Show service area

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// Copyright 2024 Esri
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import ArcGIS
import SwiftUI

struct ShowServiceAreaView: View {
    // MARK: - View

    /// The currently selected graphic type.
    ///
    /// Used to track whether to add facilities or barriers to the map.
    @State private var selectedGraphicType: GraphicType = .facility
    /// The error shown in the error alert.
    @State private var error: Error?
    /// First time break property set in first stepper.
    @State private var firstTimeBreak: Int = 3
    /// Second time break property set in second stepper.
    @State private var secondTimeBreak: Int = 8
    /// A Boolean value indicating whether the time breaks settings are presented.
    @State private var settingsArePresented = false

    /// The data model for the sample.
    @StateObject private var model = Model()

    var body: some View {
        MapView(map: model.map, graphicsOverlays: model.graphicsOverlays)
            .onSingleTapGesture { _, point in
                switch selectedGraphicType {
                case .facility:
                    model.addFacilityGraphic(at: point)
                case .barrier:
                    model.addBarrierGraphic(at: point)
                }
            }
            .toolbar {
                ToolbarItemGroup(placement: .bottomBar) {
                    Picker("Mode", selection: $selectedGraphicType) {
                        ForEach(GraphicType.allCases, id: \.self) {
                            Text($0.label)
                        }
                    }
                    .pickerStyle(.segmented)
                    Spacer()
                    Button("Time Breaks", systemImage: "gear") {
                        settingsArePresented = true
                    }
                    .popover(isPresented: $settingsArePresented) {
                        NavigationStack {
                            Form {
                                Stepper("First: \(firstTimeBreak)", value: $firstTimeBreak, in: 1...15)
                                Stepper("Second: \(secondTimeBreak)", value: $secondTimeBreak, in: 1...15)
                            }
                            .navigationTitle("Time Breaks")
                            .navigationBarTitleDisplayMode(.inline)
                            .toolbar {
                                ToolbarItem(placement: .confirmationAction) {
                                    Button("Done") { settingsArePresented = false }
                                }
                            }
                        }
                        .presentationDetents([.fraction(0.25)])
                        .frame(idealWidth: 320, idealHeight: 160)
                    }
                    Spacer()
                    Button("Service Area") {
                        Task {
                            do {
                                try await model.showServiceArea(timeBreaks: [Double(firstTimeBreak), Double(secondTimeBreak)])
                            } catch {
                                self.error = error
                            }
                        }
                    }
                    Spacer()
                    Button("Clear", systemImage: "trash") {
                        model.removeAllGraphics()
                    }
                }
            }
            .errorAlert(presentingError: $error)
    }
}

private extension ShowServiceAreaView {
    // MARK: - GraphicType

    enum GraphicType: Equatable, CaseIterable {
        case facility, barrier

        /// The string representation of this graphic type.
        var label: String {
            switch self {
            case .barrier: "Barriers"
            case .facility: "Facilities"
            }
        }
    }
}

private extension ShowServiceAreaView {
    // MARK: - Model

    @MainActor
    class Model: ObservableObject {
        /// A map with terrain style centered over San Diego.
        let map: Map = {
            let map = Map(basemapStyle: .arcGISTerrain)
            map.initialViewpoint = Viewpoint(
                center: Point(
                    x: -13041154,
                    y: 3858170,
                    spatialReference: .webMercator
                ),
                scale: 60_000
            )
            return map
        }()

        private let facilitiesGraphicsOverlay: GraphicsOverlay = {
            let facilitiesGraphicsOverlay = GraphicsOverlay()
            let facilitySymbol = PictureMarkerSymbol(image: .pinBlueStar)
            // Offsets symbol in Y to align image properly.
            facilitySymbol.offsetY = 21
            // Assigns renderer on facilities graphics overlay using the picture marker symbol.
            facilitiesGraphicsOverlay.renderer = SimpleRenderer(symbol: facilitySymbol)
            return facilitiesGraphicsOverlay
        }()

        private let barriersGraphicsOverlay: GraphicsOverlay = {
            let barriersGraphicsOverlay = GraphicsOverlay()
            let barrierSymbol = SimpleFillSymbol(style: .diagonalCross, color: .red, outline: nil)
            // Sets symbol on barrier graphics overlay using renderer.
            barriersGraphicsOverlay.renderer = SimpleRenderer(symbol: barrierSymbol)
            return barriersGraphicsOverlay
        }()

        private let serviceAreaGraphicsOverlay = GraphicsOverlay()

        /// The graphics overlays used by this model.
        var graphicsOverlays: [GraphicsOverlay] {
            return [facilitiesGraphicsOverlay, barriersGraphicsOverlay, serviceAreaGraphicsOverlay]
        }

        private let serviceAreaTask = ServiceAreaTask(url: .serviceArea)

        private var serviceAreaParameters: ServiceAreaParameters!

