Resolve display names in mentions in real time (#3051)

* Resolve display names in mentions in real time

* Use `LocalRoomMemberProfilesCache` to avoid having to implement `TextMessagePresenter`

* Also use local composition provider for `MentionSpanProvider`

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/messages/RoomMemberProfilesCache.kt

@@ -0,0 +1,44 @@
+/*
+ * 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
+ *
+ *     http://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.ui.messages
+
+import androidx.compose.runtime.staticCompositionLocalOf
+import io.element.android.libraries.matrix.api.core.UserId
+import io.element.android.libraries.matrix.api.room.RoomMember
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import javax.inject.Inject
+
+class RoomMemberProfilesCache @Inject constructor() {
+    private val cache = MutableStateFlow(mapOf<UserId, RoomMember>())
+
+    private val _lastCacheUpdate = MutableStateFlow(0L)
+    val lastCacheUpdate: StateFlow<Long> = _lastCacheUpdate
+
+    fun replace(items: List<RoomMember>) {
+        cache.value = items.associateBy { it.userId }
+        _lastCacheUpdate.tryEmit(_lastCacheUpdate.value + 1)
+    }
+
+    fun getDisplayName(userId: UserId): String? {
+        return cache.value[userId]?.disambiguatedDisplayName
+    }
+}
+
+val LocalRoomMemberProfilesCache = staticCompositionLocalOf {
+    RoomMemberProfilesCache()
+}