/**
 * TrackerMap
 * Copyright (C) 2021-2022  Iván Ávalos <avalos@disroot.org>, Henoch Ojeda <imhenoch@protonmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
import SwiftUI
import Combine
import WhirlyGlobeMaplyComponent
import shared

struct MapView: UIViewControllerRepresentable {
    typealias UIViewControllerType = OurMaplyViewController
    
    @Binding var mapLayer: MapLayer
    @Binding var markers: [Marker]
    var markerCallback: ((Int32?) -> Void)?
    var link: BaseMapLink
    
    class Coordinator: NSObject, MaplyViewControllerDelegate {
        var parent: MapView
        var uiViewController: OurMaplyViewController?
        var loader: MaplyQuadImageLoader? = nil
        
        // Source: https://stackoverflow.com/questions/65923718
        var cancellable: AnyCancellable?
        var link: BaseMapLink? {
            didSet {
                cancellable = link?.$action.sink(receiveValue: { action in
                    guard let action = action else {
                        return
                    }
                    self.uiViewController?.action(action)
                })
            }
        }
        
        init(_ uiViewController: MapView) {
            self.parent = uiViewController
        }
        
        func maplyViewController(_ viewC: MaplyViewController,
                                 didTapAt coord: MaplyCoordinate) {
            if let callback = parent.markerCallback {
                callback(nil)
            }
        }
        
        func maplyViewController(_ viewC: MaplyViewController,
                                 didSelect selectedObj: NSObject,
                                 atLoc coord: MaplyCoordinate,
                                 onScreen screenPt: CGPoint) {
            if let marker = selectedObj as? MaplyScreenMarker {
                if let id = marker.userObject as? Int32 {
                    if let callback = parent.markerCallback {
                        callback(id)
                    }
                }
            }
        }
    }
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    func makeUIViewController(context: Context) -> OurMaplyViewController {
        let mapViewController = OurMaplyViewController(mapType: .typeFlat)
        mapViewController.delegate = context.coordinator
        
        let tileInfo = Utils.tileInfoFrom(layer: mapLayer)
        mapViewController.setZoomLimits(minZoom: mapLayer.minZoom,
                                        maxZoom: mapLayer.maxZoom)
        
        let sampleParams = MaplySamplingParams()
        sampleParams.coordSys = MaplySphericalMercator(webStandard: ())
        sampleParams.coverPoles = true
        sampleParams.edgeMatching = true
        sampleParams.minZoom = tileInfo.minZoom
        sampleParams.maxZoom = tileInfo.maxZoom
        sampleParams.singleLevel = true
        sampleParams.maxTiles = 25
        
        let loader = MaplyQuadImageLoader(params: sampleParams, tileInfo: tileInfo, viewC: mapViewController)
        loader?.baseDrawPriority = kMaplyImageLayerDrawPriorityDefault
        loader?.imageFormat = .imageUShort565
        context.coordinator.loader = loader
        
        DispatchQueue.main.async {
            let point = MaplyCoordinateMakeWithDegrees(-100.36, 23.191)
            mapViewController.focusOn(point: point, height: 0.4, animated: false)
        }
        
        return mapViewController
    }
    
    func updateUIViewController(_ uiViewController: OurMaplyViewController, context: Context) {
        context.coordinator.uiViewController = uiViewController
        context.coordinator.link = link
        
        // MARK: - Set map layer
        context.coordinator.loader?.changeTileInfo(Utils.tileInfoFrom(layer: mapLayer))
        uiViewController.setZoomLimits(minZoom: mapLayer.minZoom,
                                       maxZoom: mapLayer.maxZoom)
        
        // MARK: - Set markers
        uiViewController.display(markers: markers,
                                 isReport: false)
    }
    
    static func dismantleUIViewController(_ uiViewController: MaplyViewController, coordinator: Coordinator) {
        coordinator.loader?.shutdown()
        uiViewController.teardown()
    }
}

class OurMaplyViewController: MaplyViewController {
    enum Action {
        case zoomIn
        case zoomOut
    }
    
    private var objects = [MaplyComponentObject]()
    private var geofenceObjects = [MaplyComponentObject]()
    
    func action(_ action: Action) {
        DispatchQueue.main.async {
            switch action {
            case .zoomIn:
                self.zoomIn()
            case .zoomOut:
                self.zoomOut()
            }
        }
    }
    
    func focusOn(point: MaplyCoordinate,
                 height: Float = 0.0000264,
                 animated: Bool = true) {
        let z = max(height, getMinZoom())
        if animated {
            animate(toPosition: point, height: z, time: 0.2)
        } else {
            setPosition(point, height: z)
        }
    }
    
    func zoomIn() {
        let pos = getPosition()
        let zoom = currentMapScale() / 2
        focusOn(point: pos, height: height(forMapScale: zoom))
    }
    
    func zoomOut() {
        let pos = getPosition()
        let zoom = currentMapScale() * 2
        focusOn(point: pos, height: height(forMapScale: zoom))
    }
    
    func clear(geofences: Bool = false) {
        if geofences {
            remove(geofenceObjects)
            geofenceObjects.removeAll()
        } else {
            remove(objects)
            objects.removeAll()
        }
    }
    
