import 'package:aves/image_fetcher.dart';
import 'package:aves/thumbnail.dart';
import 'package:draggable_scrollbar/draggable_scrollbar.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

void main() {
  runApp(MyApp());
}

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

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  Future<List> imageLoader;
  ScrollController scrollController = ScrollController();

  @override
  void initState() {
    super.initState();
    imageCache.maximumSizeBytes = 100 * 1024 * 1024;
  }

  @override
  Widget build(BuildContext context) {
    if (imageLoader == null) {
      imageLoader = ImageFetcher.getImageEntries();
    }
    var columnCount = 4;
    var extent = MediaQuery.of(context).size.width / columnCount;
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: FutureBuilder(
          future: imageLoader,
          builder: (futureContext, AsyncSnapshot<List> snapshot) {
            switch (snapshot.connectionState) {
              case ConnectionState.none:
                return Text('None');
              case ConnectionState.active:
              case ConnectionState.waiting:
                return Text('Awaiting result...');
              case ConnectionState.done:
                if (snapshot.hasError) return Text('Error: ${snapshot.error}');
                var imageEntryList = snapshot.data;
                return Container(
                  padding: EdgeInsets.symmetric(vertical: 0.0),
                  child: DraggableScrollbar.arrows(
                    labelTextBuilder: (double offset) => Text(
                      "${offset ~/ 1}",
                      style: TextStyle(color: Colors.blueGrey),
                    ),
                    controller: scrollController,
                    child: GridView.builder(
                      controller: scrollController,
                      gridDelegate: SliverGridDelegateWithMaxCrossAxisExtent(
                        maxCrossAxisExtent: extent,
                      ),
                      itemBuilder: (gridContext, index) {
                        return Thumbnail(
                          entry: imageEntryList[index] as Map,
                          extent: extent,
                        );
                      },
                      itemCount: imageEntryList.length,
                    ),
                  ),
                );
            }
            return null;
          }),
    );
  }
}