add pagination for pages

lib/pages/fcs_shipment/model/fcs_shipment_model.dart

@@ -4,100 +4,48 @@ import 'package:cloud_firestore/cloud_firestore.dart';
 import 'package:fcs/data/services/services.dart';
 import 'package:fcs/domain/constants.dart';
 import 'package:fcs/domain/entities/fcs_shipment.dart';
-import 'package:fcs/helpers/paginator.dart';
 import 'package:fcs/pages/main/model/base_model.dart';
 import 'package:logging/logging.dart';
 
+import '../../../pagination/paginator_listener.dart';
+
 class FcsShipmentModel extends BaseModel {
   final log = Logger('FcsShipmentModel');
-
-  StreamSubscription<QuerySnapshot>? listener;
-  List<FcsShipment> _fcsShipments = [];
-  List<FcsShipment> get fcsShipments => _selectedIndex == 1
-      ? _fcsShipments
-      : List<FcsShipment>.from(_shipped!.values);
-
-  Paginator? _shipped;
+  PaginatorListener<FcsShipment>? fcsShipments;
   bool isLoading = false;
-  int _selectedIndex = 1;
-  set selectedIndex(int index) {
-    _selectedIndex = index;
+  int selectedIndex = 1;
+
+  onChanged(int index) {
+    selectedIndex = index;
+    loadFcsShipments(selectedIndex);
     notifyListeners();
   }
 
-  int get selectedIndex => _selectedIndex;
-
-  @override
-  void privilegeChanged() {
-    super.privilegeChanged();
-    _loadFcsShipments();
-  }
-
-  initData() {
-    _selectedIndex = 1;
-    _loadFcsShipments();
-
-    if (_shipped != null) _shipped!.close();
-    _shipped = _getShipped();
-    _shipped!.load();
-  }
-
-  Future<void> _loadFcsShipments() async {
+  loadFcsShipments(int index) {
     if (user == null || !user!.hasFcsShipments()) return;
-    String path = "/$fcs_shipment_collection/";
-    if (listener != null) listener!.cancel();
-    _fcsShipments = [];
-    try {
-      listener = FirebaseFirestore.instance
-          .collection("$path")
-          .where("status", isEqualTo: fcs_shipment_confirmed_status)
-          .where("is_deleted", isEqualTo: false)
-          .orderBy("shipment_number", descending: true)
-          .snapshots()
-          .listen((QuerySnapshot snapshot) {
-        _fcsShipments.clear();
-        _fcsShipments = snapshot.docs.map((documentSnapshot) {
-          var s = FcsShipment.fromMap(
-              documentSnapshot.data() as Map<String, dynamic>,
-              documentSnapshot.id);
-          return s;
-        }).toList();
-        notifyListeners();
-      });
-    } catch (e) {
-      log.warning("Error!! $e");
+
+    String path = "/$fcs_shipment_collection";
+    Query col = FirebaseFirestore.instance.collection(path);
+    Query pageQuery = FirebaseFirestore.instance.collection(path);
+
+    if (index == 1) {
+      col = col.where("status", isEqualTo: fcs_shipment_confirmed_status);
+      pageQuery =
+          pageQuery.where("status", isEqualTo: fcs_shipment_confirmed_status);
     }
-  }
 
-  Paginator _getShipped() {
-    if (user == null || !user!.hasFcsShipments()) throw "No Privilege";
+    if (index == 2) {
+      col = col.where("status", isEqualTo: fcs_shipment_shipped_status);
+      pageQuery =
+          pageQuery.where("status", isEqualTo: fcs_shipment_shipped_status);
+    }
 
-    var pageQuery = FirebaseFirestore.instance
-        .collection("/$fcs_shipment_collection")
-        .where("status", isEqualTo: fcs_shipment_shipped_status)
-        .where("is_deleted", isEqualTo: false)
-        .orderBy("shipment_number", descending: true);
-    var paginator = new Paginator(pageQuery, rowPerLoad: 20, toObj: (data, id) {
-      return FcsShipment.fromMap(data, id);
-    });
-    return paginator;
-  }
+    pageQuery = pageQuery.orderBy("shipment_number", descending: true);
 
-  Future<void> loadMore() async {
-    if (_shipped!.ended || _selectedIndex == 1) return;
-    isLoading = true;
-    notifyListeners();
-    await _shipped!.load(onFinished: () {
-      isLoading = false;
-      notifyListeners();
-    });
-  }
-
-  Future<void> refresh() async {
-    if (_selectedIndex == 1) return;
-    await _shipped!.refresh(onFinished: () {
-      notifyListeners();
-    });
+    fcsShipments?.close();
+    fcsShipments = PaginatorListener<FcsShipment>(
+        col, pageQuery, (data, id) => FcsShipment.fromMap(data, id),
+        rowPerLoad: 30);
   }
 
   Future<List<FcsShipment>> getActiveFcsShipments() async {
@@ -157,9 +105,7 @@ class FcsShipmentModel extends BaseModel {
 
   @override
   logout() async {
-    if (listener != null) await listener!.cancel();
-    if (_shipped != null) _shipped!.close();
-    _fcsShipments = [];
+    fcsShipments?.close();
   }
 
   Future<void> create(FcsShipment fcsShipment) {