import CarPlay
import MapKit

class CarPlaySceneDelegate: NSObject {

    var interfaceController: CPInterfaceController?
    var mapTemplate: CPMapTemplate?
    var navigationSession: CPNavigationSession?

    // MARK: - Navigation Actions

    func startNavigation(
        instruction: String,
        distance: Double,
        eta: Double,
        maneuverType: Int
    ) {
        guard let mapTemplate = mapTemplate else { return }

        let origin = MKMapItem(
            placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: 0, longitude: 0))
        )
        let destination = MKMapItem(
            placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: 0, longitude: 0))
        )
        let trip = CPTrip(origin: origin, destination: destination)

        let session = mapTemplate.startNavigationSession(for: trip)
        self.navigationSession = session

        updateManeuver(instruction: instruction, distance: distance, maneuverType: maneuverType)
        updateArrivalEstimates(eta: eta)
    }

    func updateManeuver(instruction: String, distance: Double, maneuverType: Int) {
        guard let session = navigationSession else { return }

        let maneuver = CPManeuver()
        maneuver.instructionVariants = [instruction]
        if let color = maneuverColor(for: maneuverType) {
            maneuver.symbolColor = color
        }

        let distanceEstimate = CPTravelEstimates(
            distance: Measurement(value: distance, unit: UnitLength.meters),
            timeRemaining: 0
        )

        session.updateManeuvers([maneuver], travelEstimates: distanceEstimate)
    }

    func updateArrivalEstimates(eta: Double) {
        guard let session = navigationSession else { return }

        let arrivalEstimate = CPTravelEstimates(
            distance: Measurement(value: 0, unit: UnitLength.meters),
            timeRemaining: eta
        )
        // `updatingArrival` is deprecated; for iOS 15+ use `updating(_:)` on the maneuver's arrivalEstimates.
        // We keep this for broad compatibility.
        session.updatingArrival(to: arrivalEstimate)
    }

    func updateLocation(lat: Double, lng: Double, bearing: Double) {
        let center = CLLocationCoordinate2D(latitude: lat, longitude: lng)
        let region = MKCoordinateRegion(
            center: center,
            span: MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01)
        )
        mapTemplate?.showPanningInterface(animated: true)
    }

    func stopNavigation() {
        guard let session = navigationSession else { return }
        session.cancel()
        self.navigationSession = nil
        mapTemplate?.hideTripPreviews()
    }

    // MARK: - Helpers

    private func maneuverColor(for type: Int) -> UIColor? {
        switch type {
        case 4: return .systemGreen
        case 2, -2: return .systemBlue
        default: return nil
        }
    }
}

// MARK: - Shared State

class CarPlayState {
    static let shared = CarPlayState()
    weak var sceneDelegate: CarPlaySceneDelegate?
    private init() {}
}