// Copyright 2020 Google LLC. All rights reserved.
//
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this
// file except in compliance with the License. You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under
// the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
// ANY KIND, either express or implied. See the License for the specific language governing
// permissions and limitations under the License.

import GoogleMaps
import UIKit

final class AnimatedCurrentLocationViewController: UIViewController {

  private var locationMarker: GMSMarker?

  private let locationManager = CLLocationManager()

  private lazy var mapView: GMSMapView = {
    let camera = GMSCameraPosition(latitude: 38.8879, longitude: -77.0200, zoom: 17)
    return GMSMapView(frame: .zero, camera: camera)
  }()

  override func loadView() {
    mapView.settings.myLocationButton = false
    mapView.settings.indoorPicker = false
    view = mapView
  }

  override func viewDidLoad() {
    super.viewDidLoad()

    // Setup location services
    guard CLLocationManager.locationServicesEnabled() else {
      print("Please enable location services")
      return
    }

    if CLLocationManager.authorizationStatus() == .denied {
      print("Please authorize location services")
      return
    }

    locationManager.requestWhenInUseAuthorization()
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.distanceFilter = 5.0
    locationManager.startUpdatingLocation()
  }
}

extension AnimatedCurrentLocationViewController: CLLocationManagerDelegate {
  func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
    if CLLocationManager.authorizationStatus() == .denied {
      print("Please authorize location services")
      return
    }
    print("Unable to get current location. Error: \(error.localizedDescription)")
  }

  func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    guard let location = locations.last else { return }
    if let existingMaker = locationMarker {
      CATransaction.begin()
      CATransaction.setAnimationDuration(2.0)
      existingMaker.position = location.coordinate
      CATransaction.commit()
    } else {
      let marker = GMSMarker(position: location.coordinate)
      // Animated walker images derived from a www.angryanimator.com tutorial.
      // See: http://www.angryanimator.com/word/2010/11/26/tutorial-2-walk-cycle/
      let animationFrames = (1...8).compactMap {
        UIImage(named: "step\($0)")
      }
      marker.icon = UIImage.animatedImage(with: animationFrames, duration: 0.8)
      // Taking into account walker's shadow.
      marker.groundAnchor = CGPoint(x: 0.5, y: 0.97)
      marker.map = mapView
      locationMarker = marker
    }
    mapView.animate(with: GMSCameraUpdate.setTarget(location.coordinate, zoom: 17))
  }
}