fix errors

lib/pages/discount/discount_list.dart

@@ -3,6 +3,8 @@ import 'package:fcs/localization/app_translations.dart';
 import 'package:fcs/pages/discount/discount_list_row.dart';
 import 'package:fcs/pages/discount/model/discount_model.dart';
 import 'package:fcs/pages/main/util.dart';
+import 'package:fcs/pages/widgets/local_popup_menu_button.dart';
+import 'package:fcs/pages/widgets/local_popupmenu.dart';
 import 'package:fcs/pages/widgets/local_text.dart';
 import 'package:fcs/pages/widgets/progress.dart';
 import 'package:flutter/cupertino.dart';
@@ -12,29 +14,48 @@ import 'package:provider/provider.dart';
 import 'discount_editor.dart';
 
 class DiscountList extends StatefulWidget {
-  final bool selected;
+  final bool selectionMode;
 
-  const DiscountList({Key key, this.selected}) : super(key: key);
+  const DiscountList({Key key, this.selectionMode}) : super(key: key);
   @override
   _DiscountListState createState() => _DiscountListState();
 }
 
 class _DiscountListState extends State<DiscountList> {
   bool _isLoading = false;
-  bool _selected = false;
+  var _controller = ScrollController();
 
   @override
   void initState() {
     super.initState();
-    if (widget.selected != null) {
-      _selected = widget.selected;
-    }
+    _controller.addListener(() async {
+      if (_controller.position.pixels == _controller.position.maxScrollExtent) {
+        Provider.of<DiscountModel>(context, listen: false).loadMore();
+      }
+    });
+    Provider.of<DiscountModel>(context, listen: false).initData();
   }
 
   @override
   Widget build(BuildContext context) {
     var discountModel = Provider.of<DiscountModel>(context);
-    print('discounts => ${discountModel.discounts}');
+
+    final popupMenu = LocalPopupMenuButton(
+      popmenus: [
+        LocalPopupMenu(
+            id: 1,
+            textKey: "discount.popupmenu.available",
+            selected: discountModel.selectedIndex == 1),
+        LocalPopupMenu(
+            id: 2,
+            textKey: "discount.popupmenu.used",
+            selected: discountModel.selectedIndex == 2)
+      ],
+      popupMenuCallback: (p) => this.setState(() {
+        discountModel.selectedIndex = p.id;
+      }),
+    );
+
     return LocalProgress(
       inAsyncCall: _isLoading,
       child: Scaffold(
@@ -48,26 +69,53 @@ class _DiscountListState extends State<DiscountList> {
             onPressed: () => Navigator.of(context).pop(),
           ),
           backgroundColor: primaryColor,
-          actions: <Widget>[
-            IconButton(
-              icon: Icon(Icons.search),
-              onPressed: () {},
-            )
-          ],
+          actions: <Widget>[popupMenu],
         ),
-        body: ListView.separated(
-          separatorBuilder: (context, index) => Divider(
-            color: Colors.black,
-            height: 1,
-          ),
-          itemCount: discountModel.discounts.length,
-          itemBuilder: (BuildContext context, int index) {
-            var discount = discountModel.discounts[index];
-            return DiscountListRow(
-              key: ValueKey(discount.id),
-              discount: discount,
-            );
-          },
+        body: Column(
+          children: [
+            Expanded(
+              child: ListView.separated(
+                separatorBuilder: (context, index) => Divider(
+                  color: Colors.black,
+                  height: 1,
+                ),
+                controller: _controller,
+                itemCount: discountModel.discounts.length,
+                itemBuilder: (BuildContext context, int index) {
+                  var discount = discountModel.discounts[index];
+                  return DiscountListRow(
+                    key: ValueKey(discount.id),
+                    discount: discount,
+                    onSelect: (d) {
+                      if (widget.selectionMode) {
+                        Navigator.pop(context, discount);
+                        return;
+                      }
+                      Navigator.push(
+                        context,
+                        CupertinoPageRoute(
+                            builder: (context) =>
+                                DiscountEditor(discount: discount)),
+                      );
+                    },
+                  );
+                },
+              ),
+            ),
+            discountModel.isLoading
+                ? Container(
+                    padding: EdgeInsets.all(8),
+                    color: primaryColor,
+                    child: Row(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        Text("Loading...",
+                            style: TextStyle(color: Colors.white)),
+                      ],
+                    ),
+                  )
+                : Container(),
+          ],
         ),
         floatingActionButton: FloatingActionButton.extended(
           onPressed: () {

lib/pages/discount/discount_list_row.dart

@@ -8,9 +8,12 @@ import 'package:flutter/material.dart';
 import 'package:flutter_icons/flutter_icons.dart';
 import 'package:intl/intl.dart';
 
