Create account: user feedback when account name is already taken (#701)

* Show snackbar when account can't be created without known reason; show error when account name is taken

* Don't crash on empty account name

app/src/main/kotlin/at/bitfire/davdroid/ui/setup/AccountDetailsPage.kt

@@ -19,6 +19,7 @@ import androidx.compose.material.Icon
 import androidx.compose.material.MaterialTheme
 import androidx.compose.material.OutlinedTextField
 import androidx.compose.material.RadioButton
+import androidx.compose.material.SnackbarHostState
 import androidx.compose.material.Text
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Email
@@ -29,9 +30,11 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringArrayResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.input.KeyboardType
@@ -43,9 +46,11 @@ import at.bitfire.davdroid.servicedetection.DavResourceFinder
 import at.bitfire.davdroid.ui.composable.Assistant
 import at.bitfire.davdroid.ui.widget.ExceptionInfoDialog
 import at.bitfire.vcard4android.GroupMethod
+import kotlinx.coroutines.launch
 
 @Composable
 fun AccountDetailsPage(
+    snackbarHostState: SnackbarHostState,
     loginInfo: LoginInfo,
     foundConfig: DavResourceFinder.Configuration,
     onBack: () -> Unit,
@@ -54,6 +59,9 @@ fun AccountDetailsPage(
 ) {
     BackHandler(onBack = onBack)
 
+    val context = LocalContext.current
+    val scope = rememberCoroutineScope()
+
     val resultOrNull by model.createAccountResult.observeAsState()
     var showExceptionInfo by remember { mutableStateOf(false) }
     LaunchedEffect(resultOrNull) {
@@ -73,9 +81,16 @@ fun AccountDetailsPage(
                                 model.createAccountResult.value = null
                             }
                         )
-                    // TODO else
-                }
+                    else
+                        scope.launch {
+                            snackbarHostState.showSnackbar(context.getString(R.string.login_account_not_created))
+                        }
+                    }
+                else -> {}
             }
+
+            // reset result
+            model.createAccountResult.value = null
         }
 
     val suggestedAccountNames = foundConfig.calDAV?.emails ?: emptyList()
@@ -86,6 +101,7 @@ fun AccountDetailsPage(
     AccountDetailsPage_Content(
         suggestedAccountNames = suggestedAccountNames,
         accountName = accountName,
+        accountNameAlreadyExists = model.accountExists(accountName).observeAsState(false).value,
         onUpdateAccountName = { accountName = it },
         onCreateAccount = {
             model.createAccount(
@@ -106,6 +122,7 @@ fun AccountDetailsPage(
 fun AccountDetailsPage_Content(
     suggestedAccountNames: List<String>,
     accountName: String,
+    accountNameAlreadyExists: Boolean,
     onUpdateAccountName: (String) -> Unit = {},
     groupMethod: GroupMethod,
     groupMethodReadOnly: Boolean,
@@ -114,7 +131,8 @@ fun AccountDetailsPage_Content(
 ) {
     Assistant(
         nextLabel = stringResource(R.string.login_create_account),
-        onNext = onCreateAccount
+        onNext = onCreateAccount,
+        nextEnabled = accountName.isNotBlank() && !accountNameAlreadyExists
     ) {
         Column(Modifier.padding(8.dp)) {
             var expanded by remember { mutableStateOf(false) }
@@ -122,10 +140,15 @@ fun AccountDetailsPage_Content(
                 expanded = expanded,
                 onExpandedChange = { expanded = it }
             ) {
+                val accountNameLabel = if (accountNameAlreadyExists)
+                    stringResource(R.string.login_account_name_already_taken)
+                else
+                    stringResource(R.string.login_account_name)
                 OutlinedTextField(
                     value = accountName,
                     onValueChange = onUpdateAccountName,
-                    label = { Text(stringResource(R.string.login_account_name)) },
+                    label = { Text(accountNameLabel) },
+                    isError = accountNameAlreadyExists,
                     singleLine = true,
                     keyboardOptions = KeyboardOptions(
                         keyboardType = KeyboardType.Email
@@ -227,6 +250,7 @@ fun AccountDetailsPage_Content_Preview() {
     AccountDetailsPage_Content(
         suggestedAccountNames = listOf("name1", "name2@example.com"),
         accountName = "account@example.com",
+        accountNameAlreadyExists = false,
         groupMethod = GroupMethod.GROUP_VCARDS,
         groupMethodReadOnly = false
     )
@@ -238,6 +262,7 @@ fun AccountDetailsPage_Content_Preview_With_Apostrophe() {
     AccountDetailsPage_Content(
         suggestedAccountNames = listOf("name1", "name2@example.com"),
         accountName = "account'example.com",
+        accountNameAlreadyExists = true,
         groupMethod = GroupMethod.CATEGORIES,
         groupMethodReadOnly = true
     )

app/src/main/kotlin/at/bitfire/davdroid/ui/setup/LoginModel.kt

@@ -5,12 +5,15 @@
 package at.bitfire.davdroid.ui.setup
 
 import android.accounts.Account
+import android.accounts.AccountManager
 import android.app.Application
 import android.content.ContentResolver
 import android.provider.CalendarContract
 import androidx.core.os.CancellationSignal
+import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.liveData
 import androidx.lifecycle.map
 import androidx.lifecycle.viewModelScope
 import at.bitfire.davdroid.InvalidAccountException
@@ -77,6 +80,19 @@ class LoginModel @Inject constructor(
     }
 
 
+    fun accountExists(accountName: String): LiveData<Boolean> = liveData {
+        val accountType = context.getString(R.string.account_type)
+        val exists =
+            if (accountName.isEmpty())
+                false
+            else
+                AccountManager.get(context)
+                    .getAccountsByType(accountType)
+                    .contains(Account(accountName, accountType))
+        emit(exists)
+    }
+
+
     interface CreateAccountResult {
         class Success(val account: Account): CreateAccountResult
         class Error(val exception: Exception?): CreateAccountResult

app/src/main/kotlin/at/bitfire/davdroid/ui/setup/LoginScreen.kt

@@ -145,6 +145,7 @@ fun LoginScreen(
                     foundConfig?.let {
                         val context = LocalContext.current
                         AccountDetailsPage(
+                            snackbarHostState = snackbarHostState,
                             loginInfo = loginInfo,
                             foundConfig = it,
                             onBack = { phase = LoginActivity.Phase.LOGIN_TYPE },