Generate offline map

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/* Copyright 2022 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.generateofflinemap

import android.app.AlertDialog
import android.os.Bundle
import android.util.Log
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.lifecycleScope
import com.arcgismaps.ApiKey
import com.arcgismaps.LoadStatus
import com.arcgismaps.geometry.Envelope
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.symbology.SimpleLineSymbol
import com.arcgismaps.mapping.symbology.SimpleLineSymbolStyle
import com.arcgismaps.mapping.view.Graphic
import com.arcgismaps.mapping.view.GraphicsOverlay
import com.arcgismaps.mapping.view.ScreenCoordinate
import com.arcgismaps.portal.Portal
import com.arcgismaps.portal.PortalItem
import com.arcgismaps.tasks.offlinemaptask.GenerateOfflineMapJob
import com.arcgismaps.tasks.offlinemaptask.GenerateOfflineMapParameters
import com.arcgismaps.tasks.offlinemaptask.OfflineMapTask
import com.arcgismaps.ArcGISEnvironment
import com.arcgismaps.Color
import com.esri.arcgismaps.sample.generateofflinemap.databinding.ActivityMainBinding
import com.esri.arcgismaps.sample.generateofflinemap.databinding.GenerateOfflineMapDialogLayoutBinding
import com.google.android.material.snackbar.Snackbar
import kotlinx.coroutines.launch
import java.io.File

class MainActivity : AppCompatActivity() {

    private val TAG = MainActivity::class.java.simpleName

    // set up data binding for the activity
    private val activityMainBinding: ActivityMainBinding by lazy {
        DataBindingUtil.setContentView(this, R.layout.activity_main)
    }

    private val mapView by lazy {
        activityMainBinding.mapView
    }

    private val takeMapOfflineButton by lazy {
        activityMainBinding.takeMapOfflineButton
    }

    private val graphicsOverlay: GraphicsOverlay by lazy { GraphicsOverlay() }

    private val downloadArea: Graphic = Graphic()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // authentication with an API key or named user is
        // required to access basemaps and other location services
        ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.API_KEY)
        // add mapView to the lifecycle
        lifecycle.addObserver(mapView)

        // disable the button until the map is loaded
        takeMapOfflineButton.isEnabled = false

        // create a portal item with the itemId of the web map
        val portal = Portal(getString(R.string.portal_url))
        val portalItem = PortalItem(portal, getString(R.string.item_id))

        // create a symbol to show a box around the extent we want to download
        downloadArea.symbol = SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.red, 2F)
        // add the graphic to the graphics overlay when it is created
        graphicsOverlay.graphics.add(downloadArea)
        val map = ArcGISMap(portalItem)
        lifecycleScope.launch {
            map.load()
                .onFailure {
                    showMessage(it.message.toString())
                }
                .onSuccess {
                    // limit the map scale to the largest layer scale
                    map.maxScale = map.operationalLayers[6].maxScale ?: 0.0
                    map.minScale = map.operationalLayers[6].minScale ?: 0.0
                    // set the map to the map view
                    mapView.map = map
                    // add the graphics overlay to the map view when it is created
                    mapView.graphicsOverlays.add(graphicsOverlay)
                }
        }
        lifecycleScope.launch {
            mapView.viewpointChanged.collect {
                // upper left corner of the area to take offline
                val minScreenPoint = ScreenCoordinate(200.0, 200.0)
                // lower right corner of the downloaded area
                val maxScreenPoint = ScreenCoordinate(
                    mapView.width - 200.0,
                    mapView.height - 200.0
                )
                // convert screen points to map points
                val minPoint = mapView.screenToLocation(minScreenPoint)
                val maxPoint = mapView.screenToLocation(maxScreenPoint)
                // use the points to define and return an envelope
                if (minPoint != null && maxPoint != null) {
                    val envelope = Envelope(minPoint, maxPoint)
                    downloadArea.geometry = envelope
                    // enable the take map offline button only after the map is loaded
                    if (!takeMapOfflineButton.isEnabled && map.loadStatus.value is LoadStatus.Loaded)
                        takeMapOfflineButton.isEnabled = true
                }
            }
        }
    }

