Show a screen while the app migrates after an update

app/src/main/java/eu/kanade/presentation/more/AppMigratingScreen.kt

@@ -0,0 +1,48 @@
+package eu.kanade.presentation.more
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.safeDrawingPadding
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.unit.dp
+import tachiyomi.i18n.MR
+import tachiyomi.presentation.core.i18n.stringResource
+
+/**
+ * Shown instead of the app while migrations from the previous version run, so a slow first launch
+ * after an update doesn't look like the app hanging.
+ */
+@Composable
+fun AppMigratingScreen() {
+    Surface(modifier = Modifier.fillMaxSize()) {
+        Column(
+            modifier = Modifier
+                .safeDrawingPadding()
+                .padding(horizontal = 32.dp),
+            verticalArrangement = Arrangement.spacedBy(16.dp, Alignment.CenterVertically),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            CircularProgressIndicator()
+            Text(
+                text = stringResource(MR.strings.app_migrating_title),
+                style = MaterialTheme.typography.titleLarge,
+                textAlign = TextAlign.Center,
+            )
+            Text(
+                text = stringResource(MR.strings.app_migrating_summary),
+                style = MaterialTheme.typography.bodyMedium,
+                color = MaterialTheme.colorScheme.onSurfaceVariant,
+                textAlign = TextAlign.Center,
+            )
+        }
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/main/MainActivity.kt

@@ -72,6 +72,7 @@ import eu.kanade.presentation.components.AppStateBanners
 import eu.kanade.presentation.components.DownloadedOnlyBannerBackgroundColor
 import eu.kanade.presentation.components.IncognitoModeBannerBackgroundColor
 import eu.kanade.presentation.components.IndexingBannerBackgroundColor
+import eu.kanade.presentation.more.AppMigratingScreen
 import eu.kanade.presentation.more.settings.screen.browse.ExtensionStoresScreen
 import eu.kanade.presentation.more.settings.screen.data.RestoreBackupScreen
 import eu.kanade.presentation.util.AssistContentScreen
@@ -95,6 +96,7 @@ import eu.kanade.tachiyomi.util.system.isNavigationBarNeedsScrim
 import eu.kanade.tachiyomi.util.system.updaterEnabled
 import eu.kanade.tachiyomi.util.view.setComposeContent
 import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.flow.drop
@@ -107,6 +109,7 @@ import mihon.app.di.AppGraph
 import mihon.app.di.appGraph
 import mihon.core.metro.metroGraph
 import mihon.core.migration.Migrator
+import mihon.domain.database.repository.DatabaseRepository
 import mihon.feature.support.SupportUsScreen
 import mihon.icons.materialsymbols.MaterialSymbols
 import mihon.icons.materialsymbols.automirroredrounded.OpenInNew
@@ -138,6 +141,10 @@ class MainActivity : BaseActivity() {
 
     @Inject private lateinit var chapterCache: ChapterCache
 
+    @Inject private lateinit var databaseRepository: DatabaseRepository
+
+    private val isAppMigrating = MutableStateFlow(Migrator.isRunning)
+
     @Inject private lateinit var getIncognitoState: GetIncognitoState
 
     @Inject private lateinit var extensionManager: ExtensionManager
@@ -160,7 +167,10 @@ class MainActivity : BaseActivity() {
 
         super.onCreate(savedInstanceState)
 
-        Migrator.awaitAndRelease()
+        lifecycleScope.launch {
+            Migrator.awaitAndRelease()
+            isAppMigrating.value = false
+        }
 
         // Do not let the launcher create a new activity http://stackoverflow.com/questions/16283079
         if (!isTaskRoot) {
@@ -169,6 +179,15 @@ class MainActivity : BaseActivity() {
         }
 
         setComposeContent {
+            val appMigrating by isAppMigrating.collectAsState()
+            val databaseMigrating by databaseRepository.isMigrating.collectAsState()
+            if (appMigrating || databaseMigrating) {
+                AppMigratingScreen()
+                // Release the splash screen so the reason for the wait shows
+                LaunchedEffect(Unit) { ready = true }
+                return@setComposeContent
+            }
+
             val context = LocalContext.current
 
             var incognito by remember { mutableStateOf(false) }