Remove dependency on survey.tileSources, instead use default Firebase storage imagery path

ground/src/main/java/com/google/android/ground/Config.kt

@@ -55,10 +55,11 @@ object Config {
   const val MAX_MEDIA_UPLOAD_RETRY_COUNT = 5
 
   // TODO(#1730): Make sub-paths configurable and stop hardcoding here.
+  const val DEFAULT_MOG_TILE_URL = "/offline-imagery/default/"
   const val DEFAULT_MOG_MIN_ZOOM = 8
   const val DEFAULT_MOG_MAX_ZOOM = 14
 
-  fun getMogSources(path: String = "/offline-imagery/default/") =
+  fun getMogSources(path: String) =
     listOf(
       MogSource(
         0 ..< DEFAULT_MOG_MIN_ZOOM,

ground/src/main/java/com/google/android/ground/model/Survey.kt

@@ -24,6 +24,7 @@ data class Survey(
   val title: String,
   val description: String,
   val jobMap: Map<String, Job>,
+  // TODO(#1730): Allow tile source configuration from a non-survey accessible source.
   val tileSources: List<TileSource> = listOf(),
   val acl: Map<String, String> = mapOf()
 ) {

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

@@ -109,7 +109,7 @@ constructor(
 
   fun getOfflineTileSourcesFlow() =
     surveyRepository.activeSurveyFlow.combine(getOfflineAreaBounds()) { survey, bounds ->
-      applyBounds(survey?.tileSources, bounds)
+      applyBounds(getDefaultTileSources(), bounds)
     }
 
   private suspend fun applyBounds(
@@ -143,15 +143,12 @@ constructor(
     return MogClient(mogCollection, remoteStorageManager)
   }
 
-  private fun getMogSources(): List<MogSource> = Config.getMogSources(getFirstTileSourceUrl())
+  private fun getMogSources(): List<MogSource> =
+    Config.getMogSources(getDefaultTileSources().first().url)
 
-  /**
-   * Returns the URL of the first tile source in the current survey, or throws an error if no survey
-   * is active or if no tile sources are defined.
-   */
-  private fun getFirstTileSourceUrl() =
-    surveyRepository.activeSurvey?.tileSources?.firstOrNull()?.url
-      ?: error("Survey has no tile sources")
+  /** Returns the default configured tile sources. */
+  fun getDefaultTileSources(): List<TileSource> =
+    listOf(TileSource(url = Config.DEFAULT_MOG_TILE_URL, type = TileSource.Type.MOG_COLLECTION))
 
   suspend fun hasHiResImagery(bounds: Bounds): Boolean {
     val client = getMogClient()

ground/src/main/java/com/google/android/ground/ui/home/HomeScreenViewModel.kt

@@ -34,14 +34,15 @@ class HomeScreenViewModel
 @Inject
 internal constructor(
   private val navigator: Navigator,
-  private val surveyRepository: SurveyRepository,
+  surveyRepository: SurveyRepository,
 ) : AbstractViewModel() {
 
   private val _openDrawerRequests: MutableSharedFlow<Unit> = MutableSharedFlow()
   val openDrawerRequestsFlow: SharedFlow<Unit> = _openDrawerRequests.asSharedFlow()
 
+  // TODO(#1730): Allow tile source configuration from a non-survey accessible source.
   val showOfflineAreaMenuItem: LiveData<Boolean> =
-    surveyRepository.activeSurveyFlow.map { it?.tileSources?.isNotEmpty() ?: false }.asLiveData()
+    surveyRepository.activeSurveyFlow.map { true }.asLiveData()
 
   fun openNavDrawer() {
     viewModelScope.launch { _openDrawerRequests.emit(Unit) }

