Set up location-driven geotriggers

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// Copyright 2021 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 UIKit
import ArcGIS

class SetUpLocationDrivenGeotriggersViewController: UIViewController {
    // MARK: Storyboard views

    /// The map view managed by the view controller.
    @IBOutlet var mapView: AGSMapView! {
        didSet {
            mapView.map = makeMap()
        }
    }
    /// The label to display fence geotrigger notification status.
    @IBOutlet var fenceGeotriggerLabel: UILabel!
    /// The label to display names of the currently nearby features.
    @IBOutlet var nearbyFeaturesLabel: UILabel!

    @IBOutlet var currentSectionBarButtonItem: UIBarButtonItem!
    @IBOutlet var pointOfInterestBarButtonItem: UIBarButtonItem!

    // MARK: Instance properties

    /// A simulated location data source for demo purposes.
    var simulatedLocationDataSource: AGSSimulatedLocationDataSource!

    /// A dictionary for the feature names in each fence geotrigger.
    /// - Key: The name of a fence geotrigger.
    /// - Value: An array of names of features within the fence.
    var featureNamesInFenceGeotrigger: [String: [String]] = [:] {
        didSet {
            currentSectionBarButtonItem.isEnabled = currentSectionName != nil
            pointOfInterestBarButtonItem.isEnabled = !nearbyPOINames.isEmpty
        }
    }

    /// A dictionary for nearby features.
    var nearbyFeatures: [String: AGSArcGISFeature] = [:]
    /// An array of observers for geotrigger monitor notifications.
    var observers: [NSObjectProtocol] = []
    /// An array of geotrigger monitors.
    var geotriggerMonitors: [AGSGeotriggerMonitor] = []

    /// The name of the current garden section feature. If currently not in any
    /// garden section, it will be `nil`.
    var currentSectionName: String? {
        featureNamesInFenceGeotrigger[Self.sectionFenceGeotriggerName]?.last
    }
    /// The names of nearby point-of-interest features.
    var nearbyPOINames: [String] {
        featureNamesInFenceGeotrigger[Self.poiFenceGeotriggerName] ?? []
    }

    // MARK: Methods

    /// Create a map.
    func makeMap() -> AGSMap {
        // Load a map with predefined tile basemap, feature styles, and labels.
        let map = AGSMap(item: AGSPortalItem(portal: .arcGISOnline(withLoginRequired: false), itemID: "6ab0e91dc39e478cae4f408e1a36a308"))
        map.load { [weak self] _ in
            guard let self = self else { return }

            // Set up location display with a simulated location data source.
            let locationDataSource = self.makeDataSource(polylineJSONString: Self.walkingTourPolylineJSON)
            self.simulatedLocationDataSource = locationDataSource
            self.startDisplayingLocation(using: locationDataSource)

            // Get the service feature tables from the map's operational layers.
            if let operationalLayers = map.operationalLayers as? [AGSFeatureLayer],
               let gardenSectionsLayer = operationalLayers.first(where: { $0.item?.itemID == "1ba816341ea04243832136379b8951d9" }),
               let gardenPOIsLayer = operationalLayers.first(where: { $0.item?.itemID == "7c6280c290c34ae8aeb6b5c4ec841167" }),
               let gardenSections = gardenSectionsLayer.featureTable as? AGSServiceFeatureTable,
               let gardenPOIs = gardenPOIsLayer.featureTable as? AGSServiceFeatureTable {
                // Create geotriggers for each of the service feature tables.
                let geotriggerFeed = AGSLocationGeotriggerFeed(locationDataSource: locationDataSource)
                self.startMonitoring(feed: geotriggerFeed, featureTable: gardenSections, bufferDistance: 0.0, fenceGeotriggerName: Self.sectionFenceGeotriggerName)
                self.startMonitoring(feed: geotriggerFeed, featureTable: gardenPOIs, bufferDistance: 10.0, fenceGeotriggerName: Self.poiFenceGeotriggerName)
            }
        }
        return map
    }

    /// Create a simulated location data source from a GeoJSON.
    func makeDataSource(polylineJSONString: String) -> AGSSimulatedLocationDataSource {
        let simulatedDataSource = AGSSimulatedLocationDataSource()
        let jsonObject = try? JSONSerialization.jsonObject(with: polylineJSONString.data(using: .utf8)!)
        let routePolyline = try? AGSPolyline.fromJSON(jsonObject!) as? AGSPolyline
        // Densify the polyline to control the simulation speed.
        let densifiedRoute = AGSGeometryEngine.geodeticDensifyGeometry(
            routePolyline!,
            maxSegmentLength: 50.0,
            lengthUnit: .meters(),
            curveType: .geodesic
        ) as! AGSPolyline
        simulatedDataSource.setLocationsWith(densifiedRoute)
        return simulatedDataSource
    }

