add a logout button that clears datastore when tapped

android/Omnivore/app/src/main/java/app/omnivore/omnivore/DatastoreRepository.kt

@@ -19,6 +19,7 @@ private val Context.dataStore: DataStore<Preferences> by preferencesDataStore(
 
 interface DatastoreRepository {
   val hasAuthTokenFlow: Flow<Boolean>
+  suspend fun clear()
   suspend fun putString(key: String, value: String)
   suspend fun putInt(key: String, value: Int)
   suspend fun getString(key: String): String?
@@ -54,6 +55,10 @@ class OmnivoreDatastore @Inject constructor(
     return preferences[preferencesKey]
   }
 
+  override suspend fun clear() {
+    context.dataStore.edit { it.clear() }
+  }
+
   override val hasAuthTokenFlow: Flow<Boolean> = context
     .dataStore.data.map { preferences ->
       val key = stringPreferencesKey(DatastoreKeys.omnivoreAuthToken)

android/Omnivore/app/src/main/java/app/omnivore/omnivore/LoginViewModel.kt

@@ -48,4 +48,10 @@ class LoginViewModel @Inject constructor(
       }
     }
   }
+
+  fun logout() {
+    viewModelScope.launch {
+      datastoreRepo.clear()
+    }
+  }
 }

android/Omnivore/app/src/main/java/app/omnivore/omnivore/MainActivity.kt

@@ -37,7 +37,7 @@ class MainActivity : ComponentActivity() {
       OmnivoreTheme {
         // A surface container using the 'background' color from the theme
         Surface(modifier = Modifier.fillMaxSize(), color = MaterialTheme.colors.background) {
-          rootView(viewModel)
+          RootView(viewModel)
         }
       }
     }
@@ -45,18 +45,18 @@ class MainActivity : ComponentActivity() {
 }
 
 @Composable
-fun rootView(viewModel: LoginViewModel) {
+fun RootView(viewModel: LoginViewModel) {
   val hasAuthToken: Boolean by viewModel.hasAuthTokenLiveData.observeAsState(false)
 
   if (hasAuthToken) {
-    loggedInView()
+    LoggedInView(viewModel)
   } else {
     LoginView(viewModel)
   }
 }
 
 @Composable
-fun loggedInView() {
+fun LoggedInView(viewModel: LoginViewModel) {
   Column(
     verticalArrangement = Arrangement.Center,
     horizontalAlignment = Alignment.CenterHorizontally,
@@ -65,6 +65,12 @@ fun loggedInView() {
       .fillMaxSize()
   ) {
     Text("You have a valid auth token. Nice. Go save something in Chrome!")
+
+    Button(onClick = {
+      viewModel.logout()
+    }) {
+      Text(text = "Logout")
+    }
   }
 }