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

@@ -90,7 +90,7 @@ internal constructor(
       )
 
   init {
-    remoteTileSources = surveyRepository.activeSurvey!!.tileSources
+    remoteTileSources = offlineAreaRepository.getDefaultTileSources()
   }
 
   fun onDownloadClick() {

ground/src/test/java/com/google/android/ground/ui/home/HomeScreenFragmentTest.kt

@@ -39,19 +39,19 @@ import com.google.android.ground.ui.common.Navigator
 import com.sharedtest.FakeData
 import com.squareup.picasso.Picasso
 import dagger.hilt.android.testing.HiltAndroidTest
-import javax.inject.Inject
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.advanceUntilIdle
-import org.hamcrest.CoreMatchers.not
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.robolectric.ParameterizedRobolectricTestRunner
 import org.robolectric.RobolectricTestRunner
+import javax.inject.Inject
 
 abstract class AbstractHomeScreenFragmentTest : BaseHiltTest() {
 
-  @Inject lateinit var localSurveyStore: LocalSurveyStore
+  @Inject
+  lateinit var localSurveyStore: LocalSurveyStore
   private lateinit var fragment: HomeScreenFragment
   private var initializedPicasso = false
 
@@ -119,7 +119,8 @@ abstract class AbstractHomeScreenFragmentTest : BaseHiltTest() {
 @RunWith(RobolectricTestRunner::class)
 class HomeScreenFragmentTest : AbstractHomeScreenFragmentTest() {
 
-  @Inject lateinit var surveyRepository: SurveyRepository
+  @Inject
+  lateinit var surveyRepository: SurveyRepository
 
   private val surveyWithoutBasemap: Survey =
     Survey(
@@ -134,27 +135,17 @@ class HomeScreenFragmentTest : AbstractHomeScreenFragmentTest() {
   private val surveyWithTileSources: Survey =
     surveyWithoutBasemap.copy(
       tileSources =
-        listOf(
-          TileSource("http://google.com", TileSource.Type.MOG_COLLECTION),
-        ),
+      listOf(
+        TileSource("http://google.com", TileSource.Type.MOG_COLLECTION),
+      ),
       id = "SURVEY_WITH_TILE_SOURCES"
     )
 
   @Test
-  fun offlineMapImageryMenuIsDisabledWhenActiveSurveyHasNoBasemap() = runWithTestDispatcher {
+  fun `offline map imagery menu is always enabled`() = runWithTestDispatcher {
     surveyRepository.selectedSurveyId = surveyWithoutBasemap.id
     advanceUntilIdle()
 
-    openDrawer()
-    onView(withId(R.id.nav_offline_areas)).check(matches(not(isEnabled())))
-  }
-
-  @Test
-  fun offlineMapImageryMenuIsEnabledWhenActiveSurveyHasBasemap() = runWithTestDispatcher {
-    localSurveyStore.insertOrUpdateSurvey(surveyWithTileSources)
-    surveyRepository.selectedSurveyId = surveyWithTileSources.id
-    advanceUntilIdle()
-
     openDrawer()
     onView(withId(R.id.nav_offline_areas)).check(matches(isEnabled()))
   }
@@ -171,8 +162,11 @@ class NavigationDrawerItemClickTest(
   private val testLabel: String
 ) : AbstractHomeScreenFragmentTest() {
 
-  @Inject lateinit var navigator: Navigator
-  @Inject lateinit var surveyRepository: SurveyRepository
+  @Inject
+  lateinit var navigator: Navigator
+
+  @Inject
+  lateinit var surveyRepository: SurveyRepository
 
   @Test
   fun clickDrawerMenuItem() = runWithTestDispatcher {
@@ -219,19 +213,12 @@ class NavigationDrawerItemClickTest(
           true,
           "Clicking 'sync status' should navigate to fragment"
         ),
-        arrayOf(
-          "Offline map imagery",
-          TEST_SURVEY_WITHOUT_OFFLINE_TILES,
-          null,
-          false,
-          "Clicking 'offline map imagery' when survey doesn't have offline tiles should do nothing"
-        ),
         arrayOf(
           "Offline map imagery",
           TEST_SURVEY_WITH_OFFLINE_TILES,
           HomeScreenFragmentDirections.showOfflineAreas(),
           true,
-          "Clicking 'offline map imagery' when survey has offline tiles should navigate to fragment"
+          "Clicking 'offline map imagery' should navigate to fragment"
         ),
         arrayOf(
           "Settings",