Fix: Lazy loader on web and its indicator

lib/pages/main.dart

@@ -69,6 +69,8 @@ class _MainPageState extends State<MainPage> {
   List<GymItem> filteredData = [];
   List<GymItem> items = [];
   int cartLength = 0;
+  int itemViewCount = 0;
+  bool isLoading = false;
 
   @override
   void initState() {
@@ -81,6 +83,7 @@ class _MainPageState extends State<MainPage> {
     getItems(context).then((value) => setState(() {
           filteredData = value;
           items = value;
+          itemViewCount = min(5, value.length);
         }));
   }
 
@@ -92,8 +95,14 @@ class _MainPageState extends State<MainPage> {
   }
 
   void _onLoad() async {
-    await Future.delayed(const Duration(milliseconds: 1000));
-    debugPrint('aye');
+    setState(() {
+      isLoading = true;
+    });
+    await Future.delayed(const Duration(seconds: 1));
+    setState(() {
+      itemViewCount = min(filteredData.length, itemViewCount + 5);
+      isLoading = false;
+    });
   }
 
   void _onSearch() {
@@ -101,6 +110,7 @@ class _MainPageState extends State<MainPage> {
       filteredData = items
           .where((element) => (element.title).contains(searchText))
           .toList();
+      itemViewCount = filteredData.length;
     });
   }
 
@@ -190,13 +200,16 @@ class _MainPageState extends State<MainPage> {
           Expanded(
             child: LazyLoadScrollView(
               onEndOfPage: _onLoad,
-              child: Stack(
+              isLoading: isLoading,
+              child: ListView(
                 children: [
                   items.isEmpty
                       ? const Center(child: CircularProgressIndicator())
                       : filteredData.isEmpty
                           ? const Center(child: Text('Ничего не найдено'))
                           : GridView.builder(
+                              physics: const AlwaysScrollableScrollPhysics(),
+                              shrinkWrap: true,
                               gridDelegate:
                                   SliverGridDelegateWithFixedCrossAxisCount(
                                 crossAxisCount: min(
@@ -204,7 +217,7 @@ class _MainPageState extends State<MainPage> {
                                         .toInt(),
                                     8),
                               ),
-                              itemCount: filteredData.length,
+                              itemCount: itemViewCount,
                               itemBuilder: (context, index) {
                                 final product = filteredData[index];
                                 return ProductCard(
@@ -225,6 +238,34 @@ class _MainPageState extends State<MainPage> {
                                 );
                               },
                             ),
+                  itemViewCount > 0
+                      ? Padding(
+                          padding: const EdgeInsets.symmetric(vertical: 10),
+                          child: Center(
+                            child: itemViewCount < filteredData.length
+                                ? !isLoading
+                                    ? ElevatedButton(
+                                        onPressed: _onLoad,
+                                        style: ElevatedButton.styleFrom(
+                                          backgroundColor:
+                                              Theme.of(context).primaryColor,
+                                          shape: const RoundedRectangleBorder(
+                                            borderRadius: BorderRadius.all(
+                                                Radius.circular(50)),
+                                          ),
+                                          foregroundColor: Colors.white,
+                                        ),
+                                        child: const Text('Загрузить ещё'),
+                                      )
+                                    : const CircularProgressIndicator()
+                                : const Text(
+                                    'Конец списка',
+                                    style: TextStyle(
+                                        fontSize: 10, color: Color(0x88000000)),
+                                  ),
+                          ),
+                        )
+                      : const SizedBox.shrink(),
                 ],
               ),
             ),