add paginator

lib/helpers/paginator.dart

@@ -1,50 +1,50 @@
 import 'dart:async';
 
 import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:fcs/pages/widgets/callbacks.dart';
 import 'package:logging/logging.dart';
 
+typedef ToObj = Function(Map<String, dynamic> data, String id);
+
 /*
  * Pagination load data in page 
  */
-class Pagination {
-  final log = Logger('PaginationModel');
+class Paginator<T> {
+  final log = Logger('Paginator');
 
   final int rowPerLoad;
   DocumentSnapshot prev;
   bool ended = false;
+  bool isLoading = false;
+  List<T> values = [];
+  ToObj toObj;
 
   Query pageQuery;
 
-  Pagination(Query pageQuery, {this.rowPerLoad = 20}) {
-    this.pageQuery = pageQuery;
-    initData();
-  }
-
-  void initData() async {
+  Paginator(this.pageQuery, {this.rowPerLoad = 20, this.toObj}) {
     _clearState();
-    load();
   }
 
   void _clearState() {
     prev = null;
     ended = false;
-    if (controller != null) controller.close();
-  }
-
-  StreamController<DocumentSnapshot> controller;
-  Stream<DocumentSnapshot> get stream {
-    if (controller != null) {
-      controller.close();
-    }
-    controller = StreamController<DocumentSnapshot>(onCancel: _clearState);
-    return controller.stream;
+    isLoading = false;
+    values = [];
   }
 
   void close() {
     _clearState();
   }
 
-  Future<bool> load() async {
+  Future<void> refresh({CallBack onFinished}) async {
+    _clearState();
+    await load();
+    if (onFinished != null) onFinished();
+  }
+
+  Future<bool> load({CallBack onFinished}) async {
+    if (ended) return null;
+    isLoading = true;
     Query _query =
         prev != null ? pageQuery.startAfterDocument(prev) : pageQuery;
     try {
@@ -56,14 +56,14 @@ class Pagination {
         ended = count < rowPerLoad;
         prev = count > 0 ? snapshot.documents[count - 1] : prev;
         snapshot.documents.forEach((e) {
-          controller.add(e);
+          values.add(toObj(e.data, e.documentID));
         });
-        if (ended) {
-          controller.add(null);
-        }
       });
     } catch (e) {
       log.warning("Error!! $e");
+    } finally {
+      isLoading = false;
+      if (onFinished != null) onFinished();
     }
     return ended;
   }