LONDON-IOS/GME Remit/Utilities/Database/Rx+UserDefaultsWrapper.swift

//
//  Rx+UserDefaultsWrapper.swift
//  GME Remit
//
//  Created by InKwon James Kim on 2020/01/10.
//  Copyright © 2020 Gobal Money Express Co. Ltd. All rights reserved.
//

import RxSwift
import RxCocoa

extension UserDefaultsWrapper: ReactiveCompatible {}

extension Reactive where Base: UserDefaults {
  public func `default`<E: Equatable>(_ type: E.Type, _ keyPath: String) -> Observable<E?> {
    let center = NotificationCenter.default
    let initial = base.object(forKey: keyPath) as? E
    let changes = center.rx.notification(UserDefaults.didChangeNotification)
      .map { _ in
        self.base.object(forKey: keyPath) as? E
    }
    
    return Observable<E?>.just(initial)
      .concat(changes)
      .distinctUntilChanged { previous, next in
        guard let previous = previous, let next = next else {
          return false
        }
        return previous == next
    }
  }
}

extension Reactive where Base: UserDefaultsWrapper<GMEDB.UserKeys> {
  func set(key: GMEDB.UserKeys) -> Binder<String?> {
    return Binder(self.base) { db, value in
      db.set(value, key)
    }
  }
  
  func string(key: GMEDB.UserKeys) -> Observable<String?> {
    return UserDefaults.standard.rx.default(String.self, key.rawValue)
  }
}