    /**
     * Use the generate offline map job to generate an offline map.
     *
     * @param view: the button which calls this function
     */
    fun createOfflineMapJob(view: View) {
        // offline map path
        val offlineMapPath = getExternalFilesDir(null)?.path + "/offlineMap"
        // delete any offline map already in the cache
        File(offlineMapPath).deleteRecursively()
        // specify the extent, min scale, and max scale as parameters
        var minScale: Double = mapView.mapScale.value
        val maxScale: Double = mapView.map?.maxScale ?: 0.0
        // minScale must always be larger than maxScale
        if (minScale <= maxScale) {
            minScale = maxScale + 1
        }
        // get the geometry of the downloadArea
        val geometry = downloadArea.geometry
        if (geometry == null) {
            showMessage("Could not get geometry of the downloadArea")
            return
        }
        // set the offline map parameters
        val generateOfflineMapParameters = GenerateOfflineMapParameters(
            geometry, minScale, maxScale
        ).apply {
            // set job to cancel on any errors
            continueOnErrors = false
        }
        // get the map from the MapView
        val map = mapView.map
        if (map == null) {
            showMessage("Could not get map from MapView")
            return
        }
        // create an offline map task with the map
        val offlineMapTask = OfflineMapTask(map)
        // create an offline map job with the download directory path and parameters and start the job
        val offlineMapJob = offlineMapTask.generateOfflineMap(
            generateOfflineMapParameters,
            offlineMapPath
        )
        // create an alert dialog to show the download progress
        val progressDialogLayoutBinding =
            GenerateOfflineMapDialogLayoutBinding.inflate(layoutInflater)
        val progressDialog = createProgressDialog(offlineMapJob).apply {
            setCancelable(false)
            setView(progressDialogLayoutBinding.root)
            show()
        }
        // handle offline job loading, error and succeed status
        lifecycleScope.launch {
            displayOfflineMapFromJob(offlineMapJob, progressDialogLayoutBinding, progressDialog)
        }
    }

    /**
     * Initiates, and tracks the result of the [offlineMapJob] while displaying
     * the progress to the [progressDialog]
     */
    private suspend fun displayOfflineMapFromJob(
        offlineMapJob: GenerateOfflineMapJob,
        progressDialogLayout: GenerateOfflineMapDialogLayoutBinding,
        progressDialog: AlertDialog
    ) {
        // create a flow-collector for the job's progress
        lifecycleScope.launch {
            offlineMapJob.progress.collect {
                // display the current job's progress value
                val progressPercentage = offlineMapJob.progress.value
                progressDialogLayout.progressBar.progress = progressPercentage
                progressDialogLayout.progressTextView.text = "$progressPercentage%"
            }
        }

        // start the job
        offlineMapJob.start()
        offlineMapJob.result().onSuccess {
            mapView.map = it.offlineMap
            graphicsOverlay.graphics.clear()
            // disable and remove the button to take the map offline once the offline map is showing
            takeMapOfflineButton.isEnabled = false
            takeMapOfflineButton.visibility = View.GONE

            showMessage("Map saved at: " + offlineMapJob.downloadDirectoryPath)

            // close the progress dialog
            progressDialog.dismiss()
        }.onFailure {
            progressDialog.dismiss()
            showMessage(it.message.toString())
        }

    }

    /**
     * Create a progress dialog box for tracking the generate offline map job.
     *
     * @param job the generate offline map job progress to be tracked
     * @return an AlertDialog set with the dialog layout view
     */
    private fun createProgressDialog(job: GenerateOfflineMapJob): AlertDialog {
        val builder = AlertDialog.Builder(this).apply {
            setTitle("Generating offline map...")
            // provide a cancel button on the dialog
            setNegativeButton("Cancel") { _, _ ->
                lifecycleScope.launch { job.cancel() }
            }
            setCancelable(true)
            val dialogLayoutBinding = GenerateOfflineMapDialogLayoutBinding.inflate(layoutInflater)
            setView(dialogLayoutBinding.root)
        }
        return builder.create()
    }

    private fun showMessage(message: String) {
        Log.e(TAG, message)
        Snackbar.make(activityMainBinding.root, message, Snackbar.LENGTH_SHORT).show()
    }
}