home_page.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_unit/app/convert.dart';
import 'package:flutter_unit/app/res/cons.dart';
import 'package:flutter_unit/app/router.dart';
import 'package:flutter_unit/blocs/bloc_exp.dart';
import 'package:flutter_unit/components/permanent/feedback_widget.dart';
import 'package:flutter_unit/model/widget_model.dart';
import 'package:flutter_unit/views/common/empty_page.dart';
import 'package:flutter_unit/views/items/home_item_support.dart';
import 'package:flutter_unit/views/pages/home/toly_app_bar.dart';

import 'background.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> with AutomaticKeepAliveClientMixin{
  ScrollController _ctrl;
  double _limitY = 35;
  double _height = kToolbarHeight * 2 - 20;

  @override
  void initState() {
    _ctrl = ScrollController()..addListener(_updateAppBarHeight);
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    super.build(context);
    var color = context.bloc<HomeBloc>().state.homeColor;
    return Scaffold(
      appBar: TolyAppBar(
        selectIndex: Cons.tabColors.indexOf(color.value),
        preferredSize: Size.fromHeight(_height),
        onItemClick: _switchTab,
      ),
      body: Stack(
        children: <Widget>[
          BlocBuilder<GlobalBloc, GlobalState>(builder: _buildBackground),
          BlocBuilder<HomeBloc, HomeState>(builder: _buildContent)
        ],
      ),
    );
  }

  Widget _buildBackground(BuildContext context, GlobalState state) {
    if (state.showBackGround) {
      return Background();
    }
    return Container();
  }

  Widget _buildContent(BuildContext context, HomeState state) {
    if (state is WidgetsLoaded) {
      var items = state.widgets;
      if (items.isEmpty) return EmptyPage();
      return ListView.builder(
          controller: _ctrl,
          itemBuilder: (_, index) => _buildHomeItem(items[index]),
          itemCount: items.length);
    }
    if (state is WidgetsLoadFailed) {
      return Container(
        child: Text('加载数据异常'),
      );
    }
    return Container();
  }

  Widget _buildHomeItem(WidgetModel model) =>
      BlocBuilder<GlobalBloc, GlobalState>(
        condition: (p, c) => (p.itemStyleIndex != c.itemStyleIndex),
        builder: (_, state) {
          return FeedbackWidget(
                duration: const Duration(milliseconds: 200),
                onPressed: () => _toDetailPage(model),
                child: HomeItemSupport.get(model, state.itemStyleIndex));
        },
      );

  _updateAppBarHeight() {
    if (_ctrl.offset < _limitY * 4) {
      setState(() {
        _height = kToolbarHeight * 2 - 20 - _ctrl.offset / 4;
      });
    }
  }

  _switchTab(int index, Color color) {
    if (_ctrl.hasClients) _ctrl.jumpTo(0);
    BlocProvider.of<HomeBloc>(context)
        .add(EventTabTap(Convert.toFamily(index)));
  }

  _toDetailPage(WidgetModel model) async {
    BlocProvider.of<DetailBloc>(context).add(FetchWidgetDetail(model));
    Navigator.pushNamed(context, Router.widget_detail, arguments: model);
  }

  @override
  bool get wantKeepAlive => true;

}