import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'SliverAppBar Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'SliverAppBar Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
  ScrollController _scrollController;
  bool _IsSearching;
  Icon actionIcon = new Icon(Icons.search);
  Widget appBarTitle = new Text("Produtores");
  final TextEditingController _searchQuery = new TextEditingController();
  List<String> _searchList = List();

  @override
  void initState() {
    _scrollController = ScrollController(initialScrollOffset: 200.0);
    _IsSearching = false;
    super.initState();
  }

  void _handleSearchStart() {
    setState(() {
      _IsSearching = true;
    });
  }

  void _handleSearchEnd() {
    setState(() {
      this.actionIcon = new Icon(
        Icons.search,
        color: Colors.white,
      );
      this.appBarTitle = new Text(
        "Produtores",
        style: TextStyle(color: Colors.white),
      );
      _IsSearching = false;
      _searchQuery.clear();
    });
  }

  void searchOperation(String searchText) {
    String name = "";
    if (_IsSearching) {}
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: appBarTitle,
        centerTitle: true,
        actions: <Widget>[
          IconButton(
            icon: actionIcon,
            onPressed: () {
              setState(() {
                if (this.actionIcon.icon == Icons.search) {
                  this.actionIcon = new Icon(Icons.close);
                  this.appBarTitle = new TextField(
                    controller: _searchQuery,
                    style: TextStyle(color: Colors.white),
                    decoration: InputDecoration(
                        prefixIcon: Icon(
                          Icons.search,
                          color: Colors.white,
                        ),
                        hintText: "Pesquisar...",
                        hintStyle: TextStyle(color: Colors.white)),
                    onChanged: searchOperation,
                  );
                  _handleSearchStart();
                } else {
                  _handleSearchEnd();
                }
              });
            },
          )
        ],
      ),
      body: Container(
        child: _searchList.length != 0 || _searchQuery.text.isNotEmpty
            ? AnimatedContainer
            : ListView(
                children: List<String>.generate(50, (i) => "Item $i")
                    .map((f) => ListTile(
                          title: Text(f),
                        ))
                    .toList(),
              ),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.clear),
      ),
      /*CustomScrollView(
        controller: _scrollController,
        slivers: <Widget>[
          SliverAppBar(
            pinned: true,
            title: Text(
              widget.title,
            ),
            centerTitle: false,
            flexibleSpace: FlexibleSpaceBar(
              collapseMode: CollapseMode.parallax,
              background: Image.network(
                "https://images.pexels.com/photos/169573/pexels-photo-169573.jpeg?cs=srgb&dl=apple-black-and-white-black-and-white-169573.jpg&fm=jpg",
                fit: BoxFit.fill,
              ),
            ),
            expandedHeight: 256.0,
          ),
          SliverList(
            delegate: SliverChildListDelegate(
              List<String>.generate(50, (i) => "Item $i")
                  .map((f) => ListTile(
                        title: Text(f),
                      ))
                  .toList(),
            ),
          ),
        ],
      ),*/
    );
  }
}