add homepage

lib/base/base_viewmodel.dart

@@ -0,0 +1,41 @@
+import 'package:flutter/cupertino.dart';
+
+class BaseViewModel extends ChangeNotifier {
+  PageState currentState = PageState.START;
+
+  void loading({bool notify = false}) {
+    currentState = PageState.LOADING;
+    if (notify) {
+      notifyListeners();
+    }
+  }
+
+  void success({bool notify = true}) {
+    currentState = PageState.CONTENT;
+    if (notify) {
+      notifyListeners();
+    }
+  }
+
+  void failed({bool notify = false}) {
+    currentState = PageState.FAILED;
+    if (notify) {
+      notifyListeners();
+    }
+  }
+
+  void empty({bool notify = false}) {
+    currentState = PageState.EMPTY;
+    if (notify) {
+      notifyListeners();
+    }
+  }
+}
+
+enum PageState {
+  START,
+  LOADING,
+  EMPTY,
+  CONTENT,
+  FAILED,
+}