import Foundation
import UIKit
import AsyncDisplayKit
import Display
import SwiftSignalKit
import MapKit

let defaultMapSpan = MKCoordinateSpan(latitudeDelta: 0.016, longitudeDelta: 0.016)
let viewMapSpan = MKCoordinateSpan(latitudeDelta: 0.008, longitudeDelta: 0.008)
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
        }
    }
}

private class PickerAnnotationContainerView: UIView {
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        let result = super.hitTest(point, with: event)
        if result == self {
            return nil
        }
        return result
    }
}

private class LocationMapView: MKMapView, UIGestureRecognizerDelegate {
    var customHitTest: ((CGPoint) -> Bool)?
    private var allowSelectionChanges = true
    
    @objc override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if let customHitTest = self.customHitTest, customHitTest(gestureRecognizer.location(in: self)) {
            return false
        }
        return self.allowSelectionChanges
    }
    
    public override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        let pointInside = super.point(inside: point, with: event)
        if !pointInside {
            return pointInside
        }
        
        for annotation in self.annotations(in: self.visibleMapRect) where annotation is LocationPinAnnotation {
            guard let view = self.view(for: annotation as! MKAnnotation) else {
                continue
            }
            if view.frame.insetBy(dx: -16.0, dy: -16.0).contains(point) {
                self.allowSelectionChanges = true
                return true
            }
        }
        self.allowSelectionChanges = false
        
        return pointInside
    }
}

func generateHeadingArrowImage() -> UIImage? {
    return generateImage(CGSize(width: 88.0, height: 88.0), contextGenerator: { size, context in
        let bounds = CGRect(origin: CGPoint(), size: size)
        context.clear(bounds)
    
        context.move(to: CGPoint(x: 44.0, y: 44.0))
        context.addArc(center: CGPoint(x: 44.0, y: 44.0), radius: 44.0, startAngle: CGFloat.pi / 2.0 + CGFloat.pi / 6.0, endAngle: CGFloat.pi / 2.0 - CGFloat.pi / 6.0, clockwise: true)
        context.clip()
        
        var locations: [CGFloat] = [0.0, 0.5, 1.0]
        let colors: [CGColor] = [UIColor(rgb: 0x007ee5, alpha: 0.0).cgColor, UIColor(rgb: 0x007ee5, alpha: 0.75).cgColor, UIColor(rgb: 0x007ee5, alpha: 0.0).cgColor]
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let gradient = CGGradient(colorsSpace: colorSpace, colors: colors as CFArray, locations: &locations)!
        
        context.drawLinearGradient(gradient, start: CGPoint(), end: CGPoint(x: 0.0, y: bounds.size.height), options: CGGradientDrawingOptions())
    })
}

private func generateProximityDim(size: CGSize, rect: CGRect) -> UIImage {
    return generateImage(size, rotatedContext: { size, context in
        context.clear(CGRect(origin: CGPoint(), size: size))
        context.setFillColor(UIColor(rgb: 0x000000, alpha: 0.4).cgColor)
        context.fill(CGRect(origin: CGPoint(), size: size))
        
        context.setBlendMode(.clear)
        context.fillEllipse(in: rect)
    })!
}

final class LocationMapNode: ASDisplayNode, MKMapViewDelegate {
    private let locationPromise = Promise<CLLocation?>(nil)
    
    private let pickerAnnotationContainerView: PickerAnnotationContainerView
    private weak var userLocationAnnotationView: MKAnnotationView?
    private var headingArrowView: UIImageView?
    
    private let pinDisposable = MetaDisposable()
    
    private var mapView: LocationMapView? {
        return self.view as? LocationMapView
    }
    
    var returnedToUserLocation = true
    var ignoreRegionChanges = false
    var isDragging = false
    var beganInteractiveDragging: (() -> Void)?
    var endedInteractiveDragging: ((CLLocationCoordinate2D) -> Void)?
    
    var annotationSelected: ((LocationPinAnnotation?) -> Void)?
    var userLocationAnnotationSelected: (() -> Void)?
        
