fix(login): preserve state after activity recreation

app/src/main/java/one/mixin/android/ui/landing/LandingActivity.kt

@@ -63,23 +63,25 @@ class LandingActivity : BaseActivity() {
         SystemUIManager.setSafePadding(window, color = colorFromAttribute(R.attr.bg_white), imePadding = true)
         checkVersion()
         setContentView(binding.root)
-        val pin = intent.getStringExtra(ARGS_PIN)
-        val from = intent.getIntExtra(ARGS_FROM, -1)
-        val phoneNumber = intent.getStringExtra(ARGS_PHONE_NUM)
-        val fragment =
-            if (pin != null) {
-                MobileFragment.newInstance(pin, FROM_CHANGE_PHONE_ACCOUNT)
-            } else if (from == FROM_CHANGE_PHONE_ACCOUNT) {
-                MobileFragment.newInstance(from = FROM_CHANGE_PHONE_ACCOUNT)
-            } else if (from == FROM_VERIFY_MOBILE_REMINDER) {
-                MobileFragment.newInstance(from = FROM_VERIFY_MOBILE_REMINDER, phoneNumber = phoneNumber)
-            } else {
-                lifecycleScope.launch(Dispatchers.IO) {
-                    jobManager.clear()
+        if (shouldInitializeLanding(savedInstanceState != null)) {
+            val pin = intent.getStringExtra(ARGS_PIN)
+            val from = intent.getIntExtra(ARGS_FROM, -1)
+            val phoneNumber = intent.getStringExtra(ARGS_PHONE_NUM)
+            val fragment =
+                if (pin != null) {
+                    MobileFragment.newInstance(pin, FROM_CHANGE_PHONE_ACCOUNT)
+                } else if (from == FROM_CHANGE_PHONE_ACCOUNT) {
+                    MobileFragment.newInstance(from = FROM_CHANGE_PHONE_ACCOUNT)
+                } else if (from == FROM_VERIFY_MOBILE_REMINDER) {
+                    MobileFragment.newInstance(from = FROM_VERIFY_MOBILE_REMINDER, phoneNumber = phoneNumber)
+                } else {
+                    lifecycleScope.launch(Dispatchers.IO) {
+                        jobManager.clear()
+                    }
+                    LandingFragment.newInstance()
                 }
-                LandingFragment.newInstance()
-            }
-        replaceFragment(fragment, R.id.container)
+            replaceFragment(fragment, R.id.container)
+        }
     }
 
     private fun checkVersion(){
@@ -93,3 +95,5 @@ class LandingActivity : BaseActivity() {
         }
     }
 }
+
+internal fun shouldInitializeLanding(hasSavedInstanceState: Boolean) = !hasSavedInstanceState

app/src/main/java/one/mixin/android/ui/landing/MnemonicPhraseFragment.kt

@@ -78,6 +78,8 @@ class MnemonicPhraseFragment : BaseFragment(R.layout.fragment_compose) {
         const val ARGS_MNEMONIC_PHRASE = "mnemonic_phrase"
         private const val ARGS_PENDING_IMPORT_MNEMONIC = "pending_import_mnemonic"
         private const val ARGS_PASTED_MNEMONIC = "pasted_mnemonic"
+        private const val STATE_ERROR_INFO = "error_info"
+        private const val STATE_REQUEST_FAILED = "request_failed"
 
         fun newInstance(
             words: ArrayList<String>? = null,
@@ -129,12 +131,27 @@ class MnemonicPhraseFragment : BaseFragment(R.layout.fragment_compose) {
             LogViewerBottomSheet.newInstance().showNow(parentFragmentManager, LogViewerBottomSheet.TAG)
             true
         }
+        errorInfo = savedInstanceState?.getString(STATE_ERROR_INFO)
+        val restoredRequestFailed = savedInstanceState?.getBoolean(STATE_REQUEST_FAILED) == true
         binding.compose.setContent {
             MnemonicPhrasePage(!words.isNullOrEmpty(), errorInfo) {
                 anonymousRequest(words)
             }
         }
-        anonymousRequest(words)
+        if (shouldRequestAnonymousLogin(restoredRequestFailed)) {
+            anonymousRequest(words)
+        } else {
+            landingViewModel.updateMnemonicPhraseState(MnemonicPhraseState.Failure)
+        }
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        errorInfo?.let { outState.putString(STATE_ERROR_INFO, it) }
+        outState.putBoolean(
+            STATE_REQUEST_FAILED,
+            landingViewModel.mnemonicPhraseState.value == MnemonicPhraseState.Failure,
+        )
     }
 
     private fun applySafeTopPadding(rootView: View) {
@@ -476,3 +493,5 @@ class MnemonicPhraseFragment : BaseFragment(R.layout.fragment_compose) {
         }
     }
 }
+
+internal fun shouldRequestAnonymousLogin(restoredRequestFailed: Boolean) = !restoredRequestFailed

app/src/test/java/one/mixin/android/ui/landing/LandingActivityStateRestorationTest.kt

@@ -0,0 +1,27 @@
+package one.mixin.android.ui.landing
+
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class LandingActivityStateRestorationTest {
+    @Test
+    fun `initializes landing content on first creation`() {
+        assertTrue(shouldInitializeLanding(hasSavedInstanceState = false))
+    }
+
+    @Test
+    fun `keeps restored fragment stack after recreation`() {
+        assertFalse(shouldInitializeLanding(hasSavedInstanceState = true))
+    }
+
+    @Test
+    fun `preserves captcha failure without an error message`() {
+        assertFalse(shouldRequestAnonymousLogin(restoredRequestFailed = true))
+    }
+
+    @Test
+    fun `starts anonymous login when no failure was restored`() {
+        assertTrue(shouldRequestAnonymousLogin(restoredRequestFailed = false))
+    }
+}