import Foundation

public protocol FocusableField: Hashable {
  var next: Self? { get }
}

extension FocusableField where Self: CaseIterable, Self: Equatable {
  
  public var next: Self? {
    
    guard let index = Self.allCases.firstIndex(of: self)
    else { return nil }
    
    let endIndex = Self.allCases.endIndex
    let nextIndex = Self.allCases.index(after: index)
    
    guard nextIndex < endIndex else { return nil }
    return Self.allCases[nextIndex]
    
  }
}