Add EventMenuBuilder to manage ordering on event menu actions

Riot/Modules/Room/EventMenu/EventMenuBuilder.swift

@@ -0,0 +1,50 @@
+// 
+// Copyright 2021 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.
+//
+
+import Foundation
+
+/// Class to build an event menu.
+@objcMembers
+class EventMenuBuilder: NSObject {
+    
+    private var items: [EventMenuItemType: UIAlertAction] = [:]
+    
+    /// Returns true if no items or only one item with the type `EventMenuItemType.cancel`.
+    var isEmpty: Bool {
+        return items.isEmpty || (items.count == 1 && items.first?.key == .cancel)
+    }
+    
+    /// Add a menu item.
+    /// - Parameters:
+    ///   - type: item type
+    ///   - action: alert action
+    func addItem(withType type: EventMenuItemType,
+                 action: UIAlertAction) {
+        items[type] = action
+    }
+    
+    /// Builds the action menu items.
+    /// - Returns: alert actions. Sorted by item types.
+    func build() -> [UIAlertAction] {
+        items.sorted(by: { $0.key < $1.key }).map { $1 }
+    }
+    
+    /// Reset the builder. Builder will be empty after this method call.
+    func reset() {
+        items.removeAll()
+    }
+    
+}