import Foundation
import Display
import SwiftSignalKit
import MapKit

let defaultMapSpan = MKCoordinateSpan(latitudeDelta: 0.016, longitudeDelta: 0.016)
private let pinOffset = CGPoint(x: 0.0, y: 33.0)

public enum LocationMapMode {
    case map
    case sattelite
    case hybrid
    
    var mapType: MKMapType {
        switch self {
            case .sattelite:
                return .satellite
            case .hybrid:
                return .hybrid
            default:
                return .standard
        }
    }
}

class LocationMapNode: ASDisplayNode, MKMapViewDelegate {
    private let locationPromise = Promise<CLLocation?>(nil)
    
    private weak var userLocationAnnotationView: MKAnnotationView?
    
    private var mapView: MKMapView? {
        return self.view as? MKMapView
    }
    
    var ignoreRegionChanges = false
    var dragging = false
    var beganInteractiveDragging: (() -> Void)?
    var endedInteractiveDragging: ((CLLocationCoordinate2D) -> Void)?
    var annotationSelected: ((LocationPinAnnotation?) -> Void)?
    
    override init() {
        super.init()
        
        self.setViewBlock({
            return MKMapView()
        })
    }
    
    override func didLoad() {
        super.didLoad()
        
        self.mapView?.interactiveTransitionGestureRecognizerTest = { p in
            if p.x > 44.0 {
                return true
            } else {
                return false
            }
        }
        self.mapView?.delegate = self
        self.mapView?.mapType = self.mapMode.mapType
        self.mapView?.isRotateEnabled = self.isRotateEnabled
        self.mapView?.showsUserLocation = true
        self.mapView?.showsPointsOfInterest = false
    }
    
    var isRotateEnabled: Bool = true {
        didSet {
            self.mapView?.isRotateEnabled = self.isRotateEnabled
        }
    }
    
    var mapMode: LocationMapMode = .map {
        didSet {
            self.mapView?.mapType = self.mapMode.mapType
        }
    }
    
    func setMapCenter(coordinate: CLLocationCoordinate2D, span: MKCoordinateSpan = defaultMapSpan, offset: CGPoint = CGPoint(), animated: Bool = false) {
        let region = MKCoordinateRegion(center: coordinate, span: span)
        self.ignoreRegionChanges = true
        if offset == CGPoint() {
            self.mapView?.setRegion(region, animated: animated)
        } else {
            let mapRect = MKMapRect(region: region)
            self.mapView?.setVisibleMapRect(mapRect, edgePadding: UIEdgeInsets(top: offset.y, left: offset.x, bottom: 0.0, right: 0.0), animated: animated)
        }
         self.ignoreRegionChanges = false
    }
    
    func mapView(_ mapView: MKMapView, regionWillChangeAnimated animated: Bool) {
        guard !self.ignoreRegionChanges, let scrollView = mapView.subviews.first, let gestureRecognizers = scrollView.gestureRecognizers else {
            return
        }
        
        for gestureRecognizer in gestureRecognizers {
            if gestureRecognizer.state == .began || gestureRecognizer.state == .ended {
                self.dragging = true
                self.beganInteractiveDragging?()
                break
            }
        }
    }
    
    func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
        if self.dragging, let coordinate = self.mapCenterCoordinate {
            self.dragging = false
            self.endedInteractiveDragging?(coordinate)
        }
    }
    
    func mapView(_ mapView: MKMapView, didUpdate userLocation: MKUserLocation) {
        guard let location = userLocation.location else {
            return
        }
        userLocation.title = ""
        self.locationPromise.set(.single(location))
    }
    
    func mapView(_ mapView: MKMapView, didFailToLocateUserWithError error: Error) {
        self.locationPromise.set(.single(nil))
    }
    
    func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        if annotation === mapView.userLocation {
            return nil
        }
        
        if let annotation = annotation as? LocationPinAnnotation {
            var view = mapView.dequeueReusableAnnotationView(withIdentifier: locationPinReuseIdentifier)
            if view == nil {
                view = LocationPinAnnotationView(annotation: annotation)
            }
            return view
        }
        
        return nil
    }
    
    func mapView(_ mapView: MKMapView, didAdd views: [MKAnnotationView]) {
        for view in views {
            if view.annotation is MKUserLocation {
                self.userLocationAnnotationView = view
            } else if let view = view as? LocationPinAnnotationView {
                view.setZPosition(-1.0)
            }
        }
    }
    
    func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
        guard let annotation = view.annotation as? LocationPinAnnotation else {
            return
        }
        
        if let view = view as? LocationPinAnnotationView {
            view.setZPosition(nil)
        }
        
        self.annotationSelected?(annotation)
    }
    
    func mapView(_ mapView: MKMapView, didDeselect view: MKAnnotationView) {
        if let view = view as? LocationPinAnnotationView {
            view.setZPosition(-1.0)
        }
        
        Queue.mainQueue().after(0.05) {
            if mapView.selectedAnnotations.isEmpty {
                self.annotationSelected?(nil)
            }
        }
    }
    
    var userLocation: Signal<CLLocation?, NoError> {
        return self.locationPromise.get()
    }
    
    var mapCenterCoordinate: CLLocationCoordinate2D? {
        guard let mapView = self.mapView else {
            return nil
        }
        return mapView.convert(CGPoint(x: (mapView.frame.width + pinOffset.x) / 2.0, y: (mapView.frame.height + pinOffset.y) / 2.0), toCoordinateFrom: mapView)
    }
    
    func resetAnnotationSelection() {
        guard let mapView = self.mapView else {
            return
        }
        for annotation in mapView.selectedAnnotations {
            mapView.deselectAnnotation(annotation, animated: true)
        }
    }
    
    
    var annotations: [LocationPinAnnotation] = [] {
        didSet {
            guard let mapView = self.mapView else {
                return
            }
            
            var dict: [String: LocationPinAnnotation] = [:]
            for annotation in self.annotations {
                if let identifier = annotation.location.venue?.id {
                    dict[identifier] = annotation
                }
            }
            
            var annotationsToRemove = Set<LocationPinAnnotation>()
            for annotation in mapView.annotations {
                guard let annotation = annotation as? LocationPinAnnotation else {
                    continue
                }
                
                if let identifier = annotation.location.venue?.id, let updatedAnnotation = dict[identifier] {
                    annotation.coordinate = updatedAnnotation.coordinate
                    dict[identifier] = nil
                } else {
                    annotationsToRemove.insert(annotation)
                }
            }
            
            mapView.removeAnnotations(Array(annotationsToRemove))
            mapView.addAnnotations(Array(dict.values))
        }
    }
}