    /// Create a geotrigger monitor and start observing its notifications.
    /// - Parameters:
    ///   - feed: The `AGSGeotriggerFeed` that is monitored for changes.
    ///   - featureTable: The `AGSFeatureTable` that contains the features to use
    ///    in the `AGSFeatureFenceParameters`.
    ///   - bufferDistance: A buffer distance in meters to apply to the features
    ///   when checking if an `AGSFenceGeotrigger` condition is met.
    ///   - fenceGeotriggerName: The name for the `AGSFenceGeotrigger`.
    func startMonitoring(feed: AGSGeotriggerFeed, featureTable: AGSServiceFeatureTable, bufferDistance: Double, fenceGeotriggerName: String) {
        let fenceParameters = AGSFeatureFenceParameters(featureTable: featureTable, bufferDistance: bufferDistance)
        // The Arcade expression in the fence geotrigger returns the value for
        // the "name" field of the feature that triggered the monitor.
        let fenceGeotrigger = AGSFenceGeotrigger(
            feed: feed,
            ruleType: .enterOrExit,
            fenceParameters: fenceParameters,
            messageExpression: AGSArcadeExpression(expression: "$fenceFeature.name"),
            name: fenceGeotriggerName
        )

        // Create and start the geotrigger monitor.
        let geotriggerMonitor = AGSGeotriggerMonitor(geotrigger: fenceGeotrigger)
        geotriggerMonitor.start()
        geotriggerMonitors.append(geotriggerMonitor)

        // Observe geotrigger notifications.
        let observer = NotificationCenter.default.addObserver(
            forName: .AGSGeotriggerMonitorDidTrigger,
            object: geotriggerMonitor,
            queue: nil,
            using: { [weak self] note in self?.handleGeotriggerNotification(note) }
        )
        observers.append(observer)
    }

    /// Handle the notifications posted by `AGSGeotriggerMonitor` when the fence
    /// geotrigger condition has been met.
    func handleGeotriggerNotification(_ notification: Notification) {
        // `AGSFenceGeotriggerNotificationInfo` provides information about the
        // geotrigger monitor and the (fence) geotrigger that was triggered.
        guard let fenceNotificationInfo = notification.userInfo?[AGSGeotriggerNotificationInfoKey] as? AGSFenceGeotriggerNotificationInfo else { return }

        // The feature name from the Arcade expression.
        let featureName = fenceNotificationInfo.message
        let fenceFeature = fenceNotificationInfo.fenceGeoElement as! AGSArcGISFeature
        let geotriggerName = fenceNotificationInfo.geotriggerMonitor.geotrigger.name

        DispatchQueue.main.async { [weak self] in
            guard let self = self else { return }
            switch fenceNotificationInfo.fenceNotificationType {
            case .entered:
                // The user enters a geofence: add the feature for future querying.
                self.featureNamesInFenceGeotrigger[geotriggerName, default: []].append(featureName)
                self.nearbyFeatures[featureName] = fenceFeature
            case .exited:
                // The user leaves the geofence: remove the feature from the dicts.
                if let poppedFeatureName = self.featureNamesInFenceGeotrigger[geotriggerName]?.popLast() {
                    self.nearbyFeatures.removeValue(forKey: poppedFeatureName)
                }
            @unknown default:
                fatalError("Unexpected fence notification type.")
            }

            // Update status labels.
            self.updateStatusLabels(featureName: featureName, notificationType: fenceNotificationInfo.fenceNotificationType)
        }
    }

    // MARK: UI

    func startDisplayingLocation(using locationDataSource: AGSLocationDataSource) {
        mapView.locationDisplay.dataSource = locationDataSource
        mapView.locationDisplay.autoPanMode = .recenter
        mapView.locationDisplay.initialZoomScale = 1000
        mapView.locationDisplay.start()
    }

    func updateStatusLabels(featureName: String, notificationType: AGSFenceNotificationType) {
        let typeString = notificationType == .entered ? "Entered" : "Exited"
        let fenceGeotriggerText = String(format: "%@ the geofence of %@", typeString, featureName)
        let nearbyFeaturesText: String
        if nearbyFeatures.keys.isEmpty {
            nearbyFeaturesText = "No nearby features."
        } else {
            nearbyFeaturesText = String(format: "Nearby: %@", ListFormatter.localizedString(byJoining: nearbyFeatures.keys.sorted()))
        }
        fenceGeotriggerLabel.text = fenceGeotriggerText
        nearbyFeaturesLabel.text = nearbyFeaturesText
    }

