Add custom dynamic entity data source

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// Copyright 2023 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 AddCustomDynamicEntityDataSourceView: View {
    /// A map with an ArcGIS oceans basemap style and a dynamic entity layer.
    @State private var map = makeMap()

    /// The dynamic entity layer that is displaying our custom data.
    private var dynamicEntityLayer: DynamicEntityLayer {
        map.operationalLayers.first as! DynamicEntityLayer
    }

    /// The point on the screen the user tapped.
    @State private var tappedScreenPoint: CGPoint?

    /// The placement of the callout.
    @State private var calloutPlacement: CalloutPlacement?

    var body: some View {
        MapViewReader { proxy in
            MapView(map: map)
                .onSingleTapGesture { screenPoint, _ in
                    tappedScreenPoint = screenPoint
                }
                .callout(placement: $calloutPlacement.animation(.default.speed(2))) { placement in
                    let attributes = (placement.geoElement as! DynamicEntityObservation).attributes
                    VStack(alignment: .leading) {
                        // Display all the attributes in the callout.
                        ForEach(attributes.sorted(by: { $0.key < $1.key }), id: \.key) { item in
                            Text("\(item.key): \(String(describing: item.value))")
                        }
                    }
                }
                .task(id: tappedScreenPoint) {
                    let newCalloutPlacement: CalloutPlacement?
                    if let tappedScreenPoint,
                       let identifyResult = try? await proxy.identify(
                        on: dynamicEntityLayer,
                        screenPoint: tappedScreenPoint,
                        tolerance: 2
                       ) {
                        // Set the callout placement to the observation that was tapped on.
                        newCalloutPlacement = identifyResult.geoElements.first.map { .geoElement($0) }
                    } else {
                        // Hides the callout.
                        newCalloutPlacement = nil
                    }
                    calloutPlacement = newCalloutPlacement
                }
        }
    }

    /// Makes a map with a dynamic entity layer.
    private static func makeMap() -> Map {
        let map = Map(basemapStyle: .arcGISOceans)
        map.initialViewpoint = Viewpoint(
            latitude: 47.984,
            longitude: -123.657,
            scale: 3e6
        )

        // The meta data for the custom dynamic entity data source.
        let info = DynamicEntityDataSourceInfo(
            entityIDFieldName: "MMSI",
            fields: [
                Field(type: .text, name: "MMSI", alias: "MMSI", length: 256),
                Field(type: .float64, name: "SOG", alias: "SOG", length: 8),
                Field(type: .float64, name: "COG", alias: "COG", length: 8),
                Field(type: .text, name: "VesselName", alias: "VesselName", length: 256),
                Field(type: .text, name: "CallSign", alias: "CallSign", length: 256)
            ]
        )

        info.spatialReference = .wgs84

        // Create our custom data source from our custom data feed.
        let customDataSource = CustomDynamicEntityDataSource(info: info) { VesselFeed() }

        let dynamicEntityLayer = DynamicEntityLayer(dataSource: customDataSource)

        // Set display tracking properties on the layer.
        let trackDisplayProperties = dynamicEntityLayer.trackDisplayProperties
        trackDisplayProperties.showsPreviousObservations = true
        trackDisplayProperties.showsTrackLine = true
        trackDisplayProperties.maximumObservations = 20

        // Create the label definition so we can show the vessel name on top of
        // each dynamic entity.
        let labelDefinition = LabelDefinition(
            labelExpression: SimpleLabelExpression(simpleExpression: "[VesselName]"),
            textSymbol: TextSymbol(color: .red, size: 12)
        )
        labelDefinition.placement = .pointAboveCenter

        dynamicEntityLayer.addLabelDefinition(labelDefinition)
        dynamicEntityLayer.labelsAreEnabled = true

        map.addOperationalLayer(dynamicEntityLayer)

        return map
    }
}

/// The vessel feed that is emitting custom dynamic entity events.
private struct VesselFeed: CustomDynamicEntityFeed {
    let events = URL.selectedVesselsDataSource.lines.map { line in
        // Delay observations to simulate live data.
        try await Task.sleep(nanoseconds: 10_000_000)

        let decoder = JSONDecoder()
        let vessel = try decoder.decode(
            AddCustomDynamicEntityDataSourceView.Vessel.self,
            from: line.data(using: .utf8)!
        )

        // The location of the vessel that was decoded from the JSON.
        let location = vessel.geometry

        // We successfully decoded the vessel JSON so we should
        // add that vessel as a new observation.
        return CustomDynamicEntityFeedEvent.newObservation(
            geometry: Point(x: location.x, y: location.y, spatialReference: .wgs84),
            attributes: vessel.attributes
        )
    }
}

private extension URL {
    /// The URL to the selected vessels JSON Lines data.
    static var selectedVesselsDataSource: URL {
        Bundle.main.url(
            forResource: "AIS_MarineCadastre_SelectedVessels_CustomDataSource",
            withExtension: "jsonl"
        )!
    }
}