add paginator

lib/pages/fcs_shipment/model/fcs_shipment_model.dart

@@ -4,6 +4,7 @@ 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';
 
@@ -11,27 +12,43 @@ class FcsShipmentModel extends BaseModel {
   final log = Logger('FcsShipmentModel');
 
   StreamSubscription<QuerySnapshot> listener;
-  List<FcsShipment> fcsShipments = [];
+  List<FcsShipment> _fcsShipments = [];
+  List<FcsShipment> get fcsShipments => _selectedIndex == 1
+      ? _fcsShipments
+      : List<FcsShipment>.from(_delivered.values);
+
+  Paginator _delivered;
+  bool isLoading = false;
+  int _selectedIndex = 1;
+  set selectedIndex(int index) {
+    _selectedIndex = index;
+    notifyListeners();
+  }
+
+  get selectedIndex => _selectedIndex;
 
   @override
   void privilegeChanged() {
     super.privilegeChanged();
     _loadFcsShipments();
+
+    if (_delivered != null) _delivered.close();
+    _delivered = _getDelivered();
   }
 
   Future<void> _loadFcsShipments() async {
     if (user == null || !user.hasFcsShipments()) return;
     String path = "/$fcs_shipment_collection/";
     if (listener != null) listener.cancel();
-    fcsShipments = [];
+    _fcsShipments = [];
     try {
       listener = Firestore.instance
           .collection("$path")
           .orderBy("shipment_number", descending: true)
           .snapshots()
           .listen((QuerySnapshot snapshot) {
-        fcsShipments.clear();
-        fcsShipments = snapshot.documents.map((documentSnapshot) {
+        _fcsShipments.clear();
+        _fcsShipments = snapshot.documents.map((documentSnapshot) {
           var s = FcsShipment.fromMap(
               documentSnapshot.data, documentSnapshot.documentID);
           return s;
@@ -43,6 +60,36 @@ class FcsShipmentModel extends BaseModel {
     }
   }
 
+  Paginator _getDelivered() {
+    if (user == null || !user.hasFcsShipments()) return null;
+
+    var pageQuery = Firestore.instance
+        .collection("/$fcs_shipment_collection")
+        .where("is_delivered", isEqualTo: true)
+        .where("is_deleted", isEqualTo: false)
+        .orderBy("current_status_date", descending: true);
+    var paginator = new Paginator(pageQuery, rowPerLoad: 20, toObj: (data, id) {
+      return FcsShipment.fromMap(data, id);
+    });
+    return paginator;
+  }
+
+  Future<void> loadMore() async {
+    if (_delivered.ended) return;
+    isLoading = true;
+    notifyListeners();
+    await _delivered.load(onFinished: () {
+      isLoading = false;
+      notifyListeners();
+    });
+  }
+
+  Future<void> refresh() async {
+    await _delivered.refresh(onFinished: () {
+      notifyListeners();
+    });
+  }
+
   void initUser(user) {
     super.initUser(user);
   }
@@ -50,7 +97,8 @@ class FcsShipmentModel extends BaseModel {
   @override
   logout() async {
     if (listener != null) await listener.cancel();
-    fcsShipments = [];
+    if (_delivered != null) _delivered.close();
+    _fcsShipments = [];
   }
 
   Future<void> create(FcsShipment fcsShipment) {