Add poll history scaffolding

RiotSwiftUI/Modules/Room/PollHistory/PollHistoryViewModel.swift

@@ -0,0 +1,42 @@
+//
+// 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 SwiftUI
+
+typealias PollHistoryViewModelType = StateStoreViewModel<PollHistoryViewState, PollHistoryViewAction>
+
+class PollHistoryViewModel: PollHistoryViewModelType, PollHistoryViewModelProtocol {
+    var completion: ((PollHistoryViewModelResult) -> Void)?
+
+    init(promptType: PollHistoryPromptType, initialCount: Int = 0) {
+        super.init(initialViewState: PollHistoryViewState(promptType: promptType, count: 0))
+    }
+
+    // MARK: - Public
+
+    override func process(viewAction: PollHistoryViewAction) {
+        switch viewAction {
+        case .accept:
+            completion?(.accept)
+        case .cancel:
+            completion?(.cancel)
+        case .incrementCount:
+            state.count += 1
+        case .decrementCount:
+            state.count -= 1
+        }
+    }
+}