Error Handling for urlConnection

app/src/main/java/com/google/android/ground/repository/OfflineAreaRepository.kt

@@ -85,7 +85,7 @@ constructor(
    * Downloads tiles in the specified bounds and stores them in the local filesystem. Emits the
    * number of bytes processed and total expected bytes as the download progresses.
    */
-  suspend fun downloadTiles(bounds: Bounds): Flow<Pair<Int, Int>> = flow {
+  fun downloadTiles(bounds: Bounds): Flow<Pair<Int, Int>> = flow {
     val requests = mogClient.buildTilesRequests(bounds)
     val totalBytes = requests.sumOf { it.totalBytes }
     var bytesDownloaded = 0

app/src/main/java/com/google/android/ground/ui/map/gms/mog/UrlInputStream.kt

@@ -22,7 +22,7 @@ import java.io.InputStream
 import java.net.HttpURLConnection
 import java.net.URL
 
-const val READ_TIMEOUT_MS = 5 * 1000
+private const val READ_TIMEOUT_MS = 5 * 1000
 
 /**
  * @constructor Creates a [UrlInputStream] by opening a connection to an actual URL, requesting the

app/src/main/java/com/google/android/ground/ui/offlineareas/selector/OfflineAreaSelectorFragment.kt

@@ -20,10 +20,13 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.Toast
 import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
 import androidx.navigation.fragment.findNavController
 import com.google.android.ground.R
 import com.google.android.ground.databinding.OfflineAreaSelectorFragBinding
@@ -68,8 +71,17 @@ class OfflineAreaSelectorFragment : AbstractMapContainerFragment() {
 
   override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
     super.onViewCreated(view, savedInstanceState)
-    viewModel.isDownloadProgressVisible.observe(viewLifecycleOwner) {
-      showDownloadProgressDialog(it)
+    viewLifecycleOwner.lifecycleScope.launch {
+      repeatOnLifecycle(Lifecycle.State.RESUMED) {
+        viewModel.isDownloadProgressVisible.observe(viewLifecycleOwner) {
+          showDownloadProgressDialog(it)
+        }
+        viewModel.isFailure.observe(viewLifecycleOwner) {
+          if (it) {
+            Toast.makeText(context, R.string.offline_area_download_error, Toast.LENGTH_LONG).show()
+          }
+        }
+      }
     }
 
     lifecycleScope.launch {

app/src/main/java/com/google/android/ground/ui/offlineareas/selector/OfflineAreaSelectorViewModel.kt

@@ -39,6 +39,7 @@ import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.asSharedFlow
+import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.launch
 
 private const val MIN_DOWNLOAD_ZOOM_LEVEL = 9
@@ -78,6 +79,7 @@ internal constructor(
   val downloadProgress = MutableLiveData(0f)
   val bottomText = MutableLiveData<String?>(null)
   val downloadButtonEnabled = MutableLiveData(false)
+  val isFailure = MutableLiveData(false)
 
   private val _navigate = MutableSharedFlow<UiState>(replay = 0)
   val navigate = _navigate.asSharedFlow()
@@ -100,20 +102,29 @@ internal constructor(
 
     isDownloadProgressVisible.value = true
     downloadProgress.value = 0f
-    downloadJob =
-      viewModelScope.launch(ioDispatcher) {
-        offlineAreaRepository.downloadTiles(viewport!!).collect { (bytesDownloaded, totalBytes) ->
-          val progressValue =
-            if (totalBytes > 0) {
-              (bytesDownloaded.toFloat() / totalBytes.toFloat()).coerceIn(0f, 1f)
-            } else {
-              0f
-            }
-          downloadProgress.postValue(progressValue)
+    downloadJob = viewModelScope.launch(ioDispatcher) {
+      offlineAreaRepository
+        .downloadTiles(viewport!!)
+        .catch {
+          isFailure.postValue(true)
+          isDownloadProgressVisible.postValue(false)
         }
-        isDownloadProgressVisible.postValue(false)
-        _navigate.emit(UiState.OfflineAreaBackToHomeScreen)
+        .collect { (bytesDownloaded, totalBytes) ->
+          updateDownloadProgress(bytesDownloaded, totalBytes)
+        }
+      isDownloadProgressVisible.postValue(false)
+      _navigate.emit(UiState.OfflineAreaBackToHomeScreen)
+    }
+  }
+
+  private fun updateDownloadProgress(bytesDownloaded: Int, totalBytes: Int) {
+    val progressValue =
+      if (totalBytes > 0) {
+        (bytesDownloaded.toFloat() / totalBytes.toFloat()).coerceIn(0f, 1f)
+      } else {
+        0f
       }
+    downloadProgress.postValue(progressValue)
   }
 
