UIAlertController+Rx.swift

//
//  UIAlertController+Rx.swift
//

import Foundation
import RxSwift

protocol RxAlertActionType {
    associatedtype Result

    var title: String? { get }
    var style: UIAlertActionStyle { get }
    var result: Result { get }
}

struct RxAlertAction<R>: RxAlertActionType {
    typealias Result = R

    let title: String?
    let style: UIAlertActionStyle
    let result: R
}

struct RxDefaultAlertAction: RxAlertActionType {
    typealias Result = RxAlertControllerResult

    let title: String?
    let style: UIAlertActionStyle
    let result: Result
}

enum RxAlertControllerResult {
    case Ok
}

extension UIAlertController {
    static func rx_presentAlert<Action: RxAlertActionType, Result where Action.Result == Result>(viewController: UIViewController, title: String, message: String, preferredStyle: UIAlertControllerStyle = .Alert, animated: Bool = true, actions: [Action]) -> Observable<Result> {
        return Observable.create { observer -> Disposable in
            let alertController = UIAlertController(title: title, message: message, preferredStyle: preferredStyle)

            actions.map { rxAction in
                UIAlertAction(title: rxAction.title, style: rxAction.style, handler: { _ in
                    observer.onNext(rxAction.result)
                    observer.onCompleted()
                })
                }
                .forEach(alertController.addAction)

            viewController.presentViewController(alertController, animated: animated, completion: nil)

            return AnonymousDisposable { _ in
                alertController.dismissViewControllerAnimated(true, completion: nil)
            }
        }
    }
}