import 'dart:typed_data';
import 'dart:ui' as ui;

import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Maps 2.0.x Demo',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: MyHomePage(title: 'Maps 2.0.x Demo'),
    );
  }
}

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  GoogleMapController? controller;
  TileOverlay? _tileOverlay;

  void _onMapCreated(GoogleMapController controller) {
    this.controller = controller;
  }

  @override
  void dispose() {
    super.dispose();
  }

  void _removeTileOverlay() {
    setState(() {
      _tileOverlay = null;
    });
  }

  void _addTileOverlay() {
    final TileOverlay tileOverlay = TileOverlay(
      tileOverlayId: TileOverlayId('tile_overlay_1'),
      tileProvider: _DebugTileProvider(),
    );
    setState(() {
      _tileOverlay = tileOverlay;
    });
  }

  void _clearTileCache() {
    if (_tileOverlay != null && controller != null) {
      controller!.clearTileCache(_tileOverlay!.tileOverlayId);
    }
  }

  @override
  Widget build(BuildContext context) {
    Set<TileOverlay> overlays = <TileOverlay>{
      if (_tileOverlay != null) _tileOverlay!,
    };
    return Scaffold(
      appBar: AppBar(title: Text(widget.title)),
      body: Column(
        mainAxisSize: MainAxisSize.min,
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: <Widget>[
          Center(
            child: SizedBox(
              width: 350.0,
              height: 300.0,
              child: GoogleMap(
                initialCameraPosition: const CameraPosition(
                  target: LatLng(59.935460, 30.325177),
                  zoom: 7.0,
                ),
                tileOverlays: overlays,
                onMapCreated: _onMapCreated,
              ),
            ),
          ),
          TextButton(
            child: const Text('Add tile overlay'),
            onPressed: _addTileOverlay,
          ),
          TextButton(
            child: const Text('Remove tile overlay'),
            onPressed: _removeTileOverlay,
          ),
          TextButton(
            child: const Text('Clear tile cache'),
            onPressed: _clearTileCache,
          ),
        ],
      ),
    );
  }
}

class _DebugTileProvider implements TileProvider {
  _DebugTileProvider() {
    boxPaint.isAntiAlias = true;
    boxPaint.color = Colors.blue;
    boxPaint.strokeWidth = 2.0;
    boxPaint.style = PaintingStyle.stroke;
  }

  static const int width = 100;
  static const int height = 100;
  static final Paint boxPaint = Paint();
  static final TextStyle textStyle = TextStyle(
    color: Colors.red,
    fontSize: 20,
  );

  @override
  Future<Tile> getTile(int x, int y, int? zoom) async {
    final ui.PictureRecorder recorder = ui.PictureRecorder();
    final Canvas canvas = Canvas(recorder);
    final TextSpan textSpan = TextSpan(
      text: '$x,$y',
      style: textStyle,
    );
    final TextPainter textPainter = TextPainter(
      text: textSpan,
      textDirection: TextDirection.ltr,
    );
    textPainter.layout(
      minWidth: 0.0,
      maxWidth: width.toDouble(),
    );
    final Offset offset = const Offset(0, 0);
    textPainter.paint(canvas, offset);
    canvas.drawRect(
        Rect.fromLTRB(0, 0, width.toDouble(), width.toDouble()), boxPaint);
    final ui.Picture picture = recorder.endRecording();
    final Uint8List byteData = await picture
        .toImage(width, height)
        .then((ui.Image image) =>
            image.toByteData(format: ui.ImageByteFormat.png))
        .then((ByteData? byteData) => byteData!.buffer.asUint8List());
    return Tile(width, height, byteData);
  }
}