   fun onCancelClick() {

app/src/main/res/values-es/strings.xml

@@ -52,6 +52,7 @@
   <string name="settings">Configuración</string>
   <string name="offline_area_viewer_title">Área descargada</string>
   <string name="offline_area_viewer_remove_button">Eliminar del dispositivo</string>
+  <string name="offline_area_download_error">¡Error de descarga. Por favor inténtalo de nuevo</string>
   <!-- Label of button used enter the offline area selector. -->
   <string name="offline_area_selector_select">Seleccionar área</string>
   <string name="no_basemaps_downloaded">No se ha descargado ningún mapa para su uso sin conexión</string>

app/src/main/res/values-fr/strings.xml

@@ -53,6 +53,7 @@
   <string name="settings">Paramètres</string>
   <string name="offline_area_viewer_title">Zone téléchargée</string>
   <string name="offline_area_viewer_remove_button">Supprimer de l&#8217;appareil</string>
+  <string name="offline_area_download_error">Échec du téléchargement. Veuillez réessayer</string>
   <!-- Label of button used enter the offline area selector. -->
   <string name="offline_area_selector_select">Sélectionnez une zone</string>
   <string name="no_basemaps_downloaded">Aucune image n&#8217;a été téléchargée pour l&#8217;utilisation hors ligne. Appuyez sur « Sélectionner et télécharger » pour commencer.</string>

app/src/main/res/values-pt/strings.xml

@@ -52,6 +52,7 @@
   <string name="settings">Configurações</string>
   <string name="offline_area_viewer_title">Área descarregada</string>
   <string name="offline_area_viewer_remove_button">Remover do dispositivo</string>
+  <string name="offline_area_download_error">Falha no download! Por favor, tente novamente</string>
   <!-- Label of button used enter the offline area selector. -->
   <string name="offline_area_selector_select">Selecionar área</string>
   <string name="no_basemaps_downloaded">Nenhuma imagem de mapa descarregada para uso offline</string>

app/src/main/res/values/strings.xml

@@ -53,6 +53,7 @@
   <string name="settings">Settings</string>
   <string name="offline_area_viewer_title">Downloaded area</string>
   <string name="offline_area_viewer_remove_button">Remove from device</string>
+  <string name="offline_area_download_error">Download failed. Please try again</string>
   <!-- Label of button used enter the offline area selector. -->
   <string name="offline_area_selector_select">Select area</string>
   <string name="no_basemaps_downloaded">No map imagery downloaded for offline use</string>

app/src/test/java/com/google/android/ground/ui/offlineareas/selector/OfflineAreaSelectorFragmentTest.kt

@@ -22,6 +22,8 @@ import androidx.compose.ui.test.junit4.createAndroidComposeRule
 import androidx.compose.ui.test.onNodeWithText
 import androidx.compose.ui.test.performClick
 import androidx.lifecycle.Observer
+import android.widget.Toast
+import androidx.lifecycle.lifecycleScope
 import androidx.test.espresso.Espresso.onView
 import androidx.test.espresso.assertion.ViewAssertions.matches
 import androidx.test.espresso.matcher.ViewMatchers.hasDescendant
@@ -33,20 +35,25 @@ import com.google.android.ground.BaseHiltTest
 import com.google.android.ground.R
 import com.google.android.ground.launchFragmentInHiltContainer
 import com.google.android.ground.repository.OfflineAreaRepository
+import com.google.common.truth.Truth.assertThat
 import dagger.hilt.android.testing.HiltAndroidTest
 import javax.inject.Inject
 import junit.framework.Assert.assertFalse
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.test.advanceUntilIdle
 import org.junit.Assert.assertNull
+import junit.framework.TestCase.assertEquals
+import kotlinx.coroutines.launch
 import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.Mockito.mock
 import org.mockito.kotlin.any
 import org.mockito.kotlin.whenever
+import org.mockito.Mockito.verify
 import org.robolectric.RobolectricTestRunner
+import org.robolectric.shadows.ShadowToast
 
 @HiltAndroidTest
 @RunWith(RobolectricTestRunner::class)
@@ -125,4 +132,31 @@ class OfflineAreaSelectorFragmentTest : BaseHiltTest() {
 
     viewModel.downloadProgress.removeObserver(observer)
   }
+
+  @Test
+  fun `test failure case displays toast`() = runWithTestDispatcher {
+    val isFailureObserver = mock(Observer::class.java) as Observer<Boolean>
+    fragment.viewLifecycleOwner.lifecycleScope.launch {
+      viewModel.isFailure.observeForever(isFailureObserver)
+      viewModel.isFailure.postValue(true)
+    }
+
+    verify(isFailureObserver).onChanged(true)
+
+    ShadowToast.reset()
+
+    advanceUntilIdle()
+
+    val toast = ShadowToast.getLatestToast()
+    assertThat(ShadowToast.shownToastCount()).isEqualTo(1)
+    assertEquals(toast.duration, Toast.LENGTH_LONG)
+    assertEquals(
+      ShadowToast.getTextOfLatestToast(),
+      fragment.getString(R.string.offline_area_download_error),
+    )
+
+    fragment.viewLifecycleOwner.lifecycleScope.launch {
+      viewModel.isFailure.removeObserver(isFailureObserver)
+    }
+  }
 }