    func showPopups(for features: [AGSArcGISFeature]) {
        let popups = features.map(AGSPopup.init)
        let popupsViewController = AGSPopupsViewController(popups: popups)
        popupsViewController.delegate = self
        // Display the view controller as a formsheet - specified for iPads.
        popupsViewController.modalPresentationStyle = .formSheet
        popupsViewController.isModalInPresentation = true
        // Present the popups view controller.
        present(popupsViewController, animated: true) {
            // Stop location updates when it is presented.
            self.mapView.locationDisplay.stop()
        }
    }

    // MARK: Actions

    @IBAction func currentSectionButtonTapped(_ sender: UIBarButtonItem) {
        let sectionFeature = nearbyFeatures[currentSectionName!]!
        showPopups(for: [sectionFeature])
    }

    @IBAction func pointOfInterestButtonTapped(_ sender: UIBarButtonItem) {
        let poiFeatures = nearbyPOINames
            .compactMap { nearbyFeatures[$0] }
            .sorted { ($0.attributes["name"] as! String) < ($1.attributes["name"] as! String) }
        showPopups(for: poiFeatures)
    }

    // MARK: UIViewController

    override func viewDidLoad() {
        super.viewDidLoad()
        // Add the source code button item to the right of navigation bar.
        (navigationItem.rightBarButtonItem as? SourceCodeBarButtonItem)?.filenames = ["SetUpLocationDrivenGeotriggersViewController"]
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        // Restart the simulated location updates.
        if simulatedLocationDataSource != nil {
            mapView.locationDisplay.start()
        }
        geotriggerMonitors.forEach { monitor in
            if monitor.status == .stopped {
                monitor.start()
                // Observe geotrigger notifications.
                let observer = NotificationCenter.default.addObserver(
                    forName: .AGSGeotriggerMonitorDidTrigger,
                    object: monitor,
                    queue: nil,
                    using: { [weak self] note in self?.handleGeotriggerNotification(note) }
                )
                observers.append(observer)
            }
        }
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        // Stop location updates when the view disappears.
        mapView.locationDisplay.stop()
        geotriggerMonitors.forEach { $0.stop() }
        observers.forEach(NotificationCenter.default.removeObserver)
        observers.removeAll(keepingCapacity: true)
        // Clear all received "entered" notifications.
        featureNamesInFenceGeotrigger.removeAll(keepingCapacity: true)
    }
}

// MARK: - AGSPopupsViewControllerDelegate

extension SetUpLocationDrivenGeotriggersViewController: AGSPopupsViewControllerDelegate {
    func popupsViewControllerDidFinishViewingPopups(_ popupsViewController: AGSPopupsViewController) {
        // Dismiss the popups view controller.
        dismiss(animated: true)
        // Restart the simulated location updates.
        mapView.locationDisplay.autoPanMode = .recenter
        mapView.locationDisplay.start()
    }
}

// MARK: - Constants

extension SetUpLocationDrivenGeotriggersViewController {
    static let sectionFenceGeotriggerName = "Section Fence Geotrigger"
    static let poiFenceGeotriggerName = "POI Fence Geotrigger"

