Identify graphics

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/* Copyright 2025 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
 *
 *    http://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.
 *
 */

package com.esri.arcgismaps.sample.identifygraphics.components

import android.app.Application
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.viewModelScope
import androidx.compose.ui.unit.dp
import com.arcgismaps.Color
import com.arcgismaps.geometry.Point
import com.arcgismaps.geometry.Polygon
import com.arcgismaps.geometry.PolygonBuilder
import com.arcgismaps.geometry.SpatialReference
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.symbology.SimpleFillSymbol
import com.arcgismaps.mapping.symbology.SimpleFillSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleRenderer
import com.arcgismaps.mapping.view.Graphic
import com.arcgismaps.mapping.view.GraphicsOverlay
import com.arcgismaps.mapping.view.ScreenCoordinate
import com.arcgismaps.toolkit.geoviewcompose.MapViewProxy
import com.esri.arcgismaps.sample.sampleslib.components.MessageDialogViewModel
import kotlinx.coroutines.launch

class IdentifyGraphicsViewModel(app: Application) : AndroidViewModel(app) {

    // Create a polygon from a list of points
    private val polygon: Polygon = PolygonBuilder(SpatialReference.webMercator()).apply {
        addPoint(Point(x = -20e5, y = 20e5))
        addPoint(Point(x = 20e5, y = 20e5))
        addPoint(Point(x = 20e5, y = -20e5))
        addPoint(Point(x = -20e5, y = -20e5))
    }.toGeometry()

    // ArcGISMap displayed by the MapView using a topographic basemap.
    val arcGISMap = ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
        // Set an initial viewpoint with the polygon graphic centered on the screen.
        initialViewpoint = Viewpoint(
            center = polygon.extent.center,
            scale = 1.3e8
        )
    }

    // MapViewProxy enables identify operations from the ViewModel.
    val mapViewProxy = MapViewProxy()

    // Graphics overlay that holds the polygon graphic and a renderer.
    private val graphicsOverlay = GraphicsOverlay().apply {
        // Configure the graphics overlay with a renderer and add a graphic for the polygon.
        val polygonFillSymbol = SimpleFillSymbol(
            style = SimpleFillSymbolStyle.Solid,
            color = Color.yellow
        )

        renderer = SimpleRenderer(polygonFillSymbol)
        graphics.add(Graphic(geometry = polygon))
    }

    val graphicsOverlays = listOf(graphicsOverlay)

    // Dialog view model to present error messages.
    val messageDialogVM = MessageDialogViewModel()

    init {
        // Load the map and handle any load failures.
        viewModelScope.launch {
            arcGISMap.load().onFailure { error ->
                messageDialogVM.showMessageDialog(error)
            }
        }
    }

    /**
     * Called when single tap is detected on the map. Identifies graphics in [graphicsOverlay] near the
     * [screenCoordinate] using [mapViewProxy], then shows the number of identified graphics in an
     * alert dialog.
     */
    fun identifyGraphics(screenCoordinate: ScreenCoordinate) {
        viewModelScope.launch {
            mapViewProxy.identify(
                graphicsOverlay = graphicsOverlay,
                screenCoordinate = screenCoordinate,
                tolerance = 12.dp,
                returnPopupsOnly = false,
                maximumResults = 10
            ).onSuccess { identifyResult ->
                val count = identifyResult.graphics.size
                val message = if (count > 0) {
                    "Tapped on $count graphic(s)."
                } else {
                    "No graphics at tapped location."
                }
                // Show an alert dialog with the identify result.
                messageDialogVM.showMessageDialog(
                    title = "Identify Result",
                    description = message
                )
            }.onFailure { error ->
                messageDialogVM.showMessageDialog(error)
            }
        }
    }
}