NetworkViewModel.swift

import Foundation
import Combine

protocol NetworkViewModel: ObservableObject {

	associatedtype NetworkResource: Decodable

	var objectWillChange: ObservableObjectPublisher { get }
	var resource: Resource<NetworkResource> { get set }
	var network: Network { get set }
	var route: NetworkRoute { get }
	var bag: Set<AnyCancellable> { get set }

	func onAppear()
}

extension NetworkViewModel {

	func fetch(route: NetworkRoute) {

		(network.fetch(route: route) as AnyPublisher<NetworkResource, Error>)
			.receive(on: RunLoop.main)
			.sink(receiveCompletion: { completion in
				switch completion {
				case .failure(let error):
					self.resource = .error(error)
					self.objectWillChange.send()
				default:
					break
				}
			}, receiveValue: { decodable in
				self.resource = .success(decodable)
				self.objectWillChange.send()
			})
			.store(in: &bag)
	}

	func onAppear() {
		fetch(route: route)
	}
}