git-touch-android-ios-app/lib/scaffolds/refresh.dart

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:git_touch/models/theme.dart';
import 'package:provider/provider.dart';
import '../widgets/loading.dart';
import '../widgets/error_reload.dart';

class RefreshScaffold<T> extends StatefulWidget {
  final Widget title;
  final Widget Function(T payload) bodyBuilder;
  final Future<T> Function(int activeTab) onRefresh;
  final Widget Function(T payload) trailingBuilder;
  final List<String> tabs;

  RefreshScaffold({
    @required this.title,
    @required this.bodyBuilder,
    @required this.onRefresh,
    this.trailingBuilder,
    this.tabs,
  });

  @override
  _RefreshScaffoldState createState() => _RefreshScaffoldState();
}

class _RefreshScaffoldState<T> extends State<RefreshScaffold<T>> {
  bool _loading;
  T _payload;
  String _error = '';
  int _activeTab = 0;

  @override
  void initState() {
    super.initState();
    _refresh();
  }

  Widget _buildBody() {
    if (_error.isNotEmpty) {
      return ErrorReload(text: _error, onTap: _refresh);
    } else if (_payload == null) {
      return Loading(more: false);
    } else {
      return widget.bodyBuilder(_payload);
    }
  }

  Future<void> _refresh([int activeTab]) async {
    try {
      setState(() {
        _error = '';
        _loading = true;
        if (activeTab != null) {
          _activeTab = activeTab;
        }
      });
      _payload = await widget.onRefresh(activeTab);
    } catch (err) {
      _error = err.toString();
      throw err;
    } finally {
      if (mounted) {
        setState(() {
          _loading = false;
        });
      }
    }
  }

  Widget _buildTrailing() {
    if (_payload == null || widget.trailingBuilder == null) return null;

    return widget.trailingBuilder(_payload);
  }

  List<Widget> _buildActions() {
    if (_payload == null || widget.trailingBuilder == null) return null;
    var w = widget.trailingBuilder(_payload);
    return [if (w != null) w];
  }

  @override
  Widget build(BuildContext context) {
    switch (Provider.of<ThemeModel>(context).theme) {
      case AppThemeType.cupertino:
        return CupertinoPageScaffold(
          navigationBar: CupertinoNavigationBar(
            middle: widget.tabs == null
                ? widget.title
                : DefaultTextStyle(
                    style: TextStyle(),
                    child: CupertinoSegmentedControl(
                      groupValue: _activeTab,
                      onValueChanged: _refresh,
                      children: widget.tabs.asMap().map((key, text) => MapEntry(
                          key,
                          Padding(
                            padding: const EdgeInsets.symmetric(horizontal: 4),
                            child: Text(text),
                          ))),
                    ),
                  ),
            trailing: widget.tabs == null ? _buildTrailing() : null,
          ),
          child: SafeArea(
            child: CustomScrollView(
              slivers: <Widget>[
                CupertinoSliverRefreshControl(onRefresh: _refresh),
                SliverToBoxAdapter(child: _buildBody())
              ],
            ),
          ),
        );
      default:
        var w = Scaffold(
          appBar: AppBar(
            title: widget.title,
            actions: _buildActions(),
            bottom: widget.tabs == null
                ? null
                : TabBar(
                    onTap: _refresh,
                    tabs: widget.tabs
                        .map((text) => Tab(text: text.toUpperCase()))
                        .toList(),
                  ),
          ),
          body: RefreshIndicator(
            onRefresh: _refresh,
            child: SingleChildScrollView(child: _buildBody()),
          ),
        );
        if (widget.tabs == null) {
          return w;
        }
        return DefaultTabController(length: widget.tabs.length, child: w);
    }
  }
}