Only take up to 100 suggestions for the picker.

This was broken before.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/mentions/MentionSuggestionsProcessor.kt

@@ -17,6 +17,7 @@
 package io.element.android.features.messages.impl.mentions
 
 import io.element.android.features.messages.impl.messagecomposer.MentionSuggestion
+import io.element.android.libraries.core.data.filterUpTo
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.room.MatrixRoomMembersState
 import io.element.android.libraries.matrix.api.room.RoomMember
@@ -48,8 +49,6 @@ object MentionSuggestionsProcessor {
         canSendRoomMention: suspend () -> Boolean,
     ): List<MentionSuggestion> {
         val members = roomMembersState.roomMembers()
-            // Take the first MAX_BATCH_ITEMS only
-            ?.take(MAX_BATCH_ITEMS)
         return when {
             members.isNullOrEmpty() || suggestion == null -> {
                 // Clear suggestions
@@ -61,7 +60,7 @@ object MentionSuggestionsProcessor {
                         // Replace suggestions
                         val matchingMembers = getMemberSuggestions(
                             query = suggestion.text,
-                            roomMembers = roomMembersState.roomMembers(),
+                            roomMembers = members,
                             currentUserId = currentUserId,
                             canSendRoomMention = canSendRoomMention()
                         )
@@ -95,8 +94,8 @@ object MentionSuggestionsProcessor {
             }
 
             val matchingMembers = roomMembers
-                // Search only in joined members, exclude the current user
-                .filter { member ->
+                // Search only in joined members, up to MAX_BATCH_ITEMS, exclude the current user
+                .filterUpTo(MAX_BATCH_ITEMS) { member ->
                     isJoinedMemberAndNotSelf(member) && memberMatchesQuery(member, query)
                 }
                 .map(MentionSuggestion::Member)

libraries/core/src/main/kotlin/io/element/android/libraries/core/data/FilterUpTo.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2023 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.core.data
+
+/**
+ * Returns a list containing first [count] elements matching the given [predicate].
+ * If the list contains less elements matching the [predicate], then all of them are returned.
+ *
+ * @param count the maximum number of elements to take.
+ * @param predicate the predicate used to match elements.
+ * @return a list containing first [count] elements matching the given [predicate].
+ */
+inline fun <T> Iterable<T>.filterUpTo(count: Int, predicate: (T) -> Boolean): List<T> {
+    val result = mutableListOf<T>()
+    for (element in this) {
+        if (predicate(element)) {
+            result.add(element)
+            if (result.size == count) {
+                break
+            }
+        }
+    }
+    return result
+}