import Foundation
import Combine
import SwiftUI

extension Cancellable {
    func erase() -> AnyCancellable {
        return AnyCancellable(self)
    }
}

@available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
class BindablePublisher<Output>: BindableObject {
    var bag: [AnyCancellable] = []
    let didChange: AnyPublisher<Output, Never>
    public internal(set) var value: Output?

    public init<PublisherType: Publisher>
        (_ publisher: PublisherType)
        where Output == PublisherType.Output, PublisherType.Failure == Never {
            self.didChange = publisher.eraseToAnyPublisher()
            self.didChange
                .receive(on: RunLoop.main)
                .sink { self.value = $0 }
                .erase()
                .store(in: &bag)
    }
}

@available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
extension Publisher where Failure == Never {
    func bindableObject() -> BindablePublisher<Output> {
        return BindablePublisher(self)
    }
}