+typedef OnSelect(Discount discount);
+
 class DiscountListRow extends StatelessWidget {
+  final OnSelect onSelect;
   final Discount discount;
-  DiscountListRow({Key key, this.discount}) : super(key: key);
+  DiscountListRow({Key key, this.discount, this.onSelect}) : super(key: key);
 
   final DateFormat dateFormat = new DateFormat("dd MMM yyyy");
 
@@ -18,11 +21,9 @@ class DiscountListRow extends StatelessWidget {
   Widget build(BuildContext context) {
     return InkWell(
       onTap: () {
-        Navigator.push(
-          context,
-          CupertinoPageRoute(
-              builder: (context) => DiscountEditor(discount: discount)),
-        );
+        if (onSelect != null) {
+          onSelect(discount);
+        }
       },
       child: Container(
         padding: EdgeInsets.only(left: 15, right: 15),

lib/pages/discount/model/discount_model.dart

@@ -2,7 +2,9 @@ import 'dart:async';
 
 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/discount.dart';
+import 'package:fcs/helpers/paginator.dart';
 import 'package:fcs/pages/main/model/base_model.dart';
 import 'package:logging/logging.dart';
 
@@ -11,7 +13,28 @@ class DiscountModel extends BaseModel {
 
   StreamSubscription<QuerySnapshot> listener;
 
-  List<Discount> discounts = [];
+  List<Discount> _discounts = [];
+  List<Discount> get discounts =>
+      _selectedIndex == 1 ? _discounts : List<Discount>.from(_used.values);
+
+  Paginator _used;
+  bool isLoading = false;
+  int _selectedIndex = 1;
+  set selectedIndex(int index) {
+    _selectedIndex = index;
+    notifyListeners();
+  }
+
+  get selectedIndex => _selectedIndex;
+
+  initData() {
+    _selectedIndex = 1;
+    _load();
+
+    if (_used != null) _used.close();
+    _used = _getUsed();
+    _used.load();
+  }
 
   void initUser(user) {
     super.initUser(user);
@@ -22,7 +45,7 @@ class DiscountModel extends BaseModel {
     if (listener != null) listener.cancel();
     try {
       listener = Firestore.instance
-          .collection("/discounts")
+          .collection("/$discounts_collection")
           .orderBy("code", descending: false)
           .snapshots()
           .listen((snaps) {
@@ -37,9 +60,42 @@ class DiscountModel extends BaseModel {
     }
   }
 
+  Paginator _getUsed() {
+    if (user == null || !user.hasFcsShipments()) return null;
+
+    var pageQuery = Firestore.instance
+        .collection("/$discounts_collection")
+        .where("status", isEqualTo: fcs_shipment_shipped_status)
+        .orderBy("code", descending: false);
+    var paginator = new Paginator(pageQuery, rowPerLoad: 20, toObj: (data, id) {
+      return Discount.fromMap(data, id);
+    });
+    return paginator;
+  }
+
+  Future<void> loadMore() async {
+    if (_used.ended || _selectedIndex == 1) return;
+    isLoading = true;
+    notifyListeners();
+    await _used.load(onFinished: () {
+      isLoading = false;
+      notifyListeners();
+    });
+  }
+
+  Future<void> refresh() async {
+    if (_selectedIndex == 1) return;
+    await _used.refresh(onFinished: () {
+      notifyListeners();
+    });
+  }
+
   @override
   logout() async {
-    discounts = [];
+    if (listener != null) await listener.cancel();
+    if (_used != null) _used.close();
+
+    _discounts = [];
   }
 
   Future<void> addDiscount(Discount discount) async {