    var proximityDimView = UIImageView()
    var proximityRadius: Double? {
        didSet {
            if let radius = self.proximityRadius, let mapView = self.mapView {
                let region = MKCoordinateRegion(center: mapView.userLocation.coordinate, latitudinalMeters: radius * 2.0, longitudinalMeters: radius * 2.0)
                let rect = mapView.convert(region, toRectTo: mapView)
                if proximityDimView.image == nil {
                    proximityDimView.layer.animateAlpha(from: 0.0, to: 1.0, duration: 0.2)
                }
                
                if oldValue == 0 {
                    UIView.transition(with: proximityDimView, duration: 0.2, options: .transitionCrossDissolve) {
                        self.proximityDimView.image = generateProximityDim(size: mapView.bounds.size, rect: rect)
                    } completion: { _ in
                        
                    }
                } else {
                    proximityDimView.image = generateProximityDim(size: mapView.bounds.size, rect: rect)
                }
            } else {
                if proximityDimView.image != nil {
                    UIView.transition(with: proximityDimView, duration: 0.2, options: .transitionCrossDissolve) {
                        self.proximityDimView.image = nil
                    } completion: { _ in
                        
                    }
                }
            }
        }
    }
    
    override init() {
        self.pickerAnnotationContainerView = PickerAnnotationContainerView()
        self.pickerAnnotationContainerView.isHidden = true
        
        super.init()
        
        self.setViewBlock({
            return LocationMapView()
        })
    }
    
    override func didLoad() {
        super.didLoad()
        
        self.headingArrowView = UIImageView()
        self.headingArrowView?.frame = CGRect(origin: CGPoint(), size: CGSize(width: 88.0, height: 88.0))
        self.headingArrowView?.image = generateHeadingArrowImage()
        
        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
        self.mapView?.customHitTest = { [weak self] point in
            guard let strongSelf = self, let annotationView = strongSelf.customUserLocationAnnotationView else {
                return false
            }
            
            if let annotationRect = annotationView.superview?.convert(annotationView.frame.insetBy(dx: -16.0, dy: -16.0), to: strongSelf.mapView), annotationRect.contains(point) {
                strongSelf.userLocationAnnotationSelected?()
                return true
            }
            
            return false
        }
        
        self.mapView?.addSubview(self.proximityDimView)
        self.view.addSubview(self.pickerAnnotationContainerView)
    }
    
    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(), isUserLocation: Bool = false, hidePicker: Bool = false, 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
        
        if isUserLocation {
            if !self.returnedToUserLocation {
                self.returnedToUserLocation = true
                self.pickerAnnotationView?.setRaised(true, animated: true)
            }
        } else if self.hasPickerAnnotation, let customUserLocationAnnotationView = self.customUserLocationAnnotationView, customUserLocationAnnotationView.isHidden, hidePicker {
            self.pickerAnnotationContainerView.isHidden = true
            customUserLocationAnnotationView.setSelected(false, animated: false)
            customUserLocationAnnotationView.isHidden = false
            customUserLocationAnnotationView.animateAppearance()
        }
    }
    
    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.isDragging = true
                self.returnedToUserLocation = false
                self.beganInteractiveDragging?()
                
                self.switchToPicking(raise: true, animated: true)
                break
            }
        }
    }
    
    func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
        let wasDragging = self.isDragging
        if self.isDragging {
            self.isDragging = false
            if let coordinate = self.mapCenterCoordinate {
                self.endedInteractiveDragging?(coordinate)
            }
        }
        
        if let pickerAnnotationView = self.pickerAnnotationView {
            if pickerAnnotationView.isRaised && (wasDragging || self.returnedToUserLocation) {
                self.schedulePin(wasDragging: wasDragging)
            }
        }
    }
    
    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
                if let headingArrowView = self.headingArrowView {
                    view.addSubview(headingArrowView)
                    headingArrowView.center = CGPoint(x: view.frame.width / 2.0, y: view.frame.height / 2.0)
                }
                if let annotationView = self.customUserLocationAnnotationView {
                    view.addSubview(annotationView)
                }
            } else if let view = view as? LocationPinAnnotationView {
                view.setZPosition(view.defaultZPosition)
            }
        }
    }
    
