Make sure that PerformCreate[ExternalEmail]User can be invoked multiple times without throwing errors

Recover from "Username already taken or not allowed" error when creating new user accounts.

auth/domain/src/main/kotlin/me/proton/core/auth/domain/usecase/signup/PerformCreateExternalEmailUser.kt

@@ -19,13 +19,14 @@
 package me.proton.core.auth.domain.usecase.signup
 
 import me.proton.core.auth.domain.repository.AuthRepository
+import me.proton.core.auth.domain.usecase.PerformLogin
 import me.proton.core.crypto.common.keystore.EncryptedString
 import me.proton.core.crypto.common.keystore.KeyStoreCrypto
 import me.proton.core.crypto.common.keystore.decrypt
 import me.proton.core.crypto.common.keystore.use
 import me.proton.core.crypto.common.srp.SrpCrypto
+import me.proton.core.domain.entity.UserId
 import me.proton.core.user.domain.entity.CreateUserType
-import me.proton.core.user.domain.entity.User
 import me.proton.core.user.domain.repository.UserRepository
 import javax.inject.Inject
 
@@ -33,15 +34,21 @@ class PerformCreateExternalEmailUser @Inject constructor(
     private val authRepository: AuthRepository,
     private val userRepository: UserRepository,
     private val srpCrypto: SrpCrypto,
-    private val keyStoreCrypto: KeyStoreCrypto
+    private val keyStoreCrypto: KeyStoreCrypto,
+    private val performLogin: PerformLogin
 ) {
 
     suspend operator fun invoke(
         email: String,
         password: EncryptedString,
         referrer: String?
-    ): User {
+    ): UserId {
         require(email.isNotBlank()) { "Email must not be empty." }
+
+        if (!userRepository.isUsernameAvailable(email)) {
+            return performLogin.invoke(email, password).userId
+        }
+
         val modulus = authRepository.randomModulus()
 
         password.decrypt(keyStoreCrypto).toByteArray().use { decryptedPassword ->
@@ -57,7 +64,7 @@ class PerformCreateExternalEmailUser @Inject constructor(
                 referrer = referrer,
                 type = CreateUserType.Normal,
                 auth = auth
-            )
+            ).userId
         }
     }
 }

auth/domain/src/main/kotlin/me/proton/core/auth/domain/usecase/signup/PerformCreateUser.kt

@@ -19,13 +19,14 @@
 package me.proton.core.auth.domain.usecase.signup
 
 import me.proton.core.auth.domain.repository.AuthRepository
+import me.proton.core.auth.domain.usecase.PerformLogin
 import me.proton.core.crypto.common.keystore.EncryptedString
 import me.proton.core.crypto.common.keystore.KeyStoreCrypto
 import me.proton.core.crypto.common.keystore.decrypt
 import me.proton.core.crypto.common.keystore.use
 import me.proton.core.crypto.common.srp.SrpCrypto
+import me.proton.core.domain.entity.UserId
 import me.proton.core.user.domain.entity.CreateUserType
-import me.proton.core.user.domain.entity.User
 import me.proton.core.user.domain.repository.UserRepository
 import javax.inject.Inject
 
@@ -33,7 +34,8 @@ class PerformCreateUser @Inject constructor(
     private val authRepository: AuthRepository,
     private val userRepository: UserRepository,
     private val srpCrypto: SrpCrypto,
-    private val keyStoreCrypto: KeyStoreCrypto
+    private val keyStoreCrypto: KeyStoreCrypto,
+    private val performLogin: PerformLogin
 ) {
 
     suspend operator fun invoke(
@@ -42,13 +44,18 @@ class PerformCreateUser @Inject constructor(
         recoveryEmail: String?,
         recoveryPhone: String?,
         referrer: String?,
-        type: CreateUserType,
-    ): User {
+        type: CreateUserType
+    ): UserId {
         require(
-            (recoveryEmail == null && recoveryPhone == null) ||
-                (recoveryEmail == null && recoveryPhone != null) ||
-                (recoveryEmail != null && recoveryPhone == null)
+            recoveryEmail == null && recoveryPhone == null ||
+                recoveryEmail == null && recoveryPhone != null ||
+                recoveryEmail != null && recoveryPhone == null
         ) { "Recovery Email and Phone could not be set together" }
+
+        if (!userRepository.isUsernameAvailable(username)) {
+            return performLogin.invoke(username, password).userId
+        }
+
         val modulus = authRepository.randomModulus()
 
