Add basic infinite scrolling (still has bugs)

lib/api/client.dart

@@ -7,6 +7,8 @@ class Client {
   final JsonEncoder _encoder = new JsonEncoder();
   final String _token;
   final String _base;
+  int _maxPages;
+  int get maxPages => _maxPages;
 
   String get base => _base;
 
@@ -69,6 +71,7 @@ class Client {
       throw new ApiException(
           response.statusCode, response.request.url.toString());
     }
+    _maxPages = response.headers["x-pagination-total-pages"] != null ? int.parse(response.headers["x-pagination-total-pages"]) : 0;
     return _decoder.convert(response.body);
   }
 }

lib/api/service.dart

@@ -4,6 +4,8 @@ import 'package:meta/meta.dart';
 class APIService {
   final Client _client;
 
+  int get maxPages => _client.maxPages;
+
   @protected
   Client get client => _client;
 

lib/pages/list/list.dart

@@ -22,6 +22,7 @@ class _ListPageState extends State<ListPage> {
   List<Task> _tasks = [];
   List<Task> _loadingTasks = [];
   bool _loading = true;
+  int _currentPage = 1;
 
   @override
   void initState() {
@@ -54,12 +55,20 @@ class _ListPageState extends State<ListPage> {
         body: !this._loading
             ? RefreshIndicator(
                 child: _tasks.length > 0
-                    ? ListView(
-                        padding: EdgeInsets.symmetric(vertical: 8.0),
-                        children: ListTile.divideTiles(
-                                context: context, tiles: _listTasks())
-                            .toList(),
-                      )
+                    ? ListView.builder(
+                    padding: EdgeInsets.symmetric(vertical: 8.0),
+                    itemBuilder: (context, i) {
+                      if (i.isOdd) return Divider();
+
+                      final index = i ~/ 2;
+                      if (index >= _tasks.length && VikunjaGlobal.of(context).taskService.maxPages < _currentPage) {
+                        _currentPage++;
+                        _loadTasksForPage(_currentPage);
+                      }
+                      return TaskTile(
+                        task: _tasks[index],
+                      );
+                    })
                     : Center(child: Text('This list is empty.')),
                 onRefresh: _loadList,
               )
@@ -95,13 +104,17 @@ class _ListPageState extends State<ListPage> {
       setState(() {
         _loading = false;
         _list = list;
-        // Load tasks
-        VikunjaGlobal.of(context).taskService.getAll(
-            list.id, {"sort_by": "done", "order_by": "asc"}).then((tasks) {
-          setState(() {
-            _tasks = tasks;
-          });
-        });
+      });
+      _loadTasksForPage(_currentPage);
+    });
+  }
+
+  Future<void> _loadTasksForPage(int page) {
+    return VikunjaGlobal.of(context).taskService.getAll(
+        _list.id, {"sort_by": "done", "order_by": "asc", "page": page.toString()}).then((tasks) {
+      setState(() {
+        _loading = false;
+        _tasks.addAll(tasks);
       });
     });
   }

lib/service/mocked_services.dart

@@ -140,6 +140,9 @@ class MockedTaskService implements TaskService {
   Future<List<Task>> getAll(int listId, [Map<String, String> queryParameters]) {
     return Future.value(_tasks.values.toList());
   }
+
+  @override
+  int get maxPages => 1;
 }
 
 class MockedUserService implements UserService {

lib/service/services.dart

@@ -27,6 +27,8 @@ abstract class TaskService {
   Future delete(int taskId);
   Future<Task> add(int listId, Task task);
   Future<List<Task>> getAll(int listId, [Map<String, String> queryParameters]);
+  // TODO: Avoid having to add this to each abstract class
+  int get maxPages;
 }
 
 abstract class UserService {