    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)
        
        if let annotationView = self.customUserLocationAnnotationView, annotationView.isSelected {
            annotationView.setSelected(false, animated: true)
        }
    }
    
    func mapView(_ mapView: MKMapView, didDeselect view: MKAnnotationView) {
        if let view = view as? LocationPinAnnotationView {
            Queue.mainQueue().after(0.2) {
                view.setZPosition(view.defaultZPosition)
            }
        }
        
        Queue.mainQueue().after(0.05) {
            if mapView.selectedAnnotations.isEmpty {
                if !self.isDragging {
                    self.annotationSelected?(nil)
                }
                if let annotationView = self.customUserLocationAnnotationView, !annotationView.isSelected {
                    annotationView.setSelected(true, animated: true)
                }
            }
        }
    }
    
    var circleOverlay: MKCircle?
    var activeProximityRadius: Double? {
        didSet {
            if let activeProximityRadius = self.activeProximityRadius {
                if let circleOverlay = self.circleOverlay {
                    self.circleOverlay = nil
                    self.mapView?.removeOverlay(circleOverlay)
                }
                if let location = self.currentUserLocation {
                    let overlay = MKCircle(center: location.coordinate, radius: activeProximityRadius)
                    self.circleOverlay = overlay
                    self.mapView?.addOverlay(overlay)
                }
            } else {
                if let circleOverlay = self.circleOverlay {
                    self.circleOverlay = nil
                    self.mapView?.removeOverlay(circleOverlay)
                }
            }
        }
    }
    
    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        if let circle = overlay as? MKCircle {
            let renderer = MKCircleRenderer(circle: circle)
            renderer.fillColor = .clear
            renderer.strokeColor = UIColor(rgb: 0xc3baaf)
            renderer.lineWidth = 1.0
            renderer.lineDashPattern = [5, 3]
            return renderer
        } else {
            return MKOverlayRenderer()
        }
    }
    
    var distance: Double? {
        if let annotation = self.annotations.first, let location = self.currentUserLocation {
            return location.distance(from: CLLocation(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude))
        }
        return nil
    }
    
    var currentUserLocation: CLLocation? {
        return self.mapView?.userLocation.location
    }
    
    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)
    }
    
    var mapSpan: MKCoordinateSpan? {
        guard let mapView = self.mapView else {
            return nil
        }
        return mapView.region.span
    }
    
    func resetAnnotationSelection() {
        guard let mapView = self.mapView else {
            return
        }
        for annotation in mapView.selectedAnnotations {
            mapView.deselectAnnotation(annotation, animated: true)
        }
    }
    
    var pickerAnnotationView: LocationPinAnnotationView? = nil
    var hasPickerAnnotation: Bool = false {
        didSet {
            if self.hasPickerAnnotation, let annotation = self.userLocationAnnotation {
                let pickerAnnotationView = LocationPinAnnotationView(annotation: annotation)
                pickerAnnotationView.center = CGPoint(x: self.pickerAnnotationContainerView.frame.width / 2.0, y: self.pickerAnnotationContainerView.frame.height / 2.0 + 16.0)
                self.pickerAnnotationContainerView.addSubview(pickerAnnotationView)
                self.pickerAnnotationView = pickerAnnotationView
            } else {
                self.pickerAnnotationView?.removeFromSuperview()
                self.pickerAnnotationView = nil
            }
        }
    }
    
    func switchToPicking(raise: Bool = false, animated: Bool) {
        guard self.hasPickerAnnotation else {
            return
        }
        
        self.customUserLocationAnnotationView?.isHidden = true
        self.pickerAnnotationContainerView.isHidden = false
        if let pickerAnnotationView = self.pickerAnnotationView, !pickerAnnotationView.isRaised {
            pickerAnnotationView.setCustom(true, animated: animated)
            if raise {
                pickerAnnotationView.setRaised(true, animated: animated)
            }
        }
        self.resetAnnotationSelection()
        self.resetScheduledPin()
    }
    
    var customUserLocationAnnotationView: LocationPinAnnotationView? = nil
    var userLocationAnnotation: LocationPinAnnotation? = nil {
        didSet {
            if let annotation = self.userLocationAnnotation {
                self.customUserLocationAnnotationView?.removeFromSuperview()
                
