Implemented multi select interaction (#13)

mobile/lib/modules/home/providers/home_page_state.provider.dart

@@ -0,0 +1,63 @@
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:immich_mobile/modules/home/models/home_page_state.model.dart';
+import 'package:immich_mobile/shared/models/immich_asset.model.dart';
+
+class HomePageStateNotifier extends StateNotifier<HomePageState> {
+  HomePageStateNotifier()
+      : super(
+          HomePageState(
+            isMultiSelectEnable: false,
+            selectedItems: {},
+            selectedDateGroup: {},
+          ),
+        );
+
+  void addSelectedDateGroup(String dateGroupTitle) {
+    state = state.copyWith(selectedDateGroup: {...state.selectedDateGroup, dateGroupTitle});
+  }
+
+  void removeSelectedDateGroup(String dateGroupTitle) {
+    var currentDateGroup = state.selectedDateGroup;
+
+    currentDateGroup.removeWhere((e) => e == dateGroupTitle);
+
+    state = state.copyWith(selectedDateGroup: currentDateGroup);
+  }
+
+  void enableMultiSelect(Set<ImmichAsset> selectedItems) {
+    state = state.copyWith(isMultiSelectEnable: true, selectedItems: selectedItems);
+  }
+
+  void disableMultiSelect() {
+    state = state.copyWith(isMultiSelectEnable: false, selectedItems: {}, selectedDateGroup: {});
+  }
+
+  void addSingleSelectedItem(ImmichAsset asset) {
+    state = state.copyWith(selectedItems: {...state.selectedItems, asset});
+  }
+
+  void addMultipleSelectedItems(List<ImmichAsset> assets) {
+    state = state.copyWith(selectedItems: {...state.selectedItems, ...assets});
+  }
+
+  void removeSingleSelectedItem(ImmichAsset asset) {
+    Set<ImmichAsset> currentList = state.selectedItems;
+
+    currentList.removeWhere((e) => e.id == asset.id);
+
+    state = state.copyWith(selectedItems: currentList);
+  }
+
+  void removeMultipleSelectedItem(List<ImmichAsset> assets) {
+    Set<ImmichAsset> currentList = state.selectedItems;
+
+    for (ImmichAsset asset in assets) {
+      currentList.removeWhere((e) => e.id == asset.id);
+    }
+
+    state = state.copyWith(selectedItems: currentList);
+  }
+}
+
+final homePageStateProvider =
+    StateNotifierProvider<HomePageStateNotifier, HomePageState>(((ref) => HomePageStateNotifier()));