LocationManager.swift

import CoreLocation

enum LocationAuthorizationStatus {
    case always
    case whenInUse
}

final class LocationManager: NSObject, CLLocationManagerDelegate {
    
    typealias LocationAuthorizationCompletion = (CLAuthorizationStatus) -> Void
    typealias LocationRequestCompletion = (CLLocation?) -> Void
    typealias LocationUpdatesBlock = (CLLocation?) -> Void
    
    static let shared: LocationManager = LocationManager()
        
    final fileprivate var statusCompletion: LocationAuthorizationCompletion?
    final fileprivate var locationRequestCompletion: LocationRequestCompletion?
    
    final let manager: CLLocationManager = CLLocationManager()
    
    final var locationUpdates: LocationUpdatesBlock?
    
    private override init() {
        super.init()
        self.setupCommon()
    }
    
    final fileprivate func setupCommon() {
        self.manager.delegate = self
    }
    
    final func request(withAuthorizationStatus status: LocationAuthorizationStatus, and completion: @escaping LocationAuthorizationCompletion) {
        self.statusCompletion = completion
        switch status {
        case .always:
            self.manager.requestAlwaysAuthorization()
            break
        case .whenInUse:
            self.manager.requestWhenInUseAuthorization()
            break
        }
    }
    
    final func startUpdatingLocation() {
        self.manager.startUpdatingLocation()
    }
    
    final func stopUpdatingLocation() {
        self.manager.stopUpdatingLocation()
    }
    
    final func requestCurrentLocation(with completion: @escaping LocationRequestCompletion) {
        self.locationRequestCompletion = completion
        self.manager.startUpdatingLocation()
    }
    
    final func startMonitoringSignificantLocationChanges() {
        self.manager.startMonitoringSignificantLocationChanges()
    }
    
    final func stopMonitoringSignificantLocationChanges() {
        self.manager.stopMonitoringSignificantLocationChanges()
    }

    // MARK: CLLocationManagerDelegate Methods
    
    final func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
        self.statusCompletion?(status)
    }
    
    final func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        if let lastLocation = locations.last {
            if self.locationRequestCompletion != nil {
                self.stopUpdatingLocation()
                self.locationRequestCompletion?(lastLocation)
                self.locationRequestCompletion = nil
            }
            self.userLocation.value = lastLocation
            self.locationUpdates?(lastLocation)
        }
    }
    
    final func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        if self.locationRequestCompletion != nil {
            self.stopUpdatingLocation()
            self.locationRequestCompletion?(nil)
            self.locationRequestCompletion = nil
        }
    }
    
}