                let annotationView = LocationPinAnnotationView(annotation: annotation)
                annotationView.frame = annotationView.frame.offsetBy(dx: 21.0, dy: 22.0)
                if let parentView = self.userLocationAnnotationView {
                    parentView.addSubview(annotationView)
                }
                self.customUserLocationAnnotationView = annotationView
                
                self.pickerAnnotationView?.annotation = annotation
            } else {
                self.customUserLocationAnnotationView?.removeFromSuperview()
                self.customUserLocationAnnotationView = nil
            }
        }
    }
    
    var userHeading: CGFloat? = nil {
        didSet {
            if let heading = self.userHeading {
                self.headingArrowView?.isHidden = false
                self.headingArrowView?.transform = CGAffineTransform(rotationAngle: CGFloat(heading / 180.0 * CGFloat.pi))
            } else {
                self.headingArrowView?.isHidden = true
                self.headingArrowView?.transform = CGAffineTransform.identity
            }
        }
    }
    
    var annotations: [LocationPinAnnotation] = [] {
        didSet {
            guard let mapView = self.mapView else {
                return
            }
            
            var dict: [String: LocationPinAnnotation] = [:]
            for annotation in self.annotations {
                dict[annotation.id] = annotation
            }
            
            var annotationsToRemove = Set<LocationPinAnnotation>()
            for annotation in mapView.annotations {
                guard let annotation = annotation as? LocationPinAnnotation else {
                    continue
                }
                
                if let updatedAnnotation = dict[annotation.id] {
                    annotation.coordinate = updatedAnnotation.coordinate
                    dict[annotation.id] = nil
                } else {
                    annotationsToRemove.insert(annotation)
                }
            }
            
            mapView.removeAnnotations(Array(annotationsToRemove))
            mapView.addAnnotations(Array(dict.values))
        }
    }
    
    private func schedulePin(wasDragging: Bool) {
        let timeout: Double = wasDragging ? 0.38 : 0.05
         
         let signal: Signal<Never, NoError> = .complete()
         |> delay(timeout, queue: Queue.mainQueue())
         self.pinDisposable.set(signal.start(completed: { [weak self] in
            guard let strongSelf = self, let pickerAnnotationView = strongSelf.pickerAnnotationView else {
                return
            }
            
            pickerAnnotationView.setRaised(false, animated: true) { [weak self] in
                guard let strongSelf = self else {
                    return
                }
               
                if strongSelf.returnedToUserLocation {
                    strongSelf.pickerAnnotationContainerView.isHidden = true
                    strongSelf.customUserLocationAnnotationView?.isHidden = false
                }
            }
            
            if strongSelf.returnedToUserLocation {
                pickerAnnotationView.setCustom(false, animated: true)
            }
         }))
    }
    
    private func resetScheduledPin() {
        self.pinDisposable.set(nil)
    }
    
    func showAll(animated: Bool = true) {
        guard let mapView = self.mapView else {
            return
        }
        var annotations: [MKAnnotation] = []
        if let userAnnotation = self.userLocationAnnotation {
            annotations.append(userAnnotation)
        }
        annotations.append(contentsOf: self.annotations)
        
        var zoomRect: MKMapRect = MKMapRect()
        for annotation in annotations {
            let pointRegionRect = MKMapRect(region: MKCoordinateRegion(center: annotation.coordinate, latitudinalMeters: 100, longitudinalMeters: 100))
            zoomRect = zoomRect.union(pointRegionRect)
        }
        
        let insets = UIEdgeInsets()
        zoomRect = mapView.mapRectThatFits(zoomRect, edgePadding: insets)
        mapView.setVisibleMapRect(zoomRect, animated: animated)
    }
    
    func updateLayout(size: CGSize) {
        self.proximityDimView.frame = CGRect(origin: CGPoint(), size: size)
        self.pickerAnnotationContainerView.frame = CGRect(x: 0.0, y: floorToScreenPixels((size.height - size.width) / 2.0), width: size.width, height: size.width)
        if let pickerAnnotationView = self.pickerAnnotationView {
            pickerAnnotationView.center = CGPoint(x: self.pickerAnnotationContainerView.frame.width / 2.0, y: self.pickerAnnotationContainerView.frame.height / 2.0)
        }
    }
}