Introduce UserServerResolver.

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/MatrixClient.kt

@@ -121,4 +121,10 @@ interface MatrixClient : Closeable {
      * This flow will emit a new value whenever the send queue is disabled for a room.
      */
     fun sendQueueDisabledFlow(): Flow<RoomId>
+
+    /**
+     * Return the server name part of the current user ID, using the SDK, and if a failure occurs,
+     * compute it manually.
+     */
+    fun userIdServerName(): String
 }

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/server/UserServerResolver.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.api.server
+
+interface UserServerResolver {
+    fun resolve(): String
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClient.kt

@@ -280,6 +280,17 @@ class RustMatrixClient(
         }
     }
 
+    override fun userIdServerName(): String {
+        return runCatching {
+            client.userIdServerName()
+        }
+            .onFailure {
+                Timber.w(it, "Failed to get userIdServerName")
+            }
+            .getOrNull()
+            ?: sessionId.value.substringAfter(":")
+    }
+
     override suspend fun getRoom(roomId: RoomId): MatrixRoom? {
         return roomFactory.create(roomId)
     }

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/server/DefaultUserServerResolver.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.server
+
+import com.squareup.anvil.annotations.ContributesBinding
+import io.element.android.libraries.di.SessionScope
+import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.api.server.UserServerResolver
+import javax.inject.Inject
+
+@ContributesBinding(SessionScope::class)
+class DefaultUserServerResolver @Inject constructor(
+    private val matrixClient: MatrixClient,
+) : UserServerResolver {
+    override fun resolve(): String {
+        return matrixClient.userIdServerName()
+    }
+}

libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/FakeMatrixClient.kt

@@ -313,4 +313,8 @@ class FakeMatrixClient(
 
     var sendQueueDisabledFlow = emptyFlow<RoomId>()
     override fun sendQueueDisabledFlow(): Flow<RoomId> = sendQueueDisabledFlow
+
+    override fun userIdServerName(): String {
+        TODO("Not yet implemented")
+    }
 }