    /// A path in Santa Barbara Botanic Garden in GeoJSON format.
    static let walkingTourPolylineJSON = #"{"paths":[[[-119.709881177746,34.4570041646846],[-119.709875813328,34.4570152227745],[-119.709869107805,34.4570240692453],[-119.709859720074,34.4570351273326],[-119.709853014551,34.4570539260775],[-119.709847650133,34.4570760422426],[-119.709848991238,34.4570926293626],[-119.70985569676,34.4571103222869],[-119.709873131119,34.4571202745552],[-119.709889224373,34.4571302268223],[-119.709902635418,34.4571357558591],[-119.709910682045,34.4571600836165],[-119.709910682045,34.4571744591062],[-119.709902635418,34.4571833055602],[-119.709889224373,34.4571910462067],[-119.70988251885,34.4571965752394],[-119.70988251885,34.4572032100782],[-119.709889224373,34.4572175855605],[-119.709898612104,34.4572264320099],[-119.709912023149,34.4572341726524],[-119.709901294313,34.4572419132941],[-119.709895929895,34.4572507597409],[-119.709897271,34.4572596061868],[-119.709902635418,34.4572728758539],[-119.709902635418,34.4572828281028],[-119.70990934094,34.457294991961],[-119.709912023149,34.4573038384022],[-119.709886542164,34.4573115790375],[-119.709861061178,34.4573248486963],[-119.709843626819,34.4573414357669],[-119.709836921297,34.4573668692686],[-119.709843626819,34.4573934085666],[-119.709827533565,34.4574055724087],[-119.709791323744,34.4574188420525],[-119.709749749504,34.4574332174977],[-119.709709516369,34.4574431697275],[-119.709734997354,34.4574807670294],[-119.709748062646,34.4575248306656],[-119.709757450378,34.4575635337324],[-119.709770861423,34.457600025179],[-119.709785613572,34.4576387282109],[-119.70980573014,34.4576730080242],[-119.709815117871,34.4577117110223],[-119.709821823394,34.4577504140025],[-119.709821823394,34.4577869053674],[-119.709821823394,34.4578256083127],[-119.70981780008,34.4578609938471],[-119.709819141185,34.457906331541],[-119.70981460448,34.4579890675855],[-119.709818627793,34.4580675790658],[-119.70982667442,34.4581118108532],[-119.709832038838,34.4581471962662],[-119.709834721047,34.4581947453913],[-119.709836062152,34.4582323423548],[-119.709834721047,34.4582787856393],[-119.709805216748,34.4583429215611],[-119.709759619195,34.4584026342716],[-119.709700610597,34.4584612411497],[-119.709645400048,34.4585103926263],[-119.709566274882,34.4585457778704],[-119.709493855239,34.4585944325566],[-119.709458986522,34.458622077252],[-119.709424117805,34.4586198656767],[-119.709386566878,34.4586110193749],[-119.70935438037,34.4586110193749],[-119.709339628221,34.4586231830396],[-119.709324876071,34.4586585682359],[-119.709306100608,34.4586862129101],[-119.709269890786,34.4587171749343],[-119.709244409801,34.4587238096523],[-119.709229657651,34.4587293385835],[-119.709212223293,34.4587459253751],[-119.70919076562,34.4587945799446],[-119.709174672366,34.4588503400161],[-119.709157238008,34.4589288506865],[-119.709153214694,34.4589951976744],[-119.709155896903,34.4590449578807],[-119.70916394353,34.4590958238387],[-119.709186742307,34.4591323146156],[-119.709218928815,34.4591621706939],[-119.709237704278,34.4591831805204],[-119.709241727592,34.4592252001575],[-119.709238133851,34.459258658624],[-119.709219358388,34.4592796684262],[-119.709207288447,34.4592962551085],[-119.709208629552,34.4593084186733],[-119.709271661463,34.4593791884701],[-119.709310553494,34.4594267368937],[-119.709330670062,34.4594510639836],[-119.709353468838,34.4595008239182],[-119.70936285657,34.4595362087426],[-119.709423221989,34.4595943612845],[-119.709455408497,34.4596297460692],[-119.709487595005,34.459665130839],[-119.709507711573,34.4596817174446],[-119.709523804827,34.4596861405389],[-119.709557332439,34.4596894578594],[-119.709586836739,34.4596894578594],[-119.709593542261,34.4596772943501],[-119.709590860052,34.4596496500041],[-119.709572084589,34.4595777746615],[-119.709566720171,34.4595313320996],[-119.709578790112,34.4595136396883],[-119.709590860052,34.4594992646013],[-119.709627069874,34.4594882068404],[-119.709675349636,34.4595567649343],[-119.709735699339,34.4596197941001],[-119.709775932474,34.4596795058974],[-119.709802754564,34.4597126790997],[-119.709832258863,34.4597359003334],[-119.70986712758,34.4597171021923],[-119.70986980979,34.4596839289918],[-119.709865786476,34.4596308518435],[-119.709876515312,34.4595788804365],[-119.70988187973,34.4595346494263],[-119.709879197521,34.4594926299449],[-119.709852375431,34.4594539277723],[-119.709806777878,34.4593953215911],[-119.709767885847,34.4593212344729],[-119.709720947189,34.4592195028005],[-119.709708720088,34.4591478732967],[-119.709710061193,34.4591058536206],[-119.709707378984,34.459079314867],[-119.709652393699,34.4590262373344],[-119.709617524982,34.4589499383221],[-119.709626771268,34.4588695962162],[-119.709683097658,34.4588032491285],[-119.709730036316,34.4587391135603],[-119.709759540615,34.4586993052518],[-119.7097850216,34.4586650258598],[-119.710059948024,34.4587744987075],[-119.710104204473,34.4587932970608],[-119.710128443889,34.4587649224307],[-119.71019415801,34.4587096331253],[-119.710273283176,34.4586731421637],[-119.71031619852,34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}