         password.decrypt(keyStoreCrypto).toByteArray().use { decryptedPassword ->
@@ -66,7 +73,7 @@ class PerformCreateUser @Inject constructor(
                 referrer = referrer,
                 type = type,
                 auth = auth
-            )
+            ).userId
         }
     }
 }

auth/presentation/src/main/kotlin/me/proton/core/auth/presentation/viewmodel/signup/SignupViewModel.kt

@@ -35,6 +35,8 @@ import kotlinx.coroutines.launch
 import me.proton.core.account.domain.entity.AccountType
 import me.proton.core.auth.domain.usecase.signup.PerformCreateExternalEmailUser
 import me.proton.core.auth.domain.usecase.signup.PerformCreateUser
+import me.proton.core.auth.domain.usecase.userAlreadyExists
+import me.proton.core.auth.presentation.LogTag
 import me.proton.core.auth.presentation.entity.signup.RecoveryMethod
 import me.proton.core.auth.presentation.entity.signup.RecoveryMethodType
 import me.proton.core.auth.presentation.entity.signup.SubscriptionDetails
@@ -45,8 +47,6 @@ import me.proton.core.crypto.common.keystore.encrypt
 import me.proton.core.humanverification.domain.HumanVerificationManager
 import me.proton.core.humanverification.presentation.HumanVerificationOrchestrator
 import me.proton.core.humanverification.presentation.onHumanVerificationFailed
-import me.proton.core.humanverification.presentation.onHumanVerificationNeeded
-import me.proton.core.humanverification.presentation.onHumanVerificationSucceeded
 import me.proton.core.network.domain.client.ClientIdProvider
 import me.proton.core.payment.domain.entity.SubscriptionCycle
 import me.proton.core.payment.presentation.PaymentsOrchestrator
@@ -55,7 +55,9 @@ import me.proton.core.plan.presentation.PlansOrchestrator
 import me.proton.core.presentation.savedstate.flowState
 import me.proton.core.presentation.savedstate.state
 import me.proton.core.user.domain.entity.createUserType
+import me.proton.core.util.kotlin.CoreLogger
 import me.proton.core.util.kotlin.exhaustive
+import me.proton.core.util.kotlin.retryOnceWhen
 import javax.inject.Inject
 
 @HiltViewModel
@@ -228,7 +230,9 @@ internal class SignupViewModel @Inject constructor(
             username = username, password = encryptedPassword, recoveryEmail = verification.first,
             recoveryPhone = verification.second, referrer = null, type = currentAccountType.createUserType()
         )
-        emit(State.Success(result.userId.id, username, encryptedPassword))
+        emit(State.Success(result.id, username, encryptedPassword))
+    }.retryOnceWhen(Throwable::userAlreadyExists) {
+        CoreLogger.e(LogTag.FLOW_ERROR_RETRY, it, "Retrying to create a user")
     }.catch { error ->
         emit(State.Error.Message(error.message))
     }.onEach {
@@ -239,12 +243,14 @@ internal class SignupViewModel @Inject constructor(
         val externalEmail = requireNotNull(externalEmail) { "External email is not set." }
         val encryptedPassword = requireNotNull(_password) { "Password is not set (initialized)." }
         emit(State.Processing)
-        val user = performCreateExternalEmailUser(
+        val userId = performCreateExternalEmailUser(
             email = externalEmail,
             password = encryptedPassword,
             referrer = null
         )
-        emit(State.Success(user.userId.id, externalEmail, encryptedPassword))
+        emit(State.Success(userId.id, externalEmail, encryptedPassword))
+    }.retryOnceWhen(Throwable::userAlreadyExists) {
+        CoreLogger.e(LogTag.FLOW_ERROR_RETRY, it, "Retrying to create an external user")
     }.catch { error ->
         emit(State.Error.Message(error.message))
     }.onEach {