import 'package:flutter/material.dart';

const searchList = [
  "ChengDu",
  "ShangHai",
  "BeiJing",
  "TianJing",
  "NanJing",
  "ShenZheng"
];

const recentSuggest = [
  "suggest1",
  "suggest2"
];

class SearchBarDemo extends StatefulWidget {
  @override
  _SearchBarDemoState createState() => _SearchBarDemoState();
}

class _SearchBarDemoState extends State<SearchBarDemo> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('SearchBarDemo'),
        actions: <Widget>[
          IconButton(
              icon: Icon(Icons.search),
              onPressed: () =>
                  showSearch(context: context, delegate: SearchBarDelegate())),
        ],
      ),
    );
  }
}

class SearchBarDelegate extends SearchDelegate<String> {
  @override
  List<Widget> buildActions(BuildContext context) {
    return [IconButton(icon: Icon(Icons.clear), onPressed: () => query = "")];
  }

  @override
  Widget buildLeading(BuildContext context) {
    return IconButton(
        icon: AnimatedIcon(
            icon: AnimatedIcons.menu_arrow, progress: transitionAnimation),
        onPressed: () => close(context, null));
  }

  @override
  Widget buildResults(BuildContext context) {
    return Center(child: Container(
      width: 100.0,
      height: 100.0,
      child: Card(
        color: Colors.redAccent,
        child: Center(
          child: Text(query),
        ),
      ),
    ),);
  }

  @override
  Widget buildSuggestions(BuildContext context) {
    final suggestionList = query.isEmpty
        ? recentSuggest
        : searchList.where((input) => input.startsWith(query)).toList();
    return ListView.builder(
        itemCount: suggestionList.length,
        itemBuilder: (context, index) => ListTile(

          onTap: (){
            query = suggestionList[index];
            showResults(context);},

              title: RichText(
                  text: TextSpan(
                      text: suggestionList[index].substring(0, query.length),
                      style: TextStyle(
                          color: Colors.black, fontWeight: FontWeight.bold),
                      children: [
                    TextSpan(
                        text: suggestionList[index].substring(query.length),
                        style: TextStyle(color: Colors.grey))
                  ])),
            ));
  }
}
