feat: Show network activity in ListsActivity (#533)

Modify `ListsViewModel` to keep track of the number of active network
operations and export as a flow. Collect this in `ListsActivity` and
show a `LinearProgressIndicator` while it is non-zero.

app/src/main/java/app/pachli/ListsActivity.kt

@@ -118,6 +118,12 @@ class ListsActivity : BaseActivity(), MenuProvider {
                 }
             }
         }
+
+        lifecycleScope.launch {
+            viewModel.operationCount.collectLatest {
+                if (it == 0) binding.progressIndicator.hide() else binding.progressIndicator.show()
+            }
+        }
     }
 
     override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {

app/src/main/java/app/pachli/viewmodel/ListsViewModel.kt

@@ -25,6 +25,9 @@ import com.github.michaelbull.result.onFailure
 import dagger.hilt.android.lifecycle.HiltViewModel
 import javax.inject.Inject
 import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.launch
 
@@ -45,6 +48,9 @@ internal class ListsViewModel @Inject constructor(
     private val _errors = Channel<Error>()
     val errors = _errors.receiveAsFlow()
 
+    private val _operationCount = MutableStateFlow(0)
+    val operationCount = _operationCount.asStateFlow()
+
     val lists = listsRepository.lists
 
     init {
@@ -56,20 +62,26 @@ internal class ListsViewModel @Inject constructor(
     }
 
     fun createNewList(title: String, exclusive: Boolean) = viewModelScope.launch {
+        _operationCount.getAndUpdate { it + 1 }
+
         listsRepository.createList(title, exclusive).onFailure {
             _errors.send(Error.Create(title, it))
         }
-    }
+    }.invokeOnCompletion { _operationCount.getAndUpdate { it - 1 } }
 
     fun updateList(listId: String, title: String, exclusive: Boolean) = viewModelScope.launch {
+        _operationCount.getAndUpdate { it + 1 }
+
         listsRepository.editList(listId, title, exclusive).onFailure {
             _errors.send(Error.Update(title, it))
         }
-    }
+    }.invokeOnCompletion { _operationCount.getAndUpdate { it - 1 } }
 
     fun deleteList(listId: String, title: String) = viewModelScope.launch {
+        _operationCount.getAndUpdate { it + 1 }
+
         listsRepository.deleteList(listId).onFailure {
             _errors.send(Error.Delete(title, it))
         }
-    }
+    }.invokeOnCompletion { _operationCount.getAndUpdate { it - 1 } }
 }

app/src/main/res/layout/activity_lists.xml

@@ -13,6 +13,15 @@
             android:id="@+id/includedToolbar"
             layout="@layout/toolbar_basic" />
 
+        <com.google.android.material.progressindicator.LinearProgressIndicator
+            android:id="@+id/progressIndicator"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            app:layout_constraintTop_toBottomOf="@id/includedToolbar"
+            android:visibility="gone"
+            android:indeterminate="true"
+            android:contentDescription="" />
+
         <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
             android:id="@+id/swipeRefreshLayout"
             android:layout_width="0dp"