Implement new space selector bottom sheet (#6518)

* Delight: Edit layout experiment #6079

RiotSwiftUI/Modules/Spaces/SpaceSelectorBottomSheet/SpaceSelector/SpaceSelectorViewModel.swift

@@ -0,0 +1,72 @@
+//
+// 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
+import Combine
+
+typealias SpaceSelectorViewModelType = StateStoreViewModel<SpaceSelectorViewState,
+                                                                 Never,
+                                                                 SpaceSelectorViewAction>
+
+class SpaceSelectorViewModel: SpaceSelectorViewModelType, SpaceSelectorViewModelProtocol {
+
+    // MARK: - Properties
+
+    // MARK: Private
+
+    private let service: SpaceSelectorServiceProtocol
+
+    // MARK: Public
+
+    var completion: ((SpaceSelectorViewModelResult) -> Void)?
+
+    // MARK: - Setup
+
+    static func makeViewModel(service: SpaceSelectorServiceProtocol) -> SpaceSelectorViewModelProtocol {
+        return SpaceSelectorViewModel(service: service)
+    }
+
+    private init(service: SpaceSelectorServiceProtocol) {
+        self.service = service
+        super.init(initialViewState: Self.defaultState(service: service))
+    }
+
+    private static func defaultState(service: SpaceSelectorServiceProtocol) -> SpaceSelectorViewState {
+        let parentName = service.parentSpaceNameSubject.value
+        return SpaceSelectorViewState(items: service.spaceListSubject.value,
+                                      selectedSpaceId: service.selectedSpaceId,
+                                      navigationTitle: parentName ?? VectorL10n.spaceSelectorTitle)
+    }
+    
+    // MARK: - Public
+
+    override func process(viewAction: SpaceSelectorViewAction) {
+        switch viewAction {
+        case .cancel:
+            completion?(.cancel)
+        case .spaceSelected(let item):
+            if item.id == SpaceSelectorConstants.homeSpaceId {
+                completion?(.homeSelected)
+            } else {
+                completion?(.spaceSelected(item))
+            }
+        case .spaceDisclosure(let item):
+            completion?(.spaceDisclosure(item))
+        case .createSpace:
+            completion?(.createSpace)
+        }
+    }
+}