Preserve app picker state on Activity recreation (#5972)

* Preserve app picker selection on recreation

* Avoid reloading app picker data on recreation

V2rayNG/app/src/main/java/com/v2ray/ang/ui/apppicker/AppPickerViewModel.kt

@@ -8,6 +8,7 @@ import com.v2ray.ang.dto.AppInfo
 import com.v2ray.ang.ui.base.BaseViewModel
 import com.v2ray.ang.util.AppManagerUtil
 import com.v2ray.ang.util.LogUtil
+import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -26,28 +27,40 @@ class AppPickerViewModel(application: Application) : BaseViewModel(application)
     private val _displayedApps = MutableStateFlow<List<AppInfo>>(emptyList())
     val displayedApps: StateFlow<List<AppInfo>> = _displayedApps.asStateFlow()
 
-    private var appsAll: List<AppInfo> = emptyList()
+    private var allApps: List<AppInfo>? = null
     private var currentQuery: String = ""
-    private var SelectedSnapshot: Set<String> = emptySet()
+    private var selectedSnapshot: Set<String> = emptySet()
+    private var initialized = false
+    private var isAppListLoading = false
 
     fun initialize(initialSelected: Collection<String>) {
+        if (initialized) return
+        initialized = true
         _selectedPackages.value = initialSelected.toSet()
     }
 
     fun loadApps(context: Context) {
+        if (allApps != null || isAppListLoading) return
+
+        val applicationContext = context.applicationContext
+        isAppListLoading = true
         launchLoading {
             try {
-                SelectedSnapshot = _selectedPackages.value.toSet()
+                selectedSnapshot = _selectedPackages.value
                 val apps = withContext(Dispatchers.IO) {
-                    val list = AppManagerUtil.loadNetworkAppList(context)
-                    val special = createSpecialItemUnidentified(context)
+                    val list = AppManagerUtil.loadNetworkAppList(applicationContext)
+                    val special = createSpecialItemUnidentified(applicationContext)
                     sortApps(list + special)
                 }
-                appsAll = apps
+                allApps = apps
                 _displayedApps.value = applyFilter(currentQuery)
+            } catch (e: CancellationException) {
+                throw e
             } catch (e: Exception) {
                 LogUtil.e("AppPickerViewModel", "Failed to load app list", e)
                 toastError(R.string.toast_failure)
+            } finally {
+                isAppListLoading = false
             }
         }
     }
@@ -81,16 +94,18 @@ class AppPickerViewModel(application: Application) : BaseViewModel(application)
     fun getSelectedPackages(): List<String> = _selectedPackages.value.sorted()
 
     private fun applyFilter(query: String): List<AppInfo> {
-        if (query.isBlank()) return appsAll
+        val apps = allApps ?: return emptyList()
+        if (query.isBlank()) return apps
+
         val key = query.uppercase()
-        return appsAll.filter {
+        return apps.filter {
             it.appName.uppercase().contains(key) || it.packageName.uppercase().contains(key)
         }
     }
 
     private fun sortApps(apps: List<AppInfo>): List<AppInfo> {
         val collator = Collator.getInstance()
-        val snapshot = SelectedSnapshot
+        val snapshot = selectedSnapshot
         return apps.sortedWith { p1, p2 ->
             val p1Selected = snapshot.contains(p1.packageName)
             val p2Selected = snapshot.contains(p2.packageName)
@@ -116,4 +131,4 @@ class AppPickerViewModel(application: Application) : BaseViewModel(application)
             isSelected = 0
         )
     }
-}
+}

V2rayNG/app/src/test/java/com/v2ray/ang/ui/apppicker/AppPickerViewModelTest.kt

@@ -0,0 +1,23 @@
+package com.v2ray.ang.ui.apppicker
+
+import android.app.Application
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.mockito.kotlin.mock
+
+class AppPickerViewModelTest {
+
+    @Test
+    fun initialize_preservesChangesAfterFirstCall() {
+        val viewModel = AppPickerViewModel(mock<Application>())
+
+        viewModel.initialize(listOf("initial.package"))
+        viewModel.toggleApp("added.package")
+        viewModel.initialize(listOf("initial.package"))
+
+        assertEquals(
+            setOf("initial.package", "added.package"),
+            viewModel.selectedPackages.value
+        )
+    }
+}