Disable sign-in button & show error message when network is unavailab…

…le (#2067)

ground/src/main/java/com/google/android/ground/system/NetworkManager.kt

@@ -38,7 +38,7 @@ enum class NetworkStatus {
 class NetworkManager @Inject constructor(@ApplicationContext private val context: Context) {
   val networkStatusFlow = initNetworkStatusFlow()
 
-  fun initNetworkStatusFlow(): Flow<NetworkStatus> {
+  private fun initNetworkStatusFlow(): Flow<NetworkStatus> {
     val connectivityManager = context.getSystemService(ConnectivityManager::class.java)
     return callbackFlow {
       val callback =

ground/src/main/java/com/google/android/ground/ui/signin/SignInFragment.kt

@@ -19,14 +19,20 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import androidx.lifecycle.lifecycleScope
+import com.google.android.ground.R
 import com.google.android.ground.databinding.SignInFragBinding
 import com.google.android.ground.ui.common.AbstractFragment
 import com.google.android.ground.ui.common.BackPressListener
+import com.google.android.material.snackbar.Snackbar
 import dagger.hilt.android.AndroidEntryPoint
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.launch
 
 @AndroidEntryPoint(AbstractFragment::class)
 class SignInFragment : Hilt_SignInFragment(), BackPressListener {
 
+  private lateinit var binding: SignInFragBinding
   private lateinit var viewModel: SignInViewModel
 
   override fun onCreate(savedInstanceState: Bundle?) {
@@ -39,12 +45,34 @@ class SignInFragment : Hilt_SignInFragment(), BackPressListener {
     container: ViewGroup?,
     savedInstanceState: Bundle?
   ): View {
-    val binding = SignInFragBinding.inflate(inflater, container, false)
+    binding = SignInFragBinding.inflate(inflater, container, false)
     binding.viewModel = viewModel
     binding.lifecycleOwner = this
     return binding.root
   }
 
+  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+    super.onViewCreated(view, savedInstanceState)
+
+    lifecycleScope.launch(Dispatchers.Main) {
+      viewModel.getNetworkFlow().collect { connected ->
+        if (!connected) {
+          displayNetworkError()
+        }
+        binding.signInButton.isEnabled = connected
+      }
+    }
+  }
+
+  private fun displayNetworkError() {
+    Snackbar.make(
+        requireView(),
+        getString(R.string.network_error_when_signing_in),
+        Snackbar.LENGTH_LONG
+      )
+      .show()
+  }
+
   override fun onBack(): Boolean {
     // Workaround to exit on back from sign-in screen since for some reason
     // popUpTo is not working on signOut action.

ground/src/main/java/com/google/android/ground/ui/signin/SignInViewModel.kt

@@ -15,12 +15,31 @@
  */
 package com.google.android.ground.ui.signin
 
+import androidx.lifecycle.viewModelScope
 import com.google.android.ground.repository.UserRepository
+import com.google.android.ground.system.NetworkManager
+import com.google.android.ground.system.NetworkStatus
 import com.google.android.ground.ui.common.AbstractViewModel
 import javax.inject.Inject
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.mapLatest
+import kotlinx.coroutines.flow.shareIn
+
+class SignInViewModel
+@Inject
+internal constructor(
+  private val networkManager: NetworkManager,
+  private val userRepository: UserRepository
+) : AbstractViewModel() {
+
+  @OptIn(ExperimentalCoroutinesApi::class)
+  fun getNetworkFlow(): Flow<Boolean> =
+    networkManager.networkStatusFlow
+      .mapLatest { it == NetworkStatus.AVAILABLE }
+      .shareIn(viewModelScope, SharingStarted.Lazily, replay = 0)
 
-class SignInViewModel @Inject internal constructor(private val userRepository: UserRepository) :
-  AbstractViewModel() {
   fun onSignInButtonClick() {
     userRepository.signIn()
   }

ground/src/main/res/values/strings.xml

@@ -124,4 +124,5 @@
   <string name="offline_area_list_item_icon">Offline area list item icon</string>
   <string name="no_surveys_available">No surveys available. Contact your survey organizer to get access.</string>
   <string name="previous">Previous</string>
+  <string name="network_error_when_signing_in">Connect to the internet to sign in</string>
 </resources>

ground/src/test/java/com/google/android/ground/ui/signin/SignInFragmentTest.kt

@@ -17,24 +17,37 @@ package com.google.android.ground.ui.signin
 
 import androidx.test.espresso.Espresso.onView
 import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
+import androidx.test.espresso.matcher.ViewMatchers.isNotEnabled
 import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.espresso.matcher.ViewMatchers.withText
 import com.google.android.ground.BaseHiltTest
 import com.google.android.ground.R
 import com.google.android.ground.launchFragmentInHiltContainer
+import com.google.android.ground.system.NetworkManager
+import com.google.android.ground.system.NetworkStatus
 import com.google.android.ground.system.auth.SignInState
 import com.google.common.truth.Truth.assertThat
 import com.sharedtest.FakeData
 import com.sharedtest.system.auth.FakeAuthenticationManager
+import dagger.hilt.android.testing.BindValue
 import dagger.hilt.android.testing.HiltAndroidTest
 import javax.inject.Inject
+import kotlinx.coroutines.flow.flowOf
+import org.hamcrest.Matchers.allOf
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.mockito.Mock
+import org.mockito.kotlin.whenever
 import org.robolectric.RobolectricTestRunner
 
 @HiltAndroidTest
 @RunWith(RobolectricTestRunner::class)
 class SignInFragmentTest : BaseHiltTest() {
 
+  @BindValue @Mock lateinit var networkManager: NetworkManager
+
   @Inject lateinit var fakeAuthenticationManager: FakeAuthenticationManager
 
   override fun setUp() {
@@ -43,7 +56,8 @@ class SignInFragmentTest : BaseHiltTest() {
   }
 
   @Test
-  fun buttonClick_shouldSignIn() {
+  fun `Clicking sign-in button when network is available should attempt login`() {
+    whenever(networkManager.networkStatusFlow).thenReturn(flowOf(NetworkStatus.AVAILABLE))
     launchFragmentInHiltContainer<SignInFragment>()
     fakeAuthenticationManager.setUser(TEST_USER)
 
@@ -55,7 +69,24 @@ class SignInFragmentTest : BaseHiltTest() {
   }
 
   @Test
-  fun pressBack_shouldFinishActivity() {
+  fun `Sign-in button should be disabled when network is not available`() {
+    whenever(networkManager.networkStatusFlow).thenReturn(flowOf(NetworkStatus.UNAVAILABLE))
+    launchFragmentInHiltContainer<SignInFragment>()
+    fakeAuthenticationManager.setUser(TEST_USER)
+
+    onView(allOf(withId(R.id.sign_in_button), isDisplayed(), isNotEnabled())).perform(click())
+
+    // Assert that the sign-in state is still signed out
+    fakeAuthenticationManager.signInState
+      .test()
+      .assertValue(SignInState(SignInState.State.SIGNED_OUT, Result.success(null)))
+
+    onView(withId(com.google.android.material.R.id.snackbar_text))
+      .check(matches(withText(R.string.network_error_when_signing_in)))
+  }
+
+  @Test
+  fun `Back press should finish activity`() {
     launchFragmentInHiltContainer<SignInFragment> {
       val fragment = this as SignInFragment
       assertThat(fragment.onBack()).isFalse()