    func display(markers: [Marker],
                 isReport: Bool,
                 center: Bool = false) {
        clear()
        
        let points = markers.map { marker in
            MaplyCoordinateMakeWithDegrees(Float(marker.longitude),
                                           Float(marker.latitude))
        }
        
        let fontSize = 11.0
        let colorReport = Color.green
        let colorLabel = Color.secondary
        let colorLabelOutline = Color.systemBackground
        
        let vectorDesc: [AnyHashable : Any] = [
            kMaplyColor: colorReport,
            kMaplyVecWidth: 20.0
        ]
        
        let labelDesc: [AnyHashable : Any] = [
            kMaplyFont: UIFont.boldSystemFont(ofSize: fontSize),
            kMaplyTextColor: colorLabel,
            kMaplyTextOutlineColor: colorLabelOutline,
            kMaplyTextOutlineSize: 3.0
        ]
    
        /* MARK: - Draw markers for positions */
        let screenMarkers = markers.enumerated().map { (i, marker) -> MaplyScreenMarker in
            let screenMarker = MaplyScreenMarker()
            screenMarker.layoutImportance = .greatestFiniteMagnitude
            screenMarker.loc = MaplyCoordinateMakeWithDegrees(Float(marker.longitude),
                                                              Float(marker.latitude))
            var type: Marker.Type_ = .default_
            if isReport {
                // For reports, position, start and end icons must be different
                switch i {
                case markers.startIndex: type = .reportStart
                case markers.endIndex: type = .reportEnd
                default: type = .reportPosition
                }
            } else {
                type = marker.type
            }
            screenMarker.image = getIcon(markerType: type)
            
            var size = 50.0
            if isReport {
                // For reports, position, start and end sizes must be different
                switch i {
                case markers.startIndex: size = 50.0
                case markers.endIndex: size = 50.0
                default: size = 25.0
                }
            }
            screenMarker.size = CGSize(width: size, height: size)
            screenMarker.userObject = marker.id
            screenMarker.selectable = true
            
            return screenMarker
        }
        
        if let objs = addScreenMarkers(screenMarkers, desc: nil, mode: .any) {
            objects.append(objs)
        }
        
        /* MARK: - Add labels for markers */
        if !isReport && !markers.isEmpty {
            let screenLabels = markers.map { marker -> MaplyScreenLabel in
                let label = MaplyScreenLabel()
                label.layoutImportance = .greatestFiniteMagnitude
                var text = marker.name
                if marker.name.count >= 20 {
                    let end = marker.name.index(marker.name.startIndex, offsetBy: 20)
                    text = String(marker.name[..<end])
                }
                label.text = text
                label.loc = MaplyCoordinateMakeWithDegrees(Float(marker.longitude),
                                                           Float(marker.latitude))
                label.offset = CGPoint(x: 0.0, y: 25.0)
                
                return label
            }
            
            if let objs = addScreenLabels(screenLabels, desc: labelDesc) {
                objects.append(objs)
            }
        }
        
        /* MARK: - Draw polyline for report */
        if isReport && !markers.isEmpty {
            let geoJSON: [AnyHashable : Any] = [
                "type": "FeatureCollection",
                "features": [
                    [
                        "type": "LineString",
                        "coordinates": points.map({ point in
                            [point.x, point.y]
                        })
                    ]
                ]
            ]
            if let vector = MaplyVectorObject(fromGeoJSONDictionary: geoJSON) {
                if let objs = addVectors([vector], desc: vectorDesc, mode: .any) {
                    objects.append(objs)
                }
            }
        }
        
        /* MARK: - Center map to bounds */
        if center && !markers.isEmpty {
            let box = MaplyBoundingBoxExpandByFraction(
                MaplyBoundingBoxFromCoordinates(points, UInt32(points.count)), 0.1)
            let center = MaplyCoordinate(x: (box.ur.x + box.ll.x) / 2,
                                         y: (box.ur.y + box.ll.y) / 2)
            let zoom = max(findHeight(toViewBounds: box, pos: center), getMinZoom())
            setPosition(center, height: zoom)
        }
    }
    
    func setZoomLimits(minZoom: Int32, maxZoom: Int32) {
        setZoomLimitsMin(
            height(forMapScale: Float(truncating:
                MapCalculus.companion.zoomLevelToScale(zoom: maxZoom)
                ?? MapCalculus.companion.zoomLevelToScale(zoom: 21)!
            )),
            max: height(forMapScale: Float(truncating:
                MapCalculus.companion.zoomLevelToScale(zoom: minZoom)
                ?? MapCalculus.companion.zoomLevelToScale(zoom: 1)!
            )))
    }
    
    private func getIcon(markerType: Marker.Type_) -> UIImage {
        return UIImage(named: MarkerTransformations
                        .markerTypeToImageName(markerType: markerType))!
    }
}

// Source: https://stackoverflow.com/questions/65923718
class BaseMapLink: ObservableObject {
    @Published var action: OurMaplyViewController.Action?
    
    func zoomIn() {
        action = .zoomIn
    }
    
    func zoomOut() {
        action = .zoomOut
    }
}