import UIKit
import Mapbox

class ViewController: UIViewController, MGLMapViewDelegate {
    var mapView : MGLMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        createUI()
    }
    
    func createUI() {
        let url = URL(string: "mapbox://styles/mapbox/streets-v11")
        mapView = MGLMapView(frame: view.bounds, styleURL: url)
        mapView.delegate = self
        mapView.setCenter(CLLocationCoordinate2D(latitude: 59.31, longitude: 18.06), zoomLevel: 9, animated: false)
        self.view.addSubview(mapView)
        mapView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            mapView.leftAnchor.constraint(equalTo: view.leftAnchor),
            mapView.rightAnchor.constraint(equalTo: view.rightAnchor),
            mapView.topAnchor.constraint(equalTo: view.topAnchor),
            mapView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
        ])
        
        let button1 = UIButton()
        button1.setTitle("up", for: .normal)
        button1.setTitleColor(.systemBlue, for: .normal)
        button1.backgroundColor = .systemBackground
        button1.addTarget(self, action: #selector(up), for: .touchUpInside)

    
        let button2 = UIButton()
        button2.setTitle("down", for: .normal)
        button2.setTitleColor(.systemBlue, for: .normal)
        button2.backgroundColor = .systemBackground
        button2.addTarget(self, action: #selector(down), for: .touchUpInside)
        
        let buttons = UIStackView(arrangedSubviews: [button1, button2])
        buttons.translatesAutoresizingMaskIntoConstraints = false
        buttons.spacing = 32.0
        self.view.addSubview(buttons)
        NSLayoutConstraint.activate([
            buttons.bottomAnchor.constraint(equalTo: self.view.layoutMarginsGuide.bottomAnchor),
            buttons.centerXAnchor.constraint(equalTo: self.view.centerXAnchor)
        ])
    }
    
    func bounds() -> MGLCoordinateBounds {
        let diff = 0.1
        let center = CLLocationCoordinate2D(latitude: 59.31, longitude: 18.06)
        let sw = CLLocationCoordinate2D(latitude: center.latitude - diff, longitude: center.longitude - diff);
        let ne = CLLocationCoordinate2D(latitude: center.latitude + diff, longitude: center.longitude + diff);

        return MGLCoordinateBounds(sw: sw, ne: ne);
    }
    
    func drawBounds(_ style: MGLStyle) {
        let b = bounds()
        let coordinates = [
            b.sw,
            CLLocationCoordinate2D(latitude: b.sw.latitude, longitude: b.ne.longitude),
            b.ne,
            CLLocationCoordinate2D(latitude: b.ne.latitude, longitude: b.sw.longitude),
            b.sw
        ]

        let polyline = MGLPolyline(coordinates: coordinates, count: UInt(coordinates.count))
        let source = MGLShapeSource(identifier: "polyline", shape: polyline, options: nil)
        style.addSource(source)
        
        let layer = MGLLineStyleLayer(identifier: "polyline", source: source)
        layer.lineColor = NSExpression(forConstantValue: UIColor.red)
        layer.lineWidth = NSExpression(forConstantValue: 4.0)
        style.addLayer(layer)
    }

    @objc
    func up() {
        let camera = mapView.camera(mapView.camera.copy() as! MGLMapCamera,
            fitting: bounds(),
            edgePadding:UIEdgeInsets(top: 200.0, left: 0, bottom: 0.0, right: 0))
        mapView.fly(to: camera, withDuration: 1.0, completionHandler: nil)
    }
    
    @objc
    func down() {
        let camera = mapView.camera(
            mapView.camera.copy() as! MGLMapCamera,
            fitting: bounds(),
            edgePadding:UIEdgeInsets(top: 0.0, left: 0, bottom: 200.0, right: 0))
        mapView.fly(to: camera, withDuration: 1.0, completionHandler: nil)
    }
    
    func mapView(_ mapView: MGLMapView, didFinishLoading style: MGLStyle ) {
        drawBounds(style)
    }
}

- (void)flyToCamera:(MGLMapCamera *)camera withDuration:(NSTimeInterval)duration peakAltitude:(CLLocationDistance)peakAltitude completionHandler:(nullable void (^)(void))completion;

- (void)setCamera:(MGLMapCamera *)camera withDuration:(NSTimeInterval)duration animationTimingFunction:(nullable CAMediaTimingFunction *)function edgePadding:(UIEdgeInsets)edgePadding completionHandler:(nullable void (^)(void))completion;