedDescription,
                                      preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
            self.window!.rootViewController?.present(alert, animated: false, completion: nil)
        }
    }
    
    return true
}