How can download ZIP file Extract it through our Flutter app - flutter

Question

I want to download a zip file and it should be extracted to the assigned directory through the flutter app but my app cant download the file so please help me
here is the code which doesn't download the file
if anyone knows how to resolve it please help me
problem is: the app can not download files and can't unzip it to assigned directory
`import 'dart:io';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
class Tbutton extends StatefulWidget {
final String url;
final String fileName;
Tbutton({required this.url, required this.fileName});
#override
_TbuttonState createState() => _TbuttonState();
}
class _TbuttonState extends State<Tbutton> {
bool downloading = false;
var progressString = "";
#override
Widget build(BuildContext context) {
return Card(
color: Colors.green,
elevation: 6,
child: Container(
decoration: BoxDecoration(
color: Colors.green, borderRadius: BorderRadius.circular(10)),
height: 50,
width: double.infinity,
child: TextButton(
onPressed: downloading ? null : _startDownload,
child: Text(
downloading ? progressString : "Download",
style: TextStyle(
color: Colors.white, fontSize: 25, fontWeight: FontWeight.bold),
),
),
),
);
}
void _startDownload() async {
setState(() {
downloading = true;
progressString = "Downloading...";
});
var directory = await getExternalStorageDirectory();
var filePath = "${directory!.path}Android/emulated/${widget.fileName}";
// var androidDataDirectory = Directory("${directory.path}../../");
var uri = Uri.parse(widget.url);
var request = await HttpClient().getUrl(uri);
var response = await request.close();
var bytes = await consolidateHttpClientResponseBytes(response);
File file = File(filePath);
await file.writeAsBytes(bytes);
setState(() {
downloading = false;
progressString = "Download Complete";
});
}
}
`