make loading seamless

app/src/main/java/eu/m724/vastapp/activity/login/LoginActivity.kt

@@ -107,7 +107,13 @@ class LoginActivity : ComponentActivity() {
                         verticalArrangement = Arrangement.Center,
                         horizontalAlignment = Alignment.CenterHorizontally
                     ) {
-                        LoginApp(loginViewModel)
+                        val loading by loginViewModel.fullscreenLoading.collectAsState()
+
+                        if (loading) {
+                            CircularProgressIndicator()
+                        } else {
+                            LoginApp(loginViewModel)
+                        }
                     }
                 }
             }

app/src/main/java/eu/m724/vastapp/activity/login/LoginViewModel.kt

@@ -31,25 +31,12 @@ class LoginViewModel(
     private val _apiKey = MutableStateFlow<String>("")
     var apiKey: StateFlow<String> = _apiKey.asStateFlow()
 
+    private val _fullscreenLoading = MutableStateFlow<Boolean>(false)
+    var fullscreenLoading: StateFlow<Boolean> = _fullscreenLoading.asStateFlow()
+
     private val applicationContext = getApplication<Application>().applicationContext
     private val sharedPreferences = applicationContext.getSharedPreferences("login", Context.MODE_PRIVATE)
 
-    fun loadKey() {
-        val apiKey = sharedPreferences.getString("apiKey", null)
-
-        if (apiKey != null) {
-            _apiKey.value = apiKey
-            tryLogin(LoginUiState.FullLoading)
-        }
-    }
-
-    fun tryLogin() {
-        tryLogin(LoginUiState.Loading)
-    }
-
-    fun onApiKeyChange(apiKey: String) {
-        _apiKey.update { apiKey }
-    }
 
     private fun saveKey() {
         with (sharedPreferences.edit()) {
@@ -58,7 +45,17 @@ class LoginViewModel(
         }
     }
 
-    private fun tryLogin(initialState: LoginUiState) {
+    fun loadKey() {
+        val apiKey = sharedPreferences.getString("apiKey", null)
+
+        if (apiKey != null) {
+            _apiKey.value = apiKey
+            _fullscreenLoading.value = true
+            tryLogin()
+        }
+    }
+
+    fun tryLogin() {
         val apiKey = apiKey.value
 
         val vastApi = VastApi(apiKey, cronetEngine, executor)
@@ -69,12 +66,16 @@ class LoginViewModel(
                 _uiState.value = LoginUiState.Success(user)
             }, { apiFailure ->
                 _uiState.value = LoginUiState.Idle
+                _fullscreenLoading.value = false
                 _error.postValue(apiFailure.errorMessage)
             })
         )
 
-
+        _uiState.value = LoginUiState.Loading
-        _uiState.value = initialState
         request.start()
     }
+
+    fun onApiKeyChange(apiKey: String) {
+        _apiKey.update { apiKey }
+    }
 }