//
//  LocalAuthenticationService.swift
//  Touch ID and Face ID
//
//  Created by Elias Paulino on 06/09/19.
//  Copyright © 2019 Anderson Alencar. All rights reserved.
//

import Foundation
import LocalAuthentication

enum AuthError: Error {
    case BiometricsEvaluationIsntAvaliable, AuthenticationNotGranted
}

struct AuthenticationService {
    let laContext: LAContext = .init()

    // check if the iphone has auth support
    var biometricsIsAvaliable: Bool {
        var checkingError: NSError?
        return laContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &checkingError) && checkingError == nil
    }

    // checks if ther user is the iPhone owner.
    func checkUserIdentification(reason: String, completion: @escaping (Result<Bool, Error>) -> Void) {
        guard biometricsIsAvaliable else {
            completion(.failure(AuthError.BiometricsEvaluationIsntAvaliable))
            return
        }

        laContext.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { (sucess, error) in
            if let error = error {
                completion(.failure(error))
                return
            }

            completion(.success(sucess))
        }
    }
}