import GoogleMaps

class MapViewController: UIViewController, GMSMapViewDelegate {
    var mapView: GMSMapView!
    var polygon: GMSPolygon!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 初始化地图
        let camera = GMSCameraPosition.camera(withLatitude: 37.7749, longitude: -122.4194, zoom: 12)
        mapView = GMSMapView.map(withFrame: view.bounds, camera: camera)
        mapView.delegate = self
        view.addSubview(mapView)
        
        // 创建多边形
        let path = GMSMutablePath()
        path.add(CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194))
        path.add(CLLocationCoordinate2D(latitude: 37.8049, longitude: -122.4194))
        path.add(CLLocationCoordinate2D(latitude: 37.8049, longitude: -122.3894))
        path.add(CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.3894))
        
        polygon = GMSPolygon(path: path)
        polygon.fillColor = UIColor(red: 0.25, green: 0, blue: 0, alpha: 0.2)
        polygon.strokeColor = .black
        polygon.strokeWidth = 2
        polygon.isTappable = true
        polygon.map = mapView
    }
}

extension MapViewController {
    func mapView(_ mapView: GMSMapView, didTap overlay: GMSOverlay) {
        if let tappedPolygon = overlay as? GMSPolygon {
            // 选中多边形准备拖动
            polygon = tappedPolygon
            polygon.strokeColor = .red // 高亮显示选中的多边形
        }
    }
    
    func mapView(_ mapView: GMSMapView, didLongPressAt coordinate: CLLocationCoordinate2D) {
        guard let path = polygon.path else { return }
        
        // 找到离长按点最近的多边形顶点
        var closestPointIndex = 0
        var closestDistance = Double.greatestFiniteMagnitude
        
        for i in 0..<path.count() {
            let point = path.coordinate(at: i)
            let distance = GMSGeometryDistance(point, coordinate)
            if distance < closestDistance {
                closestDistance = distance
                closestPointIndex = i
            }
        }
        
        // 如果距离足够近，则认为是拖动顶点
        if closestDistance < 100 { // 100米阈值
            path.replaceCoordinate(at: closestPointIndex, with: coordinate)
            polygon.path = path
        }
    }
}