        /// On user tapping on screen it add a facility graphic to the facilities overlay on the map at that point.
        /// - Parameter point: The coordinates for the graphic.
        func addFacilityGraphic(at point: Point) {
            let graphic = Graphic(geometry: point)
            facilitiesGraphicsOverlay.addGraphic(graphic)
        }

        /// On user tapping on screen it add a barrier graphic to the barriers overlay on the map at that point.
        /// - Parameter point: The coordinates for the graphic.
        func addBarrierGraphic(at point: Point) {
            let bufferedGeometry = GeometryEngine.buffer(around: point, distance: 500)
            let graphic = Graphic(geometry: bufferedGeometry)
            barriersGraphicsOverlay.addGraphic(graphic)
        }

        /// Gets the service area data and then renders the service area on the map.
        /// - Parameter timeBreaks: Double values that user sets for the impedance cutoffs.
        func showServiceArea(timeBreaks: [Double]) async throws {
            if serviceAreaParameters == nil {
                serviceAreaParameters = try await serviceAreaTask.makeDefaultParameters()
                serviceAreaParameters.geometryAtOverlap = .dissolve
            }
            serviceAreaGraphicsOverlay.removeAllGraphics()
            // Add the graphics to the overlays with their respective geometry types.
            serviceAreaParameters.setFacilities(
                facilitiesGraphicsOverlay.graphics.lazy.map { .init(point: $0.geometry as! Point) }
            )
            serviceAreaParameters.setPolygonBarriers(
                barriersGraphicsOverlay.graphics.lazy.map { .init(polygon: $0.geometry as! ArcGIS.Polygon) }
            )
            serviceAreaParameters.removeAllDefaultImpedanceCutoffs()
            serviceAreaParameters.addDefaultImpedanceCutoffs(timeBreaks)
            try await renderServiceAreaPolygons()
        }

        /// Asynchronously uses the service area task to solve for the service area using the parameters and then iterates through resulting
        /// polygons and creates a graphic which is added to the overlay for rendering.
        private func renderServiceAreaPolygons() async throws {
            let result = try await serviceAreaTask.solveServiceArea(using: serviceAreaParameters)
            let polygons = result.resultPolygons(forFacilityAtIndex: 0)
            for (offset, polygon) in polygons.enumerated() {
                let fillSymbol = makeServiceAreaSymbol(isFirst: offset == .zero)
                let graphic = Graphic(geometry: polygon.geometry, symbol: fillSymbol)
                serviceAreaGraphicsOverlay.addGraphic(graphic)
            }
        }

        /// Resets the graphics, removes the barriers, facilities and service area.
        func removeAllGraphics() {
            serviceAreaGraphicsOverlay.removeAllGraphics()
            facilitiesGraphicsOverlay.removeAllGraphics()
            barriersGraphicsOverlay.removeAllGraphics()
        }

        /// Sets the symbols drawn on that map for given selection.
        /// - Parameter isFirst: Tracks which element in is first in order to correctly set the color for the symbols.
        /// - Returns: Returns the symbol.
        private func makeServiceAreaSymbol(isFirst: Bool) -> Symbol {
            let lineSymbolColor: UIColor
            let fillSymbolColor: UIColor
            if isFirst {
                lineSymbolColor = UIColor(red: 0.4, green: 0.4, blue: 0, alpha: 0.3)
                fillSymbolColor = UIColor(red: 0.8, green: 0.8, blue: 0, alpha: 0.3)
            } else {
                lineSymbolColor = UIColor(red: 0, green: 0.4, blue: 0, alpha: 0.3)
                fillSymbolColor = UIColor(red: 0, green: 0.8, blue: 0, alpha: 0.3)
            }
            let outline = SimpleLineSymbol(style: .solid, color: lineSymbolColor, width: 2)
            return SimpleFillSymbol(style: .solid, color: fillSymbolColor, outline: outline)
        }
    }
}

#Preview {
    ShowServiceAreaView()
}

private extension URL {
    // MARK: - URLs

    static var serviceArea: URL {
        URL(string: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/NetworkAnalysis/SanDiego/NAServer/ServiceArea")!
    }
}